Import LLVM, at r72732.

1 files changed, 12919 insertions, 0 deletions

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
new file mode 100644
index 0000000..e6f854f
--- /dev/null
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -0,0 +1,12919 @@
+//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// InstructionCombining - Combine instructions to form fewer, simple
+// instructions.  This pass does not modify the CFG.  This pass is where
+// algebraic simplification happens.
+//
+// This pass combines things like:
+//    %Y = add i32 %X, 1
+//    %Z = add i32 %Y, 1
+// into:
+//    %Z = add i32 %X, 2
+//
+// This is a simple worklist driven algorithm.
+//
+// This pass guarantees that the following canonicalizations are performed on
+// the program:
+//    1. If a binary operator has a constant operand, it is moved to the RHS
+//    2. Bitwise operators with constant operands are always grouped so that
+//       shifts are performed first, then or's, then and's, then xor's.
+//    3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
+//    4. All cmp instructions on boolean values are replaced with logical ops
+//    5. add X, X is represented as (X*2) => (X << 1)
+//    6. Multiplies with a power-of-two constant argument are transformed into
+//       shifts.
+//   ... etc.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "instcombine"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Pass.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/ConstantRange.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/InstVisitor.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/PatternMatch.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include <algorithm>
+#include <climits>
+#include <sstream>
+using namespace llvm;
+using namespace llvm::PatternMatch;
+
+STATISTIC(NumCombined , "Number of insts combined");
+STATISTIC(NumConstProp, "Number of constant folds");
+STATISTIC(NumDeadInst , "Number of dead inst eliminated");
+STATISTIC(NumDeadStore, "Number of dead stores eliminated");
+STATISTIC(NumSunkInst , "Number of instructions sunk");
+
+namespace {
+  class VISIBILITY_HIDDEN InstCombiner
+    : public FunctionPass,
+      public InstVisitor<InstCombiner, Instruction*> {
+    // Worklist of all of the instructions that need to be simplified.
+    SmallVector<Instruction*, 256> Worklist;
+    DenseMap<Instruction*, unsigned> WorklistMap;
+    TargetData *TD;
+    bool MustPreserveLCSSA;
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    InstCombiner() : FunctionPass(&ID) {}
+
+    /// AddToWorkList - Add the specified instruction to the worklist if it
+    /// isn't already in it.
+    void AddToWorkList(Instruction *I) {
+      if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second)
+        Worklist.push_back(I);
+    }
+    
+    // RemoveFromWorkList - remove I from the worklist if it exists.
+    void RemoveFromWorkList(Instruction *I) {
+      DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
+      if (It == WorklistMap.end()) return; // Not in worklist.
+      
+      // Don't bother moving everything down, just null out the slot.
+      Worklist[It->second] = 0;
+      
+      WorklistMap.erase(It);
+    }
+    
+    Instruction *RemoveOneFromWorkList() {
+      Instruction *I = Worklist.back();
+      Worklist.pop_back();
+      WorklistMap.erase(I);
+      return I;
+    }
+
+    
+    /// AddUsersToWorkList - When an instruction is simplified, add all users of
+    /// the instruction to the work lists because they might get more simplified
+    /// now.
+    ///
+    void AddUsersToWorkList(Value &I) {
+      for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
+           UI != UE; ++UI)
+        AddToWorkList(cast<Instruction>(*UI));
+    }
+
+    /// AddUsesToWorkList - When an instruction is simplified, add operands to
+    /// the work lists because they might get more simplified now.
+    ///
+    void AddUsesToWorkList(Instruction &I) {
+      for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
+        if (Instruction *Op = dyn_cast<Instruction>(*i))
+          AddToWorkList(Op);
+    }
+    
+    /// AddSoonDeadInstToWorklist - The specified instruction is about to become
+    /// dead.  Add all of its operands to the worklist, turning them into
+    /// undef's to reduce the number of uses of those instructions.
+    ///
+    /// Return the specified operand before it is turned into an undef.
+    ///
+    Value *AddSoonDeadInstToWorklist(Instruction &I, unsigned op) {
+      Value *R = I.getOperand(op);
+      
+      for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
+        if (Instruction *Op = dyn_cast<Instruction>(*i)) {
+          AddToWorkList(Op);
+          // Set the operand to undef to drop the use.
+          *i = UndefValue::get(Op->getType());
+        }
+      
+      return R;
+    }
+
+  public:
+    virtual bool runOnFunction(Function &F);
+    
+    bool DoOneIteration(Function &F, unsigned ItNum);
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.addRequired<TargetData>();
+      AU.addPreservedID(LCSSAID);
+      AU.setPreservesCFG();
+    }
+
+    TargetData &getTargetData() const { return *TD; }
+
+    // Visitation implementation - Implement instruction combining for different
+    // instruction types.  The semantics are as follows:
+    // Return Value:
+    //    null        - No change was made
+    //     I          - Change was made, I is still valid, I may be dead though
+    //   otherwise    - Change was made, replace I with returned instruction
+    //
+    Instruction *visitAdd(BinaryOperator &I);
+    Instruction *visitSub(BinaryOperator &I);
+    Instruction *visitMul(BinaryOperator &I);
+    Instruction *visitURem(BinaryOperator &I);
+    Instruction *visitSRem(BinaryOperator &I);
+    Instruction *visitFRem(BinaryOperator &I);
+    bool SimplifyDivRemOfSelect(BinaryOperator &I);
+    Instruction *commonRemTransforms(BinaryOperator &I);
+    Instruction *commonIRemTransforms(BinaryOperator &I);
+    Instruction *commonDivTransforms(BinaryOperator &I);
+    Instruction *commonIDivTransforms(BinaryOperator &I);
+    Instruction *visitUDiv(BinaryOperator &I);
+    Instruction *visitSDiv(BinaryOperator &I);
+    Instruction *visitFDiv(BinaryOperator &I);
+    Instruction *FoldAndOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
+    Instruction *visitAnd(BinaryOperator &I);
+    Instruction *FoldOrOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
+    Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
+                                     Value *A, Value *B, Value *C);
+    Instruction *visitOr (BinaryOperator &I);
+    Instruction *visitXor(BinaryOperator &I);
+    Instruction *visitShl(BinaryOperator &I);
+    Instruction *visitAShr(BinaryOperator &I);
+    Instruction *visitLShr(BinaryOperator &I);
+    Instruction *commonShiftTransforms(BinaryOperator &I);
+    Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
+                                      Constant *RHSC);
+    Instruction *visitFCmpInst(FCmpInst &I);
+    Instruction *visitICmpInst(ICmpInst &I);
+    Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
+    Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
+                                                Instruction *LHS,
+                                                ConstantInt *RHS);
+    Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
+                                ConstantInt *DivRHS);
+
+    Instruction *FoldGEPICmp(User *GEPLHS, Value *RHS,
+                             ICmpInst::Predicate Cond, Instruction &I);
+    Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
+                                     BinaryOperator &I);
+    Instruction *commonCastTransforms(CastInst &CI);
+    Instruction *commonIntCastTransforms(CastInst &CI);
+    Instruction *commonPointerCastTransforms(CastInst &CI);
+    Instruction *visitTrunc(TruncInst &CI);
+    Instruction *visitZExt(ZExtInst &CI);
+    Instruction *visitSExt(SExtInst &CI);
+    Instruction *visitFPTrunc(FPTruncInst &CI);
+    Instruction *visitFPExt(CastInst &CI);
+    Instruction *visitFPToUI(FPToUIInst &FI);
+    Instruction *visitFPToSI(FPToSIInst &FI);
+    Instruction *visitUIToFP(CastInst &CI);
+    Instruction *visitSIToFP(CastInst &CI);
+    Instruction *visitPtrToInt(PtrToIntInst &CI);
+    Instruction *visitIntToPtr(IntToPtrInst &CI);
+    Instruction *visitBitCast(BitCastInst &CI);
+    Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
+                                Instruction *FI);
+    Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*);
+    Instruction *visitSelectInst(SelectInst &SI);
+    Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
+    Instruction *visitCallInst(CallInst &CI);
+    Instruction *visitInvokeInst(InvokeInst &II);
+    Instruction *visitPHINode(PHINode &PN);
+    Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
+    Instruction *visitAllocationInst(AllocationInst &AI);
+    Instruction *visitFreeInst(FreeInst &FI);
+    Instruction *visitLoadInst(LoadInst &LI);
+    Instruction *visitStoreInst(StoreInst &SI);
+    Instruction *visitBranchInst(BranchInst &BI);
+    Instruction *visitSwitchInst(SwitchInst &SI);
+    Instruction *visitInsertElementInst(InsertElementInst &IE);
+    Instruction *visitExtractElementInst(ExtractElementInst &EI);
+    Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
+    Instruction *visitExtractValueInst(ExtractValueInst &EV);
+
+    // visitInstruction - Specify what to return for unhandled instructions...
+    Instruction *visitInstruction(Instruction &I) { return 0; }
+
+  private:
+    Instruction *visitCallSite(CallSite CS);
+    bool transformConstExprCastCall(CallSite CS);
+    Instruction *transformCallThroughTrampoline(CallSite CS);
+    Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
+                                   bool DoXform = true);
+    bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
+    DbgDeclareInst *hasOneUsePlusDeclare(Value *V);
+
+
+  public:
+    // InsertNewInstBefore - insert an instruction New before instruction Old
+    // in the program.  Add the new instruction to the worklist.
+    //
+    Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
+      assert(New && New->getParent() == 0 &&
+             "New instruction already inserted into a basic block!");
+      BasicBlock *BB = Old.getParent();
+      BB->getInstList().insert(&Old, New);  // Insert inst
+      AddToWorkList(New);
+      return New;
+    }
+
+    /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
+    /// This also adds the cast to the worklist.  Finally, this returns the
+    /// cast.
+    Value *InsertCastBefore(Instruction::CastOps opc, Value *V, const Type *Ty,
+                            Instruction &Pos) {
+      if (V->getType() == Ty) return V;
+
+      if (Constant *CV = dyn_cast<Constant>(V))
+        return ConstantExpr::getCast(opc, CV, Ty);
+      
+      Instruction *C = CastInst::Create(opc, V, Ty, V->getName(), &Pos);
+      AddToWorkList(C);
+      return C;
+    }
+        
+    Value *InsertBitCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
+      return InsertCastBefore(Instruction::BitCast, V, Ty, Pos);
+    }
+
+
+    // ReplaceInstUsesWith - This method is to be used when an instruction is
+    // found to be dead, replacable with another preexisting expression.  Here
+    // we add all uses of I to the worklist, replace all uses of I with the new
+    // value, then return I, so that the inst combiner will know that I was
+    // modified.
+    //
+    Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
+      AddUsersToWorkList(I);         // Add all modified instrs to worklist
+      if (&I != V) {
+        I.replaceAllUsesWith(V);
+        return &I;
+      } else {
+        // If we are replacing the instruction with itself, this must be in a
+        // segment of unreachable code, so just clobber the instruction.
+        I.replaceAllUsesWith(UndefValue::get(I.getType()));
+        return &I;
+      }
+    }
+
+    // EraseInstFromFunction - When dealing with an instruction that has side
+    // effects or produces a void value, we can't rely on DCE to delete the
+    // instruction.  Instead, visit methods should return the value returned by
+    // this function.
+    Instruction *EraseInstFromFunction(Instruction &I) {
+      assert(I.use_empty() && "Cannot erase instruction that is used!");
+      AddUsesToWorkList(I);
+      RemoveFromWorkList(&I);
+      I.eraseFromParent();
+      return 0;  // Don't do anything with FI
+    }
+        
+    void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
+                           APInt &KnownOne, unsigned Depth = 0) const {
+      return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth);
+    }
+    
+    bool MaskedValueIsZero(Value *V, const APInt &Mask, 
+                           unsigned Depth = 0) const {
+      return llvm::MaskedValueIsZero(V, Mask, TD, Depth);
+    }
+    unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const {
+      return llvm::ComputeNumSignBits(Op, TD, Depth);
+    }
+
+  private:
+
+    /// SimplifyCommutative - This performs a few simplifications for 
+    /// commutative operators.
+    bool SimplifyCommutative(BinaryOperator &I);
+
+    /// SimplifyCompare - This reorders the operands of a CmpInst to get them in
+    /// most-complex to least-complex order.
+    bool SimplifyCompare(CmpInst &I);
+
+    /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
+    /// based on the demanded bits.
+    Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask, 
+                                   APInt& KnownZero, APInt& KnownOne,
+                                   unsigned Depth);
+    bool SimplifyDemandedBits(Use &U, APInt DemandedMask, 
+                              APInt& KnownZero, APInt& KnownOne,
+                              unsigned Depth=0);
+        
+    /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
+    /// SimplifyDemandedBits knows about.  See if the instruction has any
+    /// properties that allow us to simplify its operands.
+    bool SimplifyDemandedInstructionBits(Instruction &Inst);
+        
+    Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
+                                      APInt& UndefElts, unsigned Depth = 0);
+      
+    // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
+    // PHI node as operand #0, see if we can fold the instruction into the PHI
+    // (which is only possible if all operands to the PHI are constants).
+    Instruction *FoldOpIntoPhi(Instruction &I);
+
+    // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
+    // operator and they all are only used by the PHI, PHI together their
+    // inputs, and do the operation once, to the result of the PHI.
+    Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
+    Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
+    Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
+
+    
+    Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
+                          ConstantInt *AndRHS, BinaryOperator &TheAnd);
+    
+    Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
+                              bool isSub, Instruction &I);
+    Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
+                                 bool isSigned, bool Inside, Instruction &IB);
+    Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocationInst &AI);
+    Instruction *MatchBSwap(BinaryOperator &I);
+    bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
+    Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
+    Instruction *SimplifyMemSet(MemSetInst *MI);
+
+
+    Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
+
+    bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
+                                    unsigned CastOpc, int &NumCastsRemoved);
+    unsigned GetOrEnforceKnownAlignment(Value *V,
+                                        unsigned PrefAlign = 0);
+
+  };
+}
+
+char InstCombiner::ID = 0;
+static RegisterPass<InstCombiner>
+X("instcombine", "Combine redundant instructions");
+
+// getComplexity:  Assign a complexity or rank value to LLVM Values...
+//   0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
+static unsigned getComplexity(Value *V) {
+  if (isa<Instruction>(V)) {
+    if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
+      return 3;
+    return 4;
+  }
+  if (isa<Argument>(V)) return 3;
+  return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
+}
+
+// isOnlyUse - Return true if this instruction will be deleted if we stop using
+// it.
+static bool isOnlyUse(Value *V) {
+  return V->hasOneUse() || isa<Constant>(V);
+}
+
+// getPromotedType - Return the specified type promoted as it would be to pass
+// though a va_arg area...
+static const Type *getPromotedType(const Type *Ty) {
+  if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
+    if (ITy->getBitWidth() < 32)
+      return Type::Int32Ty;
+  }
+  return Ty;
+}
+
+/// getBitCastOperand - If the specified operand is a CastInst, a constant
+/// expression bitcast, or a GetElementPtrInst with all zero indices, return the
+/// operand value, otherwise return null.
+static Value *getBitCastOperand(Value *V) {
+  if (BitCastInst *I = dyn_cast<BitCastInst>(V))
+    // BitCastInst?
+    return I->getOperand(0);
+  else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) {
+    // GetElementPtrInst?
+    if (GEP->hasAllZeroIndices())
+      return GEP->getOperand(0);
+  } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
+    if (CE->getOpcode() == Instruction::BitCast)
+      // BitCast ConstantExp?
+      return CE->getOperand(0);
+    else if (CE->getOpcode() == Instruction::GetElementPtr) {
+      // GetElementPtr ConstantExp?
+      for (User::op_iterator I = CE->op_begin() + 1, E = CE->op_end();
+           I != E; ++I) {
+        ConstantInt *CI = dyn_cast<ConstantInt>(I);
+        if (!CI || !CI->isZero())
+          // Any non-zero indices? Not cast-like.
+          return 0;
+      }
+      // All-zero indices? This is just like casting.
+      return CE->getOperand(0);
+    }
+  }
+  return 0;
+}
+
+/// This function is a wrapper around CastInst::isEliminableCastPair. It
+/// simply extracts arguments and returns what that function returns.
+static Instruction::CastOps 
+isEliminableCastPair(
+  const CastInst *CI, ///< The first cast instruction
+  unsigned opcode,       ///< The opcode of the second cast instruction
+  const Type *DstTy,     ///< The target type for the second cast instruction
+  TargetData *TD         ///< The target data for pointer size
+) {
+  
+  const Type *SrcTy = CI->getOperand(0)->getType();   // A from above
+  const Type *MidTy = CI->getType();                  // B from above
+
+  // Get the opcodes of the two Cast instructions
+  Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
+  Instruction::CastOps secondOp = Instruction::CastOps(opcode);
+
+  unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
+                                                DstTy, TD->getIntPtrType());
+  
+  // We don't want to form an inttoptr or ptrtoint that converts to an integer
+  // type that differs from the pointer size.
+  if ((Res == Instruction::IntToPtr && SrcTy != TD->getIntPtrType()) ||
+      (Res == Instruction::PtrToInt && DstTy != TD->getIntPtrType()))
+    Res = 0;
+  
+  return Instruction::CastOps(Res);
+}
+
+/// ValueRequiresCast - Return true if the cast from "V to Ty" actually results
+/// in any code being generated.  It does not require codegen if V is simple
+/// enough or if the cast can be folded into other casts.
+static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V, 
+                              const Type *Ty, TargetData *TD) {
+  if (V->getType() == Ty || isa<Constant>(V)) return false;
+  
+  // If this is another cast that can be eliminated, it isn't codegen either.
+  if (const CastInst *CI = dyn_cast<CastInst>(V))
+    if (isEliminableCastPair(CI, opcode, Ty, TD)) 
+      return false;
+  return true;
+}
+
+// SimplifyCommutative - This performs a few simplifications for commutative
+// operators:
+//
+//  1. Order operands such that they are listed from right (least complex) to
+//     left (most complex).  This puts constants before unary operators before
+//     binary operators.
+//
+//  2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
+//  3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
+//
+bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
+  bool Changed = false;
+  if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
+    Changed = !I.swapOperands();
+
+  if (!I.isAssociative()) return Changed;
+  Instruction::BinaryOps Opcode = I.getOpcode();
+  if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
+    if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
+      if (isa<Constant>(I.getOperand(1))) {
+        Constant *Folded = ConstantExpr::get(I.getOpcode(),
+                                             cast<Constant>(I.getOperand(1)),
+                                             cast<Constant>(Op->getOperand(1)));
+        I.setOperand(0, Op->getOperand(0));
+        I.setOperand(1, Folded);
+        return true;
+      } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
+        if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
+            isOnlyUse(Op) && isOnlyUse(Op1)) {
+          Constant *C1 = cast<Constant>(Op->getOperand(1));
+          Constant *C2 = cast<Constant>(Op1->getOperand(1));
+
+          // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
+          Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
+          Instruction *New = BinaryOperator::Create(Opcode, Op->getOperand(0),
+                                                    Op1->getOperand(0),
+                                                    Op1->getName(), &I);
+          AddToWorkList(New);
+          I.setOperand(0, New);
+          I.setOperand(1, Folded);
+          return true;
+        }
+    }
+  return Changed;
+}
+
+/// SimplifyCompare - For a CmpInst this function just orders the operands
+/// so that theyare listed from right (least complex) to left (most complex).
+/// This puts constants before unary operators before binary operators.
+bool InstCombiner::SimplifyCompare(CmpInst &I) {
+  if (getComplexity(I.getOperand(0)) >= getComplexity(I.getOperand(1)))
+    return false;
+  I.swapOperands();
+  // Compare instructions are not associative so there's nothing else we can do.
+  return true;
+}
+
+// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
+// if the LHS is a constant zero (which is the 'negate' form).
+//
+static inline Value *dyn_castNegVal(Value *V) {
+  if (BinaryOperator::isNeg(V))
+    return BinaryOperator::getNegArgument(V);
+
+  // Constants can be considered to be negated values if they can be folded.
+  if (ConstantInt *C = dyn_cast<ConstantInt>(V))
+    return ConstantExpr::getNeg(C);
+
+  if (ConstantVector *C = dyn_cast<ConstantVector>(V))
+    if (C->getType()->getElementType()->isInteger())
+      return ConstantExpr::getNeg(C);
+
+  return 0;
+}
+
+static inline Value *dyn_castNotVal(Value *V) {
+  if (BinaryOperator::isNot(V))
+    return BinaryOperator::getNotArgument(V);
+
+  // Constants can be considered to be not'ed values...
+  if (ConstantInt *C = dyn_cast<ConstantInt>(V))
+    return ConstantInt::get(~C->getValue());
+  return 0;
+}
+
+// dyn_castFoldableMul - If this value is a multiply that can be folded into
+// other computations (because it has a constant operand), return the
+// non-constant operand of the multiply, and set CST to point to the multiplier.
+// Otherwise, return null.
+//
+static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
+  if (V->hasOneUse() && V->getType()->isInteger())
+    if (Instruction *I = dyn_cast<Instruction>(V)) {
+      if (I->getOpcode() == Instruction::Mul)
+        if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
+          return I->getOperand(0);
+      if (I->getOpcode() == Instruction::Shl)
+        if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
+          // The multiplier is really 1 << CST.
+          uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
+          uint32_t CSTVal = CST->getLimitedValue(BitWidth);
+          CST = ConstantInt::get(APInt(BitWidth, 1).shl(CSTVal));
+          return I->getOperand(0);
+        }
+    }
+  return 0;
+}
+
+/// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
+/// expression, return it.
+static User *dyn_castGetElementPtr(Value *V) {
+  if (isa<GetElementPtrInst>(V)) return cast<User>(V);
+  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
+    if (CE->getOpcode() == Instruction::GetElementPtr)
+      return cast<User>(V);
+  return false;
+}
+
+/// getOpcode - If this is an Instruction or a ConstantExpr, return the
+/// opcode value. Otherwise return UserOp1.
+static unsigned getOpcode(const Value *V) {
+  if (const Instruction *I = dyn_cast<Instruction>(V))
+    return I->getOpcode();
+  if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
+    return CE->getOpcode();
+  // Use UserOp1 to mean there's no opcode.
+  return Instruction::UserOp1;
+}
+
+/// AddOne - Add one to a ConstantInt
+static ConstantInt *AddOne(ConstantInt *C) {
+  APInt Val(C->getValue());
+  return ConstantInt::get(++Val);
+}
+/// SubOne - Subtract one from a ConstantInt
+static ConstantInt *SubOne(ConstantInt *C) {
+  APInt Val(C->getValue());
+  return ConstantInt::get(--Val);
+}
+/// Add - Add two ConstantInts together
+static ConstantInt *Add(ConstantInt *C1, ConstantInt *C2) {
+  return ConstantInt::get(C1->getValue() + C2->getValue());
+}
+/// And - Bitwise AND two ConstantInts together
+static ConstantInt *And(ConstantInt *C1, ConstantInt *C2) {
+  return ConstantInt::get(C1->getValue() & C2->getValue());
+}
+/// Subtract - Subtract one ConstantInt from another
+static ConstantInt *Subtract(ConstantInt *C1, ConstantInt *C2) {
+  return ConstantInt::get(C1->getValue() - C2->getValue());
+}
+/// Multiply - Multiply two ConstantInts together
+static ConstantInt *Multiply(ConstantInt *C1, ConstantInt *C2) {
+  return ConstantInt::get(C1->getValue() * C2->getValue());
+}
+/// MultiplyOverflows - True if the multiply can not be expressed in an int
+/// this size.
+static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
+  uint32_t W = C1->getBitWidth();
+  APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
+  if (sign) {
+    LHSExt.sext(W * 2);
+    RHSExt.sext(W * 2);
+  } else {
+    LHSExt.zext(W * 2);
+    RHSExt.zext(W * 2);
+  }
+
+  APInt MulExt = LHSExt * RHSExt;
+
+  if (sign) {
+    APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
+    APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
+    return MulExt.slt(Min) || MulExt.sgt(Max);
+  } else 
+    return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
+}
+
+
+/// ShrinkDemandedConstant - Check to see if the specified operand of the 
+/// specified instruction is a constant integer.  If so, check to see if there
+/// are any bits set in the constant that are not demanded.  If so, shrink the
+/// constant and return true.
+static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo, 
+                                   APInt Demanded) {
+  assert(I && "No instruction?");
+  assert(OpNo < I->getNumOperands() && "Operand index too large");
+
+  // If the operand is not a constant integer, nothing to do.
+  ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
+  if (!OpC) return false;
+
+  // If there are no bits set that aren't demanded, nothing to do.
+  Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
+  if ((~Demanded & OpC->getValue()) == 0)
+    return false;
+
+  // This instruction is producing bits that are not demanded. Shrink the RHS.
+  Demanded &= OpC->getValue();
+  I->setOperand(OpNo, ConstantInt::get(Demanded));
+  return true;
+}
+
+// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a 
+// set of known zero and one bits, compute the maximum and minimum values that
+// could have the specified known zero and known one bits, returning them in
+// min/max.
+static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero,
+                                                   const APInt& KnownOne,
+                                                   APInt& Min, APInt& Max) {
+  assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
+         KnownZero.getBitWidth() == Min.getBitWidth() &&
+         KnownZero.getBitWidth() == Max.getBitWidth() &&
+         "KnownZero, KnownOne and Min, Max must have equal bitwidth.");
+  APInt UnknownBits = ~(KnownZero|KnownOne);
+
+  // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
+  // bit if it is unknown.
+  Min = KnownOne;
+  Max = KnownOne|UnknownBits;
+  
+  if (UnknownBits.isNegative()) { // Sign bit is unknown
+    Min.set(Min.getBitWidth()-1);
+    Max.clear(Max.getBitWidth()-1);
+  }
+}
+
+// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
+// a set of known zero and one bits, compute the maximum and minimum values that
+// could have the specified known zero and known one bits, returning them in
+// min/max.
+static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero,
+                                                     const APInt &KnownOne,
+                                                     APInt &Min, APInt &Max) {
+  assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
+         KnownZero.getBitWidth() == Min.getBitWidth() &&
+         KnownZero.getBitWidth() == Max.getBitWidth() &&
+         "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
+  APInt UnknownBits = ~(KnownZero|KnownOne);
+  
+  // The minimum value is when the unknown bits are all zeros.
+  Min = KnownOne;
+  // The maximum value is when the unknown bits are all ones.
+  Max = KnownOne|UnknownBits;
+}
+
+/// SimplifyDemandedInstructionBits - Inst is an integer instruction that
+/// SimplifyDemandedBits knows about.  See if the instruction has any
+/// properties that allow us to simplify its operands.
+bool InstCombiner::SimplifyDemandedInstructionBits(Instruction &Inst) {
+  unsigned BitWidth = cast<IntegerType>(Inst.getType())->getBitWidth();
+  APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+  APInt DemandedMask(APInt::getAllOnesValue(BitWidth));
+  
+  Value *V = SimplifyDemandedUseBits(&Inst, DemandedMask, 
+                                     KnownZero, KnownOne, 0);
+  if (V == 0) return false;
+  if (V == &Inst) return true;
+  ReplaceInstUsesWith(Inst, V);
+  return true;
+}
+
+/// SimplifyDemandedBits - This form of SimplifyDemandedBits simplifies the
+/// specified instruction operand if possible, updating it in place.  It returns
+/// true if it made any change and false otherwise.
+bool InstCombiner::SimplifyDemandedBits(Use &U, APInt DemandedMask, 
+                                        APInt &KnownZero, APInt &KnownOne,
+                                        unsigned Depth) {
+  Value *NewVal = SimplifyDemandedUseBits(U.get(), DemandedMask,
+                                          KnownZero, KnownOne, Depth);
+  if (NewVal == 0) return false;
+  U.set(NewVal);
+  return true;
+}
+
+
+/// SimplifyDemandedUseBits - This function attempts to replace V with a simpler
+/// value based on the demanded bits.  When this function is called, it is known
+/// that only the bits set in DemandedMask of the result of V are ever used
+/// downstream. Consequently, depending on the mask and V, it may be possible
+/// to replace V with a constant or one of its operands. In such cases, this
+/// function does the replacement and returns true. In all other cases, it
+/// returns false after analyzing the expression and setting KnownOne and known
+/// to be one in the expression.  KnownZero contains all the bits that are known
+/// to be zero in the expression. These are provided to potentially allow the
+/// caller (which might recursively be SimplifyDemandedBits itself) to simplify
+/// the expression. KnownOne and KnownZero always follow the invariant that 
+/// KnownOne & KnownZero == 0. That is, a bit can't be both 1 and 0. Note that
+/// the bits in KnownOne and KnownZero may only be accurate for those bits set
+/// in DemandedMask. Note also that the bitwidth of V, DemandedMask, KnownZero
+/// and KnownOne must all be the same.
+///
+/// This returns null if it did not change anything and it permits no
+/// simplification.  This returns V itself if it did some simplification of V's
+/// operands based on the information about what bits are demanded. This returns
+/// some other non-null value if it found out that V is equal to another value
+/// in the context where the specified bits are demanded, but not for all users.
+Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
+                                             APInt &KnownZero, APInt &KnownOne,
+                                             unsigned Depth) {
+  assert(V != 0 && "Null pointer of Value???");
+  assert(Depth <= 6 && "Limit Search Depth");
+  uint32_t BitWidth = DemandedMask.getBitWidth();
+  const Type *VTy = V->getType();
+  assert((TD || !isa<PointerType>(VTy)) &&
+         "SimplifyDemandedBits needs to know bit widths!");
+  assert((!TD || TD->getTypeSizeInBits(VTy) == BitWidth) &&
+         (!isa<IntegerType>(VTy) ||
+          VTy->getPrimitiveSizeInBits() == BitWidth) &&
+         KnownZero.getBitWidth() == BitWidth &&
+         KnownOne.getBitWidth() == BitWidth &&
+         "Value *V, DemandedMask, KnownZero and KnownOne \
+          must have same BitWidth");
+  if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+    // We know all of the bits for a constant!
+    KnownOne = CI->getValue() & DemandedMask;
+    KnownZero = ~KnownOne & DemandedMask;
+    return 0;
+  }
+  if (isa<ConstantPointerNull>(V)) {
+    // We know all of the bits for a constant!
+    KnownOne.clear();
+    KnownZero = DemandedMask;
+    return 0;
+  }
+
+  KnownZero.clear();
+  KnownOne.clear();
+  if (DemandedMask == 0) {   // Not demanding any bits from V.
+    if (isa<UndefValue>(V))
+      return 0;
+    return UndefValue::get(VTy);
+  }
+  
+  if (Depth == 6)        // Limit search depth.
+    return 0;
+  
+  APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
+  APInt &RHSKnownZero = KnownZero, &RHSKnownOne = KnownOne;
+
+  Instruction *I = dyn_cast<Instruction>(V);
+  if (!I) {
+    ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
+    return 0;        // Only analyze instructions.
+  }
+
+  // If there are multiple uses of this value and we aren't at the root, then
+  // we can't do any simplifications of the operands, because DemandedMask
+  // only reflects the bits demanded by *one* of the users.
+  if (Depth != 0 && !I->hasOneUse()) {
+    // Despite the fact that we can't simplify this instruction in all User's
+    // context, we can at least compute the knownzero/knownone bits, and we can
+    // do simplifications that apply to *just* the one user if we know that
+    // this instruction has a simpler value in that context.
+    if (I->getOpcode() == Instruction::And) {
+      // If either the LHS or the RHS are Zero, the result is zero.
+      ComputeMaskedBits(I->getOperand(1), DemandedMask,
+                        RHSKnownZero, RHSKnownOne, Depth+1);
+      ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownZero,
+                        LHSKnownZero, LHSKnownOne, Depth+1);
+      
+      // If all of the demanded bits are known 1 on one side, return the other.
+      // These bits cannot contribute to the result of the 'and' in this
+      // context.
+      if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) == 
+          (DemandedMask & ~LHSKnownZero))
+        return I->getOperand(0);
+      if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) == 
+          (DemandedMask & ~RHSKnownZero))
+        return I->getOperand(1);
+      
+      // If all of the demanded bits in the inputs are known zeros, return zero.
+      if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
+        return Constant::getNullValue(VTy);
+      
+    } else if (I->getOpcode() == Instruction::Or) {
+      // We can simplify (X|Y) -> X or Y in the user's context if we know that
+      // only bits from X or Y are demanded.
+      
+      // If either the LHS or the RHS are One, the result is One.
+      ComputeMaskedBits(I->getOperand(1), DemandedMask, 
+                        RHSKnownZero, RHSKnownOne, Depth+1);
+      ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownOne, 
+                        LHSKnownZero, LHSKnownOne, Depth+1);
+      
+      // If all of the demanded bits are known zero on one side, return the
+      // other.  These bits cannot contribute to the result of the 'or' in this
+      // context.
+      if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) == 
+          (DemandedMask & ~LHSKnownOne))
+        return I->getOperand(0);
+      if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) == 
+          (DemandedMask & ~RHSKnownOne))
+        return I->getOperand(1);
+      
+      // If all of the potentially set bits on one side are known to be set on
+      // the other side, just use the 'other' side.
+      if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) == 
+          (DemandedMask & (~RHSKnownZero)))
+        return I->getOperand(0);
+      if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) == 
+          (DemandedMask & (~LHSKnownZero)))
+        return I->getOperand(1);
+    }
+    
+    // Compute the KnownZero/KnownOne bits to simplify things downstream.
+    ComputeMaskedBits(I, DemandedMask, KnownZero, KnownOne, Depth);
+    return 0;
+  }
+  
+  // If this is the root being simplified, allow it to have multiple uses,
+  // just set the DemandedMask to all bits so that we can try to simplify the
+  // operands.  This allows visitTruncInst (for example) to simplify the
+  // operand of a trunc without duplicating all the logic below.
+  if (Depth == 0 && !V->hasOneUse())
+    DemandedMask = APInt::getAllOnesValue(BitWidth);
+  
+  switch (I->getOpcode()) {
+  default:
+    ComputeMaskedBits(I, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
+    break;
+  case Instruction::And:
+    // If either the LHS or the RHS are Zero, the result is zero.
+    if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
+                             RHSKnownZero, RHSKnownOne, Depth+1) ||
+        SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownZero,
+                             LHSKnownZero, LHSKnownOne, Depth+1))
+      return I;
+    assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?"); 
+    assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?"); 
+
+    // If all of the demanded bits are known 1 on one side, return the other.
+    // These bits cannot contribute to the result of the 'and'.
+    if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) == 
+        (DemandedMask & ~LHSKnownZero))
+      return I->getOperand(0);
+    if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) == 
+        (DemandedMask & ~RHSKnownZero))
+      return I->getOperand(1);
+    
+    // If all of the demanded bits in the inputs are known zeros, return zero.
+    if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
+      return Constant::getNullValue(VTy);
+      
+    // If the RHS is a constant, see if we can simplify it.
+    if (ShrinkDemandedConstant(I, 1, DemandedMask & ~LHSKnownZero))
+      return I;
+      
+    // Output known-1 bits are only known if set in both the LHS & RHS.
+    RHSKnownOne &= LHSKnownOne;
+    // Output known-0 are known to be clear if zero in either the LHS | RHS.
+    RHSKnownZero |= LHSKnownZero;
+    break;
+  case Instruction::Or:
+    // If either the LHS or the RHS are One, the result is One.
+    if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask, 
+                             RHSKnownZero, RHSKnownOne, Depth+1) ||
+        SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownOne, 
+                             LHSKnownZero, LHSKnownOne, Depth+1))
+      return I;
+    assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?"); 
+    assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?"); 
+    
+    // If all of the demanded bits are known zero on one side, return the other.
+    // These bits cannot contribute to the result of the 'or'.
+    if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) == 
+        (DemandedMask & ~LHSKnownOne))
+      return I->getOperand(0);
+    if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) == 
+        (DemandedMask & ~RHSKnownOne))
+      return I->getOperand(1);
+
+    // If all of the potentially set bits on one side are known to be set on
+    // the other side, just use the 'other' side.
+    if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) == 
+        (DemandedMask & (~RHSKnownZero)))
+      return I->getOperand(0);
+    if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) == 
+        (DemandedMask & (~LHSKnownZero)))
+      return I->getOperand(1);
+        
+    // If the RHS is a constant, see if we can simplify it.
+    if (ShrinkDemandedConstant(I, 1, DemandedMask))
+      return I;
+          
+    // Output known-0 bits are only known if clear in both the LHS & RHS.
+    RHSKnownZero &= LHSKnownZero;
+    // Output known-1 are known to be set if set in either the LHS | RHS.
+    RHSKnownOne |= LHSKnownOne;
+    break;
+  case Instruction::Xor: {
+    if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
+                             RHSKnownZero, RHSKnownOne, Depth+1) ||
+        SimplifyDemandedBits(I->getOperandUse(0), DemandedMask, 
+                             LHSKnownZero, LHSKnownOne, Depth+1))
+      return I;
+    assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?"); 
+    assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?"); 
+    
+    // If all of the demanded bits are known zero on one side, return the other.
+    // These bits cannot contribute to the result of the 'xor'.
+    if ((DemandedMask & RHSKnownZero) == DemandedMask)
+      return I->getOperand(0);
+    if ((DemandedMask & LHSKnownZero) == DemandedMask)
+      return I->getOperand(1);
+    
+    // Output known-0 bits are known if clear or set in both the LHS & RHS.
+    APInt KnownZeroOut = (RHSKnownZero & LHSKnownZero) | 
+                         (RHSKnownOne & LHSKnownOne);
+    // Output known-1 are known to be set if set in only one of the LHS, RHS.
+    APInt KnownOneOut = (RHSKnownZero & LHSKnownOne) | 
+                        (RHSKnownOne & LHSKnownZero);
+    
+    // If all of the demanded bits are known to be zero on one side or the
+    // other, turn this into an *inclusive* or.
+    //    e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
+    if ((DemandedMask & ~RHSKnownZero & ~LHSKnownZero) == 0) {
+      Instruction *Or =
+        BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
+                                 I->getName());
+      return InsertNewInstBefore(Or, *I);
+    }
+    
+    // If all of the demanded bits on one side are known, and all of the set
+    // bits on that side are also known to be set on the other side, turn this
+    // into an AND, as we know the bits will be cleared.
+    //    e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
+    if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) { 
+      // all known
+      if ((RHSKnownOne & LHSKnownOne) == RHSKnownOne) {
+        Constant *AndC = ConstantInt::get(~RHSKnownOne & DemandedMask);
+        Instruction *And = 
+          BinaryOperator::CreateAnd(I->getOperand(0), AndC, "tmp");
+        return InsertNewInstBefore(And, *I);
+      }
+    }
+    
+    // If the RHS is a constant, see if we can simplify it.
+    // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
+    if (ShrinkDemandedConstant(I, 1, DemandedMask))
+      return I;
+    
+    RHSKnownZero = KnownZeroOut;
+    RHSKnownOne  = KnownOneOut;
+    break;
+  }
+  case Instruction::Select:
+    if (SimplifyDemandedBits(I->getOperandUse(2), DemandedMask,
+                             RHSKnownZero, RHSKnownOne, Depth+1) ||
+        SimplifyDemandedBits(I->getOperandUse(1), DemandedMask, 
+                             LHSKnownZero, LHSKnownOne, Depth+1))
+      return I;
+    assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?"); 
+    assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?"); 
+    
+    // If the operands are constants, see if we can simplify them.
+    if (ShrinkDemandedConstant(I, 1, DemandedMask) ||
+        ShrinkDemandedConstant(I, 2, DemandedMask))
+      return I;
+    
+    // Only known if known in both the LHS and RHS.
+    RHSKnownOne &= LHSKnownOne;
+    RHSKnownZero &= LHSKnownZero;
+    break;
+  case Instruction::Trunc: {
+    unsigned truncBf = I->getOperand(0)->getType()->getPrimitiveSizeInBits();
+    DemandedMask.zext(truncBf);
+    RHSKnownZero.zext(truncBf);
+    RHSKnownOne.zext(truncBf);
+    if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask, 
+                             RHSKnownZero, RHSKnownOne, Depth+1))
+      return I;
+    DemandedMask.trunc(BitWidth);
+    RHSKnownZero.trunc(BitWidth);
+    RHSKnownOne.trunc(BitWidth);
+    assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?"); 
+    break;
+  }
+  case Instruction::BitCast:
+    if (!I->getOperand(0)->getType()->isInteger())
+      return false;  // vector->int or fp->int?
+    if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
+                             RHSKnownZero, RHSKnownOne, Depth+1))
+      return I;
+    assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?"); 
+    break;
+  case Instruction::ZExt: {
+    // Compute the bits in the result that are not present in the input.
+    unsigned SrcBitWidth =I->getOperand(0)->getType()->getPrimitiveSizeInBits();
+    
+    DemandedMask.trunc(SrcBitWidth);
+    RHSKnownZero.trunc(SrcBitWidth);
+    RHSKnownOne.trunc(SrcBitWidth);
+    if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
+                             RHSKnownZero, RHSKnownOne, Depth+1))
+      return I;
+    DemandedMask.zext(BitWidth);
+    RHSKnownZero.zext(BitWidth);
+    RHSKnownOne.zext(BitWidth);
+    assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?"); 
+    // The top bits are known to be zero.
+    RHSKnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
+    break;
+  }
+  case Instruction::SExt: {
+    // Compute the bits in the result that are not present in the input.
+    unsigned SrcBitWidth =I->getOperand(0)->getType()->getPrimitiveSizeInBits();
+    
+    APInt InputDemandedBits = DemandedMask & 
+                              APInt::getLowBitsSet(BitWidth, SrcBitWidth);
+
+    APInt NewBits(APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth));
+    // If any of the sign extended bits are demanded, we know that the sign
+    // bit is demanded.
+    if ((NewBits & DemandedMask) != 0)
+      InputDemandedBits.set(SrcBitWidth-1);
+      
+    InputDemandedBits.trunc(SrcBitWidth);
+    RHSKnownZero.trunc(SrcBitWidth);
+    RHSKnownOne.trunc(SrcBitWidth);
+    if (SimplifyDemandedBits(I->getOperandUse(0), InputDemandedBits,
+                             RHSKnownZero, RHSKnownOne, Depth+1))
+      return I;
+    InputDemandedBits.zext(BitWidth);
+    RHSKnownZero.zext(BitWidth);
+    RHSKnownOne.zext(BitWidth);
+    assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?"); 
+      
+    // If the sign bit of the input is known set or clear, then we know the
+    // top bits of the result.
+
+    // If the input sign bit is known zero, or if the NewBits are not demanded
+    // convert this into a zero extension.
+    if (RHSKnownZero[SrcBitWidth-1] || (NewBits & ~DemandedMask) == NewBits) {
+      // Convert to ZExt cast
+      CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName());
+      return InsertNewInstBefore(NewCast, *I);
+    } else if (RHSKnownOne[SrcBitWidth-1]) {    // Input sign bit known set
+      RHSKnownOne |= NewBits;
+    }
+    break;
+  }
+  case Instruction::Add: {
+    // Figure out what the input bits are.  If the top bits of the and result
+    // are not demanded, then the add doesn't demand them from its input
+    // either.
+    unsigned NLZ = DemandedMask.countLeadingZeros();
+      
+    // If there is a constant on the RHS, there are a variety of xformations
+    // we can do.
+    if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
+      // If null, this should be simplified elsewhere.  Some of the xforms here
+      // won't work if the RHS is zero.
+      if (RHS->isZero())
+        break;
+      
+      // If the top bit of the output is demanded, demand everything from the
+      // input.  Otherwise, we demand all the input bits except NLZ top bits.
+      APInt InDemandedBits(APInt::getLowBitsSet(BitWidth, BitWidth - NLZ));
+
+      // Find information about known zero/one bits in the input.
+      if (SimplifyDemandedBits(I->getOperandUse(0), InDemandedBits, 
+                               LHSKnownZero, LHSKnownOne, Depth+1))
+        return I;
+
+      // If the RHS of the add has bits set that can't affect the input, reduce
+      // the constant.
+      if (ShrinkDemandedConstant(I, 1, InDemandedBits))
+        return I;
+      
+      // Avoid excess work.
+      if (LHSKnownZero == 0 && LHSKnownOne == 0)
+        break;
+      
+      // Turn it into OR if input bits are zero.
+      if ((LHSKnownZero & RHS->getValue()) == RHS->getValue()) {
+        Instruction *Or =
+          BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
+                                   I->getName());
+        return InsertNewInstBefore(Or, *I);
+      }
+      
+      // We can say something about the output known-zero and known-one bits,
+      // depending on potential carries from the input constant and the
+      // unknowns.  For example if the LHS is known to have at most the 0x0F0F0
+      // bits set and the RHS constant is 0x01001, then we know we have a known
+      // one mask of 0x00001 and a known zero mask of 0xE0F0E.
+      
+      // To compute this, we first compute the potential carry bits.  These are
+      // the bits which may be modified.  I'm not aware of a better way to do
+      // this scan.
+      const APInt &RHSVal = RHS->getValue();
+      APInt CarryBits((~LHSKnownZero + RHSVal) ^ (~LHSKnownZero ^ RHSVal));
+      
+      // Now that we know which bits have carries, compute the known-1/0 sets.
+      
+      // Bits are known one if they are known zero in one operand and one in the
+      // other, and there is no input carry.
+      RHSKnownOne = ((LHSKnownZero & RHSVal) | 
+                     (LHSKnownOne & ~RHSVal)) & ~CarryBits;
+      
+      // Bits are known zero if they are known zero in both operands and there
+      // is no input carry.
+      RHSKnownZero = LHSKnownZero & ~RHSVal & ~CarryBits;
+    } else {
+      // If the high-bits of this ADD are not demanded, then it does not demand
+      // the high bits of its LHS or RHS.
+      if (DemandedMask[BitWidth-1] == 0) {
+        // Right fill the mask of bits for this ADD to demand the most
+        // significant bit and all those below it.
+        APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
+        if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
+                                 LHSKnownZero, LHSKnownOne, Depth+1) ||
+            SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
+                                 LHSKnownZero, LHSKnownOne, Depth+1))
+          return I;
+      }
+    }
+    break;
+  }
+  case Instruction::Sub:
+    // If the high-bits of this SUB are not demanded, then it does not demand
+    // the high bits of its LHS or RHS.
+    if (DemandedMask[BitWidth-1] == 0) {
+      // Right fill the mask of bits for this SUB to demand the most
+      // significant bit and all those below it.
+      uint32_t NLZ = DemandedMask.countLeadingZeros();
+      APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
+      if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
+                               LHSKnownZero, LHSKnownOne, Depth+1) ||
+          SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
+                               LHSKnownZero, LHSKnownOne, Depth+1))
+        return I;
+    }
+    // Otherwise just hand the sub off to ComputeMaskedBits to fill in
+    // the known zeros and ones.
+    ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
+    break;
+  case Instruction::Shl:
+    if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+      uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+      APInt DemandedMaskIn(DemandedMask.lshr(ShiftAmt));
+      if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn, 
+                               RHSKnownZero, RHSKnownOne, Depth+1))
+        return I;
+      assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+      RHSKnownZero <<= ShiftAmt;
+      RHSKnownOne  <<= ShiftAmt;
+      // low bits known zero.
+      if (ShiftAmt)
+        RHSKnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt);
+    }
+    break;
+  case Instruction::LShr:
+    // For a logical shift right
+    if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+      uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+      
+      // Unsigned shift right.
+      APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
+      if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
+                               RHSKnownZero, RHSKnownOne, Depth+1))
+        return I;
+      assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+      RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
+      RHSKnownOne  = APIntOps::lshr(RHSKnownOne, ShiftAmt);
+      if (ShiftAmt) {
+        // Compute the new bits that are at the top now.
+        APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
+        RHSKnownZero |= HighBits;  // high bits known zero.
+      }
+    }
+    break;
+  case Instruction::AShr:
+    // If this is an arithmetic shift right and only the low-bit is set, we can
+    // always convert this into a logical shr, even if the shift amount is
+    // variable.  The low bit of the shift cannot be an input sign bit unless
+    // the shift amount is >= the size of the datatype, which is undefined.
+    if (DemandedMask == 1) {
+      // Perform the logical shift right.
+      Instruction *NewVal = BinaryOperator::CreateLShr(
+                        I->getOperand(0), I->getOperand(1), I->getName());
+      return InsertNewInstBefore(NewVal, *I);
+    }    
+
+    // If the sign bit is the only bit demanded by this ashr, then there is no
+    // need to do it, the shift doesn't change the high bit.
+    if (DemandedMask.isSignBit())
+      return I->getOperand(0);
+    
+    if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+      uint32_t ShiftAmt = SA->getLimitedValue(BitWidth);
+      
+      // Signed shift right.
+      APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
+      // If any of the "high bits" are demanded, we should set the sign bit as
+      // demanded.
+      if (DemandedMask.countLeadingZeros() <= ShiftAmt)
+        DemandedMaskIn.set(BitWidth-1);
+      if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
+                               RHSKnownZero, RHSKnownOne, Depth+1))
+        return I;
+      assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
+      // Compute the new bits that are at the top now.
+      APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
+      RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
+      RHSKnownOne  = APIntOps::lshr(RHSKnownOne, ShiftAmt);
+        
+      // Handle the sign bits.
+      APInt SignBit(APInt::getSignBit(BitWidth));
+      // Adjust to where it is now in the mask.
+      SignBit = APIntOps::lshr(SignBit, ShiftAmt);  
+        
+      // If the input sign bit is known to be zero, or if none of the top bits
+      // are demanded, turn this into an unsigned shift right.
+      if (BitWidth <= ShiftAmt || RHSKnownZero[BitWidth-ShiftAmt-1] || 
+          (HighBits & ~DemandedMask) == HighBits) {
+        // Perform the logical shift right.
+        Instruction *NewVal = BinaryOperator::CreateLShr(
+                          I->getOperand(0), SA, I->getName());
+        return InsertNewInstBefore(NewVal, *I);
+      } else if ((RHSKnownOne & SignBit) != 0) { // New bits are known one.
+        RHSKnownOne |= HighBits;
+      }
+    }
+    break;
+  case Instruction::SRem:
+    if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
+      APInt RA = Rem->getValue().abs();
+      if (RA.isPowerOf2()) {
+        if (DemandedMask.ule(RA))    // srem won't affect demanded bits
+          return I->getOperand(0);
+
+        APInt LowBits = RA - 1;
+        APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
+        if (SimplifyDemandedBits(I->getOperandUse(0), Mask2,
+                                 LHSKnownZero, LHSKnownOne, Depth+1))
+          return I;
+
+        if (LHSKnownZero[BitWidth-1] || ((LHSKnownZero & LowBits) == LowBits))
+          LHSKnownZero |= ~LowBits;
+
+        KnownZero |= LHSKnownZero & DemandedMask;
+
+        assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?"); 
+      }
+    }
+    break;
+  case Instruction::URem: {
+    APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0);
+    APInt AllOnes = APInt::getAllOnesValue(BitWidth);
+    if (SimplifyDemandedBits(I->getOperandUse(0), AllOnes,
+                             KnownZero2, KnownOne2, Depth+1) ||
+        SimplifyDemandedBits(I->getOperandUse(1), AllOnes,
+                             KnownZero2, KnownOne2, Depth+1))
+      return I;
+
+    unsigned Leaders = KnownZero2.countLeadingOnes();
+    Leaders = std::max(Leaders,
+                       KnownZero2.countLeadingOnes());
+    KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & DemandedMask;
+    break;
+  }
+  case Instruction::Call:
+    if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+      switch (II->getIntrinsicID()) {
+      default: break;
+      case Intrinsic::bswap: {
+        // If the only bits demanded come from one byte of the bswap result,
+        // just shift the input byte into position to eliminate the bswap.
+        unsigned NLZ = DemandedMask.countLeadingZeros();
+        unsigned NTZ = DemandedMask.countTrailingZeros();
+          
+        // Round NTZ down to the next byte.  If we have 11 trailing zeros, then
+        // we need all the bits down to bit 8.  Likewise, round NLZ.  If we
+        // have 14 leading zeros, round to 8.
+        NLZ &= ~7;
+        NTZ &= ~7;
+        // If we need exactly one byte, we can do this transformation.
+        if (BitWidth-NLZ-NTZ == 8) {
+          unsigned ResultBit = NTZ;
+          unsigned InputBit = BitWidth-NTZ-8;
+          
+          // Replace this with either a left or right shift to get the byte into
+          // the right place.
+          Instruction *NewVal;
+          if (InputBit > ResultBit)
+            NewVal = BinaryOperator::CreateLShr(I->getOperand(1),
+                    ConstantInt::get(I->getType(), InputBit-ResultBit));
+          else
+            NewVal = BinaryOperator::CreateShl(I->getOperand(1),
+                    ConstantInt::get(I->getType(), ResultBit-InputBit));
+          NewVal->takeName(I);
+          return InsertNewInstBefore(NewVal, *I);
+        }
+          
+        // TODO: Could compute known zero/one bits based on the input.
+        break;
+      }
+      }
+    }
+    ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
+    break;
+  }
+  
+  // If the client is only demanding bits that we know, return the known
+  // constant.
+  if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) {
+    Constant *C = ConstantInt::get(RHSKnownOne);
+    if (isa<PointerType>(V->getType()))
+      C = ConstantExpr::getIntToPtr(C, V->getType());
+    return C;
+  }
+  return false;
+}
+
+
+/// SimplifyDemandedVectorElts - The specified value produces a vector with
+/// any number of elements. DemandedElts contains the set of elements that are
+/// actually used by the caller.  This method analyzes which elements of the
+/// operand are undef and returns that information in UndefElts.
+///
+/// If the information about demanded elements can be used to simplify the
+/// operation, the operation is simplified, then the resultant value is
+/// returned.  This returns null if no change was made.
+Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
+                                                APInt& UndefElts,
+                                                unsigned Depth) {
+  unsigned VWidth = cast<VectorType>(V->getType())->getNumElements();
+  APInt EltMask(APInt::getAllOnesValue(VWidth));
+  assert((DemandedElts & ~EltMask) == 0 && "Invalid DemandedElts!");
+
+  if (isa<UndefValue>(V)) {
+    // If the entire vector is undefined, just return this info.
+    UndefElts = EltMask;
+    return 0;
+  } else if (DemandedElts == 0) { // If nothing is demanded, provide undef.
+    UndefElts = EltMask;
+    return UndefValue::get(V->getType());
+  }
+
+  UndefElts = 0;
+  if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) {
+    const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
+    Constant *Undef = UndefValue::get(EltTy);
+
+    std::vector<Constant*> Elts;
+    for (unsigned i = 0; i != VWidth; ++i)
+      if (!DemandedElts[i]) {   // If not demanded, set to undef.
+        Elts.push_back(Undef);
+        UndefElts.set(i);
+      } else if (isa<UndefValue>(CP->getOperand(i))) {   // Already undef.
+        Elts.push_back(Undef);
+        UndefElts.set(i);
+      } else {                               // Otherwise, defined.
+        Elts.push_back(CP->getOperand(i));
+      }
+
+    // If we changed the constant, return it.
+    Constant *NewCP = ConstantVector::get(Elts);
+    return NewCP != CP ? NewCP : 0;
+  } else if (isa<ConstantAggregateZero>(V)) {
+    // Simplify the CAZ to a ConstantVector where the non-demanded elements are
+    // set to undef.
+    
+    // Check if this is identity. If so, return 0 since we are not simplifying
+    // anything.
+    if (DemandedElts == ((1ULL << VWidth) -1))
+      return 0;
+    
+    const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
+    Constant *Zero = Constant::getNullValue(EltTy);
+    Constant *Undef = UndefValue::get(EltTy);
+    std::vector<Constant*> Elts;
+    for (unsigned i = 0; i != VWidth; ++i) {
+      Constant *Elt = DemandedElts[i] ? Zero : Undef;
+      Elts.push_back(Elt);
+    }
+    UndefElts = DemandedElts ^ EltMask;
+    return ConstantVector::get(Elts);
+  }
+  
+  // Limit search depth.
+  if (Depth == 10)
+    return 0;
+
+  // If multiple users are using the root value, procede with
+  // simplification conservatively assuming that all elements
+  // are needed.
+  if (!V->hasOneUse()) {
+    // Quit if we find multiple users of a non-root value though.
+    // They'll be handled when it's their turn to be visited by
+    // the main instcombine process.
+    if (Depth != 0)
+      // TODO: Just compute the UndefElts information recursively.
+      return 0;
+
+    // Conservatively assume that all elements are needed.
+    DemandedElts = EltMask;
+  }
+  
+  Instruction *I = dyn_cast<Instruction>(V);
+  if (!I) return 0;        // Only analyze instructions.
+  
+  bool MadeChange = false;
+  APInt UndefElts2(VWidth, 0);
+  Value *TmpV;
+  switch (I->getOpcode()) {
+  default: break;
+    
+  case Instruction::InsertElement: {
+    // If this is a variable index, we don't know which element it overwrites.
+    // demand exactly the same input as we produce.
+    ConstantInt *Idx = dyn_cast<ConstantInt>(I->getOperand(2));
+    if (Idx == 0) {
+      // Note that we can't propagate undef elt info, because we don't know
+      // which elt is getting updated.
+      TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
+                                        UndefElts2, Depth+1);
+      if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+      break;
+    }
+    
+    // If this is inserting an element that isn't demanded, remove this
+    // insertelement.
+    unsigned IdxNo = Idx->getZExtValue();
+    if (IdxNo >= VWidth || !DemandedElts[IdxNo])
+      return AddSoonDeadInstToWorklist(*I, 0);
+    
+    // Otherwise, the element inserted overwrites whatever was there, so the
+    // input demanded set is simpler than the output set.
+    APInt DemandedElts2 = DemandedElts;
+    DemandedElts2.clear(IdxNo);
+    TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts2,
+                                      UndefElts, Depth+1);
+    if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+
+    // The inserted element is defined.
+    UndefElts.clear(IdxNo);
+    break;
+  }
+  case Instruction::ShuffleVector: {
+    ShuffleVectorInst *Shuffle = cast<ShuffleVectorInst>(I);
+    uint64_t LHSVWidth =
+      cast<VectorType>(Shuffle->getOperand(0)->getType())->getNumElements();
+    APInt LeftDemanded(LHSVWidth, 0), RightDemanded(LHSVWidth, 0);
+    for (unsigned i = 0; i < VWidth; i++) {
+      if (DemandedElts[i]) {
+        unsigned MaskVal = Shuffle->getMaskValue(i);
+        if (MaskVal != -1u) {
+          assert(MaskVal < LHSVWidth * 2 &&
+                 "shufflevector mask index out of range!");
+          if (MaskVal < LHSVWidth)
+            LeftDemanded.set(MaskVal);
+          else
+            RightDemanded.set(MaskVal - LHSVWidth);
+        }
+      }
+    }
+
+    APInt UndefElts4(LHSVWidth, 0);
+    TmpV = SimplifyDemandedVectorElts(I->getOperand(0), LeftDemanded,
+                                      UndefElts4, Depth+1);
+    if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+
+    APInt UndefElts3(LHSVWidth, 0);
+    TmpV = SimplifyDemandedVectorElts(I->getOperand(1), RightDemanded,
+                                      UndefElts3, Depth+1);
+    if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
+
+    bool NewUndefElts = false;
+    for (unsigned i = 0; i < VWidth; i++) {
+      unsigned MaskVal = Shuffle->getMaskValue(i);
+      if (MaskVal == -1u) {
+        UndefElts.set(i);
+      } else if (MaskVal < LHSVWidth) {
+        if (UndefElts4[MaskVal]) {
+          NewUndefElts = true;
+          UndefElts.set(i);
+        }
+      } else {
+        if (UndefElts3[MaskVal - LHSVWidth]) {
+          NewUndefElts = true;
+          UndefElts.set(i);
+        }
+      }
+    }
+
+    if (NewUndefElts) {
+      // Add additional discovered undefs.
+      std::vector<Constant*> Elts;
+      for (unsigned i = 0; i < VWidth; ++i) {
+        if (UndefElts[i])
+          Elts.push_back(UndefValue::get(Type::Int32Ty));
+        else
+          Elts.push_back(ConstantInt::get(Type::Int32Ty,
+                                          Shuffle->getMaskValue(i)));
+      }
+      I->setOperand(2, ConstantVector::get(Elts));
+      MadeChange = true;
+    }
+    break;
+  }
+  case Instruction::BitCast: {
+    // Vector->vector casts only.
+    const VectorType *VTy = dyn_cast<VectorType>(I->getOperand(0)->getType());
+    if (!VTy) break;
+    unsigned InVWidth = VTy->getNumElements();
+    APInt InputDemandedElts(InVWidth, 0);
+    unsigned Ratio;
+
+    if (VWidth == InVWidth) {
+      // If we are converting from <4 x i32> -> <4 x f32>, we demand the same
+      // elements as are demanded of us.
+      Ratio = 1;
+      InputDemandedElts = DemandedElts;
+    } else if (VWidth > InVWidth) {
+      // Untested so far.
+      break;
+      
+      // If there are more elements in the result than there are in the source,
+      // then an input element is live if any of the corresponding output
+      // elements are live.
+      Ratio = VWidth/InVWidth;
+      for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
+        if (DemandedElts[OutIdx])
+          InputDemandedElts.set(OutIdx/Ratio);
+      }
+    } else {
+      // Untested so far.
+      break;
+      
+      // If there are more elements in the source than there are in the result,
+      // then an input element is live if the corresponding output element is
+      // live.
+      Ratio = InVWidth/VWidth;
+      for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
+        if (DemandedElts[InIdx/Ratio])
+          InputDemandedElts.set(InIdx);
+    }
+    
+    // div/rem demand all inputs, because they don't want divide by zero.
+    TmpV = SimplifyDemandedVectorElts(I->getOperand(0), InputDemandedElts,
+                                      UndefElts2, Depth+1);
+    if (TmpV) {
+      I->setOperand(0, TmpV);
+      MadeChange = true;
+    }
+    
+    UndefElts = UndefElts2;
+    if (VWidth > InVWidth) {
+      assert(0 && "Unimp");
+      // If there are more elements in the result than there are in the source,
+      // then an output element is undef if the corresponding input element is
+      // undef.
+      for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
+        if (UndefElts2[OutIdx/Ratio])
+          UndefElts.set(OutIdx);
+    } else if (VWidth < InVWidth) {
+      assert(0 && "Unimp");
+      // If there are more elements in the source than there are in the result,
+      // then a result element is undef if all of the corresponding input
+      // elements are undef.
+      UndefElts = ~0ULL >> (64-VWidth);  // Start out all undef.
+      for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
+        if (!UndefElts2[InIdx])            // Not undef?
+          UndefElts.clear(InIdx/Ratio);    // Clear undef bit.
+    }
+    break;
+  }
+  case Instruction::And:
+  case Instruction::Or:
+  case Instruction::Xor:
+  case Instruction::Add:
+  case Instruction::Sub:
+  case Instruction::Mul:
+    // div/rem demand all inputs, because they don't want divide by zero.
+    TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
+                                      UndefElts, Depth+1);
+    if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+    TmpV = SimplifyDemandedVectorElts(I->getOperand(1), DemandedElts,
+                                      UndefElts2, Depth+1);
+    if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
+      
+    // Output elements are undefined if both are undefined.  Consider things
+    // like undef&0.  The result is known zero, not undef.
+    UndefElts &= UndefElts2;
+    break;
+    
+  case Instruction::Call: {
+    IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
+    if (!II) break;
+    switch (II->getIntrinsicID()) {
+    default: break;
+      
+    // Binary vector operations that work column-wise.  A dest element is a
+    // function of the corresponding input elements from the two inputs.
+    case Intrinsic::x86_sse_sub_ss:
+    case Intrinsic::x86_sse_mul_ss:
+    case Intrinsic::x86_sse_min_ss:
+    case Intrinsic::x86_sse_max_ss:
+    case Intrinsic::x86_sse2_sub_sd:
+    case Intrinsic::x86_sse2_mul_sd:
+    case Intrinsic::x86_sse2_min_sd:
+    case Intrinsic::x86_sse2_max_sd:
+      TmpV = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
+                                        UndefElts, Depth+1);
+      if (TmpV) { II->setOperand(1, TmpV); MadeChange = true; }
+      TmpV = SimplifyDemandedVectorElts(II->getOperand(2), DemandedElts,
+                                        UndefElts2, Depth+1);
+      if (TmpV) { II->setOperand(2, TmpV); MadeChange = true; }
+
+      // If only the low elt is demanded and this is a scalarizable intrinsic,
+      // scalarize it now.
+      if (DemandedElts == 1) {
+        switch (II->getIntrinsicID()) {
+        default: break;
+        case Intrinsic::x86_sse_sub_ss:
+        case Intrinsic::x86_sse_mul_ss:
+        case Intrinsic::x86_sse2_sub_sd:
+        case Intrinsic::x86_sse2_mul_sd:
+          // TODO: Lower MIN/MAX/ABS/etc
+          Value *LHS = II->getOperand(1);
+          Value *RHS = II->getOperand(2);
+          // Extract the element as scalars.
+          LHS = InsertNewInstBefore(new ExtractElementInst(LHS, 0U,"tmp"), *II);
+          RHS = InsertNewInstBefore(new ExtractElementInst(RHS, 0U,"tmp"), *II);
+          
+          switch (II->getIntrinsicID()) {
+          default: assert(0 && "Case stmts out of sync!");
+          case Intrinsic::x86_sse_sub_ss:
+          case Intrinsic::x86_sse2_sub_sd:
+            TmpV = InsertNewInstBefore(BinaryOperator::CreateSub(LHS, RHS,
+                                                        II->getName()), *II);
+            break;
+          case Intrinsic::x86_sse_mul_ss:
+          case Intrinsic::x86_sse2_mul_sd:
+            TmpV = InsertNewInstBefore(BinaryOperator::CreateMul(LHS, RHS,
+                                                         II->getName()), *II);
+            break;
+          }
+          
+          Instruction *New =
+            InsertElementInst::Create(UndefValue::get(II->getType()), TmpV, 0U,
+                                      II->getName());
+          InsertNewInstBefore(New, *II);
+          AddSoonDeadInstToWorklist(*II, 0);
+          return New;
+        }            
+      }
+        
+      // Output elements are undefined if both are undefined.  Consider things
+      // like undef&0.  The result is known zero, not undef.
+      UndefElts &= UndefElts2;
+      break;
+    }
+    break;
+  }
+  }
+  return MadeChange ? I : 0;
+}
+
+
+/// AssociativeOpt - Perform an optimization on an associative operator.  This
+/// function is designed to check a chain of associative operators for a
+/// potential to apply a certain optimization.  Since the optimization may be
+/// applicable if the expression was reassociated, this checks the chain, then
+/// reassociates the expression as necessary to expose the optimization
+/// opportunity.  This makes use of a special Functor, which must define
+/// 'shouldApply' and 'apply' methods.
+///
+template<typename Functor>
+static Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
+  unsigned Opcode = Root.getOpcode();
+  Value *LHS = Root.getOperand(0);
+
+  // Quick check, see if the immediate LHS matches...
+  if (F.shouldApply(LHS))
+    return F.apply(Root);
+
+  // Otherwise, if the LHS is not of the same opcode as the root, return.
+  Instruction *LHSI = dyn_cast<Instruction>(LHS);
+  while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
+    // Should we apply this transform to the RHS?
+    bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
+
+    // If not to the RHS, check to see if we should apply to the LHS...
+    if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
+      cast<BinaryOperator>(LHSI)->swapOperands();   // Make the LHS the RHS
+      ShouldApply = true;
+    }
+
+    // If the functor wants to apply the optimization to the RHS of LHSI,
+    // reassociate the expression from ((? op A) op B) to (? op (A op B))
+    if (ShouldApply) {
+      // Now all of the instructions are in the current basic block, go ahead
+      // and perform the reassociation.
+      Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
+
+      // First move the selected RHS to the LHS of the root...
+      Root.setOperand(0, LHSI->getOperand(1));
+
+      // Make what used to be the LHS of the root be the user of the root...
+      Value *ExtraOperand = TmpLHSI->getOperand(1);
+      if (&Root == TmpLHSI) {
+        Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
+        return 0;
+      }
+      Root.replaceAllUsesWith(TmpLHSI);          // Users now use TmpLHSI
+      TmpLHSI->setOperand(1, &Root);             // TmpLHSI now uses the root
+      BasicBlock::iterator ARI = &Root; ++ARI;
+      TmpLHSI->moveBefore(ARI);                  // Move TmpLHSI to after Root
+      ARI = Root;
+
+      // Now propagate the ExtraOperand down the chain of instructions until we
+      // get to LHSI.
+      while (TmpLHSI != LHSI) {
+        Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
+        // Move the instruction to immediately before the chain we are
+        // constructing to avoid breaking dominance properties.
+        NextLHSI->moveBefore(ARI);
+        ARI = NextLHSI;
+
+        Value *NextOp = NextLHSI->getOperand(1);
+        NextLHSI->setOperand(1, ExtraOperand);
+        TmpLHSI = NextLHSI;
+        ExtraOperand = NextOp;
+      }
+
+      // Now that the instructions are reassociated, have the functor perform
+      // the transformation...
+      return F.apply(Root);
+    }
+
+    LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
+  }
+  return 0;
+}
+
+namespace {
+
+// AddRHS - Implements: X + X --> X << 1
+struct AddRHS {
+  Value *RHS;
+  AddRHS(Value *rhs) : RHS(rhs) {}
+  bool shouldApply(Value *LHS) const { return LHS == RHS; }
+  Instruction *apply(BinaryOperator &Add) const {
+    return BinaryOperator::CreateShl(Add.getOperand(0),
+                                     ConstantInt::get(Add.getType(), 1));
+  }
+};
+
+// AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
+//                 iff C1&C2 == 0
+struct AddMaskingAnd {
+  Constant *C2;
+  AddMaskingAnd(Constant *c) : C2(c) {}
+  bool shouldApply(Value *LHS) const {
+    ConstantInt *C1;
+    return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
+           ConstantExpr::getAnd(C1, C2)->isNullValue();
+  }
+  Instruction *apply(BinaryOperator &Add) const {
+    return BinaryOperator::CreateOr(Add.getOperand(0), Add.getOperand(1));
+  }
+};
+
+}
+
+static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
+                                             InstCombiner *IC) {
+  if (CastInst *CI = dyn_cast<CastInst>(&I)) {
+    return IC->InsertCastBefore(CI->getOpcode(), SO, I.getType(), I);
+  }
+
+  // Figure out if the constant is the left or the right argument.
+  bool ConstIsRHS = isa<Constant>(I.getOperand(1));
+  Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
+
+  if (Constant *SOC = dyn_cast<Constant>(SO)) {
+    if (ConstIsRHS)
+      return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
+    return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
+  }
+
+  Value *Op0 = SO, *Op1 = ConstOperand;
+  if (!ConstIsRHS)
+    std::swap(Op0, Op1);
+  Instruction *New;
+  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
+    New = BinaryOperator::Create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
+  else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
+    New = CmpInst::Create(CI->getOpcode(), CI->getPredicate(), Op0, Op1, 
+                          SO->getName()+".cmp");
+  else {
+    assert(0 && "Unknown binary instruction type!");
+    abort();
+  }
+  return IC->InsertNewInstBefore(New, I);
+}
+
+// FoldOpIntoSelect - Given an instruction with a select as one operand and a
+// constant as the other operand, try to fold the binary operator into the
+// select arguments.  This also works for Cast instructions, which obviously do
+// not have a second operand.
+static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
+                                     InstCombiner *IC) {
+  // Don't modify shared select instructions
+  if (!SI->hasOneUse()) return 0;
+  Value *TV = SI->getOperand(1);
+  Value *FV = SI->getOperand(2);
+
+  if (isa<Constant>(TV) || isa<Constant>(FV)) {
+    // Bool selects with constant operands can be folded to logical ops.
+    if (SI->getType() == Type::Int1Ty) return 0;
+
+    Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
+    Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
+
+    return SelectInst::Create(SI->getCondition(), SelectTrueVal,
+                              SelectFalseVal);
+  }
+  return 0;
+}
+
+
+/// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
+/// node as operand #0, see if we can fold the instruction into the PHI (which
+/// is only possible if all operands to the PHI are constants).
+Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
+  PHINode *PN = cast<PHINode>(I.getOperand(0));
+  unsigned NumPHIValues = PN->getNumIncomingValues();
+  if (!PN->hasOneUse() || NumPHIValues == 0) return 0;
+
+  // Check to see if all of the operands of the PHI are constants.  If there is
+  // one non-constant value, remember the BB it is.  If there is more than one
+  // or if *it* is a PHI, bail out.
+  BasicBlock *NonConstBB = 0;
+  for (unsigned i = 0; i != NumPHIValues; ++i)
+    if (!isa<Constant>(PN->getIncomingValue(i))) {
+      if (NonConstBB) return 0;  // More than one non-const value.
+      if (isa<PHINode>(PN->getIncomingValue(i))) return 0;  // Itself a phi.
+      NonConstBB = PN->getIncomingBlock(i);
+      
+      // If the incoming non-constant value is in I's block, we have an infinite
+      // loop.
+      if (NonConstBB == I.getParent())
+        return 0;
+    }
+  
+  // If there is exactly one non-constant value, we can insert a copy of the
+  // operation in that block.  However, if this is a critical edge, we would be
+  // inserting the computation one some other paths (e.g. inside a loop).  Only
+  // do this if the pred block is unconditionally branching into the phi block.
+  if (NonConstBB) {
+    BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
+    if (!BI || !BI->isUnconditional()) return 0;
+  }
+
+  // Okay, we can do the transformation: create the new PHI node.
+  PHINode *NewPN = PHINode::Create(I.getType(), "");
+  NewPN->reserveOperandSpace(PN->getNumOperands()/2);
+  InsertNewInstBefore(NewPN, *PN);
+  NewPN->takeName(PN);
+
+  // Next, add all of the operands to the PHI.
+  if (I.getNumOperands() == 2) {
+    Constant *C = cast<Constant>(I.getOperand(1));
+    for (unsigned i = 0; i != NumPHIValues; ++i) {
+      Value *InV = 0;
+      if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
+        if (CmpInst *CI = dyn_cast<CmpInst>(&I))
+          InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
+        else
+          InV = ConstantExpr::get(I.getOpcode(), InC, C);
+      } else {
+        assert(PN->getIncomingBlock(i) == NonConstBB);
+        if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I)) 
+          InV = BinaryOperator::Create(BO->getOpcode(),
+                                       PN->getIncomingValue(i), C, "phitmp",
+                                       NonConstBB->getTerminator());
+        else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
+          InV = CmpInst::Create(CI->getOpcode(), 
+                                CI->getPredicate(),
+                                PN->getIncomingValue(i), C, "phitmp",
+                                NonConstBB->getTerminator());
+        else
+          assert(0 && "Unknown binop!");
+        
+        AddToWorkList(cast<Instruction>(InV));
+      }
+      NewPN->addIncoming(InV, PN->getIncomingBlock(i));
+    }
+  } else { 
+    CastInst *CI = cast<CastInst>(&I);
+    const Type *RetTy = CI->getType();
+    for (unsigned i = 0; i != NumPHIValues; ++i) {
+      Value *InV;
+      if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
+        InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
+      } else {
+        assert(PN->getIncomingBlock(i) == NonConstBB);
+        InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i), 
+                               I.getType(), "phitmp", 
+                               NonConstBB->getTerminator());
+        AddToWorkList(cast<Instruction>(InV));
+      }
+      NewPN->addIncoming(InV, PN->getIncomingBlock(i));
+    }
+  }
+  return ReplaceInstUsesWith(I, NewPN);
+}
+
+
+/// WillNotOverflowSignedAdd - Return true if we can prove that:
+///    (sext (add LHS, RHS))  === (add (sext LHS), (sext RHS))
+/// This basically requires proving that the add in the original type would not
+/// overflow to change the sign bit or have a carry out.
+bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
+  // There are different heuristics we can use for this.  Here are some simple
+  // ones.
+  
+  // Add has the property that adding any two 2's complement numbers can only 
+  // have one carry bit which can change a sign.  As such, if LHS and RHS each
+  // have at least two sign bits, we know that the addition of the two values will
+  // sign extend fine.
+  if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
+    return true;
+  
+  
+  // If one of the operands only has one non-zero bit, and if the other operand
+  // has a known-zero bit in a more significant place than it (not including the
+  // sign bit) the ripple may go up to and fill the zero, but won't change the
+  // sign.  For example, (X & ~4) + 1.
+  
+  // TODO: Implement.
+  
+  return false;
+}
+
+
+Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
+  bool Changed = SimplifyCommutative(I);
+  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+
+  if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+    // X + undef -> undef
+    if (isa<UndefValue>(RHS))
+      return ReplaceInstUsesWith(I, RHS);
+
+    // X + 0 --> X
+    if (!I.getType()->isFPOrFPVector()) { // NOTE: -0 + +0 = +0.
+      if (RHSC->isNullValue())
+        return ReplaceInstUsesWith(I, LHS);
+    } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
+      if (CFP->isExactlyValue(ConstantFP::getNegativeZero
+                              (I.getType())->getValueAPF()))
+        return ReplaceInstUsesWith(I, LHS);
+    }
+
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
+      // X + (signbit) --> X ^ signbit
+      const APInt& Val = CI->getValue();
+      uint32_t BitWidth = Val.getBitWidth();
+      if (Val == APInt::getSignBit(BitWidth))
+        return BinaryOperator::CreateXor(LHS, RHS);
+      
+      // See if SimplifyDemandedBits can simplify this.  This handles stuff like
+      // (X & 254)+1 -> (X&254)|1
+      if (!isa<VectorType>(I.getType()) && SimplifyDemandedInstructionBits(I))
+        return &I;
+
+      // zext(i1) - 1  ->  select i1, 0, -1
+      if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
+        if (CI->isAllOnesValue() &&
+            ZI->getOperand(0)->getType() == Type::Int1Ty)
+          return SelectInst::Create(ZI->getOperand(0),
+                                    Constant::getNullValue(I.getType()),
+                                    ConstantInt::getAllOnesValue(I.getType()));
+    }
+
+    if (isa<PHINode>(LHS))
+      if (Instruction *NV = FoldOpIntoPhi(I))
+        return NV;
+    
+    ConstantInt *XorRHS = 0;
+    Value *XorLHS = 0;
+    if (isa<ConstantInt>(RHSC) &&
+        match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
+      uint32_t TySizeBits = I.getType()->getPrimitiveSizeInBits();
+      const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
+      
+      uint32_t Size = TySizeBits / 2;
+      APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
+      APInt CFF80Val(-C0080Val);
+      do {
+        if (TySizeBits > Size) {
+          // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
+          // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
+          if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
+              (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
+            // This is a sign extend if the top bits are known zero.
+            if (!MaskedValueIsZero(XorLHS, 
+                   APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
+              Size = 0;  // Not a sign ext, but can't be any others either.
+            break;
+          }
+        }
+        Size >>= 1;
+        C0080Val = APIntOps::lshr(C0080Val, Size);
+        CFF80Val = APIntOps::ashr(CFF80Val, Size);
+      } while (Size >= 1);
+      
+      // FIXME: This shouldn't be necessary. When the backends can handle types
+      // with funny bit widths then this switch statement should be removed. It
+      // is just here to get the size of the "middle" type back up to something
+      // that the back ends can handle.
+      const Type *MiddleType = 0;
+      switch (Size) {
+        default: break;
+        case 32: MiddleType = Type::Int32Ty; break;
+        case 16: MiddleType = Type::Int16Ty; break;
+        case  8: MiddleType = Type::Int8Ty; break;
+      }
+      if (MiddleType) {
+        Instruction *NewTrunc = new TruncInst(XorLHS, MiddleType, "sext");
+        InsertNewInstBefore(NewTrunc, I);
+        return new SExtInst(NewTrunc, I.getType(), I.getName());
+      }
+    }
+  }
+
+  if (I.getType() == Type::Int1Ty)
+    return BinaryOperator::CreateXor(LHS, RHS);
+
+  // X + X --> X << 1
+  if (I.getType()->isInteger()) {
+    if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
+
+    if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
+      if (RHSI->getOpcode() == Instruction::Sub)
+        if (LHS == RHSI->getOperand(1))                   // A + (B - A) --> B
+          return ReplaceInstUsesWith(I, RHSI->getOperand(0));
+    }
+    if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
+      if (LHSI->getOpcode() == Instruction::Sub)
+        if (RHS == LHSI->getOperand(1))                   // (B - A) + A --> B
+          return ReplaceInstUsesWith(I, LHSI->getOperand(0));
+    }
+  }
+
+  // -A + B  -->  B - A
+  // -A + -B  -->  -(A + B)
+  if (Value *LHSV = dyn_castNegVal(LHS)) {
+    if (LHS->getType()->isIntOrIntVector()) {
+      if (Value *RHSV = dyn_castNegVal(RHS)) {
+        Instruction *NewAdd = BinaryOperator::CreateAdd(LHSV, RHSV, "sum");
+        InsertNewInstBefore(NewAdd, I);
+        return BinaryOperator::CreateNeg(NewAdd);
+      }
+    }
+    
+    return BinaryOperator::CreateSub(RHS, LHSV);
+  }
+
+  // A + -B  -->  A - B
+  if (!isa<Constant>(RHS))
+    if (Value *V = dyn_castNegVal(RHS))
+      return BinaryOperator::CreateSub(LHS, V);
+
+
+  ConstantInt *C2;
+  if (Value *X = dyn_castFoldableMul(LHS, C2)) {
+    if (X == RHS)   // X*C + X --> X * (C+1)
+      return BinaryOperator::CreateMul(RHS, AddOne(C2));
+
+    // X*C1 + X*C2 --> X * (C1+C2)
+    ConstantInt *C1;
+    if (X == dyn_castFoldableMul(RHS, C1))
+      return BinaryOperator::CreateMul(X, Add(C1, C2));
+  }
+
+  // X + X*C --> X * (C+1)
+  if (dyn_castFoldableMul(RHS, C2) == LHS)
+    return BinaryOperator::CreateMul(LHS, AddOne(C2));
+
+  // X + ~X --> -1   since   ~X = -X-1
+  if (dyn_castNotVal(LHS) == RHS || dyn_castNotVal(RHS) == LHS)
+    return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+  
+
+  // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
+  if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
+    if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
+      return R;
+  
+  // A+B --> A|B iff A and B have no bits set in common.
+  if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
+    APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
+    APInt LHSKnownOne(IT->getBitWidth(), 0);
+    APInt LHSKnownZero(IT->getBitWidth(), 0);
+    ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
+    if (LHSKnownZero != 0) {
+      APInt RHSKnownOne(IT->getBitWidth(), 0);
+      APInt RHSKnownZero(IT->getBitWidth(), 0);
+      ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
+      
+      // No bits in common -> bitwise or.
+      if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
+        return BinaryOperator::CreateOr(LHS, RHS);
+    }
+  }
+
+  // W*X + Y*Z --> W * (X+Z)  iff W == Y
+  if (I.getType()->isIntOrIntVector()) {
+    Value *W, *X, *Y, *Z;
+    if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
+        match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
+      if (W != Y) {
+        if (W == Z) {
+          std::swap(Y, Z);
+        } else if (Y == X) {
+          std::swap(W, X);
+        } else if (X == Z) {
+          std::swap(Y, Z);
+          std::swap(W, X);
+        }
+      }
+
+      if (W == Y) {
+        Value *NewAdd = InsertNewInstBefore(BinaryOperator::CreateAdd(X, Z,
+                                                            LHS->getName()), I);
+        return BinaryOperator::CreateMul(W, NewAdd);
+      }
+    }
+  }
+
+  if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
+    Value *X = 0;
+    if (match(LHS, m_Not(m_Value(X))))    // ~X + C --> (C-1) - X
+      return BinaryOperator::CreateSub(SubOne(CRHS), X);
+
+    // (X & FF00) + xx00  -> (X+xx00) & FF00
+    if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
+      Constant *Anded = And(CRHS, C2);
+      if (Anded == CRHS) {
+        // See if all bits from the first bit set in the Add RHS up are included
+        // in the mask.  First, get the rightmost bit.
+        const APInt& AddRHSV = CRHS->getValue();
+
+        // Form a mask of all bits from the lowest bit added through the top.
+        APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
+
+        // See if the and mask includes all of these bits.
+        APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
+
+        if (AddRHSHighBits == AddRHSHighBitsAnd) {
+          // Okay, the xform is safe.  Insert the new add pronto.
+          Value *NewAdd = InsertNewInstBefore(BinaryOperator::CreateAdd(X, CRHS,
+                                                            LHS->getName()), I);
+          return BinaryOperator::CreateAnd(NewAdd, C2);
+        }
+      }
+    }
+
+    // Try to fold constant add into select arguments.
+    if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
+      if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+        return R;
+  }
+
+  // add (cast *A to intptrtype) B -> 
+  //   cast (GEP (cast *A to sbyte*) B)  -->  intptrtype
+  {
+    CastInst *CI = dyn_cast<CastInst>(LHS);
+    Value *Other = RHS;
+    if (!CI) {
+      CI = dyn_cast<CastInst>(RHS);
+      Other = LHS;
+    }
+    if (CI && CI->getType()->isSized() && 
+        (CI->getType()->getPrimitiveSizeInBits() == 
+         TD->getIntPtrType()->getPrimitiveSizeInBits()) 
+        && isa<PointerType>(CI->getOperand(0)->getType())) {
+      unsigned AS =
+        cast<PointerType>(CI->getOperand(0)->getType())->getAddressSpace();
+      Value *I2 = InsertBitCastBefore(CI->getOperand(0),
+                                      PointerType::get(Type::Int8Ty, AS), I);
+      I2 = InsertNewInstBefore(GetElementPtrInst::Create(I2, Other, "ctg2"), I);
+      return new PtrToIntInst(I2, CI->getType());
+    }
+  }
+  
+  // add (select X 0 (sub n A)) A  -->  select X A n
+  {
+    SelectInst *SI = dyn_cast<SelectInst>(LHS);
+    Value *A = RHS;
+    if (!SI) {
+      SI = dyn_cast<SelectInst>(RHS);
+      A = LHS;
+    }
+    if (SI && SI->hasOneUse()) {
+      Value *TV = SI->getTrueValue();
+      Value *FV = SI->getFalseValue();
+      Value *N;
+
+      // Can we fold the add into the argument of the select?
+      // We check both true and false select arguments for a matching subtract.
+      if (match(FV, m_Zero()) && match(TV, m_Sub(m_Value(N), m_Specific(A))))
+        // Fold the add into the true select value.
+        return SelectInst::Create(SI->getCondition(), N, A);
+      if (match(TV, m_Zero()) && match(FV, m_Sub(m_Value(N), m_Specific(A))))
+        // Fold the add into the false select value.
+        return SelectInst::Create(SI->getCondition(), A, N);
+    }
+  }
+  
+  // Check for X+0.0.  Simplify it to X if we know X is not -0.0.
+  if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
+    if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS))
+      return ReplaceInstUsesWith(I, LHS);
+
+  // Check for (add (sext x), y), see if we can merge this into an
+  // integer add followed by a sext.
+  if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
+    // (add (sext x), cst) --> (sext (add x, cst'))
+    if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
+      Constant *CI = 
+        ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
+      if (LHSConv->hasOneUse() &&
+          ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
+          WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
+        // Insert the new, smaller add.
+        Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0), 
+                                                        CI, "addconv");
+        InsertNewInstBefore(NewAdd, I);
+        return new SExtInst(NewAdd, I.getType());
+      }
+    }
+    
+    // (add (sext x), (sext y)) --> (sext (add int x, y))
+    if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
+      // Only do this if x/y have the same type, if at last one of them has a
+      // single use (so we don't increase the number of sexts), and if the
+      // integer add will not overflow.
+      if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
+          (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
+          WillNotOverflowSignedAdd(LHSConv->getOperand(0),
+                                   RHSConv->getOperand(0))) {
+        // Insert the new integer add.
+        Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0), 
+                                                        RHSConv->getOperand(0),
+                                                        "addconv");
+        InsertNewInstBefore(NewAdd, I);
+        return new SExtInst(NewAdd, I.getType());
+      }
+    }
+  }
+  
+  // Check for (add double (sitofp x), y), see if we can merge this into an
+  // integer add followed by a promotion.
+  if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
+    // (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
+    // ... if the constant fits in the integer value.  This is useful for things
+    // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
+    // requires a constant pool load, and generally allows the add to be better
+    // instcombined.
+    if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
+      Constant *CI = 
+      ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
+      if (LHSConv->hasOneUse() &&
+          ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
+          WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
+        // Insert the new integer add.
+        Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0), 
+                                                        CI, "addconv");
+        InsertNewInstBefore(NewAdd, I);
+        return new SIToFPInst(NewAdd, I.getType());
+      }
+    }
+    
+    // (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
+    if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
+      // Only do this if x/y have the same type, if at last one of them has a
+      // single use (so we don't increase the number of int->fp conversions),
+      // and if the integer add will not overflow.
+      if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
+          (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
+          WillNotOverflowSignedAdd(LHSConv->getOperand(0),
+                                   RHSConv->getOperand(0))) {
+        // Insert the new integer add.
+        Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0), 
+                                                        RHSConv->getOperand(0),
+                                                        "addconv");
+        InsertNewInstBefore(NewAdd, I);
+        return new SIToFPInst(NewAdd, I.getType());
+      }
+    }
+  }
+  
+  return Changed ? &I : 0;
+}
+
+Instruction *InstCombiner::visitSub(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  if (Op0 == Op1 &&                        // sub X, X  -> 0
+      !I.getType()->isFPOrFPVector())
+    return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+  // If this is a 'B = x-(-A)', change to B = x+A...
+  if (Value *V = dyn_castNegVal(Op1))
+    return BinaryOperator::CreateAdd(Op0, V);
+
+  if (isa<UndefValue>(Op0))
+    return ReplaceInstUsesWith(I, Op0);    // undef - X -> undef
+  if (isa<UndefValue>(Op1))
+    return ReplaceInstUsesWith(I, Op1);    // X - undef -> undef
+
+  if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
+    // Replace (-1 - A) with (~A)...
+    if (C->isAllOnesValue())
+      return BinaryOperator::CreateNot(Op1);
+
+    // C - ~X == X + (1+C)
+    Value *X = 0;
+    if (match(Op1, m_Not(m_Value(X))))
+      return BinaryOperator::CreateAdd(X, AddOne(C));
+
+    // -(X >>u 31) -> (X >>s 31)
+    // -(X >>s 31) -> (X >>u 31)
+    if (C->isZero()) {
+      if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) {
+        if (SI->getOpcode() == Instruction::LShr) {
+          if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
+            // Check to see if we are shifting out everything but the sign bit.
+            if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
+                SI->getType()->getPrimitiveSizeInBits()-1) {
+              // Ok, the transformation is safe.  Insert AShr.
+              return BinaryOperator::Create(Instruction::AShr, 
+                                          SI->getOperand(0), CU, SI->getName());
+            }
+          }
+        }
+        else if (SI->getOpcode() == Instruction::AShr) {
+          if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
+            // Check to see if we are shifting out everything but the sign bit.
+            if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
+                SI->getType()->getPrimitiveSizeInBits()-1) {
+              // Ok, the transformation is safe.  Insert LShr. 
+              return BinaryOperator::CreateLShr(
+                                          SI->getOperand(0), CU, SI->getName());
+            }
+          }
+        }
+      }
+    }
+
+    // Try to fold constant sub into select arguments.
+    if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+      if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+        return R;
+  }
+
+  if (I.getType() == Type::Int1Ty)
+    return BinaryOperator::CreateXor(Op0, Op1);
+
+  if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
+    if (Op1I->getOpcode() == Instruction::Add &&
+        !Op0->getType()->isFPOrFPVector()) {
+      if (Op1I->getOperand(0) == Op0)              // X-(X+Y) == -Y
+        return BinaryOperator::CreateNeg(Op1I->getOperand(1), I.getName());
+      else if (Op1I->getOperand(1) == Op0)         // X-(Y+X) == -Y
+        return BinaryOperator::CreateNeg(Op1I->getOperand(0), I.getName());
+      else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
+        if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
+          // C1-(X+C2) --> (C1-C2)-X
+          return BinaryOperator::CreateSub(Subtract(CI1, CI2), 
+                                           Op1I->getOperand(0));
+      }
+    }
+
+    if (Op1I->hasOneUse()) {
+      // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
+      // is not used by anyone else...
+      //
+      if (Op1I->getOpcode() == Instruction::Sub &&
+          !Op1I->getType()->isFPOrFPVector()) {
+        // Swap the two operands of the subexpr...
+        Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
+        Op1I->setOperand(0, IIOp1);
+        Op1I->setOperand(1, IIOp0);
+
+        // Create the new top level add instruction...
+        return BinaryOperator::CreateAdd(Op0, Op1);
+      }
+
+      // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
+      //
+      if (Op1I->getOpcode() == Instruction::And &&
+          (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
+        Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
+
+        Value *NewNot =
+          InsertNewInstBefore(BinaryOperator::CreateNot(OtherOp, "B.not"), I);
+        return BinaryOperator::CreateAnd(Op0, NewNot);
+      }
+
+      // 0 - (X sdiv C)  -> (X sdiv -C)
+      if (Op1I->getOpcode() == Instruction::SDiv)
+        if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
+          if (CSI->isZero())
+            if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
+              return BinaryOperator::CreateSDiv(Op1I->getOperand(0),
+                                               ConstantExpr::getNeg(DivRHS));
+
+      // X - X*C --> X * (1-C)
+      ConstantInt *C2 = 0;
+      if (dyn_castFoldableMul(Op1I, C2) == Op0) {
+        Constant *CP1 = Subtract(ConstantInt::get(I.getType(), 1), C2);
+        return BinaryOperator::CreateMul(Op0, CP1);
+      }
+    }
+  }
+
+  if (!Op0->getType()->isFPOrFPVector())
+    if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+      if (Op0I->getOpcode() == Instruction::Add) {
+        if (Op0I->getOperand(0) == Op1)             // (Y+X)-Y == X
+          return ReplaceInstUsesWith(I, Op0I->getOperand(1));
+        else if (Op0I->getOperand(1) == Op1)        // (X+Y)-Y == X
+          return ReplaceInstUsesWith(I, Op0I->getOperand(0));
+      } else if (Op0I->getOpcode() == Instruction::Sub) {
+        if (Op0I->getOperand(0) == Op1)             // (X-Y)-X == -Y
+          return BinaryOperator::CreateNeg(Op0I->getOperand(1), I.getName());
+      }
+    }
+
+  ConstantInt *C1;
+  if (Value *X = dyn_castFoldableMul(Op0, C1)) {
+    if (X == Op1)  // X*C - X --> X * (C-1)
+      return BinaryOperator::CreateMul(Op1, SubOne(C1));
+
+    ConstantInt *C2;   // X*C1 - X*C2 -> X * (C1-C2)
+    if (X == dyn_castFoldableMul(Op1, C2))
+      return BinaryOperator::CreateMul(X, Subtract(C1, C2));
+  }
+  return 0;
+}
+
+/// isSignBitCheck - Given an exploded icmp instruction, return true if the
+/// comparison only checks the sign bit.  If it only checks the sign bit, set
+/// TrueIfSigned if the result of the comparison is true when the input value is
+/// signed.
+static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
+                           bool &TrueIfSigned) {
+  switch (pred) {
+  case ICmpInst::ICMP_SLT:   // True if LHS s< 0
+    TrueIfSigned = true;
+    return RHS->isZero();
+  case ICmpInst::ICMP_SLE:   // True if LHS s<= RHS and RHS == -1
+    TrueIfSigned = true;
+    return RHS->isAllOnesValue();
+  case ICmpInst::ICMP_SGT:   // True if LHS s> -1
+    TrueIfSigned = false;
+    return RHS->isAllOnesValue();
+  case ICmpInst::ICMP_UGT:
+    // True if LHS u> RHS and RHS == high-bit-mask - 1
+    TrueIfSigned = true;
+    return RHS->getValue() ==
+      APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
+  case ICmpInst::ICMP_UGE: 
+    // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
+    TrueIfSigned = true;
+    return RHS->getValue().isSignBit();
+  default:
+    return false;
+  }
+}
+
+Instruction *InstCombiner::visitMul(BinaryOperator &I) {
+  bool Changed = SimplifyCommutative(I);
+  Value *Op0 = I.getOperand(0);
+
+  if (isa<UndefValue>(I.getOperand(1)))              // undef * X -> 0
+    return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+  // Simplify mul instructions with a constant RHS...
+  if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+
+      // ((X << C1)*C2) == (X * (C2 << C1))
+      if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
+        if (SI->getOpcode() == Instruction::Shl)
+          if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
+            return BinaryOperator::CreateMul(SI->getOperand(0),
+                                             ConstantExpr::getShl(CI, ShOp));
+
+      if (CI->isZero())
+        return ReplaceInstUsesWith(I, Op1);  // X * 0  == 0
+      if (CI->equalsInt(1))                  // X * 1  == X
+        return ReplaceInstUsesWith(I, Op0);
+      if (CI->isAllOnesValue())              // X * -1 == 0 - X
+        return BinaryOperator::CreateNeg(Op0, I.getName());
+
+      const APInt& Val = cast<ConstantInt>(CI)->getValue();
+      if (Val.isPowerOf2()) {          // Replace X*(2^C) with X << C
+        return BinaryOperator::CreateShl(Op0,
+                 ConstantInt::get(Op0->getType(), Val.logBase2()));
+      }
+    } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
+      if (Op1F->isNullValue())
+        return ReplaceInstUsesWith(I, Op1);
+
+      // "In IEEE floating point, x*1 is not equivalent to x for nans.  However,
+      // ANSI says we can drop signals, so we can do this anyway." (from GCC)
+      if (Op1F->isExactlyValue(1.0))
+        return ReplaceInstUsesWith(I, Op0);  // Eliminate 'mul double %X, 1.0'
+    } else if (isa<VectorType>(Op1->getType())) {
+      if (isa<ConstantAggregateZero>(Op1))
+        return ReplaceInstUsesWith(I, Op1);
+
+      if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
+        if (Op1V->isAllOnesValue())              // X * -1 == 0 - X
+          return BinaryOperator::CreateNeg(Op0, I.getName());
+
+        // As above, vector X*splat(1.0) -> X in all defined cases.
+        if (Constant *Splat = Op1V->getSplatValue()) {
+          if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
+            if (F->isExactlyValue(1.0))
+              return ReplaceInstUsesWith(I, Op0);
+          if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat))
+            if (CI->equalsInt(1))
+              return ReplaceInstUsesWith(I, Op0);
+        }
+      }
+    }
+    
+    if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
+      if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
+          isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(Op1)) {
+        // Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
+        Instruction *Add = BinaryOperator::CreateMul(Op0I->getOperand(0),
+                                                     Op1, "tmp");
+        InsertNewInstBefore(Add, I);
+        Value *C1C2 = ConstantExpr::getMul(Op1, 
+                                           cast<Constant>(Op0I->getOperand(1)));
+        return BinaryOperator::CreateAdd(Add, C1C2);
+        
+      }
+
+    // Try to fold constant mul into select arguments.
+    if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+      if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+        return R;
+
+    if (isa<PHINode>(Op0))
+      if (Instruction *NV = FoldOpIntoPhi(I))
+        return NV;
+  }
+
+  if (Value *Op0v = dyn_castNegVal(Op0))     // -X * -Y = X*Y
+    if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
+      return BinaryOperator::CreateMul(Op0v, Op1v);
+
+  // (X / Y) *  Y = X - (X % Y)
+  // (X / Y) * -Y = (X % Y) - X
+  {
+    Value *Op1 = I.getOperand(1);
+    BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
+    if (!BO ||
+        (BO->getOpcode() != Instruction::UDiv && 
+         BO->getOpcode() != Instruction::SDiv)) {
+      Op1 = Op0;
+      BO = dyn_cast<BinaryOperator>(I.getOperand(1));
+    }
+    Value *Neg = dyn_castNegVal(Op1);
+    if (BO && BO->hasOneUse() &&
+        (BO->getOperand(1) == Op1 || BO->getOperand(1) == Neg) &&
+        (BO->getOpcode() == Instruction::UDiv ||
+         BO->getOpcode() == Instruction::SDiv)) {
+      Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
+
+      Instruction *Rem;
+      if (BO->getOpcode() == Instruction::UDiv)
+        Rem = BinaryOperator::CreateURem(Op0BO, Op1BO);
+      else
+        Rem = BinaryOperator::CreateSRem(Op0BO, Op1BO);
+
+      InsertNewInstBefore(Rem, I);
+      Rem->takeName(BO);
+
+      if (Op1BO == Op1)
+        return BinaryOperator::CreateSub(Op0BO, Rem);
+      else
+        return BinaryOperator::CreateSub(Rem, Op0BO);
+    }
+  }
+
+  if (I.getType() == Type::Int1Ty)
+    return BinaryOperator::CreateAnd(Op0, I.getOperand(1));
+
+  // If one of the operands of the multiply is a cast from a boolean value, then
+  // we know the bool is either zero or one, so this is a 'masking' multiply.
+  // See if we can simplify things based on how the boolean was originally
+  // formed.
+  CastInst *BoolCast = 0;
+  if (ZExtInst *CI = dyn_cast<ZExtInst>(Op0))
+    if (CI->getOperand(0)->getType() == Type::Int1Ty)
+      BoolCast = CI;
+  if (!BoolCast)
+    if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(1)))
+      if (CI->getOperand(0)->getType() == Type::Int1Ty)
+        BoolCast = CI;
+  if (BoolCast) {
+    if (ICmpInst *SCI = dyn_cast<ICmpInst>(BoolCast->getOperand(0))) {
+      Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
+      const Type *SCOpTy = SCIOp0->getType();
+      bool TIS = false;
+      
+      // If the icmp is true iff the sign bit of X is set, then convert this
+      // multiply into a shift/and combination.
+      if (isa<ConstantInt>(SCIOp1) &&
+          isSignBitCheck(SCI->getPredicate(), cast<ConstantInt>(SCIOp1), TIS) &&
+          TIS) {
+        // Shift the X value right to turn it into "all signbits".
+        Constant *Amt = ConstantInt::get(SCIOp0->getType(),
+                                          SCOpTy->getPrimitiveSizeInBits()-1);
+        Value *V =
+          InsertNewInstBefore(
+            BinaryOperator::Create(Instruction::AShr, SCIOp0, Amt,
+                                            BoolCast->getOperand(0)->getName()+
+                                            ".mask"), I);
+
+        // If the multiply type is not the same as the source type, sign extend
+        // or truncate to the multiply type.
+        if (I.getType() != V->getType()) {
+          uint32_t SrcBits = V->getType()->getPrimitiveSizeInBits();
+          uint32_t DstBits = I.getType()->getPrimitiveSizeInBits();
+          Instruction::CastOps opcode = 
+            (SrcBits == DstBits ? Instruction::BitCast : 
+             (SrcBits < DstBits ? Instruction::SExt : Instruction::Trunc));
+          V = InsertCastBefore(opcode, V, I.getType(), I);
+        }
+
+        Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
+        return BinaryOperator::CreateAnd(V, OtherOp);
+      }
+    }
+  }
+
+  return Changed ? &I : 0;
+}
+
+/// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
+/// instruction.
+bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
+  SelectInst *SI = cast<SelectInst>(I.getOperand(1));
+  
+  // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
+  int NonNullOperand = -1;
+  if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
+    if (ST->isNullValue())
+      NonNullOperand = 2;
+  // div/rem X, (Cond ? Y : 0) -> div/rem X, Y
+  if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
+    if (ST->isNullValue())
+      NonNullOperand = 1;
+  
+  if (NonNullOperand == -1)
+    return false;
+  
+  Value *SelectCond = SI->getOperand(0);
+  
+  // Change the div/rem to use 'Y' instead of the select.
+  I.setOperand(1, SI->getOperand(NonNullOperand));
+  
+  // Okay, we know we replace the operand of the div/rem with 'Y' with no
+  // problem.  However, the select, or the condition of the select may have
+  // multiple uses.  Based on our knowledge that the operand must be non-zero,
+  // propagate the known value for the select into other uses of it, and
+  // propagate a known value of the condition into its other users.
+  
+  // If the select and condition only have a single use, don't bother with this,
+  // early exit.
+  if (SI->use_empty() && SelectCond->hasOneUse())
+    return true;
+  
+  // Scan the current block backward, looking for other uses of SI.
+  BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
+  
+  while (BBI != BBFront) {
+    --BBI;
+    // If we found a call to a function, we can't assume it will return, so
+    // information from below it cannot be propagated above it.
+    if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
+      break;
+    
+    // Replace uses of the select or its condition with the known values.
+    for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
+         I != E; ++I) {
+      if (*I == SI) {
+        *I = SI->getOperand(NonNullOperand);
+        AddToWorkList(BBI);
+      } else if (*I == SelectCond) {
+        *I = NonNullOperand == 1 ? ConstantInt::getTrue() :
+                                   ConstantInt::getFalse();
+        AddToWorkList(BBI);
+      }
+    }
+    
+    // If we past the instruction, quit looking for it.
+    if (&*BBI == SI)
+      SI = 0;
+    if (&*BBI == SelectCond)
+      SelectCond = 0;
+    
+    // If we ran out of things to eliminate, break out of the loop.
+    if (SelectCond == 0 && SI == 0)
+      break;
+    
+  }
+  return true;
+}
+
+
+/// This function implements the transforms on div instructions that work
+/// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
+/// used by the visitors to those instructions.
+/// @brief Transforms common to all three div instructions
+Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  // undef / X -> 0        for integer.
+  // undef / X -> undef    for FP (the undef could be a snan).
+  if (isa<UndefValue>(Op0)) {
+    if (Op0->getType()->isFPOrFPVector())
+      return ReplaceInstUsesWith(I, Op0);
+    return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+  }
+
+  // X / undef -> undef
+  if (isa<UndefValue>(Op1))
+    return ReplaceInstUsesWith(I, Op1);
+
+  return 0;
+}
+
+/// This function implements the transforms common to both integer division
+/// instructions (udiv and sdiv). It is called by the visitors to those integer
+/// division instructions.
+/// @brief Common integer divide transforms
+Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  // (sdiv X, X) --> 1     (udiv X, X) --> 1
+  if (Op0 == Op1) {
+    if (const VectorType *Ty = dyn_cast<VectorType>(I.getType())) {
+      ConstantInt *CI = ConstantInt::get(Ty->getElementType(), 1);
+      std::vector<Constant*> Elts(Ty->getNumElements(), CI);
+      return ReplaceInstUsesWith(I, ConstantVector::get(Elts));
+    }
+
+    ConstantInt *CI = ConstantInt::get(I.getType(), 1);
+    return ReplaceInstUsesWith(I, CI);
+  }
+  
+  if (Instruction *Common = commonDivTransforms(I))
+    return Common;
+  
+  // Handle cases involving: [su]div X, (select Cond, Y, Z)
+  // This does not apply for fdiv.
+  if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
+    return &I;
+
+  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+    // div X, 1 == X
+    if (RHS->equalsInt(1))
+      return ReplaceInstUsesWith(I, Op0);
+
+    // (X / C1) / C2  -> X / (C1*C2)
+    if (Instruction *LHS = dyn_cast<Instruction>(Op0))
+      if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
+        if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
+          if (MultiplyOverflows(RHS, LHSRHS, I.getOpcode()==Instruction::SDiv))
+            return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+          else 
+            return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
+                                          Multiply(RHS, LHSRHS));
+        }
+
+    if (!RHS->isZero()) { // avoid X udiv 0
+      if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+        if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+          return R;
+      if (isa<PHINode>(Op0))
+        if (Instruction *NV = FoldOpIntoPhi(I))
+          return NV;
+    }
+  }
+
+  // 0 / X == 0, we don't need to preserve faults!
+  if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
+    if (LHS->equalsInt(0))
+      return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+  // It can't be division by zero, hence it must be division by one.
+  if (I.getType() == Type::Int1Ty)
+    return ReplaceInstUsesWith(I, Op0);
+
+  if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
+    if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue()))
+      // div X, 1 == X
+      if (X->isOne())
+        return ReplaceInstUsesWith(I, Op0);
+  }
+
+  return 0;
+}
+
+Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  // Handle the integer div common cases
+  if (Instruction *Common = commonIDivTransforms(I))
+    return Common;
+
+  if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
+    // X udiv C^2 -> X >> C
+    // Check to see if this is an unsigned division with an exact power of 2,
+    // if so, convert to a right shift.
+    if (C->getValue().isPowerOf2())  // 0 not included in isPowerOf2
+      return BinaryOperator::CreateLShr(Op0, 
+               ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
+
+    // X udiv C, where C >= signbit
+    if (C->getValue().isNegative()) {
+      Value *IC = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_ULT, Op0, C),
+                                      I);
+      return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
+                                ConstantInt::get(I.getType(), 1));
+    }
+  }
+
+  // X udiv (C1 << N), where C1 is "1<<C2"  -->  X >> (N+C2)
+  if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
+    if (RHSI->getOpcode() == Instruction::Shl &&
+        isa<ConstantInt>(RHSI->getOperand(0))) {
+      const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
+      if (C1.isPowerOf2()) {
+        Value *N = RHSI->getOperand(1);
+        const Type *NTy = N->getType();
+        if (uint32_t C2 = C1.logBase2()) {
+          Constant *C2V = ConstantInt::get(NTy, C2);
+          N = InsertNewInstBefore(BinaryOperator::CreateAdd(N, C2V, "tmp"), I);
+        }
+        return BinaryOperator::CreateLShr(Op0, N);
+      }
+    }
+  }
+  
+  // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
+  // where C1&C2 are powers of two.
+  if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) 
+    if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
+      if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2)))  {
+        const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
+        if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
+          // Compute the shift amounts
+          uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
+          // Construct the "on true" case of the select
+          Constant *TC = ConstantInt::get(Op0->getType(), TSA);
+          Instruction *TSI = BinaryOperator::CreateLShr(
+                                                 Op0, TC, SI->getName()+".t");
+          TSI = InsertNewInstBefore(TSI, I);
+  
+          // Construct the "on false" case of the select
+          Constant *FC = ConstantInt::get(Op0->getType(), FSA); 
+          Instruction *FSI = BinaryOperator::CreateLShr(
+                                                 Op0, FC, SI->getName()+".f");
+          FSI = InsertNewInstBefore(FSI, I);
+
+          // construct the select instruction and return it.
+          return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName());
+        }
+      }
+  return 0;
+}
+
+Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  // Handle the integer div common cases
+  if (Instruction *Common = commonIDivTransforms(I))
+    return Common;
+
+  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+    // sdiv X, -1 == -X
+    if (RHS->isAllOnesValue())
+      return BinaryOperator::CreateNeg(Op0);
+  }
+
+  // If the sign bits of both operands are zero (i.e. we can prove they are
+  // unsigned inputs), turn this into a udiv.
+  if (I.getType()->isInteger()) {
+    APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
+    if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
+      // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
+      return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
+    }
+  }      
+  
+  return 0;
+}
+
+Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
+  return commonDivTransforms(I);
+}
+
+/// This function implements the transforms on rem instructions that work
+/// regardless of the kind of rem instruction it is (urem, srem, or frem). It 
+/// is used by the visitors to those instructions.
+/// @brief Transforms common to all three rem instructions
+Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  if (isa<UndefValue>(Op0)) {             // undef % X -> 0
+    if (I.getType()->isFPOrFPVector())
+      return ReplaceInstUsesWith(I, Op0);  // X % undef -> undef (could be SNaN)
+    return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+  }
+  if (isa<UndefValue>(Op1))
+    return ReplaceInstUsesWith(I, Op1);  // X % undef -> undef
+
+  // Handle cases involving: rem X, (select Cond, Y, Z)
+  if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
+    return &I;
+
+  return 0;
+}
+
+/// This function implements the transforms common to both integer remainder
+/// instructions (urem and srem). It is called by the visitors to those integer
+/// remainder instructions.
+/// @brief Common integer remainder transforms
+Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  if (Instruction *common = commonRemTransforms(I))
+    return common;
+
+  // 0 % X == 0 for integer, we don't need to preserve faults!
+  if (Constant *LHS = dyn_cast<Constant>(Op0))
+    if (LHS->isNullValue())
+      return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+    // X % 0 == undef, we don't need to preserve faults!
+    if (RHS->equalsInt(0))
+      return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
+    
+    if (RHS->equalsInt(1))  // X % 1 == 0
+      return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+    if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
+      if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
+        if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+          return R;
+      } else if (isa<PHINode>(Op0I)) {
+        if (Instruction *NV = FoldOpIntoPhi(I))
+          return NV;
+      }
+
+      // See if we can fold away this rem instruction.
+      if (SimplifyDemandedInstructionBits(I))
+        return &I;
+    }
+  }
+
+  return 0;
+}
+
+Instruction *InstCombiner::visitURem(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  if (Instruction *common = commonIRemTransforms(I))
+    return common;
+  
+  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+    // X urem C^2 -> X and C
+    // Check to see if this is an unsigned remainder with an exact power of 2,
+    // if so, convert to a bitwise and.
+    if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
+      if (C->getValue().isPowerOf2())
+        return BinaryOperator::CreateAnd(Op0, SubOne(C));
+  }
+
+  if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
+    // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)  
+    if (RHSI->getOpcode() == Instruction::Shl &&
+        isa<ConstantInt>(RHSI->getOperand(0))) {
+      if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
+        Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
+        Value *Add = InsertNewInstBefore(BinaryOperator::CreateAdd(RHSI, N1,
+                                                                   "tmp"), I);
+        return BinaryOperator::CreateAnd(Op0, Add);
+      }
+    }
+  }
+
+  // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
+  // where C1&C2 are powers of two.
+  if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
+    if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
+      if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
+        // STO == 0 and SFO == 0 handled above.
+        if ((STO->getValue().isPowerOf2()) && 
+            (SFO->getValue().isPowerOf2())) {
+          Value *TrueAnd = InsertNewInstBefore(
+            BinaryOperator::CreateAnd(Op0, SubOne(STO), SI->getName()+".t"), I);
+          Value *FalseAnd = InsertNewInstBefore(
+            BinaryOperator::CreateAnd(Op0, SubOne(SFO), SI->getName()+".f"), I);
+          return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd);
+        }
+      }
+  }
+  
+  return 0;
+}
+
+Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  // Handle the integer rem common cases
+  if (Instruction *common = commonIRemTransforms(I))
+    return common;
+  
+  if (Value *RHSNeg = dyn_castNegVal(Op1))
+    if (!isa<Constant>(RHSNeg) ||
+        (isa<ConstantInt>(RHSNeg) &&
+         cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
+      // X % -Y -> X % Y
+      AddUsesToWorkList(I);
+      I.setOperand(1, RHSNeg);
+      return &I;
+    }
+
+  // If the sign bits of both operands are zero (i.e. we can prove they are
+  // unsigned inputs), turn this into a urem.
+  if (I.getType()->isInteger()) {
+    APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
+    if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
+      // X srem Y -> X urem Y, iff X and Y don't have sign bit set
+      return BinaryOperator::CreateURem(Op0, Op1, I.getName());
+    }
+  }
+
+  // If it's a constant vector, flip any negative values positive.
+  if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
+    unsigned VWidth = RHSV->getNumOperands();
+
+    bool hasNegative = false;
+    for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
+      if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
+        if (RHS->getValue().isNegative())
+          hasNegative = true;
+
+    if (hasNegative) {
+      std::vector<Constant *> Elts(VWidth);
+      for (unsigned i = 0; i != VWidth; ++i) {
+        if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
+          if (RHS->getValue().isNegative())
+            Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
+          else
+            Elts[i] = RHS;
+        }
+      }
+
+      Constant *NewRHSV = ConstantVector::get(Elts);
+      if (NewRHSV != RHSV) {
+        AddUsesToWorkList(I);
+        I.setOperand(1, NewRHSV);
+        return &I;
+      }
+    }
+  }
+
+  return 0;
+}
+
+Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
+  return commonRemTransforms(I);
+}
+
+// isOneBitSet - Return true if there is exactly one bit set in the specified
+// constant.
+static bool isOneBitSet(const ConstantInt *CI) {
+  return CI->getValue().isPowerOf2();
+}
+
+// isHighOnes - Return true if the constant is of the form 1+0+.
+// This is the same as lowones(~X).
+static bool isHighOnes(const ConstantInt *CI) {
+  return (~CI->getValue() + 1).isPowerOf2();
+}
+
+/// getICmpCode - Encode a icmp predicate into a three bit mask.  These bits
+/// are carefully arranged to allow folding of expressions such as:
+///
+///      (A < B) | (A > B) --> (A != B)
+///
+/// Note that this is only valid if the first and second predicates have the
+/// same sign. Is illegal to do: (A u< B) | (A s> B) 
+///
+/// Three bits are used to represent the condition, as follows:
+///   0  A > B
+///   1  A == B
+///   2  A < B
+///
+/// <=>  Value  Definition
+/// 000     0   Always false
+/// 001     1   A >  B
+/// 010     2   A == B
+/// 011     3   A >= B
+/// 100     4   A <  B
+/// 101     5   A != B
+/// 110     6   A <= B
+/// 111     7   Always true
+///  
+static unsigned getICmpCode(const ICmpInst *ICI) {
+  switch (ICI->getPredicate()) {
+    // False -> 0
+  case ICmpInst::ICMP_UGT: return 1;  // 001
+  case ICmpInst::ICMP_SGT: return 1;  // 001
+  case ICmpInst::ICMP_EQ:  return 2;  // 010
+  case ICmpInst::ICMP_UGE: return 3;  // 011
+  case ICmpInst::ICMP_SGE: return 3;  // 011
+  case ICmpInst::ICMP_ULT: return 4;  // 100
+  case ICmpInst::ICMP_SLT: return 4;  // 100
+  case ICmpInst::ICMP_NE:  return 5;  // 101
+  case ICmpInst::ICMP_ULE: return 6;  // 110
+  case ICmpInst::ICMP_SLE: return 6;  // 110
+    // True -> 7
+  default:
+    assert(0 && "Invalid ICmp predicate!");
+    return 0;
+  }
+}
+
+/// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp
+/// predicate into a three bit mask. It also returns whether it is an ordered
+/// predicate by reference.
+static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
+  isOrdered = false;
+  switch (CC) {
+  case FCmpInst::FCMP_ORD: isOrdered = true; return 0;  // 000
+  case FCmpInst::FCMP_UNO:                   return 0;  // 000
+  case FCmpInst::FCMP_OGT: isOrdered = true; return 1;  // 001
+  case FCmpInst::FCMP_UGT:                   return 1;  // 001
+  case FCmpInst::FCMP_OEQ: isOrdered = true; return 2;  // 010
+  case FCmpInst::FCMP_UEQ:                   return 2;  // 010
+  case FCmpInst::FCMP_OGE: isOrdered = true; return 3;  // 011
+  case FCmpInst::FCMP_UGE:                   return 3;  // 011
+  case FCmpInst::FCMP_OLT: isOrdered = true; return 4;  // 100
+  case FCmpInst::FCMP_ULT:                   return 4;  // 100
+  case FCmpInst::FCMP_ONE: isOrdered = true; return 5;  // 101
+  case FCmpInst::FCMP_UNE:                   return 5;  // 101
+  case FCmpInst::FCMP_OLE: isOrdered = true; return 6;  // 110
+  case FCmpInst::FCMP_ULE:                   return 6;  // 110
+    // True -> 7
+  default:
+    // Not expecting FCMP_FALSE and FCMP_TRUE;
+    assert(0 && "Unexpected FCmp predicate!");
+    return 0;
+  }
+}
+
+/// getICmpValue - This is the complement of getICmpCode, which turns an
+/// opcode and two operands into either a constant true or false, or a brand 
+/// new ICmp instruction. The sign is passed in to determine which kind
+/// of predicate to use in the new icmp instruction.
+static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS) {
+  switch (code) {
+  default: assert(0 && "Illegal ICmp code!");
+  case  0: return ConstantInt::getFalse();
+  case  1: 
+    if (sign)
+      return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
+    else
+      return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
+  case  2: return new ICmpInst(ICmpInst::ICMP_EQ,  LHS, RHS);
+  case  3: 
+    if (sign)
+      return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
+    else
+      return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
+  case  4: 
+    if (sign)
+      return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
+    else
+      return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
+  case  5: return new ICmpInst(ICmpInst::ICMP_NE,  LHS, RHS);
+  case  6: 
+    if (sign)
+      return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
+    else
+      return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
+  case  7: return ConstantInt::getTrue();
+  }
+}
+
+/// getFCmpValue - This is the complement of getFCmpCode, which turns an
+/// opcode and two operands into either a FCmp instruction. isordered is passed
+/// in to determine which kind of predicate to use in the new fcmp instruction.
+static Value *getFCmpValue(bool isordered, unsigned code,
+                           Value *LHS, Value *RHS) {
+  switch (code) {
+  default: assert(0 && "Illegal FCmp code!");
+  case  0:
+    if (isordered)
+      return new FCmpInst(FCmpInst::FCMP_ORD, LHS, RHS);
+    else
+      return new FCmpInst(FCmpInst::FCMP_UNO, LHS, RHS);
+  case  1: 
+    if (isordered)
+      return new FCmpInst(FCmpInst::FCMP_OGT, LHS, RHS);
+    else
+      return new FCmpInst(FCmpInst::FCMP_UGT, LHS, RHS);
+  case  2: 
+    if (isordered)
+      return new FCmpInst(FCmpInst::FCMP_OEQ, LHS, RHS);
+    else
+      return new FCmpInst(FCmpInst::FCMP_UEQ, LHS, RHS);
+  case  3: 
+    if (isordered)
+      return new FCmpInst(FCmpInst::FCMP_OGE, LHS, RHS);
+    else
+      return new FCmpInst(FCmpInst::FCMP_UGE, LHS, RHS);
+  case  4: 
+    if (isordered)
+      return new FCmpInst(FCmpInst::FCMP_OLT, LHS, RHS);
+    else
+      return new FCmpInst(FCmpInst::FCMP_ULT, LHS, RHS);
+  case  5: 
+    if (isordered)
+      return new FCmpInst(FCmpInst::FCMP_ONE, LHS, RHS);
+    else
+      return new FCmpInst(FCmpInst::FCMP_UNE, LHS, RHS);
+  case  6: 
+    if (isordered)
+      return new FCmpInst(FCmpInst::FCMP_OLE, LHS, RHS);
+    else
+      return new FCmpInst(FCmpInst::FCMP_ULE, LHS, RHS);
+  case  7: return ConstantInt::getTrue();
+  }
+}
+
+/// PredicatesFoldable - Return true if both predicates match sign or if at
+/// least one of them is an equality comparison (which is signless).
+static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
+  return (ICmpInst::isSignedPredicate(p1) == ICmpInst::isSignedPredicate(p2)) ||
+         (ICmpInst::isSignedPredicate(p1) && ICmpInst::isEquality(p2)) ||
+         (ICmpInst::isSignedPredicate(p2) && ICmpInst::isEquality(p1));
+}
+
+namespace { 
+// FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
+struct FoldICmpLogical {
+  InstCombiner &IC;
+  Value *LHS, *RHS;
+  ICmpInst::Predicate pred;
+  FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
+    : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
+      pred(ICI->getPredicate()) {}
+  bool shouldApply(Value *V) const {
+    if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
+      if (PredicatesFoldable(pred, ICI->getPredicate()))
+        return ((ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS) ||
+                (ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS));
+    return false;
+  }
+  Instruction *apply(Instruction &Log) const {
+    ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
+    if (ICI->getOperand(0) != LHS) {
+      assert(ICI->getOperand(1) == LHS);
+      ICI->swapOperands();  // Swap the LHS and RHS of the ICmp
+    }
+
+    ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
+    unsigned LHSCode = getICmpCode(ICI);
+    unsigned RHSCode = getICmpCode(RHSICI);
+    unsigned Code;
+    switch (Log.getOpcode()) {
+    case Instruction::And: Code = LHSCode & RHSCode; break;
+    case Instruction::Or:  Code = LHSCode | RHSCode; break;
+    case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
+    default: assert(0 && "Illegal logical opcode!"); return 0;
+    }
+
+    bool isSigned = ICmpInst::isSignedPredicate(RHSICI->getPredicate()) || 
+                    ICmpInst::isSignedPredicate(ICI->getPredicate());
+      
+    Value *RV = getICmpValue(isSigned, Code, LHS, RHS);
+    if (Instruction *I = dyn_cast<Instruction>(RV))
+      return I;
+    // Otherwise, it's a constant boolean value...
+    return IC.ReplaceInstUsesWith(Log, RV);
+  }
+};
+} // end anonymous namespace
+
+// OptAndOp - This handles expressions of the form ((val OP C1) & C2).  Where
+// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'.  Op is
+// guaranteed to be a binary operator.
+Instruction *InstCombiner::OptAndOp(Instruction *Op,
+                                    ConstantInt *OpRHS,
+                                    ConstantInt *AndRHS,
+                                    BinaryOperator &TheAnd) {
+  Value *X = Op->getOperand(0);
+  Constant *Together = 0;
+  if (!Op->isShift())
+    Together = And(AndRHS, OpRHS);
+
+  switch (Op->getOpcode()) {
+  case Instruction::Xor:
+    if (Op->hasOneUse()) {
+      // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
+      Instruction *And = BinaryOperator::CreateAnd(X, AndRHS);
+      InsertNewInstBefore(And, TheAnd);
+      And->takeName(Op);
+      return BinaryOperator::CreateXor(And, Together);
+    }
+    break;
+  case Instruction::Or:
+    if (Together == AndRHS) // (X | C) & C --> C
+      return ReplaceInstUsesWith(TheAnd, AndRHS);
+
+    if (Op->hasOneUse() && Together != OpRHS) {
+      // (X | C1) & C2 --> (X | (C1&C2)) & C2
+      Instruction *Or = BinaryOperator::CreateOr(X, Together);
+      InsertNewInstBefore(Or, TheAnd);
+      Or->takeName(Op);
+      return BinaryOperator::CreateAnd(Or, AndRHS);
+    }
+    break;
+  case Instruction::Add:
+    if (Op->hasOneUse()) {
+      // Adding a one to a single bit bit-field should be turned into an XOR
+      // of the bit.  First thing to check is to see if this AND is with a
+      // single bit constant.
+      const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
+
+      // If there is only one bit set...
+      if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
+        // Ok, at this point, we know that we are masking the result of the
+        // ADD down to exactly one bit.  If the constant we are adding has
+        // no bits set below this bit, then we can eliminate the ADD.
+        const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
+
+        // Check to see if any bits below the one bit set in AndRHSV are set.
+        if ((AddRHS & (AndRHSV-1)) == 0) {
+          // If not, the only thing that can effect the output of the AND is
+          // the bit specified by AndRHSV.  If that bit is set, the effect of
+          // the XOR is to toggle the bit.  If it is clear, then the ADD has
+          // no effect.
+          if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
+            TheAnd.setOperand(0, X);
+            return &TheAnd;
+          } else {
+            // Pull the XOR out of the AND.
+            Instruction *NewAnd = BinaryOperator::CreateAnd(X, AndRHS);
+            InsertNewInstBefore(NewAnd, TheAnd);
+            NewAnd->takeName(Op);
+            return BinaryOperator::CreateXor(NewAnd, AndRHS);
+          }
+        }
+      }
+    }
+    break;
+
+  case Instruction::Shl: {
+    // We know that the AND will not produce any of the bits shifted in, so if
+    // the anded constant includes them, clear them now!
+    //
+    uint32_t BitWidth = AndRHS->getType()->getBitWidth();
+    uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
+    APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
+    ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShlMask);
+
+    if (CI->getValue() == ShlMask) { 
+    // Masking out bits that the shift already masks
+      return ReplaceInstUsesWith(TheAnd, Op);   // No need for the and.
+    } else if (CI != AndRHS) {                  // Reducing bits set in and.
+      TheAnd.setOperand(1, CI);
+      return &TheAnd;
+    }
+    break;
+  }
+  case Instruction::LShr:
+  {
+    // We know that the AND will not produce any of the bits shifted in, so if
+    // the anded constant includes them, clear them now!  This only applies to
+    // unsigned shifts, because a signed shr may bring in set bits!
+    //
+    uint32_t BitWidth = AndRHS->getType()->getBitWidth();
+    uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
+    APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
+    ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShrMask);
+
+    if (CI->getValue() == ShrMask) {   
+    // Masking out bits that the shift already masks.
+      return ReplaceInstUsesWith(TheAnd, Op);
+    } else if (CI != AndRHS) {
+      TheAnd.setOperand(1, CI);  // Reduce bits set in and cst.
+      return &TheAnd;
+    }
+    break;
+  }
+  case Instruction::AShr:
+    // Signed shr.
+    // See if this is shifting in some sign extension, then masking it out
+    // with an and.
+    if (Op->hasOneUse()) {
+      uint32_t BitWidth = AndRHS->getType()->getBitWidth();
+      uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
+      APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
+      Constant *C = ConstantInt::get(AndRHS->getValue() & ShrMask);
+      if (C == AndRHS) {          // Masking out bits shifted in.
+        // (Val ashr C1) & C2 -> (Val lshr C1) & C2
+        // Make the argument unsigned.
+        Value *ShVal = Op->getOperand(0);
+        ShVal = InsertNewInstBefore(
+            BinaryOperator::CreateLShr(ShVal, OpRHS, 
+                                   Op->getName()), TheAnd);
+        return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
+      }
+    }
+    break;
+  }
+  return 0;
+}
+
+
+/// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
+/// true, otherwise (V < Lo || V >= Hi).  In pratice, we emit the more efficient
+/// (V-Lo) <u Hi-Lo.  This method expects that Lo <= Hi. isSigned indicates
+/// whether to treat the V, Lo and HI as signed or not. IB is the location to
+/// insert new instructions.
+Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
+                                           bool isSigned, bool Inside, 
+                                           Instruction &IB) {
+  assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ? 
+            ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
+         "Lo is not <= Hi in range emission code!");
+    
+  if (Inside) {
+    if (Lo == Hi)  // Trivially false.
+      return new ICmpInst(ICmpInst::ICMP_NE, V, V);
+
+    // V >= Min && V < Hi --> V < Hi
+    if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
+      ICmpInst::Predicate pred = (isSigned ? 
+        ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
+      return new ICmpInst(pred, V, Hi);
+    }
+
+    // Emit V-Lo <u Hi-Lo
+    Constant *NegLo = ConstantExpr::getNeg(Lo);
+    Instruction *Add = BinaryOperator::CreateAdd(V, NegLo, V->getName()+".off");
+    InsertNewInstBefore(Add, IB);
+    Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
+    return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
+  }
+
+  if (Lo == Hi)  // Trivially true.
+    return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
+
+  // V < Min || V >= Hi -> V > Hi-1
+  Hi = SubOne(cast<ConstantInt>(Hi));
+  if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
+    ICmpInst::Predicate pred = (isSigned ? 
+        ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
+    return new ICmpInst(pred, V, Hi);
+  }
+
+  // Emit V-Lo >u Hi-1-Lo
+  // Note that Hi has already had one subtracted from it, above.
+  ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
+  Instruction *Add = BinaryOperator::CreateAdd(V, NegLo, V->getName()+".off");
+  InsertNewInstBefore(Add, IB);
+  Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
+  return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
+}
+
+// isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
+// any number of 0s on either side.  The 1s are allowed to wrap from LSB to
+// MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs.  0x0F0F0000 is
+// not, since all 1s are not contiguous.
+static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
+  const APInt& V = Val->getValue();
+  uint32_t BitWidth = Val->getType()->getBitWidth();
+  if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
+
+  // look for the first zero bit after the run of ones
+  MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
+  // look for the first non-zero bit
+  ME = V.getActiveBits(); 
+  return true;
+}
+
+/// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
+/// where isSub determines whether the operator is a sub.  If we can fold one of
+/// the following xforms:
+/// 
+/// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
+/// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
+/// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
+///
+/// return (A +/- B).
+///
+Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
+                                        ConstantInt *Mask, bool isSub,
+                                        Instruction &I) {
+  Instruction *LHSI = dyn_cast<Instruction>(LHS);
+  if (!LHSI || LHSI->getNumOperands() != 2 ||
+      !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
+
+  ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
+
+  switch (LHSI->getOpcode()) {
+  default: return 0;
+  case Instruction::And:
+    if (And(N, Mask) == Mask) {
+      // If the AndRHS is a power of two minus one (0+1+), this is simple.
+      if ((Mask->getValue().countLeadingZeros() + 
+           Mask->getValue().countPopulation()) == 
+          Mask->getValue().getBitWidth())
+        break;
+
+      // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
+      // part, we don't need any explicit masks to take them out of A.  If that
+      // is all N is, ignore it.
+      uint32_t MB = 0, ME = 0;
+      if (isRunOfOnes(Mask, MB, ME)) {  // begin/end bit of run, inclusive
+        uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
+        APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
+        if (MaskedValueIsZero(RHS, Mask))
+          break;
+      }
+    }
+    return 0;
+  case Instruction::Or:
+  case Instruction::Xor:
+    // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
+    if ((Mask->getValue().countLeadingZeros() + 
+         Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
+        && And(N, Mask)->isZero())
+      break;
+    return 0;
+  }
+  
+  Instruction *New;
+  if (isSub)
+    New = BinaryOperator::CreateSub(LHSI->getOperand(0), RHS, "fold");
+  else
+    New = BinaryOperator::CreateAdd(LHSI->getOperand(0), RHS, "fold");
+  return InsertNewInstBefore(New, I);
+}
+
+/// FoldAndOfICmps - Fold (icmp)&(icmp) if possible.
+Instruction *InstCombiner::FoldAndOfICmps(Instruction &I,
+                                          ICmpInst *LHS, ICmpInst *RHS) {
+  Value *Val, *Val2;
+  ConstantInt *LHSCst, *RHSCst;
+  ICmpInst::Predicate LHSCC, RHSCC;
+  
+  // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
+  if (!match(LHS, m_ICmp(LHSCC, m_Value(Val), m_ConstantInt(LHSCst))) ||
+      !match(RHS, m_ICmp(RHSCC, m_Value(Val2), m_ConstantInt(RHSCst))))
+    return 0;
+  
+  // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
+  // where C is a power of 2
+  if (LHSCst == RHSCst && LHSCC == RHSCC && LHSCC == ICmpInst::ICMP_ULT &&
+      LHSCst->getValue().isPowerOf2()) {
+    Instruction *NewOr = BinaryOperator::CreateOr(Val, Val2);
+    InsertNewInstBefore(NewOr, I);
+    return new ICmpInst(LHSCC, NewOr, LHSCst);
+  }
+  
+  // From here on, we only handle:
+  //    (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
+  if (Val != Val2) return 0;
+  
+  // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
+  if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
+      RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
+      LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
+      RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
+    return 0;
+  
+  // We can't fold (ugt x, C) & (sgt x, C2).
+  if (!PredicatesFoldable(LHSCC, RHSCC))
+    return 0;
+    
+  // Ensure that the larger constant is on the RHS.
+  bool ShouldSwap;
+  if (ICmpInst::isSignedPredicate(LHSCC) ||
+      (ICmpInst::isEquality(LHSCC) && 
+       ICmpInst::isSignedPredicate(RHSCC)))
+    ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
+  else
+    ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
+    
+  if (ShouldSwap) {
+    std::swap(LHS, RHS);
+    std::swap(LHSCst, RHSCst);
+    std::swap(LHSCC, RHSCC);
+  }
+
+  // At this point, we know we have have two icmp instructions
+  // comparing a value against two constants and and'ing the result
+  // together.  Because of the above check, we know that we only have
+  // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know 
+  // (from the FoldICmpLogical check above), that the two constants 
+  // are not equal and that the larger constant is on the RHS
+  assert(LHSCst != RHSCst && "Compares not folded above?");
+
+  switch (LHSCC) {
+  default: assert(0 && "Unknown integer condition code!");
+  case ICmpInst::ICMP_EQ:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:         // (X == 13 & X == 15) -> false
+    case ICmpInst::ICMP_UGT:        // (X == 13 & X >  15) -> false
+    case ICmpInst::ICMP_SGT:        // (X == 13 & X >  15) -> false
+      return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+    case ICmpInst::ICMP_NE:         // (X == 13 & X != 15) -> X == 13
+    case ICmpInst::ICMP_ULT:        // (X == 13 & X <  15) -> X == 13
+    case ICmpInst::ICMP_SLT:        // (X == 13 & X <  15) -> X == 13
+      return ReplaceInstUsesWith(I, LHS);
+    }
+  case ICmpInst::ICMP_NE:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_ULT:
+      if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
+        return new ICmpInst(ICmpInst::ICMP_ULT, Val, LHSCst);
+      break;                        // (X != 13 & X u< 15) -> no change
+    case ICmpInst::ICMP_SLT:
+      if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
+        return new ICmpInst(ICmpInst::ICMP_SLT, Val, LHSCst);
+      break;                        // (X != 13 & X s< 15) -> no change
+    case ICmpInst::ICMP_EQ:         // (X != 13 & X == 15) -> X == 15
+    case ICmpInst::ICMP_UGT:        // (X != 13 & X u> 15) -> X u> 15
+    case ICmpInst::ICMP_SGT:        // (X != 13 & X s> 15) -> X s> 15
+      return ReplaceInstUsesWith(I, RHS);
+    case ICmpInst::ICMP_NE:
+      if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
+        Constant *AddCST = ConstantExpr::getNeg(LHSCst);
+        Instruction *Add = BinaryOperator::CreateAdd(Val, AddCST,
+                                                     Val->getName()+".off");
+        InsertNewInstBefore(Add, I);
+        return new ICmpInst(ICmpInst::ICMP_UGT, Add,
+                            ConstantInt::get(Add->getType(), 1));
+      }
+      break;                        // (X != 13 & X != 15) -> no change
+    }
+    break;
+  case ICmpInst::ICMP_ULT:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:         // (X u< 13 & X == 15) -> false
+    case ICmpInst::ICMP_UGT:        // (X u< 13 & X u> 15) -> false
+      return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+    case ICmpInst::ICMP_SGT:        // (X u< 13 & X s> 15) -> no change
+      break;
+    case ICmpInst::ICMP_NE:         // (X u< 13 & X != 15) -> X u< 13
+    case ICmpInst::ICMP_ULT:        // (X u< 13 & X u< 15) -> X u< 13
+      return ReplaceInstUsesWith(I, LHS);
+    case ICmpInst::ICMP_SLT:        // (X u< 13 & X s< 15) -> no change
+      break;
+    }
+    break;
+  case ICmpInst::ICMP_SLT:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:         // (X s< 13 & X == 15) -> false
+    case ICmpInst::ICMP_SGT:        // (X s< 13 & X s> 15) -> false
+      return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+    case ICmpInst::ICMP_UGT:        // (X s< 13 & X u> 15) -> no change
+      break;
+    case ICmpInst::ICMP_NE:         // (X s< 13 & X != 15) -> X < 13
+    case ICmpInst::ICMP_SLT:        // (X s< 13 & X s< 15) -> X < 13
+      return ReplaceInstUsesWith(I, LHS);
+    case ICmpInst::ICMP_ULT:        // (X s< 13 & X u< 15) -> no change
+      break;
+    }
+    break;
+  case ICmpInst::ICMP_UGT:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:         // (X u> 13 & X == 15) -> X == 15
+    case ICmpInst::ICMP_UGT:        // (X u> 13 & X u> 15) -> X u> 15
+      return ReplaceInstUsesWith(I, RHS);
+    case ICmpInst::ICMP_SGT:        // (X u> 13 & X s> 15) -> no change
+      break;
+    case ICmpInst::ICMP_NE:
+      if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
+        return new ICmpInst(LHSCC, Val, RHSCst);
+      break;                        // (X u> 13 & X != 15) -> no change
+    case ICmpInst::ICMP_ULT:        // (X u> 13 & X u< 15) -> (X-14) <u 1
+      return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, false, true, I);
+    case ICmpInst::ICMP_SLT:        // (X u> 13 & X s< 15) -> no change
+      break;
+    }
+    break;
+  case ICmpInst::ICMP_SGT:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:         // (X s> 13 & X == 15) -> X == 15
+    case ICmpInst::ICMP_SGT:        // (X s> 13 & X s> 15) -> X s> 15
+      return ReplaceInstUsesWith(I, RHS);
+    case ICmpInst::ICMP_UGT:        // (X s> 13 & X u> 15) -> no change
+      break;
+    case ICmpInst::ICMP_NE:
+      if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
+        return new ICmpInst(LHSCC, Val, RHSCst);
+      break;                        // (X s> 13 & X != 15) -> no change
+    case ICmpInst::ICMP_SLT:        // (X s> 13 & X s< 15) -> (X-14) s< 1
+      return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, true, true, I);
+    case ICmpInst::ICMP_ULT:        // (X s> 13 & X u< 15) -> no change
+      break;
+    }
+    break;
+  }
+ 
+  return 0;
+}
+
+
+Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
+  bool Changed = SimplifyCommutative(I);
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  if (isa<UndefValue>(Op1))                         // X & undef -> 0
+    return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+  // and X, X = X
+  if (Op0 == Op1)
+    return ReplaceInstUsesWith(I, Op1);
+
+  // See if we can simplify any instructions used by the instruction whose sole 
+  // purpose is to compute bits we don't care about.
+  if (!isa<VectorType>(I.getType())) {
+    if (SimplifyDemandedInstructionBits(I))
+      return &I;
+  } else {
+    if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
+      if (CP->isAllOnesValue())            // X & <-1,-1> -> X
+        return ReplaceInstUsesWith(I, I.getOperand(0));
+    } else if (isa<ConstantAggregateZero>(Op1)) {
+      return ReplaceInstUsesWith(I, Op1);  // X & <0,0> -> <0,0>
+    }
+  }
+  
+  if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
+    const APInt& AndRHSMask = AndRHS->getValue();
+    APInt NotAndRHS(~AndRHSMask);
+
+    // Optimize a variety of ((val OP C1) & C2) combinations...
+    if (isa<BinaryOperator>(Op0)) {
+      Instruction *Op0I = cast<Instruction>(Op0);
+      Value *Op0LHS = Op0I->getOperand(0);
+      Value *Op0RHS = Op0I->getOperand(1);
+      switch (Op0I->getOpcode()) {
+      case Instruction::Xor:
+      case Instruction::Or:
+        // If the mask is only needed on one incoming arm, push it up.
+        if (Op0I->hasOneUse()) {
+          if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
+            // Not masking anything out for the LHS, move to RHS.
+            Instruction *NewRHS = BinaryOperator::CreateAnd(Op0RHS, AndRHS,
+                                                   Op0RHS->getName()+".masked");
+            InsertNewInstBefore(NewRHS, I);
+            return BinaryOperator::Create(
+                       cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
+          }
+          if (!isa<Constant>(Op0RHS) &&
+              MaskedValueIsZero(Op0RHS, NotAndRHS)) {
+            // Not masking anything out for the RHS, move to LHS.
+            Instruction *NewLHS = BinaryOperator::CreateAnd(Op0LHS, AndRHS,
+                                                   Op0LHS->getName()+".masked");
+            InsertNewInstBefore(NewLHS, I);
+            return BinaryOperator::Create(
+                       cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
+          }
+        }
+
+        break;
+      case Instruction::Add:
+        // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
+        // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
+        // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
+        if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
+          return BinaryOperator::CreateAnd(V, AndRHS);
+        if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
+          return BinaryOperator::CreateAnd(V, AndRHS);  // Add commutes
+        break;
+
+      case Instruction::Sub:
+        // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
+        // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
+        // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
+        if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
+          return BinaryOperator::CreateAnd(V, AndRHS);
+
+        // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
+        // has 1's for all bits that the subtraction with A might affect.
+        if (Op0I->hasOneUse()) {
+          uint32_t BitWidth = AndRHSMask.getBitWidth();
+          uint32_t Zeros = AndRHSMask.countLeadingZeros();
+          APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
+
+          ConstantInt *A = dyn_cast<ConstantInt>(Op0LHS);
+          if (!(A && A->isZero()) &&               // avoid infinite recursion.
+              MaskedValueIsZero(Op0LHS, Mask)) {
+            Instruction *NewNeg = BinaryOperator::CreateNeg(Op0RHS);
+            InsertNewInstBefore(NewNeg, I);
+            return BinaryOperator::CreateAnd(NewNeg, AndRHS);
+          }
+        }
+        break;
+
+      case Instruction::Shl:
+      case Instruction::LShr:
+        // (1 << x) & 1 --> zext(x == 0)
+        // (1 >> x) & 1 --> zext(x == 0)
+        if (AndRHSMask == 1 && Op0LHS == AndRHS) {
+          Instruction *NewICmp = new ICmpInst(ICmpInst::ICMP_EQ, Op0RHS,
+                                           Constant::getNullValue(I.getType()));
+          InsertNewInstBefore(NewICmp, I);
+          return new ZExtInst(NewICmp, I.getType());
+        }
+        break;
+      }
+
+      if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
+        if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
+          return Res;
+    } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
+      // If this is an integer truncation or change from signed-to-unsigned, and
+      // if the source is an and/or with immediate, transform it.  This
+      // frequently occurs for bitfield accesses.
+      if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
+        if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
+            CastOp->getNumOperands() == 2)
+          if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1))) {
+            if (CastOp->getOpcode() == Instruction::And) {
+              // Change: and (cast (and X, C1) to T), C2
+              // into  : and (cast X to T), trunc_or_bitcast(C1)&C2
+              // This will fold the two constants together, which may allow 
+              // other simplifications.
+              Instruction *NewCast = CastInst::CreateTruncOrBitCast(
+                CastOp->getOperand(0), I.getType(), 
+                CastOp->getName()+".shrunk");
+              NewCast = InsertNewInstBefore(NewCast, I);
+              // trunc_or_bitcast(C1)&C2
+              Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
+              C3 = ConstantExpr::getAnd(C3, AndRHS);
+              return BinaryOperator::CreateAnd(NewCast, C3);
+            } else if (CastOp->getOpcode() == Instruction::Or) {
+              // Change: and (cast (or X, C1) to T), C2
+              // into  : trunc(C1)&C2 iff trunc(C1)&C2 == C2
+              Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
+              if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS)   // trunc(C1)&C2
+                return ReplaceInstUsesWith(I, AndRHS);
+            }
+          }
+      }
+    }
+
+    // Try to fold constant and into select arguments.
+    if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+      if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+        return R;
+    if (isa<PHINode>(Op0))
+      if (Instruction *NV = FoldOpIntoPhi(I))
+        return NV;
+  }
+
+  Value *Op0NotVal = dyn_castNotVal(Op0);
+  Value *Op1NotVal = dyn_castNotVal(Op1);
+
+  if (Op0NotVal == Op1 || Op1NotVal == Op0)  // A & ~A  == ~A & A == 0
+    return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+  // (~A & ~B) == (~(A | B)) - De Morgan's Law
+  if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
+    Instruction *Or = BinaryOperator::CreateOr(Op0NotVal, Op1NotVal,
+                                               I.getName()+".demorgan");
+    InsertNewInstBefore(Or, I);
+    return BinaryOperator::CreateNot(Or);
+  }
+  
+  {
+    Value *A = 0, *B = 0, *C = 0, *D = 0;
+    if (match(Op0, m_Or(m_Value(A), m_Value(B)))) {
+      if (A == Op1 || B == Op1)    // (A | ?) & A  --> A
+        return ReplaceInstUsesWith(I, Op1);
+    
+      // (A|B) & ~(A&B) -> A^B
+      if (match(Op1, m_Not(m_And(m_Value(C), m_Value(D))))) {
+        if ((A == C && B == D) || (A == D && B == C))
+          return BinaryOperator::CreateXor(A, B);
+      }
+    }
+    
+    if (match(Op1, m_Or(m_Value(A), m_Value(B)))) {
+      if (A == Op0 || B == Op0)    // A & (A | ?)  --> A
+        return ReplaceInstUsesWith(I, Op0);
+
+      // ~(A&B) & (A|B) -> A^B
+      if (match(Op0, m_Not(m_And(m_Value(C), m_Value(D))))) {
+        if ((A == C && B == D) || (A == D && B == C))
+          return BinaryOperator::CreateXor(A, B);
+      }
+    }
+    
+    if (Op0->hasOneUse() &&
+        match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
+      if (A == Op1) {                                // (A^B)&A -> A&(A^B)
+        I.swapOperands();     // Simplify below
+        std::swap(Op0, Op1);
+      } else if (B == Op1) {                         // (A^B)&B -> B&(B^A)
+        cast<BinaryOperator>(Op0)->swapOperands();
+        I.swapOperands();     // Simplify below
+        std::swap(Op0, Op1);
+      }
+    }
+
+    if (Op1->hasOneUse() &&
+        match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
+      if (B == Op0) {                                // B&(A^B) -> B&(B^A)
+        cast<BinaryOperator>(Op1)->swapOperands();
+        std::swap(A, B);
+      }
+      if (A == Op0) {                                // A&(A^B) -> A & ~B
+        Instruction *NotB = BinaryOperator::CreateNot(B, "tmp");
+        InsertNewInstBefore(NotB, I);
+        return BinaryOperator::CreateAnd(A, NotB);
+      }
+    }
+
+    // (A&((~A)|B)) -> A&B
+    if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) ||
+        match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1)))))
+      return BinaryOperator::CreateAnd(A, Op1);
+    if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
+        match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
+      return BinaryOperator::CreateAnd(A, Op0);
+  }
+  
+  if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
+    // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
+    if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
+      return R;
+
+    if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0))
+      if (Instruction *Res = FoldAndOfICmps(I, LHS, RHS))
+        return Res;
+  }
+
+  // fold (and (cast A), (cast B)) -> (cast (and A, B))
+  if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
+    if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+      if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
+        const Type *SrcTy = Op0C->getOperand(0)->getType();
+        if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
+            // Only do this if the casts both really cause code to be generated.
+            ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0), 
+                              I.getType(), TD) &&
+            ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0), 
+                              I.getType(), TD)) {
+          Instruction *NewOp = BinaryOperator::CreateAnd(Op0C->getOperand(0),
+                                                         Op1C->getOperand(0),
+                                                         I.getName());
+          InsertNewInstBefore(NewOp, I);
+          return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
+        }
+      }
+    
+  // (X >> Z) & (Y >> Z)  -> (X&Y) >> Z  for all shifts.
+  if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
+    if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
+      if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() && 
+          SI0->getOperand(1) == SI1->getOperand(1) &&
+          (SI0->hasOneUse() || SI1->hasOneUse())) {
+        Instruction *NewOp =
+          InsertNewInstBefore(BinaryOperator::CreateAnd(SI0->getOperand(0),
+                                                        SI1->getOperand(0),
+                                                        SI0->getName()), I);
+        return BinaryOperator::Create(SI1->getOpcode(), NewOp, 
+                                      SI1->getOperand(1));
+      }
+  }
+
+  // If and'ing two fcmp, try combine them into one.
+  if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
+    if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) {
+      if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
+          RHS->getPredicate() == FCmpInst::FCMP_ORD) {
+        // (fcmp ord x, c) & (fcmp ord y, c)  -> (fcmp ord x, y)
+        if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
+          if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
+            // If either of the constants are nans, then the whole thing returns
+            // false.
+            if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
+              return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+            return new FCmpInst(FCmpInst::FCMP_ORD, LHS->getOperand(0),
+                                RHS->getOperand(0));
+          }
+      } else {
+        Value *Op0LHS, *Op0RHS, *Op1LHS, *Op1RHS;
+        FCmpInst::Predicate Op0CC, Op1CC;
+        if (match(Op0, m_FCmp(Op0CC, m_Value(Op0LHS), m_Value(Op0RHS))) &&
+            match(Op1, m_FCmp(Op1CC, m_Value(Op1LHS), m_Value(Op1RHS)))) {
+          if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
+            // Swap RHS operands to match LHS.
+            Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
+            std::swap(Op1LHS, Op1RHS);
+          }
+          if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
+            // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
+            if (Op0CC == Op1CC)
+              return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
+            else if (Op0CC == FCmpInst::FCMP_FALSE ||
+                     Op1CC == FCmpInst::FCMP_FALSE)
+              return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+            else if (Op0CC == FCmpInst::FCMP_TRUE)
+              return ReplaceInstUsesWith(I, Op1);
+            else if (Op1CC == FCmpInst::FCMP_TRUE)
+              return ReplaceInstUsesWith(I, Op0);
+            bool Op0Ordered;
+            bool Op1Ordered;
+            unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
+            unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
+            if (Op1Pred == 0) {
+              std::swap(Op0, Op1);
+              std::swap(Op0Pred, Op1Pred);
+              std::swap(Op0Ordered, Op1Ordered);
+            }
+            if (Op0Pred == 0) {
+              // uno && ueq -> uno && (uno || eq) -> ueq
+              // ord && olt -> ord && (ord && lt) -> olt
+              if (Op0Ordered == Op1Ordered)
+                return ReplaceInstUsesWith(I, Op1);
+              // uno && oeq -> uno && (ord && eq) -> false
+              // uno && ord -> false
+              if (!Op0Ordered)
+                return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+              // ord && ueq -> ord && (uno || eq) -> oeq
+              return cast<Instruction>(getFCmpValue(true, Op1Pred,
+                                                    Op0LHS, Op0RHS));
+            }
+          }
+        }
+      }
+    }
+  }
+
+  return Changed ? &I : 0;
+}
+
+/// CollectBSwapParts - Analyze the specified subexpression and see if it is
+/// capable of providing pieces of a bswap.  The subexpression provides pieces
+/// of a bswap if it is proven that each of the non-zero bytes in the output of
+/// the expression came from the corresponding "byte swapped" byte in some other
+/// value.  For example, if the current subexpression is "(shl i32 %X, 24)" then
+/// we know that the expression deposits the low byte of %X into the high byte
+/// of the bswap result and that all other bytes are zero.  This expression is
+/// accepted, the high byte of ByteValues is set to X to indicate a correct
+/// match.
+///
+/// This function returns true if the match was unsuccessful and false if so.
+/// On entry to the function the "OverallLeftShift" is a signed integer value
+/// indicating the number of bytes that the subexpression is later shifted.  For
+/// example, if the expression is later right shifted by 16 bits, the
+/// OverallLeftShift value would be -2 on entry.  This is used to specify which
+/// byte of ByteValues is actually being set.
+///
+/// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding
+/// byte is masked to zero by a user.  For example, in (X & 255), X will be
+/// processed with a bytemask of 1.  Because bytemask is 32-bits, this limits
+/// this function to working on up to 32-byte (256 bit) values.  ByteMask is
+/// always in the local (OverallLeftShift) coordinate space.
+///
+static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask,
+                              SmallVector<Value*, 8> &ByteValues) {
+  if (Instruction *I = dyn_cast<Instruction>(V)) {
+    // If this is an or instruction, it may be an inner node of the bswap.
+    if (I->getOpcode() == Instruction::Or) {
+      return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
+                               ByteValues) ||
+             CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask,
+                               ByteValues);
+    }
+  
+    // If this is a logical shift by a constant multiple of 8, recurse with
+    // OverallLeftShift and ByteMask adjusted.
+    if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
+      unsigned ShAmt = 
+        cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
+      // Ensure the shift amount is defined and of a byte value.
+      if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size()))
+        return true;
+
+      unsigned ByteShift = ShAmt >> 3;
+      if (I->getOpcode() == Instruction::Shl) {
+        // X << 2 -> collect(X, +2)
+        OverallLeftShift += ByteShift;
+        ByteMask >>= ByteShift;
+      } else {
+        // X >>u 2 -> collect(X, -2)
+        OverallLeftShift -= ByteShift;
+        ByteMask <<= ByteShift;
+        ByteMask &= (~0U >> (32-ByteValues.size()));
+      }
+
+      if (OverallLeftShift >= (int)ByteValues.size()) return true;
+      if (OverallLeftShift <= -(int)ByteValues.size()) return true;
+
+      return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, 
+                               ByteValues);
+    }
+
+    // If this is a logical 'and' with a mask that clears bytes, clear the
+    // corresponding bytes in ByteMask.
+    if (I->getOpcode() == Instruction::And &&
+        isa<ConstantInt>(I->getOperand(1))) {
+      // Scan every byte of the and mask, seeing if the byte is either 0 or 255.
+      unsigned NumBytes = ByteValues.size();
+      APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255);
+      const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
+      
+      for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) {
+        // If this byte is masked out by a later operation, we don't care what
+        // the and mask is.
+        if ((ByteMask & (1 << i)) == 0)
+          continue;
+        
+        // If the AndMask is all zeros for this byte, clear the bit.
+        APInt MaskB = AndMask & Byte;
+        if (MaskB == 0) {
+          ByteMask &= ~(1U << i);
+          continue;
+        }
+        
+        // If the AndMask is not all ones for this byte, it's not a bytezap.
+        if (MaskB != Byte)
+          return true;
+
+        // Otherwise, this byte is kept.
+      }
+
+      return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, 
+                               ByteValues);
+    }
+  }
+  
+  // Okay, we got to something that isn't a shift, 'or' or 'and'.  This must be
+  // the input value to the bswap.  Some observations: 1) if more than one byte
+  // is demanded from this input, then it could not be successfully assembled
+  // into a byteswap.  At least one of the two bytes would not be aligned with
+  // their ultimate destination.
+  if (!isPowerOf2_32(ByteMask)) return true;
+  unsigned InputByteNo = CountTrailingZeros_32(ByteMask);
+  
+  // 2) The input and ultimate destinations must line up: if byte 3 of an i32
+  // is demanded, it needs to go into byte 0 of the result.  This means that the
+  // byte needs to be shifted until it lands in the right byte bucket.  The
+  // shift amount depends on the position: if the byte is coming from the high
+  // part of the value (e.g. byte 3) then it must be shifted right.  If from the
+  // low part, it must be shifted left.
+  unsigned DestByteNo = InputByteNo + OverallLeftShift;
+  if (InputByteNo < ByteValues.size()/2) {
+    if (ByteValues.size()-1-DestByteNo != InputByteNo)
+      return true;
+  } else {
+    if (ByteValues.size()-1-DestByteNo != InputByteNo)
+      return true;
+  }
+  
+  // If the destination byte value is already defined, the values are or'd
+  // together, which isn't a bswap (unless it's an or of the same bits).
+  if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V)
+    return true;
+  ByteValues[DestByteNo] = V;
+  return false;
+}
+
+/// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
+/// If so, insert the new bswap intrinsic and return it.
+Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
+  const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
+  if (!ITy || ITy->getBitWidth() % 16 || 
+      // ByteMask only allows up to 32-byte values.
+      ITy->getBitWidth() > 32*8) 
+    return 0;   // Can only bswap pairs of bytes.  Can't do vectors.
+  
+  /// ByteValues - For each byte of the result, we keep track of which value
+  /// defines each byte.
+  SmallVector<Value*, 8> ByteValues;
+  ByteValues.resize(ITy->getBitWidth()/8);
+    
+  // Try to find all the pieces corresponding to the bswap.
+  uint32_t ByteMask = ~0U >> (32-ByteValues.size());
+  if (CollectBSwapParts(&I, 0, ByteMask, ByteValues))
+    return 0;
+  
+  // Check to see if all of the bytes come from the same value.
+  Value *V = ByteValues[0];
+  if (V == 0) return 0;  // Didn't find a byte?  Must be zero.
+  
+  // Check to make sure that all of the bytes come from the same value.
+  for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
+    if (ByteValues[i] != V)
+      return 0;
+  const Type *Tys[] = { ITy };
+  Module *M = I.getParent()->getParent()->getParent();
+  Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
+  return CallInst::Create(F, V);
+}
+
+/// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D).  Check
+/// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then
+/// we can simplify this expression to "cond ? C : D or B".
+static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
+                                         Value *C, Value *D) {
+  // If A is not a select of -1/0, this cannot match.
+  Value *Cond = 0;
+  if (!match(A, m_SelectCst<-1, 0>(m_Value(Cond))))
+    return 0;
+
+  // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B.
+  if (match(D, m_SelectCst<0, -1>(m_Specific(Cond))))
+    return SelectInst::Create(Cond, C, B);
+  if (match(D, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
+    return SelectInst::Create(Cond, C, B);
+  // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D.
+  if (match(B, m_SelectCst<0, -1>(m_Specific(Cond))))
+    return SelectInst::Create(Cond, C, D);
+  if (match(B, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
+    return SelectInst::Create(Cond, C, D);
+  return 0;
+}
+
+/// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
+Instruction *InstCombiner::FoldOrOfICmps(Instruction &I,
+                                         ICmpInst *LHS, ICmpInst *RHS) {
+  Value *Val, *Val2;
+  ConstantInt *LHSCst, *RHSCst;
+  ICmpInst::Predicate LHSCC, RHSCC;
+  
+  // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
+  if (!match(LHS, m_ICmp(LHSCC, m_Value(Val), m_ConstantInt(LHSCst))) ||
+      !match(RHS, m_ICmp(RHSCC, m_Value(Val2), m_ConstantInt(RHSCst))))
+    return 0;
+  
+  // From here on, we only handle:
+  //    (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
+  if (Val != Val2) return 0;
+  
+  // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
+  if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
+      RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
+      LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
+      RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
+    return 0;
+  
+  // We can't fold (ugt x, C) | (sgt x, C2).
+  if (!PredicatesFoldable(LHSCC, RHSCC))
+    return 0;
+  
+  // Ensure that the larger constant is on the RHS.
+  bool ShouldSwap;
+  if (ICmpInst::isSignedPredicate(LHSCC) ||
+      (ICmpInst::isEquality(LHSCC) && 
+       ICmpInst::isSignedPredicate(RHSCC)))
+    ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
+  else
+    ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
+  
+  if (ShouldSwap) {
+    std::swap(LHS, RHS);
+    std::swap(LHSCst, RHSCst);
+    std::swap(LHSCC, RHSCC);
+  }
+  
+  // At this point, we know we have have two icmp instructions
+  // comparing a value against two constants and or'ing the result
+  // together.  Because of the above check, we know that we only have
+  // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
+  // FoldICmpLogical check above), that the two constants are not
+  // equal.
+  assert(LHSCst != RHSCst && "Compares not folded above?");
+
+  switch (LHSCC) {
+  default: assert(0 && "Unknown integer condition code!");
+  case ICmpInst::ICMP_EQ:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:
+      if (LHSCst == SubOne(RHSCst)) { // (X == 13 | X == 14) -> X-13 <u 2
+        Constant *AddCST = ConstantExpr::getNeg(LHSCst);
+        Instruction *Add = BinaryOperator::CreateAdd(Val, AddCST,
+                                                     Val->getName()+".off");
+        InsertNewInstBefore(Add, I);
+        AddCST = Subtract(AddOne(RHSCst), LHSCst);
+        return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
+      }
+      break;                         // (X == 13 | X == 15) -> no change
+    case ICmpInst::ICMP_UGT:         // (X == 13 | X u> 14) -> no change
+    case ICmpInst::ICMP_SGT:         // (X == 13 | X s> 14) -> no change
+      break;
+    case ICmpInst::ICMP_NE:          // (X == 13 | X != 15) -> X != 15
+    case ICmpInst::ICMP_ULT:         // (X == 13 | X u< 15) -> X u< 15
+    case ICmpInst::ICMP_SLT:         // (X == 13 | X s< 15) -> X s< 15
+      return ReplaceInstUsesWith(I, RHS);
+    }
+    break;
+  case ICmpInst::ICMP_NE:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:          // (X != 13 | X == 15) -> X != 13
+    case ICmpInst::ICMP_UGT:         // (X != 13 | X u> 15) -> X != 13
+    case ICmpInst::ICMP_SGT:         // (X != 13 | X s> 15) -> X != 13
+      return ReplaceInstUsesWith(I, LHS);
+    case ICmpInst::ICMP_NE:          // (X != 13 | X != 15) -> true
+    case ICmpInst::ICMP_ULT:         // (X != 13 | X u< 15) -> true
+    case ICmpInst::ICMP_SLT:         // (X != 13 | X s< 15) -> true
+      return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+    }
+    break;
+  case ICmpInst::ICMP_ULT:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:         // (X u< 13 | X == 14) -> no change
+      break;
+    case ICmpInst::ICMP_UGT:        // (X u< 13 | X u> 15) -> (X-13) u> 2
+      // If RHSCst is [us]MAXINT, it is always false.  Not handling
+      // this can cause overflow.
+      if (RHSCst->isMaxValue(false))
+        return ReplaceInstUsesWith(I, LHS);
+      return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), false, false, I);
+    case ICmpInst::ICMP_SGT:        // (X u< 13 | X s> 15) -> no change
+      break;
+    case ICmpInst::ICMP_NE:         // (X u< 13 | X != 15) -> X != 15
+    case ICmpInst::ICMP_ULT:        // (X u< 13 | X u< 15) -> X u< 15
+      return ReplaceInstUsesWith(I, RHS);
+    case ICmpInst::ICMP_SLT:        // (X u< 13 | X s< 15) -> no change
+      break;
+    }
+    break;
+  case ICmpInst::ICMP_SLT:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:         // (X s< 13 | X == 14) -> no change
+      break;
+    case ICmpInst::ICMP_SGT:        // (X s< 13 | X s> 15) -> (X-13) s> 2
+      // If RHSCst is [us]MAXINT, it is always false.  Not handling
+      // this can cause overflow.
+      if (RHSCst->isMaxValue(true))
+        return ReplaceInstUsesWith(I, LHS);
+      return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), true, false, I);
+    case ICmpInst::ICMP_UGT:        // (X s< 13 | X u> 15) -> no change
+      break;
+    case ICmpInst::ICMP_NE:         // (X s< 13 | X != 15) -> X != 15
+    case ICmpInst::ICMP_SLT:        // (X s< 13 | X s< 15) -> X s< 15
+      return ReplaceInstUsesWith(I, RHS);
+    case ICmpInst::ICMP_ULT:        // (X s< 13 | X u< 15) -> no change
+      break;
+    }
+    break;
+  case ICmpInst::ICMP_UGT:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:         // (X u> 13 | X == 15) -> X u> 13
+    case ICmpInst::ICMP_UGT:        // (X u> 13 | X u> 15) -> X u> 13
+      return ReplaceInstUsesWith(I, LHS);
+    case ICmpInst::ICMP_SGT:        // (X u> 13 | X s> 15) -> no change
+      break;
+    case ICmpInst::ICMP_NE:         // (X u> 13 | X != 15) -> true
+    case ICmpInst::ICMP_ULT:        // (X u> 13 | X u< 15) -> true
+      return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+    case ICmpInst::ICMP_SLT:        // (X u> 13 | X s< 15) -> no change
+      break;
+    }
+    break;
+  case ICmpInst::ICMP_SGT:
+    switch (RHSCC) {
+    default: assert(0 && "Unknown integer condition code!");
+    case ICmpInst::ICMP_EQ:         // (X s> 13 | X == 15) -> X > 13
+    case ICmpInst::ICMP_SGT:        // (X s> 13 | X s> 15) -> X > 13
+      return ReplaceInstUsesWith(I, LHS);
+    case ICmpInst::ICMP_UGT:        // (X s> 13 | X u> 15) -> no change
+      break;
+    case ICmpInst::ICMP_NE:         // (X s> 13 | X != 15) -> true
+    case ICmpInst::ICMP_SLT:        // (X s> 13 | X s< 15) -> true
+      return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+    case ICmpInst::ICMP_ULT:        // (X s> 13 | X u< 15) -> no change
+      break;
+    }
+    break;
+  }
+  return 0;
+}
+
+/// FoldOrWithConstants - This helper function folds:
+///
+///     ((A | B) & C1) | (B & C2)
+///
+/// into:
+/// 
+///     (A & C1) | B
+///
+/// when the XOR of the two constants is "all ones" (-1).
+Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
+                                               Value *A, Value *B, Value *C) {
+  ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
+  if (!CI1) return 0;
+
+  Value *V1 = 0;
+  ConstantInt *CI2 = 0;
+  if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0;
+
+  APInt Xor = CI1->getValue() ^ CI2->getValue();
+  if (!Xor.isAllOnesValue()) return 0;
+
+  if (V1 == A || V1 == B) {
+    Instruction *NewOp =
+      InsertNewInstBefore(BinaryOperator::CreateAnd((V1 == A) ? B : A, CI1), I);
+    return BinaryOperator::CreateOr(NewOp, V1);
+  }
+
+  return 0;
+}
+
+Instruction *InstCombiner::visitOr(BinaryOperator &I) {
+  bool Changed = SimplifyCommutative(I);
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  if (isa<UndefValue>(Op1))                       // X | undef -> -1
+    return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+  // or X, X = X
+  if (Op0 == Op1)
+    return ReplaceInstUsesWith(I, Op0);
+
+  // See if we can simplify any instructions used by the instruction whose sole 
+  // purpose is to compute bits we don't care about.
+  if (!isa<VectorType>(I.getType())) {
+    if (SimplifyDemandedInstructionBits(I))
+      return &I;
+  } else if (isa<ConstantAggregateZero>(Op1)) {
+    return ReplaceInstUsesWith(I, Op0);  // X | <0,0> -> X
+  } else if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
+    if (CP->isAllOnesValue())            // X | <-1,-1> -> <-1,-1>
+      return ReplaceInstUsesWith(I, I.getOperand(1));
+  }
+    
+
+  
+  // or X, -1 == -1
+  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+    ConstantInt *C1 = 0; Value *X = 0;
+    // (X & C1) | C2 --> (X | C2) & (C1|C2)
+    if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
+      Instruction *Or = BinaryOperator::CreateOr(X, RHS);
+      InsertNewInstBefore(Or, I);
+      Or->takeName(Op0);
+      return BinaryOperator::CreateAnd(Or, 
+               ConstantInt::get(RHS->getValue() | C1->getValue()));
+    }
+
+    // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
+    if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
+      Instruction *Or = BinaryOperator::CreateOr(X, RHS);
+      InsertNewInstBefore(Or, I);
+      Or->takeName(Op0);
+      return BinaryOperator::CreateXor(Or,
+                 ConstantInt::get(C1->getValue() & ~RHS->getValue()));
+    }
+
+    // Try to fold constant and into select arguments.
+    if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+      if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+        return R;
+    if (isa<PHINode>(Op0))
+      if (Instruction *NV = FoldOpIntoPhi(I))
+        return NV;
+  }
+
+  Value *A = 0, *B = 0;
+  ConstantInt *C1 = 0, *C2 = 0;
+
+  if (match(Op0, m_And(m_Value(A), m_Value(B))))
+    if (A == Op1 || B == Op1)    // (A & ?) | A  --> A
+      return ReplaceInstUsesWith(I, Op1);
+  if (match(Op1, m_And(m_Value(A), m_Value(B))))
+    if (A == Op0 || B == Op0)    // A | (A & ?)  --> A
+      return ReplaceInstUsesWith(I, Op0);
+
+  // (A | B) | C  and  A | (B | C)                  -> bswap if possible.
+  // (A >> B) | (C << D)  and  (A << B) | (B >> C)  -> bswap if possible.
+  if (match(Op0, m_Or(m_Value(), m_Value())) ||
+      match(Op1, m_Or(m_Value(), m_Value())) ||
+      (match(Op0, m_Shift(m_Value(), m_Value())) &&
+       match(Op1, m_Shift(m_Value(), m_Value())))) {
+    if (Instruction *BSwap = MatchBSwap(I))
+      return BSwap;
+  }
+  
+  // (X^C)|Y -> (X|Y)^C iff Y&C == 0
+  if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
+      MaskedValueIsZero(Op1, C1->getValue())) {
+    Instruction *NOr = BinaryOperator::CreateOr(A, Op1);
+    InsertNewInstBefore(NOr, I);
+    NOr->takeName(Op0);
+    return BinaryOperator::CreateXor(NOr, C1);
+  }
+
+  // Y|(X^C) -> (X|Y)^C iff Y&C == 0
+  if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
+      MaskedValueIsZero(Op0, C1->getValue())) {
+    Instruction *NOr = BinaryOperator::CreateOr(A, Op0);
+    InsertNewInstBefore(NOr, I);
+    NOr->takeName(Op0);
+    return BinaryOperator::CreateXor(NOr, C1);
+  }
+
+  // (A & C)|(B & D)
+  Value *C = 0, *D = 0;
+  if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
+      match(Op1, m_And(m_Value(B), m_Value(D)))) {
+    Value *V1 = 0, *V2 = 0, *V3 = 0;
+    C1 = dyn_cast<ConstantInt>(C);
+    C2 = dyn_cast<ConstantInt>(D);
+    if (C1 && C2) {  // (A & C1)|(B & C2)
+      // If we have: ((V + N) & C1) | (V & C2)
+      // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
+      // replace with V+N.
+      if (C1->getValue() == ~C2->getValue()) {
+        if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
+            match(A, m_Add(m_Value(V1), m_Value(V2)))) {
+          // Add commutes, try both ways.
+          if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
+            return ReplaceInstUsesWith(I, A);
+          if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
+            return ReplaceInstUsesWith(I, A);
+        }
+        // Or commutes, try both ways.
+        if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
+            match(B, m_Add(m_Value(V1), m_Value(V2)))) {
+          // Add commutes, try both ways.
+          if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
+            return ReplaceInstUsesWith(I, B);
+          if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
+            return ReplaceInstUsesWith(I, B);
+        }
+      }
+      V1 = 0; V2 = 0; V3 = 0;
+    }
+    
+    // Check to see if we have any common things being and'ed.  If so, find the
+    // terms for V1 & (V2|V3).
+    if (isOnlyUse(Op0) || isOnlyUse(Op1)) {
+      if (A == B)      // (A & C)|(A & D) == A & (C|D)
+        V1 = A, V2 = C, V3 = D;
+      else if (A == D) // (A & C)|(B & A) == A & (B|C)
+        V1 = A, V2 = B, V3 = C;
+      else if (C == B) // (A & C)|(C & D) == C & (A|D)
+        V1 = C, V2 = A, V3 = D;
+      else if (C == D) // (A & C)|(B & C) == C & (A|B)
+        V1 = C, V2 = A, V3 = B;
+      
+      if (V1) {
+        Value *Or =
+          InsertNewInstBefore(BinaryOperator::CreateOr(V2, V3, "tmp"), I);
+        return BinaryOperator::CreateAnd(V1, Or);
+      }
+    }
+
+    // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) ->  C0 ? A : B, and commuted variants
+    if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D))
+      return Match;
+    if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C))
+      return Match;
+    if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D))
+      return Match;
+    if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C))
+      return Match;
+
+    // ((A&~B)|(~A&B)) -> A^B
+    if ((match(C, m_Not(m_Specific(D))) &&
+         match(B, m_Not(m_Specific(A)))))
+      return BinaryOperator::CreateXor(A, D);
+    // ((~B&A)|(~A&B)) -> A^B
+    if ((match(A, m_Not(m_Specific(D))) &&
+         match(B, m_Not(m_Specific(C)))))
+      return BinaryOperator::CreateXor(C, D);
+    // ((A&~B)|(B&~A)) -> A^B
+    if ((match(C, m_Not(m_Specific(B))) &&
+         match(D, m_Not(m_Specific(A)))))
+      return BinaryOperator::CreateXor(A, B);
+    // ((~B&A)|(B&~A)) -> A^B
+    if ((match(A, m_Not(m_Specific(B))) &&
+         match(D, m_Not(m_Specific(C)))))
+      return BinaryOperator::CreateXor(C, B);
+  }
+  
+  // (X >> Z) | (Y >> Z)  -> (X|Y) >> Z  for all shifts.
+  if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
+    if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
+      if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() && 
+          SI0->getOperand(1) == SI1->getOperand(1) &&
+          (SI0->hasOneUse() || SI1->hasOneUse())) {
+        Instruction *NewOp =
+        InsertNewInstBefore(BinaryOperator::CreateOr(SI0->getOperand(0),
+                                                     SI1->getOperand(0),
+                                                     SI0->getName()), I);
+        return BinaryOperator::Create(SI1->getOpcode(), NewOp, 
+                                      SI1->getOperand(1));
+      }
+  }
+
+  // ((A|B)&1)|(B&-2) -> (A&1) | B
+  if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
+      match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
+    Instruction *Ret = FoldOrWithConstants(I, Op1, A, B, C);
+    if (Ret) return Ret;
+  }
+  // (B&-2)|((A|B)&1) -> (A&1) | B
+  if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
+      match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
+    Instruction *Ret = FoldOrWithConstants(I, Op0, A, B, C);
+    if (Ret) return Ret;
+  }
+
+  if (match(Op0, m_Not(m_Value(A)))) {   // ~A | Op1
+    if (A == Op1)   // ~A | A == -1
+      return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+  } else {
+    A = 0;
+  }
+  // Note, A is still live here!
+  if (match(Op1, m_Not(m_Value(B)))) {   // Op0 | ~B
+    if (Op0 == B)
+      return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+    // (~A | ~B) == (~(A & B)) - De Morgan's Law
+    if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
+      Value *And = InsertNewInstBefore(BinaryOperator::CreateAnd(A, B,
+                                              I.getName()+".demorgan"), I);
+      return BinaryOperator::CreateNot(And);
+    }
+  }
+
+  // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
+  if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
+    if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
+      return R;
+
+    if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
+      if (Instruction *Res = FoldOrOfICmps(I, LHS, RHS))
+        return Res;
+  }
+    
+  // fold (or (cast A), (cast B)) -> (cast (or A, B))
+  if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
+    if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+      if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
+        if (!isa<ICmpInst>(Op0C->getOperand(0)) ||
+            !isa<ICmpInst>(Op1C->getOperand(0))) {
+          const Type *SrcTy = Op0C->getOperand(0)->getType();
+          if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
+              // Only do this if the casts both really cause code to be
+              // generated.
+              ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0), 
+                                I.getType(), TD) &&
+              ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0), 
+                                I.getType(), TD)) {
+            Instruction *NewOp = BinaryOperator::CreateOr(Op0C->getOperand(0),
+                                                          Op1C->getOperand(0),
+                                                          I.getName());
+            InsertNewInstBefore(NewOp, I);
+            return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
+          }
+        }
+      }
+  }
+  
+    
+  // (fcmp uno x, c) | (fcmp uno y, c)  -> (fcmp uno x, y)
+  if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
+    if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) {
+      if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
+          RHS->getPredicate() == FCmpInst::FCMP_UNO && 
+          LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) {
+        if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
+          if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
+            // If either of the constants are nans, then the whole thing returns
+            // true.
+            if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
+              return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+            
+            // Otherwise, no need to compare the two constants, compare the
+            // rest.
+            return new FCmpInst(FCmpInst::FCMP_UNO, LHS->getOperand(0),
+                                RHS->getOperand(0));
+          }
+      } else {
+        Value *Op0LHS, *Op0RHS, *Op1LHS, *Op1RHS;
+        FCmpInst::Predicate Op0CC, Op1CC;
+        if (match(Op0, m_FCmp(Op0CC, m_Value(Op0LHS), m_Value(Op0RHS))) &&
+            match(Op1, m_FCmp(Op1CC, m_Value(Op1LHS), m_Value(Op1RHS)))) {
+          if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
+            // Swap RHS operands to match LHS.
+            Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
+            std::swap(Op1LHS, Op1RHS);
+          }
+          if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
+            // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y).
+            if (Op0CC == Op1CC)
+              return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
+            else if (Op0CC == FCmpInst::FCMP_TRUE ||
+                     Op1CC == FCmpInst::FCMP_TRUE)
+              return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+            else if (Op0CC == FCmpInst::FCMP_FALSE)
+              return ReplaceInstUsesWith(I, Op1);
+            else if (Op1CC == FCmpInst::FCMP_FALSE)
+              return ReplaceInstUsesWith(I, Op0);
+            bool Op0Ordered;
+            bool Op1Ordered;
+            unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
+            unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
+            if (Op0Ordered == Op1Ordered) {
+              // If both are ordered or unordered, return a new fcmp with
+              // or'ed predicates.
+              Value *RV = getFCmpValue(Op0Ordered, Op0Pred|Op1Pred,
+                                       Op0LHS, Op0RHS);
+              if (Instruction *I = dyn_cast<Instruction>(RV))
+                return I;
+              // Otherwise, it's a constant boolean value...
+              return ReplaceInstUsesWith(I, RV);
+            }
+          }
+        }
+      }
+    }
+  }
+
+  return Changed ? &I : 0;
+}
+
+namespace {
+
+// XorSelf - Implements: X ^ X --> 0
+struct XorSelf {
+  Value *RHS;
+  XorSelf(Value *rhs) : RHS(rhs) {}
+  bool shouldApply(Value *LHS) const { return LHS == RHS; }
+  Instruction *apply(BinaryOperator &Xor) const {
+    return &Xor;
+  }
+};
+
+}
+
+Instruction *InstCombiner::visitXor(BinaryOperator &I) {
+  bool Changed = SimplifyCommutative(I);
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  if (isa<UndefValue>(Op1)) {
+    if (isa<UndefValue>(Op0))
+      // Handle undef ^ undef -> 0 special case. This is a common
+      // idiom (misuse).
+      return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+    return ReplaceInstUsesWith(I, Op1);  // X ^ undef -> undef
+  }
+
+  // xor X, X = 0, even if X is nested in a sequence of Xor's.
+  if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
+    assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result;
+    return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+  }
+  
+  // See if we can simplify any instructions used by the instruction whose sole 
+  // purpose is to compute bits we don't care about.
+  if (!isa<VectorType>(I.getType())) {
+    if (SimplifyDemandedInstructionBits(I))
+      return &I;
+  } else if (isa<ConstantAggregateZero>(Op1)) {
+    return ReplaceInstUsesWith(I, Op0);  // X ^ <0,0> -> X
+  }
+
+  // Is this a ~ operation?
+  if (Value *NotOp = dyn_castNotVal(&I)) {
+    // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
+    // ~(~X | Y) === (X & ~Y) - De Morgan's Law
+    if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
+      if (Op0I->getOpcode() == Instruction::And || 
+          Op0I->getOpcode() == Instruction::Or) {
+        if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
+        if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
+          Instruction *NotY =
+            BinaryOperator::CreateNot(Op0I->getOperand(1),
+                                      Op0I->getOperand(1)->getName()+".not");
+          InsertNewInstBefore(NotY, I);
+          if (Op0I->getOpcode() == Instruction::And)
+            return BinaryOperator::CreateOr(Op0NotVal, NotY);
+          else
+            return BinaryOperator::CreateAnd(Op0NotVal, NotY);
+        }
+      }
+    }
+  }
+  
+  
+  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+    if (RHS == ConstantInt::getTrue() && Op0->hasOneUse()) {
+      // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
+      if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
+        return new ICmpInst(ICI->getInversePredicate(),
+                            ICI->getOperand(0), ICI->getOperand(1));
+
+      if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
+        return new FCmpInst(FCI->getInversePredicate(),
+                            FCI->getOperand(0), FCI->getOperand(1));
+    }
+
+    // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
+    if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
+      if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {
+        if (CI->hasOneUse() && Op0C->hasOneUse()) {
+          Instruction::CastOps Opcode = Op0C->getOpcode();
+          if (Opcode == Instruction::ZExt || Opcode == Instruction::SExt) {
+            if (RHS == ConstantExpr::getCast(Opcode, ConstantInt::getTrue(),
+                                             Op0C->getDestTy())) {
+              Instruction *NewCI = InsertNewInstBefore(CmpInst::Create(
+                                     CI->getOpcode(), CI->getInversePredicate(),
+                                     CI->getOperand(0), CI->getOperand(1)), I);
+              NewCI->takeName(CI);
+              return CastInst::Create(Opcode, NewCI, Op0C->getType());
+            }
+          }
+        }
+      }
+    }
+
+    if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+      // ~(c-X) == X-c-1 == X+(-c-1)
+      if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
+        if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
+          Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
+          Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
+                                              ConstantInt::get(I.getType(), 1));
+          return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS);
+        }
+          
+      if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
+        if (Op0I->getOpcode() == Instruction::Add) {
+          // ~(X-c) --> (-c-1)-X
+          if (RHS->isAllOnesValue()) {
+            Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
+            return BinaryOperator::CreateSub(
+                           ConstantExpr::getSub(NegOp0CI,
+                                             ConstantInt::get(I.getType(), 1)),
+                                          Op0I->getOperand(0));
+          } else if (RHS->getValue().isSignBit()) {
+            // (X + C) ^ signbit -> (X + C + signbit)
+            Constant *C = ConstantInt::get(RHS->getValue() + Op0CI->getValue());
+            return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
+
+          }
+        } else if (Op0I->getOpcode() == Instruction::Or) {
+          // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
+          if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
+            Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
+            // Anything in both C1 and C2 is known to be zero, remove it from
+            // NewRHS.
+            Constant *CommonBits = And(Op0CI, RHS);
+            NewRHS = ConstantExpr::getAnd(NewRHS, 
+                                          ConstantExpr::getNot(CommonBits));
+            AddToWorkList(Op0I);
+            I.setOperand(0, Op0I->getOperand(0));
+            I.setOperand(1, NewRHS);
+            return &I;
+          }
+        }
+      }
+    }
+
+    // Try to fold constant and into select arguments.
+    if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+      if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+        return R;
+    if (isa<PHINode>(Op0))
+      if (Instruction *NV = FoldOpIntoPhi(I))
+        return NV;
+  }
+
+  if (Value *X = dyn_castNotVal(Op0))   // ~A ^ A == -1
+    if (X == Op1)
+      return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+  if (Value *X = dyn_castNotVal(Op1))   // A ^ ~A == -1
+    if (X == Op0)
+      return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+  
+  BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
+  if (Op1I) {
+    Value *A, *B;
+    if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
+      if (A == Op0) {              // B^(B|A) == (A|B)^B
+        Op1I->swapOperands();
+        I.swapOperands();
+        std::swap(Op0, Op1);
+      } else if (B == Op0) {       // B^(A|B) == (A|B)^B
+        I.swapOperands();     // Simplified below.
+        std::swap(Op0, Op1);
+      }
+    } else if (match(Op1I, m_Xor(m_Specific(Op0), m_Value(B)))) {
+      return ReplaceInstUsesWith(I, B);                      // A^(A^B) == B
+    } else if (match(Op1I, m_Xor(m_Value(A), m_Specific(Op0)))) {
+      return ReplaceInstUsesWith(I, A);                      // A^(B^A) == B
+    } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) && Op1I->hasOneUse()){
+      if (A == Op0) {                                      // A^(A&B) -> A^(B&A)
+        Op1I->swapOperands();
+        std::swap(A, B);
+      }
+      if (B == Op0) {                                      // A^(B&A) -> (B&A)^A
+        I.swapOperands();     // Simplified below.
+        std::swap(Op0, Op1);
+      }
+    }
+  }
+  
+  BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
+  if (Op0I) {
+    Value *A, *B;
+    if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && Op0I->hasOneUse()) {
+      if (A == Op1)                                  // (B|A)^B == (A|B)^B
+        std::swap(A, B);
+      if (B == Op1) {                                // (A|B)^B == A & ~B
+        Instruction *NotB =
+          InsertNewInstBefore(BinaryOperator::CreateNot(Op1, "tmp"), I);
+        return BinaryOperator::CreateAnd(A, NotB);
+      }
+    } else if (match(Op0I, m_Xor(m_Specific(Op1), m_Value(B)))) {
+      return ReplaceInstUsesWith(I, B);                      // (A^B)^A == B
+    } else if (match(Op0I, m_Xor(m_Value(A), m_Specific(Op1)))) {
+      return ReplaceInstUsesWith(I, A);                      // (B^A)^A == B
+    } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) && Op0I->hasOneUse()){
+      if (A == Op1)                                        // (A&B)^A -> (B&A)^A
+        std::swap(A, B);
+      if (B == Op1 &&                                      // (B&A)^A == ~B & A
+          !isa<ConstantInt>(Op1)) {  // Canonical form is (B&C)^C
+        Instruction *N =
+          InsertNewInstBefore(BinaryOperator::CreateNot(A, "tmp"), I);
+        return BinaryOperator::CreateAnd(N, Op1);
+      }
+    }
+  }
+  
+  // (X >> Z) ^ (Y >> Z)  -> (X^Y) >> Z  for all shifts.
+  if (Op0I && Op1I && Op0I->isShift() && 
+      Op0I->getOpcode() == Op1I->getOpcode() && 
+      Op0I->getOperand(1) == Op1I->getOperand(1) &&
+      (Op1I->hasOneUse() || Op1I->hasOneUse())) {
+    Instruction *NewOp =
+      InsertNewInstBefore(BinaryOperator::CreateXor(Op0I->getOperand(0),
+                                                    Op1I->getOperand(0),
+                                                    Op0I->getName()), I);
+    return BinaryOperator::Create(Op1I->getOpcode(), NewOp, 
+                                  Op1I->getOperand(1));
+  }
+    
+  if (Op0I && Op1I) {
+    Value *A, *B, *C, *D;
+    // (A & B)^(A | B) -> A ^ B
+    if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
+        match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
+      if ((A == C && B == D) || (A == D && B == C)) 
+        return BinaryOperator::CreateXor(A, B);
+    }
+    // (A | B)^(A & B) -> A ^ B
+    if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
+        match(Op1I, m_And(m_Value(C), m_Value(D)))) {
+      if ((A == C && B == D) || (A == D && B == C)) 
+        return BinaryOperator::CreateXor(A, B);
+    }
+    
+    // (A & B)^(C & D)
+    if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
+        match(Op0I, m_And(m_Value(A), m_Value(B))) &&
+        match(Op1I, m_And(m_Value(C), m_Value(D)))) {
+      // (X & Y)^(X & Y) -> (Y^Z) & X
+      Value *X = 0, *Y = 0, *Z = 0;
+      if (A == C)
+        X = A, Y = B, Z = D;
+      else if (A == D)
+        X = A, Y = B, Z = C;
+      else if (B == C)
+        X = B, Y = A, Z = D;
+      else if (B == D)
+        X = B, Y = A, Z = C;
+      
+      if (X) {
+        Instruction *NewOp =
+        InsertNewInstBefore(BinaryOperator::CreateXor(Y, Z, Op0->getName()), I);
+        return BinaryOperator::CreateAnd(NewOp, X);
+      }
+    }
+  }
+    
+  // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
+  if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
+    if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
+      return R;
+
+  // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
+  if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
+    if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+      if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
+        const Type *SrcTy = Op0C->getOperand(0)->getType();
+        if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
+            // Only do this if the casts both really cause code to be generated.
+            ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0), 
+                              I.getType(), TD) &&
+            ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0), 
+                              I.getType(), TD)) {
+          Instruction *NewOp = BinaryOperator::CreateXor(Op0C->getOperand(0),
+                                                         Op1C->getOperand(0),
+                                                         I.getName());
+          InsertNewInstBefore(NewOp, I);
+          return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
+        }
+      }
+  }
+
+  return Changed ? &I : 0;
+}
+
+/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
+/// overflowed for this type.
+static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
+                            ConstantInt *In2, bool IsSigned = false) {
+  Result = cast<ConstantInt>(Add(In1, In2));
+
+  if (IsSigned)
+    if (In2->getValue().isNegative())
+      return Result->getValue().sgt(In1->getValue());
+    else
+      return Result->getValue().slt(In1->getValue());
+  else
+    return Result->getValue().ult(In1->getValue());
+}
+
+/// SubWithOverflow - Compute Result = In1-In2, returning true if the result
+/// overflowed for this type.
+static bool SubWithOverflow(ConstantInt *&Result, ConstantInt *In1,
+                            ConstantInt *In2, bool IsSigned = false) {
+  Result = cast<ConstantInt>(Subtract(In1, In2));
+
+  if (IsSigned)
+    if (In2->getValue().isNegative())
+      return Result->getValue().slt(In1->getValue());
+    else
+      return Result->getValue().sgt(In1->getValue());
+  else
+    return Result->getValue().ugt(In1->getValue());
+}
+
+/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
+/// code necessary to compute the offset from the base pointer (without adding
+/// in the base pointer).  Return the result as a signed integer of intptr size.
+static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
+  TargetData &TD = IC.getTargetData();
+  gep_type_iterator GTI = gep_type_begin(GEP);
+  const Type *IntPtrTy = TD.getIntPtrType();
+  Value *Result = Constant::getNullValue(IntPtrTy);
+
+  // Build a mask for high order bits.
+  unsigned IntPtrWidth = TD.getPointerSizeInBits();
+  uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
+
+  for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
+       ++i, ++GTI) {
+    Value *Op = *i;
+    uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
+    if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
+      if (OpC->isZero()) continue;
+      
+      // Handle a struct index, which adds its field offset to the pointer.
+      if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+        Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
+        
+        if (ConstantInt *RC = dyn_cast<ConstantInt>(Result))
+          Result = ConstantInt::get(RC->getValue() + APInt(IntPtrWidth, Size));
+        else
+          Result = IC.InsertNewInstBefore(
+                   BinaryOperator::CreateAdd(Result,
+                                             ConstantInt::get(IntPtrTy, Size),
+                                             GEP->getName()+".offs"), I);
+        continue;
+      }
+      
+      Constant *Scale = ConstantInt::get(IntPtrTy, Size);
+      Constant *OC = ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
+      Scale = ConstantExpr::getMul(OC, Scale);
+      if (Constant *RC = dyn_cast<Constant>(Result))
+        Result = ConstantExpr::getAdd(RC, Scale);
+      else {
+        // Emit an add instruction.
+        Result = IC.InsertNewInstBefore(
+           BinaryOperator::CreateAdd(Result, Scale,
+                                     GEP->getName()+".offs"), I);
+      }
+      continue;
+    }
+    // Convert to correct type.
+    if (Op->getType() != IntPtrTy) {
+      if (Constant *OpC = dyn_cast<Constant>(Op))
+        Op = ConstantExpr::getIntegerCast(OpC, IntPtrTy, true);
+      else
+        Op = IC.InsertNewInstBefore(CastInst::CreateIntegerCast(Op, IntPtrTy,
+                                                                true,
+                                                      Op->getName()+".c"), I);
+    }
+    if (Size != 1) {
+      Constant *Scale = ConstantInt::get(IntPtrTy, Size);
+      if (Constant *OpC = dyn_cast<Constant>(Op))
+        Op = ConstantExpr::getMul(OpC, Scale);
+      else    // We'll let instcombine(mul) convert this to a shl if possible.
+        Op = IC.InsertNewInstBefore(BinaryOperator::CreateMul(Op, Scale,
+                                                  GEP->getName()+".idx"), I);
+    }
+
+    // Emit an add instruction.
+    if (isa<Constant>(Op) && isa<Constant>(Result))
+      Result = ConstantExpr::getAdd(cast<Constant>(Op),
+                                    cast<Constant>(Result));
+    else
+      Result = IC.InsertNewInstBefore(BinaryOperator::CreateAdd(Op, Result,
+                                                  GEP->getName()+".offs"), I);
+  }
+  return Result;
+}
+
+
+/// EvaluateGEPOffsetExpression - Return an value that can be used to compare of
+/// the *offset* implied by GEP to zero.  For example, if we have &A[i], we want
+/// to return 'i' for "icmp ne i, 0".  Note that, in general, indices can be
+/// complex, and scales are involved.  The above expression would also be legal
+/// to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32).  This
+/// later form is less amenable to optimization though, and we are allowed to
+/// generate the first by knowing that pointer arithmetic doesn't overflow.
+///
+/// If we can't emit an optimized form for this expression, this returns null.
+/// 
+static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I,
+                                          InstCombiner &IC) {
+  TargetData &TD = IC.getTargetData();
+  gep_type_iterator GTI = gep_type_begin(GEP);
+
+  // Check to see if this gep only has a single variable index.  If so, and if
+  // any constant indices are a multiple of its scale, then we can compute this
+  // in terms of the scale of the variable index.  For example, if the GEP
+  // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
+  // because the expression will cross zero at the same point.
+  unsigned i, e = GEP->getNumOperands();
+  int64_t Offset = 0;
+  for (i = 1; i != e; ++i, ++GTI) {
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
+      // Compute the aggregate offset of constant indices.
+      if (CI->isZero()) continue;
+
+      // Handle a struct index, which adds its field offset to the pointer.
+      if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+        Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
+      } else {
+        uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
+        Offset += Size*CI->getSExtValue();
+      }
+    } else {
+      // Found our variable index.
+      break;
+    }
+  }
+  
+  // If there are no variable indices, we must have a constant offset, just
+  // evaluate it the general way.
+  if (i == e) return 0;
+  
+  Value *VariableIdx = GEP->getOperand(i);
+  // Determine the scale factor of the variable element.  For example, this is
+  // 4 if the variable index is into an array of i32.
+  uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType());
+  
+  // Verify that there are no other variable indices.  If so, emit the hard way.
+  for (++i, ++GTI; i != e; ++i, ++GTI) {
+    ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
+    if (!CI) return 0;
+   
+    // Compute the aggregate offset of constant indices.
+    if (CI->isZero()) continue;
+    
+    // Handle a struct index, which adds its field offset to the pointer.
+    if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+      Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
+    } else {
+      uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
+      Offset += Size*CI->getSExtValue();
+    }
+  }
+  
+  // Okay, we know we have a single variable index, which must be a
+  // pointer/array/vector index.  If there is no offset, life is simple, return
+  // the index.
+  unsigned IntPtrWidth = TD.getPointerSizeInBits();
+  if (Offset == 0) {
+    // Cast to intptrty in case a truncation occurs.  If an extension is needed,
+    // we don't need to bother extending: the extension won't affect where the
+    // computation crosses zero.
+    if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth)
+      VariableIdx = new TruncInst(VariableIdx, TD.getIntPtrType(),
+                                  VariableIdx->getNameStart(), &I);
+    return VariableIdx;
+  }
+  
+  // Otherwise, there is an index.  The computation we will do will be modulo
+  // the pointer size, so get it.
+  uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
+  
+  Offset &= PtrSizeMask;
+  VariableScale &= PtrSizeMask;
+
+  // To do this transformation, any constant index must be a multiple of the
+  // variable scale factor.  For example, we can evaluate "12 + 4*i" as "3 + i",
+  // but we can't evaluate "10 + 3*i" in terms of i.  Check that the offset is a
+  // multiple of the variable scale.
+  int64_t NewOffs = Offset / (int64_t)VariableScale;
+  if (Offset != NewOffs*(int64_t)VariableScale)
+    return 0;
+
+  // Okay, we can do this evaluation.  Start by converting the index to intptr.
+  const Type *IntPtrTy = TD.getIntPtrType();
+  if (VariableIdx->getType() != IntPtrTy)
+    VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy,
+                                              true /*SExt*/, 
+                                              VariableIdx->getNameStart(), &I);
+  Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
+  return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I);
+}
+
+
+/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
+/// else.  At this point we know that the GEP is on the LHS of the comparison.
+Instruction *InstCombiner::FoldGEPICmp(User *GEPLHS, Value *RHS,
+                                       ICmpInst::Predicate Cond,
+                                       Instruction &I) {
+  assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
+
+  // Look through bitcasts.
+  if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS))
+    RHS = BCI->getOperand(0);
+
+  Value *PtrBase = GEPLHS->getOperand(0);
+  if (PtrBase == RHS) {
+    // ((gep Ptr, OFFSET) cmp Ptr)   ---> (OFFSET cmp 0).
+    // This transformation (ignoring the base and scales) is valid because we
+    // know pointers can't overflow.  See if we can output an optimized form.
+    Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this);
+    
+    // If not, synthesize the offset the hard way.
+    if (Offset == 0)
+      Offset = EmitGEPOffset(GEPLHS, I, *this);
+    return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
+                        Constant::getNullValue(Offset->getType()));
+  } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
+    // If the base pointers are different, but the indices are the same, just
+    // compare the base pointer.
+    if (PtrBase != GEPRHS->getOperand(0)) {
+      bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
+      IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
+                        GEPRHS->getOperand(0)->getType();
+      if (IndicesTheSame)
+        for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
+          if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
+            IndicesTheSame = false;
+            break;
+          }
+
+      // If all indices are the same, just compare the base pointers.
+      if (IndicesTheSame)
+        return new ICmpInst(ICmpInst::getSignedPredicate(Cond), 
+                            GEPLHS->getOperand(0), GEPRHS->getOperand(0));
+
+      // Otherwise, the base pointers are different and the indices are
+      // different, bail out.
+      return 0;
+    }
+
+    // If one of the GEPs has all zero indices, recurse.
+    bool AllZeros = true;
+    for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
+      if (!isa<Constant>(GEPLHS->getOperand(i)) ||
+          !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
+        AllZeros = false;
+        break;
+      }
+    if (AllZeros)
+      return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
+                          ICmpInst::getSwappedPredicate(Cond), I);
+
+    // If the other GEP has all zero indices, recurse.
+    AllZeros = true;
+    for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
+      if (!isa<Constant>(GEPRHS->getOperand(i)) ||
+          !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
+        AllZeros = false;
+        break;
+      }
+    if (AllZeros)
+      return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
+
+    if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
+      // If the GEPs only differ by one index, compare it.
+      unsigned NumDifferences = 0;  // Keep track of # differences.
+      unsigned DiffOperand = 0;     // The operand that differs.
+      for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
+        if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
+          if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
+                   GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
+            // Irreconcilable differences.
+            NumDifferences = 2;
+            break;
+          } else {
+            if (NumDifferences++) break;
+            DiffOperand = i;
+          }
+        }
+
+      if (NumDifferences == 0)   // SAME GEP?
+        return ReplaceInstUsesWith(I, // No comparison is needed here.
+                                   ConstantInt::get(Type::Int1Ty,
+                                             ICmpInst::isTrueWhenEqual(Cond)));
+
+      else if (NumDifferences == 1) {
+        Value *LHSV = GEPLHS->getOperand(DiffOperand);
+        Value *RHSV = GEPRHS->getOperand(DiffOperand);
+        // Make sure we do a signed comparison here.
+        return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
+      }
+    }
+
+    // Only lower this if the icmp is the only user of the GEP or if we expect
+    // the result to fold to a constant!
+    if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
+        (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
+      // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2)  --->  (OFFSET1 cmp OFFSET2)
+      Value *L = EmitGEPOffset(GEPLHS, I, *this);
+      Value *R = EmitGEPOffset(GEPRHS, I, *this);
+      return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
+    }
+  }
+  return 0;
+}
+
+/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
+///
+Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
+                                                Instruction *LHSI,
+                                                Constant *RHSC) {
+  if (!isa<ConstantFP>(RHSC)) return 0;
+  const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
+  
+  // Get the width of the mantissa.  We don't want to hack on conversions that
+  // might lose information from the integer, e.g. "i64 -> float"
+  int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
+  if (MantissaWidth == -1) return 0;  // Unknown.
+  
+  // Check to see that the input is converted from an integer type that is small
+  // enough that preserves all bits.  TODO: check here for "known" sign bits.
+  // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
+  unsigned InputSize = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
+  
+  // If this is a uitofp instruction, we need an extra bit to hold the sign.
+  bool LHSUnsigned = isa<UIToFPInst>(LHSI);
+  if (LHSUnsigned)
+    ++InputSize;
+  
+  // If the conversion would lose info, don't hack on this.
+  if ((int)InputSize > MantissaWidth)
+    return 0;
+  
+  // Otherwise, we can potentially simplify the comparison.  We know that it
+  // will always come through as an integer value and we know the constant is
+  // not a NAN (it would have been previously simplified).
+  assert(!RHS.isNaN() && "NaN comparison not already folded!");
+  
+  ICmpInst::Predicate Pred;
+  switch (I.getPredicate()) {
+  default: assert(0 && "Unexpected predicate!");
+  case FCmpInst::FCMP_UEQ:
+  case FCmpInst::FCMP_OEQ:
+    Pred = ICmpInst::ICMP_EQ;
+    break;
+  case FCmpInst::FCMP_UGT:
+  case FCmpInst::FCMP_OGT:
+    Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
+    break;
+  case FCmpInst::FCMP_UGE:
+  case FCmpInst::FCMP_OGE:
+    Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
+    break;
+  case FCmpInst::FCMP_ULT:
+  case FCmpInst::FCMP_OLT:
+    Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
+    break;
+  case FCmpInst::FCMP_ULE:
+  case FCmpInst::FCMP_OLE:
+    Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
+    break;
+  case FCmpInst::FCMP_UNE:
+  case FCmpInst::FCMP_ONE:
+    Pred = ICmpInst::ICMP_NE;
+    break;
+  case FCmpInst::FCMP_ORD:
+    return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+  case FCmpInst::FCMP_UNO:
+    return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+  }
+  
+  const IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
+  
+  // Now we know that the APFloat is a normal number, zero or inf.
+  
+  // See if the FP constant is too large for the integer.  For example,
+  // comparing an i8 to 300.0.
+  unsigned IntWidth = IntTy->getPrimitiveSizeInBits();
+  
+  if (!LHSUnsigned) {
+    // If the RHS value is > SignedMax, fold the comparison.  This handles +INF
+    // and large values.
+    APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false);
+    SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
+                          APFloat::rmNearestTiesToEven);
+    if (SMax.compare(RHS) == APFloat::cmpLessThan) {  // smax < 13123.0
+      if (Pred == ICmpInst::ICMP_NE  || Pred == ICmpInst::ICMP_SLT ||
+          Pred == ICmpInst::ICMP_SLE)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+    }
+  } else {
+    // If the RHS value is > UnsignedMax, fold the comparison. This handles
+    // +INF and large values.
+    APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false);
+    UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
+                          APFloat::rmNearestTiesToEven);
+    if (UMax.compare(RHS) == APFloat::cmpLessThan) {  // umax < 13123.0
+      if (Pred == ICmpInst::ICMP_NE  || Pred == ICmpInst::ICMP_ULT ||
+          Pred == ICmpInst::ICMP_ULE)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+    }
+  }
+  
+  if (!LHSUnsigned) {
+    // See if the RHS value is < SignedMin.
+    APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false);
+    SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
+                          APFloat::rmNearestTiesToEven);
+    if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
+      if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
+          Pred == ICmpInst::ICMP_SGE)
+        return ReplaceInstUsesWith(I,ConstantInt::getTrue());
+      return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+    }
+  }
+
+  // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
+  // [0, UMAX], but it may still be fractional.  See if it is fractional by
+  // casting the FP value to the integer value and back, checking for equality.
+  // Don't do this for zero, because -0.0 is not fractional.
+  Constant *RHSInt = LHSUnsigned
+    ? ConstantExpr::getFPToUI(RHSC, IntTy)
+    : ConstantExpr::getFPToSI(RHSC, IntTy);
+  if (!RHS.isZero()) {
+    bool Equal = LHSUnsigned
+      ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
+      : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
+    if (!Equal) {
+      // If we had a comparison against a fractional value, we have to adjust
+      // the compare predicate and sometimes the value.  RHSC is rounded towards
+      // zero at this point.
+      switch (Pred) {
+      default: assert(0 && "Unexpected integer comparison!");
+      case ICmpInst::ICMP_NE:  // (float)int != 4.4   --> true
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      case ICmpInst::ICMP_EQ:  // (float)int == 4.4   --> false
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+      case ICmpInst::ICMP_ULE:
+        // (float)int <= 4.4   --> int <= 4
+        // (float)int <= -4.4  --> false
+        if (RHS.isNegative())
+          return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+        break;
+      case ICmpInst::ICMP_SLE:
+        // (float)int <= 4.4   --> int <= 4
+        // (float)int <= -4.4  --> int < -4
+        if (RHS.isNegative())
+          Pred = ICmpInst::ICMP_SLT;
+        break;
+      case ICmpInst::ICMP_ULT:
+        // (float)int < -4.4   --> false
+        // (float)int < 4.4    --> int <= 4
+        if (RHS.isNegative())
+          return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+        Pred = ICmpInst::ICMP_ULE;
+        break;
+      case ICmpInst::ICMP_SLT:
+        // (float)int < -4.4   --> int < -4
+        // (float)int < 4.4    --> int <= 4
+        if (!RHS.isNegative())
+          Pred = ICmpInst::ICMP_SLE;
+        break;
+      case ICmpInst::ICMP_UGT:
+        // (float)int > 4.4    --> int > 4
+        // (float)int > -4.4   --> true
+        if (RHS.isNegative())
+          return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+        break;
+      case ICmpInst::ICMP_SGT:
+        // (float)int > 4.4    --> int > 4
+        // (float)int > -4.4   --> int >= -4
+        if (RHS.isNegative())
+          Pred = ICmpInst::ICMP_SGE;
+        break;
+      case ICmpInst::ICMP_UGE:
+        // (float)int >= -4.4   --> true
+        // (float)int >= 4.4    --> int > 4
+        if (!RHS.isNegative())
+          return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+        Pred = ICmpInst::ICMP_UGT;
+        break;
+      case ICmpInst::ICMP_SGE:
+        // (float)int >= -4.4   --> int >= -4
+        // (float)int >= 4.4    --> int > 4
+        if (!RHS.isNegative())
+          Pred = ICmpInst::ICMP_SGT;
+        break;
+      }
+    }
+  }
+
+  // Lower this FP comparison into an appropriate integer version of the
+  // comparison.
+  return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
+}
+
+Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
+  bool Changed = SimplifyCompare(I);
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  // Fold trivial predicates.
+  if (I.getPredicate() == FCmpInst::FCMP_FALSE)
+    return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+  if (I.getPredicate() == FCmpInst::FCMP_TRUE)
+    return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+  
+  // Simplify 'fcmp pred X, X'
+  if (Op0 == Op1) {
+    switch (I.getPredicate()) {
+    default: assert(0 && "Unknown predicate!");
+    case FCmpInst::FCMP_UEQ:    // True if unordered or equal
+    case FCmpInst::FCMP_UGE:    // True if unordered, greater than, or equal
+    case FCmpInst::FCMP_ULE:    // True if unordered, less than, or equal
+      return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+    case FCmpInst::FCMP_OGT:    // True if ordered and greater than
+    case FCmpInst::FCMP_OLT:    // True if ordered and less than
+    case FCmpInst::FCMP_ONE:    // True if ordered and operands are unequal
+      return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+      
+    case FCmpInst::FCMP_UNO:    // True if unordered: isnan(X) | isnan(Y)
+    case FCmpInst::FCMP_ULT:    // True if unordered or less than
+    case FCmpInst::FCMP_UGT:    // True if unordered or greater than
+    case FCmpInst::FCMP_UNE:    // True if unordered or not equal
+      // Canonicalize these to be 'fcmp uno %X, 0.0'.
+      I.setPredicate(FCmpInst::FCMP_UNO);
+      I.setOperand(1, Constant::getNullValue(Op0->getType()));
+      return &I;
+      
+    case FCmpInst::FCMP_ORD:    // True if ordered (no nans)
+    case FCmpInst::FCMP_OEQ:    // True if ordered and equal
+    case FCmpInst::FCMP_OGE:    // True if ordered and greater than or equal
+    case FCmpInst::FCMP_OLE:    // True if ordered and less than or equal
+      // Canonicalize these to be 'fcmp ord %X, 0.0'.
+      I.setPredicate(FCmpInst::FCMP_ORD);
+      I.setOperand(1, Constant::getNullValue(Op0->getType()));
+      return &I;
+    }
+  }
+    
+  if (isa<UndefValue>(Op1))                  // fcmp pred X, undef -> undef
+    return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
+
+  // Handle fcmp with constant RHS
+  if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
+    // If the constant is a nan, see if we can fold the comparison based on it.
+    if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
+      if (CFP->getValueAPF().isNaN()) {
+        if (FCmpInst::isOrdered(I.getPredicate()))   // True if ordered and...
+          return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+        assert(FCmpInst::isUnordered(I.getPredicate()) &&
+               "Comparison must be either ordered or unordered!");
+        // True if unordered.
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      }
+    }
+    
+    if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+      switch (LHSI->getOpcode()) {
+      case Instruction::PHI:
+        // Only fold fcmp into the PHI if the phi and fcmp are in the same
+        // block.  If in the same block, we're encouraging jump threading.  If
+        // not, we are just pessimizing the code by making an i1 phi.
+        if (LHSI->getParent() == I.getParent())
+          if (Instruction *NV = FoldOpIntoPhi(I))
+            return NV;
+        break;
+      case Instruction::SIToFP:
+      case Instruction::UIToFP:
+        if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
+          return NV;
+        break;
+      case Instruction::Select:
+        // If either operand of the select is a constant, we can fold the
+        // comparison into the select arms, which will cause one to be
+        // constant folded and the select turned into a bitwise or.
+        Value *Op1 = 0, *Op2 = 0;
+        if (LHSI->hasOneUse()) {
+          if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
+            // Fold the known value into the constant operand.
+            Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
+            // Insert a new FCmp of the other select operand.
+            Op2 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
+                                                      LHSI->getOperand(2), RHSC,
+                                                      I.getName()), I);
+          } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
+            // Fold the known value into the constant operand.
+            Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
+            // Insert a new FCmp of the other select operand.
+            Op1 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
+                                                      LHSI->getOperand(1), RHSC,
+                                                      I.getName()), I);
+          }
+        }
+
+        if (Op1)
+          return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
+        break;
+      }
+  }
+
+  return Changed ? &I : 0;
+}
+
+Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
+  bool Changed = SimplifyCompare(I);
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+  const Type *Ty = Op0->getType();
+
+  // icmp X, X
+  if (Op0 == Op1)
+    return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 
+                                                   I.isTrueWhenEqual()));
+
+  if (isa<UndefValue>(Op1))                  // X icmp undef -> undef
+    return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
+  
+  // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
+  // addresses never equal each other!  We already know that Op0 != Op1.
+  if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
+       isa<ConstantPointerNull>(Op0)) &&
+      (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
+       isa<ConstantPointerNull>(Op1)))
+    return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 
+                                                   !I.isTrueWhenEqual()));
+
+  // icmp's with boolean values can always be turned into bitwise operations
+  if (Ty == Type::Int1Ty) {
+    switch (I.getPredicate()) {
+    default: assert(0 && "Invalid icmp instruction!");
+    case ICmpInst::ICMP_EQ: {               // icmp eq i1 A, B -> ~(A^B)
+      Instruction *Xor = BinaryOperator::CreateXor(Op0, Op1, I.getName()+"tmp");
+      InsertNewInstBefore(Xor, I);
+      return BinaryOperator::CreateNot(Xor);
+    }
+    case ICmpInst::ICMP_NE:                  // icmp eq i1 A, B -> A^B
+      return BinaryOperator::CreateXor(Op0, Op1);
+
+    case ICmpInst::ICMP_UGT:
+      std::swap(Op0, Op1);                   // Change icmp ugt -> icmp ult
+      // FALL THROUGH
+    case ICmpInst::ICMP_ULT:{               // icmp ult i1 A, B -> ~A & B
+      Instruction *Not = BinaryOperator::CreateNot(Op0, I.getName()+"tmp");
+      InsertNewInstBefore(Not, I);
+      return BinaryOperator::CreateAnd(Not, Op1);
+    }
+    case ICmpInst::ICMP_SGT:
+      std::swap(Op0, Op1);                   // Change icmp sgt -> icmp slt
+      // FALL THROUGH
+    case ICmpInst::ICMP_SLT: {               // icmp slt i1 A, B -> A & ~B
+      Instruction *Not = BinaryOperator::CreateNot(Op1, I.getName()+"tmp");
+      InsertNewInstBefore(Not, I);
+      return BinaryOperator::CreateAnd(Not, Op0);
+    }
+    case ICmpInst::ICMP_UGE:
+      std::swap(Op0, Op1);                   // Change icmp uge -> icmp ule
+      // FALL THROUGH
+    case ICmpInst::ICMP_ULE: {               //  icmp ule i1 A, B -> ~A | B
+      Instruction *Not = BinaryOperator::CreateNot(Op0, I.getName()+"tmp");
+      InsertNewInstBefore(Not, I);
+      return BinaryOperator::CreateOr(Not, Op1);
+    }
+    case ICmpInst::ICMP_SGE:
+      std::swap(Op0, Op1);                   // Change icmp sge -> icmp sle
+      // FALL THROUGH
+    case ICmpInst::ICMP_SLE: {               //  icmp sle i1 A, B -> A | ~B
+      Instruction *Not = BinaryOperator::CreateNot(Op1, I.getName()+"tmp");
+      InsertNewInstBefore(Not, I);
+      return BinaryOperator::CreateOr(Not, Op0);
+    }
+    }
+  }
+
+  unsigned BitWidth = 0;
+  if (TD)
+    BitWidth = TD->getTypeSizeInBits(Ty);
+  else if (isa<IntegerType>(Ty))
+    BitWidth = Ty->getPrimitiveSizeInBits();
+
+  bool isSignBit = false;
+
+  // See if we are doing a comparison with a constant.
+  if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+    Value *A = 0, *B = 0;
+    
+    // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
+    if (I.isEquality() && CI->isNullValue() &&
+        match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
+      // (icmp cond A B) if cond is equality
+      return new ICmpInst(I.getPredicate(), A, B);
+    }
+    
+    // If we have an icmp le or icmp ge instruction, turn it into the
+    // appropriate icmp lt or icmp gt instruction.  This allows us to rely on
+    // them being folded in the code below.
+    switch (I.getPredicate()) {
+    default: break;
+    case ICmpInst::ICMP_ULE:
+      if (CI->isMaxValue(false))                 // A <=u MAX -> TRUE
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
+    case ICmpInst::ICMP_SLE:
+      if (CI->isMaxValue(true))                  // A <=s MAX -> TRUE
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
+    case ICmpInst::ICMP_UGE:
+      if (CI->isMinValue(false))                 // A >=u MIN -> TRUE
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
+    case ICmpInst::ICMP_SGE:
+      if (CI->isMinValue(true))                  // A >=s MIN -> TRUE
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
+    }
+    
+    // If this comparison is a normal comparison, it demands all
+    // bits, if it is a sign bit comparison, it only demands the sign bit.
+    bool UnusedBit;
+    isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
+  }
+
+  // See if we can fold the comparison based on range information we can get
+  // by checking whether bits are known to be zero or one in the input.
+  if (BitWidth != 0) {
+    APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0);
+    APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0);
+
+    if (SimplifyDemandedBits(I.getOperandUse(0),
+                             isSignBit ? APInt::getSignBit(BitWidth)
+                                       : APInt::getAllOnesValue(BitWidth),
+                             Op0KnownZero, Op0KnownOne, 0))
+      return &I;
+    if (SimplifyDemandedBits(I.getOperandUse(1),
+                             APInt::getAllOnesValue(BitWidth),
+                             Op1KnownZero, Op1KnownOne, 0))
+      return &I;
+
+    // Given the known and unknown bits, compute a range that the LHS could be
+    // in.  Compute the Min, Max and RHS values based on the known bits. For the
+    // EQ and NE we use unsigned values.
+    APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
+    APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
+    if (ICmpInst::isSignedPredicate(I.getPredicate())) {
+      ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
+                                             Op0Min, Op0Max);
+      ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
+                                             Op1Min, Op1Max);
+    } else {
+      ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
+                                               Op0Min, Op0Max);
+      ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
+                                               Op1Min, Op1Max);
+    }
+
+    // If Min and Max are known to be the same, then SimplifyDemandedBits
+    // figured out that the LHS is a constant.  Just constant fold this now so
+    // that code below can assume that Min != Max.
+    if (!isa<Constant>(Op0) && Op0Min == Op0Max)
+      return new ICmpInst(I.getPredicate(), ConstantInt::get(Op0Min), Op1);
+    if (!isa<Constant>(Op1) && Op1Min == Op1Max)
+      return new ICmpInst(I.getPredicate(), Op0, ConstantInt::get(Op1Min));
+
+    // Based on the range information we know about the LHS, see if we can
+    // simplify this comparison.  For example, (x&4) < 8  is always true.
+    switch (I.getPredicate()) {
+    default: assert(0 && "Unknown icmp opcode!");
+    case ICmpInst::ICMP_EQ:
+      if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+      break;
+    case ICmpInst::ICMP_NE:
+      if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      break;
+    case ICmpInst::ICMP_ULT:
+      if (Op0Max.ult(Op1Min))          // A <u B -> true if max(A) < min(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      if (Op0Min.uge(Op1Max))          // A <u B -> false if min(A) >= max(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+      if (Op1Min == Op0Max)            // A <u B -> A != B if max(A) == min(B)
+        return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+      if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+        if (Op1Max == Op0Min+1)        // A <u C -> A == C-1 if min(A)+1 == C
+          return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
+
+        // (x <u 2147483648) -> (x >s -1)  -> true if sign bit clear
+        if (CI->isMinValue(true))
+          return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
+                            ConstantInt::getAllOnesValue(Op0->getType()));
+      }
+      break;
+    case ICmpInst::ICMP_UGT:
+      if (Op0Min.ugt(Op1Max))          // A >u B -> true if min(A) > max(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      if (Op0Max.ule(Op1Min))          // A >u B -> false if max(A) <= max(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+
+      if (Op1Max == Op0Min)            // A >u B -> A != B if min(A) == max(B)
+        return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+      if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+        if (Op1Min == Op0Max-1)        // A >u C -> A == C+1 if max(a)-1 == C
+          return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
+
+        // (x >u 2147483647) -> (x <s 0)  -> true if sign bit set
+        if (CI->isMaxValue(true))
+          return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
+                              ConstantInt::getNullValue(Op0->getType()));
+      }
+      break;
+    case ICmpInst::ICMP_SLT:
+      if (Op0Max.slt(Op1Min))          // A <s B -> true if max(A) < min(C)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      if (Op0Min.sge(Op1Max))          // A <s B -> false if min(A) >= max(C)
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+      if (Op1Min == Op0Max)            // A <s B -> A != B if max(A) == min(B)
+        return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+      if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+        if (Op1Max == Op0Min+1)        // A <s C -> A == C-1 if min(A)+1 == C
+          return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
+      }
+      break;
+    case ICmpInst::ICMP_SGT:
+      if (Op0Min.sgt(Op1Max))          // A >s B -> true if min(A) > max(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      if (Op0Max.sle(Op1Min))          // A >s B -> false if max(A) <= min(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+
+      if (Op1Max == Op0Min)            // A >s B -> A != B if min(A) == max(B)
+        return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+      if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+        if (Op1Min == Op0Max-1)        // A >s C -> A == C+1 if max(A)-1 == C
+          return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
+      }
+      break;
+    case ICmpInst::ICMP_SGE:
+      assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
+      if (Op0Min.sge(Op1Max))          // A >=s B -> true if min(A) >= max(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      if (Op0Max.slt(Op1Min))          // A >=s B -> false if max(A) < min(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+      break;
+    case ICmpInst::ICMP_SLE:
+      assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
+      if (Op0Max.sle(Op1Min))          // A <=s B -> true if max(A) <= min(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      if (Op0Min.sgt(Op1Max))          // A <=s B -> false if min(A) > max(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+      break;
+    case ICmpInst::ICMP_UGE:
+      assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
+      if (Op0Min.uge(Op1Max))          // A >=u B -> true if min(A) >= max(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      if (Op0Max.ult(Op1Min))          // A >=u B -> false if max(A) < min(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+      break;
+    case ICmpInst::ICMP_ULE:
+      assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
+      if (Op0Max.ule(Op1Min))          // A <=u B -> true if max(A) <= min(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+      if (Op0Min.ugt(Op1Max))          // A <=u B -> false if min(A) > max(B)
+        return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+      break;
+    }
+
+    // Turn a signed comparison into an unsigned one if both operands
+    // are known to have the same sign.
+    if (I.isSignedPredicate() &&
+        ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) ||
+         (Op0KnownOne.isNegative() && Op1KnownOne.isNegative())))
+      return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
+  }
+
+  // Test if the ICmpInst instruction is used exclusively by a select as
+  // part of a minimum or maximum operation. If so, refrain from doing
+  // any other folding. This helps out other analyses which understand
+  // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
+  // and CodeGen. And in this case, at least one of the comparison
+  // operands has at least one user besides the compare (the select),
+  // which would often largely negate the benefit of folding anyway.
+  if (I.hasOneUse())
+    if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin()))
+      if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
+          (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
+        return 0;
+
+  // See if we are doing a comparison between a constant and an instruction that
+  // can be folded into the comparison.
+  if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+    // Since the RHS is a ConstantInt (CI), if the left hand side is an 
+    // instruction, see if that instruction also has constants so that the 
+    // instruction can be folded into the icmp 
+    if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+      if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
+        return Res;
+  }
+
+  // Handle icmp with constant (but not simple integer constant) RHS
+  if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
+    if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+      switch (LHSI->getOpcode()) {
+      case Instruction::GetElementPtr:
+        if (RHSC->isNullValue()) {
+          // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
+          bool isAllZeros = true;
+          for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
+            if (!isa<Constant>(LHSI->getOperand(i)) ||
+                !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
+              isAllZeros = false;
+              break;
+            }
+          if (isAllZeros)
+            return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
+                    Constant::getNullValue(LHSI->getOperand(0)->getType()));
+        }
+        break;
+
+      case Instruction::PHI:
+        // Only fold icmp into the PHI if the phi and fcmp are in the same
+        // block.  If in the same block, we're encouraging jump threading.  If
+        // not, we are just pessimizing the code by making an i1 phi.
+        if (LHSI->getParent() == I.getParent())
+          if (Instruction *NV = FoldOpIntoPhi(I))
+            return NV;
+        break;
+      case Instruction::Select: {
+        // If either operand of the select is a constant, we can fold the
+        // comparison into the select arms, which will cause one to be
+        // constant folded and the select turned into a bitwise or.
+        Value *Op1 = 0, *Op2 = 0;
+        if (LHSI->hasOneUse()) {
+          if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
+            // Fold the known value into the constant operand.
+            Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
+            // Insert a new ICmp of the other select operand.
+            Op2 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
+                                                   LHSI->getOperand(2), RHSC,
+                                                   I.getName()), I);
+          } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
+            // Fold the known value into the constant operand.
+            Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
+            // Insert a new ICmp of the other select operand.
+            Op1 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
+                                                   LHSI->getOperand(1), RHSC,
+                                                   I.getName()), I);
+          }
+        }
+
+        if (Op1)
+          return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
+        break;
+      }
+      case Instruction::Malloc:
+        // If we have (malloc != null), and if the malloc has a single use, we
+        // can assume it is successful and remove the malloc.
+        if (LHSI->hasOneUse() && isa<ConstantPointerNull>(RHSC)) {
+          AddToWorkList(LHSI);
+          return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
+                                                         !I.isTrueWhenEqual()));
+        }
+        break;
+      }
+  }
+
+  // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
+  if (User *GEP = dyn_castGetElementPtr(Op0))
+    if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
+      return NI;
+  if (User *GEP = dyn_castGetElementPtr(Op1))
+    if (Instruction *NI = FoldGEPICmp(GEP, Op0,
+                           ICmpInst::getSwappedPredicate(I.getPredicate()), I))
+      return NI;
+
+  // Test to see if the operands of the icmp are casted versions of other
+  // values.  If the ptr->ptr cast can be stripped off both arguments, we do so
+  // now.
+  if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
+    if (isa<PointerType>(Op0->getType()) && 
+        (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) { 
+      // We keep moving the cast from the left operand over to the right
+      // operand, where it can often be eliminated completely.
+      Op0 = CI->getOperand(0);
+
+      // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
+      // so eliminate it as well.
+      if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
+        Op1 = CI2->getOperand(0);
+
+      // If Op1 is a constant, we can fold the cast into the constant.
+      if (Op0->getType() != Op1->getType()) {
+        if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+          Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
+        } else {
+          // Otherwise, cast the RHS right before the icmp
+          Op1 = InsertBitCastBefore(Op1, Op0->getType(), I);
+        }
+      }
+      return new ICmpInst(I.getPredicate(), Op0, Op1);
+    }
+  }
+  
+  if (isa<CastInst>(Op0)) {
+    // Handle the special case of: icmp (cast bool to X), <cst>
+    // This comes up when you have code like
+    //   int X = A < B;
+    //   if (X) ...
+    // For generality, we handle any zero-extension of any operand comparison
+    // with a constant or another cast from the same type.
+    if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
+      if (Instruction *R = visitICmpInstWithCastAndCast(I))
+        return R;
+  }
+  
+  // See if it's the same type of instruction on the left and right.
+  if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+    if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
+      if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() &&
+          Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1)) {
+        switch (Op0I->getOpcode()) {
+        default: break;
+        case Instruction::Add:
+        case Instruction::Sub:
+        case Instruction::Xor:
+          if (I.isEquality())    // a+x icmp eq/ne b+x --> a icmp b
+            return new ICmpInst(I.getPredicate(), Op0I->getOperand(0),
+                                Op1I->getOperand(0));
+          // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
+          if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
+            if (CI->getValue().isSignBit()) {
+              ICmpInst::Predicate Pred = I.isSignedPredicate()
+                                             ? I.getUnsignedPredicate()
+                                             : I.getSignedPredicate();
+              return new ICmpInst(Pred, Op0I->getOperand(0),
+                                  Op1I->getOperand(0));
+            }
+            
+            if (CI->getValue().isMaxSignedValue()) {
+              ICmpInst::Predicate Pred = I.isSignedPredicate()
+                                             ? I.getUnsignedPredicate()
+                                             : I.getSignedPredicate();
+              Pred = I.getSwappedPredicate(Pred);
+              return new ICmpInst(Pred, Op0I->getOperand(0),
+                                  Op1I->getOperand(0));
+            }
+          }
+          break;
+        case Instruction::Mul:
+          if (!I.isEquality())
+            break;
+
+          if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
+            // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
+            // Mask = -1 >> count-trailing-zeros(Cst).
+            if (!CI->isZero() && !CI->isOne()) {
+              const APInt &AP = CI->getValue();
+              ConstantInt *Mask = ConstantInt::get(
+                                      APInt::getLowBitsSet(AP.getBitWidth(),
+                                                           AP.getBitWidth() -
+                                                      AP.countTrailingZeros()));
+              Instruction *And1 = BinaryOperator::CreateAnd(Op0I->getOperand(0),
+                                                            Mask);
+              Instruction *And2 = BinaryOperator::CreateAnd(Op1I->getOperand(0),
+                                                            Mask);
+              InsertNewInstBefore(And1, I);
+              InsertNewInstBefore(And2, I);
+              return new ICmpInst(I.getPredicate(), And1, And2);
+            }
+          }
+          break;
+        }
+      }
+    }
+  }
+  
+  // ~x < ~y --> y < x
+  { Value *A, *B;
+    if (match(Op0, m_Not(m_Value(A))) &&
+        match(Op1, m_Not(m_Value(B))))
+      return new ICmpInst(I.getPredicate(), B, A);
+  }
+  
+  if (I.isEquality()) {
+    Value *A, *B, *C, *D;
+    
+    // -x == -y --> x == y
+    if (match(Op0, m_Neg(m_Value(A))) &&
+        match(Op1, m_Neg(m_Value(B))))
+      return new ICmpInst(I.getPredicate(), A, B);
+    
+    if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
+      if (A == Op1 || B == Op1) {    // (A^B) == A  ->  B == 0
+        Value *OtherVal = A == Op1 ? B : A;
+        return new ICmpInst(I.getPredicate(), OtherVal,
+                            Constant::getNullValue(A->getType()));
+      }
+
+      if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
+        // A^c1 == C^c2 --> A == C^(c1^c2)
+        ConstantInt *C1, *C2;
+        if (match(B, m_ConstantInt(C1)) &&
+            match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
+          Constant *NC = ConstantInt::get(C1->getValue() ^ C2->getValue());
+          Instruction *Xor = BinaryOperator::CreateXor(C, NC, "tmp");
+          return new ICmpInst(I.getPredicate(), A,
+                              InsertNewInstBefore(Xor, I));
+        }
+        
+        // A^B == A^D -> B == D
+        if (A == C) return new ICmpInst(I.getPredicate(), B, D);
+        if (A == D) return new ICmpInst(I.getPredicate(), B, C);
+        if (B == C) return new ICmpInst(I.getPredicate(), A, D);
+        if (B == D) return new ICmpInst(I.getPredicate(), A, C);
+      }
+    }
+    
+    if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
+        (A == Op0 || B == Op0)) {
+      // A == (A^B)  ->  B == 0
+      Value *OtherVal = A == Op0 ? B : A;
+      return new ICmpInst(I.getPredicate(), OtherVal,
+                          Constant::getNullValue(A->getType()));
+    }
+
+    // (A-B) == A  ->  B == 0
+    if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B))))
+      return new ICmpInst(I.getPredicate(), B, 
+                          Constant::getNullValue(B->getType()));
+
+    // A == (A-B)  ->  B == 0
+    if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B))))
+      return new ICmpInst(I.getPredicate(), B,
+                          Constant::getNullValue(B->getType()));
+    
+    // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
+    if (Op0->hasOneUse() && Op1->hasOneUse() &&
+        match(Op0, m_And(m_Value(A), m_Value(B))) && 
+        match(Op1, m_And(m_Value(C), m_Value(D)))) {
+      Value *X = 0, *Y = 0, *Z = 0;
+      
+      if (A == C) {
+        X = B; Y = D; Z = A;
+      } else if (A == D) {
+        X = B; Y = C; Z = A;
+      } else if (B == C) {
+        X = A; Y = D; Z = B;
+      } else if (B == D) {
+        X = A; Y = C; Z = B;
+      }
+      
+      if (X) {   // Build (X^Y) & Z
+        Op1 = InsertNewInstBefore(BinaryOperator::CreateXor(X, Y, "tmp"), I);
+        Op1 = InsertNewInstBefore(BinaryOperator::CreateAnd(Op1, Z, "tmp"), I);
+        I.setOperand(0, Op1);
+        I.setOperand(1, Constant::getNullValue(Op1->getType()));
+        return &I;
+      }
+    }
+  }
+  return Changed ? &I : 0;
+}
+
+
+/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
+/// and CmpRHS are both known to be integer constants.
+Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
+                                          ConstantInt *DivRHS) {
+  ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
+  const APInt &CmpRHSV = CmpRHS->getValue();
+  
+  // FIXME: If the operand types don't match the type of the divide 
+  // then don't attempt this transform. The code below doesn't have the
+  // logic to deal with a signed divide and an unsigned compare (and
+  // vice versa). This is because (x /s C1) <s C2  produces different 
+  // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
+  // (x /u C1) <u C2.  Simply casting the operands and result won't 
+  // work. :(  The if statement below tests that condition and bails 
+  // if it finds it. 
+  bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
+  if (!ICI.isEquality() && DivIsSigned != ICI.isSignedPredicate())
+    return 0;
+  if (DivRHS->isZero())
+    return 0; // The ProdOV computation fails on divide by zero.
+  if (DivIsSigned && DivRHS->isAllOnesValue())
+    return 0; // The overflow computation also screws up here
+  if (DivRHS->isOne())
+    return 0; // Not worth bothering, and eliminates some funny cases
+              // with INT_MIN.
+
+  // Compute Prod = CI * DivRHS. We are essentially solving an equation
+  // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and 
+  // C2 (CI). By solving for X we can turn this into a range check 
+  // instead of computing a divide. 
+  ConstantInt *Prod = Multiply(CmpRHS, DivRHS);
+
+  // Determine if the product overflows by seeing if the product is
+  // not equal to the divide. Make sure we do the same kind of divide
+  // as in the LHS instruction that we're folding. 
+  bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
+                 ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
+
+  // Get the ICmp opcode
+  ICmpInst::Predicate Pred = ICI.getPredicate();
+
+  // Figure out the interval that is being checked.  For example, a comparison
+  // like "X /u 5 == 0" is really checking that X is in the interval [0, 5). 
+  // Compute this interval based on the constants involved and the signedness of
+  // the compare/divide.  This computes a half-open interval, keeping track of
+  // whether either value in the interval overflows.  After analysis each
+  // overflow variable is set to 0 if it's corresponding bound variable is valid
+  // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
+  int LoOverflow = 0, HiOverflow = 0;
+  ConstantInt *LoBound = 0, *HiBound = 0;
+  
+  if (!DivIsSigned) {  // udiv
+    // e.g. X/5 op 3  --> [15, 20)
+    LoBound = Prod;
+    HiOverflow = LoOverflow = ProdOV;
+    if (!HiOverflow)
+      HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false);
+  } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
+    if (CmpRHSV == 0) {       // (X / pos) op 0
+      // Can't overflow.  e.g.  X/2 op 0 --> [-1, 2)
+      LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
+      HiBound = DivRHS;
+    } else if (CmpRHSV.isStrictlyPositive()) {   // (X / pos) op pos
+      LoBound = Prod;     // e.g.   X/5 op 3 --> [15, 20)
+      HiOverflow = LoOverflow = ProdOV;
+      if (!HiOverflow)
+        HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true);
+    } else {                       // (X / pos) op neg
+      // e.g. X/5 op -3  --> [-15-4, -15+1) --> [-19, -14)
+      HiBound = AddOne(Prod);
+      LoOverflow = HiOverflow = ProdOV ? -1 : 0;
+      if (!LoOverflow) {
+        ConstantInt* DivNeg = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
+        LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg,
+                                     true) ? -1 : 0;
+       }
+    }
+  } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0.
+    if (CmpRHSV == 0) {       // (X / neg) op 0
+      // e.g. X/-5 op 0  --> [-4, 5)
+      LoBound = AddOne(DivRHS);
+      HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
+      if (HiBound == DivRHS) {     // -INTMIN = INTMIN
+        HiOverflow = 1;            // [INTMIN+1, overflow)
+        HiBound = 0;               // e.g. X/INTMIN = 0 --> X > INTMIN
+      }
+    } else if (CmpRHSV.isStrictlyPositive()) {   // (X / neg) op pos
+      // e.g. X/-5 op 3  --> [-19, -14)
+      HiBound = AddOne(Prod);
+      HiOverflow = LoOverflow = ProdOV ? -1 : 0;
+      if (!LoOverflow)
+        LoOverflow = AddWithOverflow(LoBound, HiBound, DivRHS, true) ? -1 : 0;
+    } else {                       // (X / neg) op neg
+      LoBound = Prod;       // e.g. X/-5 op -3  --> [15, 20)
+      LoOverflow = HiOverflow = ProdOV;
+      if (!HiOverflow)
+        HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, true);
+    }
+    
+    // Dividing by a negative swaps the condition.  LT <-> GT
+    Pred = ICmpInst::getSwappedPredicate(Pred);
+  }
+
+  Value *X = DivI->getOperand(0);
+  switch (Pred) {
+  default: assert(0 && "Unhandled icmp opcode!");
+  case ICmpInst::ICMP_EQ:
+    if (LoOverflow && HiOverflow)
+      return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+    else if (HiOverflow)
+      return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : 
+                          ICmpInst::ICMP_UGE, X, LoBound);
+    else if (LoOverflow)
+      return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : 
+                          ICmpInst::ICMP_ULT, X, HiBound);
+    else
+      return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
+  case ICmpInst::ICMP_NE:
+    if (LoOverflow && HiOverflow)
+      return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+    else if (HiOverflow)
+      return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : 
+                          ICmpInst::ICMP_ULT, X, LoBound);
+    else if (LoOverflow)
+      return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : 
+                          ICmpInst::ICMP_UGE, X, HiBound);
+    else
+      return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
+  case ICmpInst::ICMP_ULT:
+  case ICmpInst::ICMP_SLT:
+    if (LoOverflow == +1)   // Low bound is greater than input range.
+      return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+    if (LoOverflow == -1)   // Low bound is less than input range.
+      return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+    return new ICmpInst(Pred, X, LoBound);
+  case ICmpInst::ICMP_UGT:
+  case ICmpInst::ICMP_SGT:
+    if (HiOverflow == +1)       // High bound greater than input range.
+      return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+    else if (HiOverflow == -1)  // High bound less than input range.
+      return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+    if (Pred == ICmpInst::ICMP_UGT)
+      return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
+    else
+      return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
+  }
+}
+
+
+/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
+///
+Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
+                                                          Instruction *LHSI,
+                                                          ConstantInt *RHS) {
+  const APInt &RHSV = RHS->getValue();
+  
+  switch (LHSI->getOpcode()) {
+  case Instruction::Trunc:
+    if (ICI.isEquality() && LHSI->hasOneUse()) {
+      // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
+      // of the high bits truncated out of x are known.
+      unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
+             SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
+      APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits));
+      APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
+      ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne);
+      
+      // If all the high bits are known, we can do this xform.
+      if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
+        // Pull in the high bits from known-ones set.
+        APInt NewRHS(RHS->getValue());
+        NewRHS.zext(SrcBits);
+        NewRHS |= KnownOne;
+        return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
+                            ConstantInt::get(NewRHS));
+      }
+    }
+    break;
+      
+  case Instruction::Xor:         // (icmp pred (xor X, XorCST), CI)
+    if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
+      // If this is a comparison that tests the signbit (X < 0) or (x > -1),
+      // fold the xor.
+      if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
+          (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
+        Value *CompareVal = LHSI->getOperand(0);
+        
+        // If the sign bit of the XorCST is not set, there is no change to
+        // the operation, just stop using the Xor.
+        if (!XorCST->getValue().isNegative()) {
+          ICI.setOperand(0, CompareVal);
+          AddToWorkList(LHSI);
+          return &ICI;
+        }
+        
+        // Was the old condition true if the operand is positive?
+        bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
+        
+        // If so, the new one isn't.
+        isTrueIfPositive ^= true;
+        
+        if (isTrueIfPositive)
+          return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, SubOne(RHS));
+        else
+          return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, AddOne(RHS));
+      }
+
+      if (LHSI->hasOneUse()) {
+        // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
+        if (!ICI.isEquality() && XorCST->getValue().isSignBit()) {
+          const APInt &SignBit = XorCST->getValue();
+          ICmpInst::Predicate Pred = ICI.isSignedPredicate()
+                                         ? ICI.getUnsignedPredicate()
+                                         : ICI.getSignedPredicate();
+          return new ICmpInst(Pred, LHSI->getOperand(0),
+                              ConstantInt::get(RHSV ^ SignBit));
+        }
+
+        // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
+        if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) {
+          const APInt &NotSignBit = XorCST->getValue();
+          ICmpInst::Predicate Pred = ICI.isSignedPredicate()
+                                         ? ICI.getUnsignedPredicate()
+                                         : ICI.getSignedPredicate();
+          Pred = ICI.getSwappedPredicate(Pred);
+          return new ICmpInst(Pred, LHSI->getOperand(0),
+                              ConstantInt::get(RHSV ^ NotSignBit));
+        }
+      }
+    }
+    break;
+  case Instruction::And:         // (icmp pred (and X, AndCST), RHS)
+    if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
+        LHSI->getOperand(0)->hasOneUse()) {
+      ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
+      
+      // If the LHS is an AND of a truncating cast, we can widen the
+      // and/compare to be the input width without changing the value
+      // produced, eliminating a cast.
+      if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
+        // We can do this transformation if either the AND constant does not
+        // have its sign bit set or if it is an equality comparison. 
+        // Extending a relational comparison when we're checking the sign
+        // bit would not work.
+        if (Cast->hasOneUse() &&
+            (ICI.isEquality() ||
+             (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) {
+          uint32_t BitWidth = 
+            cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
+          APInt NewCST = AndCST->getValue();
+          NewCST.zext(BitWidth);
+          APInt NewCI = RHSV;
+          NewCI.zext(BitWidth);
+          Instruction *NewAnd = 
+            BinaryOperator::CreateAnd(Cast->getOperand(0),
+                                      ConstantInt::get(NewCST),LHSI->getName());
+          InsertNewInstBefore(NewAnd, ICI);
+          return new ICmpInst(ICI.getPredicate(), NewAnd,
+                              ConstantInt::get(NewCI));
+        }
+      }
+      
+      // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
+      // could exist), turn it into (X & (C2 << C1)) != (C3 << C1).  This
+      // happens a LOT in code produced by the C front-end, for bitfield
+      // access.
+      BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
+      if (Shift && !Shift->isShift())
+        Shift = 0;
+      
+      ConstantInt *ShAmt;
+      ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
+      const Type *Ty = Shift ? Shift->getType() : 0;  // Type of the shift.
+      const Type *AndTy = AndCST->getType();          // Type of the and.
+      
+      // We can fold this as long as we can't shift unknown bits
+      // into the mask.  This can only happen with signed shift
+      // rights, as they sign-extend.
+      if (ShAmt) {
+        bool CanFold = Shift->isLogicalShift();
+        if (!CanFold) {
+          // To test for the bad case of the signed shr, see if any
+          // of the bits shifted in could be tested after the mask.
+          uint32_t TyBits = Ty->getPrimitiveSizeInBits();
+          int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
+          
+          uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
+          if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) & 
+               AndCST->getValue()) == 0)
+            CanFold = true;
+        }
+        
+        if (CanFold) {
+          Constant *NewCst;
+          if (Shift->getOpcode() == Instruction::Shl)
+            NewCst = ConstantExpr::getLShr(RHS, ShAmt);
+          else
+            NewCst = ConstantExpr::getShl(RHS, ShAmt);
+          
+          // Check to see if we are shifting out any of the bits being
+          // compared.
+          if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != RHS) {
+            // If we shifted bits out, the fold is not going to work out.
+            // As a special case, check to see if this means that the
+            // result is always true or false now.
+            if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+              return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+            if (ICI.getPredicate() == ICmpInst::ICMP_NE)
+              return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+          } else {
+            ICI.setOperand(1, NewCst);
+            Constant *NewAndCST;
+            if (Shift->getOpcode() == Instruction::Shl)
+              NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
+            else
+              NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
+            LHSI->setOperand(1, NewAndCST);
+            LHSI->setOperand(0, Shift->getOperand(0));
+            AddToWorkList(Shift); // Shift is dead.
+            AddUsesToWorkList(ICI);
+            return &ICI;
+          }
+        }
+      }
+      
+      // Turn ((X >> Y) & C) == 0  into  (X & (C << Y)) == 0.  The later is
+      // preferable because it allows the C<<Y expression to be hoisted out
+      // of a loop if Y is invariant and X is not.
+      if (Shift && Shift->hasOneUse() && RHSV == 0 &&
+          ICI.isEquality() && !Shift->isArithmeticShift() &&
+          !isa<Constant>(Shift->getOperand(0))) {
+        // Compute C << Y.
+        Value *NS;
+        if (Shift->getOpcode() == Instruction::LShr) {
+          NS = BinaryOperator::CreateShl(AndCST, 
+                                         Shift->getOperand(1), "tmp");
+        } else {
+          // Insert a logical shift.
+          NS = BinaryOperator::CreateLShr(AndCST,
+                                          Shift->getOperand(1), "tmp");
+        }
+        InsertNewInstBefore(cast<Instruction>(NS), ICI);
+        
+        // Compute X & (C << Y).
+        Instruction *NewAnd = 
+          BinaryOperator::CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
+        InsertNewInstBefore(NewAnd, ICI);
+        
+        ICI.setOperand(0, NewAnd);
+        return &ICI;
+      }
+    }
+    break;
+    
+  case Instruction::Shl: {       // (icmp pred (shl X, ShAmt), CI)
+    ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+    if (!ShAmt) break;
+    
+    uint32_t TypeBits = RHSV.getBitWidth();
+    
+    // Check that the shift amount is in range.  If not, don't perform
+    // undefined shifts.  When the shift is visited it will be
+    // simplified.
+    if (ShAmt->uge(TypeBits))
+      break;
+    
+    if (ICI.isEquality()) {
+      // If we are comparing against bits always shifted out, the
+      // comparison cannot succeed.
+      Constant *Comp =
+        ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), ShAmt);
+      if (Comp != RHS) {// Comparing against a bit that we know is zero.
+        bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+        Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
+        return ReplaceInstUsesWith(ICI, Cst);
+      }
+      
+      if (LHSI->hasOneUse()) {
+        // Otherwise strength reduce the shift into an and.
+        uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+        Constant *Mask =
+          ConstantInt::get(APInt::getLowBitsSet(TypeBits, TypeBits-ShAmtVal));
+        
+        Instruction *AndI =
+          BinaryOperator::CreateAnd(LHSI->getOperand(0),
+                                    Mask, LHSI->getName()+".mask");
+        Value *And = InsertNewInstBefore(AndI, ICI);
+        return new ICmpInst(ICI.getPredicate(), And,
+                            ConstantInt::get(RHSV.lshr(ShAmtVal)));
+      }
+    }
+    
+    // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
+    bool TrueIfSigned = false;
+    if (LHSI->hasOneUse() &&
+        isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
+      // (X << 31) <s 0  --> (X&1) != 0
+      Constant *Mask = ConstantInt::get(APInt(TypeBits, 1) <<
+                                           (TypeBits-ShAmt->getZExtValue()-1));
+      Instruction *AndI =
+        BinaryOperator::CreateAnd(LHSI->getOperand(0),
+                                  Mask, LHSI->getName()+".mask");
+      Value *And = InsertNewInstBefore(AndI, ICI);
+      
+      return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
+                          And, Constant::getNullValue(And->getType()));
+    }
+    break;
+  }
+    
+  case Instruction::LShr:         // (icmp pred (shr X, ShAmt), CI)
+  case Instruction::AShr: {
+    // Only handle equality comparisons of shift-by-constant.
+    ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+    if (!ShAmt || !ICI.isEquality()) break;
+
+    // Check that the shift amount is in range.  If not, don't perform
+    // undefined shifts.  When the shift is visited it will be
+    // simplified.
+    uint32_t TypeBits = RHSV.getBitWidth();
+    if (ShAmt->uge(TypeBits))
+      break;
+    
+    uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+      
+    // If we are comparing against bits always shifted out, the
+    // comparison cannot succeed.
+    APInt Comp = RHSV << ShAmtVal;
+    if (LHSI->getOpcode() == Instruction::LShr)
+      Comp = Comp.lshr(ShAmtVal);
+    else
+      Comp = Comp.ashr(ShAmtVal);
+    
+    if (Comp != RHSV) { // Comparing against a bit that we know is zero.
+      bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+      Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
+      return ReplaceInstUsesWith(ICI, Cst);
+    }
+    
+    // Otherwise, check to see if the bits shifted out are known to be zero.
+    // If so, we can compare against the unshifted value:
+    //  (X & 4) >> 1 == 2  --> (X & 4) == 4.
+    if (LHSI->hasOneUse() &&
+        MaskedValueIsZero(LHSI->getOperand(0), 
+                          APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) {
+      return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
+                          ConstantExpr::getShl(RHS, ShAmt));
+    }
+      
+    if (LHSI->hasOneUse()) {
+      // Otherwise strength reduce the shift into an and.
+      APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
+      Constant *Mask = ConstantInt::get(Val);
+      
+      Instruction *AndI =
+        BinaryOperator::CreateAnd(LHSI->getOperand(0),
+                                  Mask, LHSI->getName()+".mask");
+      Value *And = InsertNewInstBefore(AndI, ICI);
+      return new ICmpInst(ICI.getPredicate(), And,
+                          ConstantExpr::getShl(RHS, ShAmt));
+    }
+    break;
+  }
+    
+  case Instruction::SDiv:
+  case Instruction::UDiv:
+    // Fold: icmp pred ([us]div X, C1), C2 -> range test
+    // Fold this div into the comparison, producing a range check. 
+    // Determine, based on the divide type, what the range is being 
+    // checked.  If there is an overflow on the low or high side, remember 
+    // it, otherwise compute the range [low, hi) bounding the new value.
+    // See: InsertRangeTest above for the kinds of replacements possible.
+    if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
+      if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
+                                          DivRHS))
+        return R;
+    break;
+
+  case Instruction::Add:
+    // Fold: icmp pred (add, X, C1), C2
+
+    if (!ICI.isEquality()) {
+      ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+      if (!LHSC) break;
+      const APInt &LHSV = LHSC->getValue();
+
+      ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
+                            .subtract(LHSV);
+
+      if (ICI.isSignedPredicate()) {
+        if (CR.getLower().isSignBit()) {
+          return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
+                              ConstantInt::get(CR.getUpper()));
+        } else if (CR.getUpper().isSignBit()) {
+          return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
+                              ConstantInt::get(CR.getLower()));
+        }
+      } else {
+        if (CR.getLower().isMinValue()) {
+          return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
+                              ConstantInt::get(CR.getUpper()));
+        } else if (CR.getUpper().isMinValue()) {
+          return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
+                              ConstantInt::get(CR.getLower()));
+        }
+      }
+    }
+    break;
+  }
+  
+  // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
+  if (ICI.isEquality()) {
+    bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+    
+    // If the first operand is (add|sub|and|or|xor|rem) with a constant, and 
+    // the second operand is a constant, simplify a bit.
+    if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
+      switch (BO->getOpcode()) {
+      case Instruction::SRem:
+        // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
+        if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
+          const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
+          if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
+            Instruction *NewRem =
+              BinaryOperator::CreateURem(BO->getOperand(0), BO->getOperand(1),
+                                         BO->getName());
+            InsertNewInstBefore(NewRem, ICI);
+            return new ICmpInst(ICI.getPredicate(), NewRem, 
+                                Constant::getNullValue(BO->getType()));
+          }
+        }
+        break;
+      case Instruction::Add:
+        // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
+        if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
+          if (BO->hasOneUse())
+            return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+                                Subtract(RHS, BOp1C));
+        } else if (RHSV == 0) {
+          // Replace ((add A, B) != 0) with (A != -B) if A or B is
+          // efficiently invertible, or if the add has just this one use.
+          Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
+          
+          if (Value *NegVal = dyn_castNegVal(BOp1))
+            return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
+          else if (Value *NegVal = dyn_castNegVal(BOp0))
+            return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
+          else if (BO->hasOneUse()) {
+            Instruction *Neg = BinaryOperator::CreateNeg(BOp1);
+            InsertNewInstBefore(Neg, ICI);
+            Neg->takeName(BO);
+            return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
+          }
+        }
+        break;
+      case Instruction::Xor:
+        // For the xor case, we can xor two constants together, eliminating
+        // the explicit xor.
+        if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
+          return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 
+                              ConstantExpr::getXor(RHS, BOC));
+        
+        // FALLTHROUGH
+      case Instruction::Sub:
+        // Replace (([sub|xor] A, B) != 0) with (A != B)
+        if (RHSV == 0)
+          return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+                              BO->getOperand(1));
+        break;
+        
+      case Instruction::Or:
+        // If bits are being or'd in that are not present in the constant we
+        // are comparing against, then the comparison could never succeed!
+        if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
+          Constant *NotCI = ConstantExpr::getNot(RHS);
+          if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
+            return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty, 
+                                                             isICMP_NE));
+        }
+        break;
+        
+      case Instruction::And:
+        if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
+          // If bits are being compared against that are and'd out, then the
+          // comparison can never succeed!
+          if ((RHSV & ~BOC->getValue()) != 0)
+            return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty,
+                                                             isICMP_NE));
+          
+          // If we have ((X & C) == C), turn it into ((X & C) != 0).
+          if (RHS == BOC && RHSV.isPowerOf2())
+            return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
+                                ICmpInst::ICMP_NE, LHSI,
+                                Constant::getNullValue(RHS->getType()));
+          
+          // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
+          if (BOC->getValue().isSignBit()) {
+            Value *X = BO->getOperand(0);
+            Constant *Zero = Constant::getNullValue(X->getType());
+            ICmpInst::Predicate pred = isICMP_NE ? 
+              ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
+            return new ICmpInst(pred, X, Zero);
+          }
+          
+          // ((X & ~7) == 0) --> X < 8
+          if (RHSV == 0 && isHighOnes(BOC)) {
+            Value *X = BO->getOperand(0);
+            Constant *NegX = ConstantExpr::getNeg(BOC);
+            ICmpInst::Predicate pred = isICMP_NE ? 
+              ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
+            return new ICmpInst(pred, X, NegX);
+          }
+        }
+      default: break;
+      }
+    } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
+      // Handle icmp {eq|ne} <intrinsic>, intcst.
+      if (II->getIntrinsicID() == Intrinsic::bswap) {
+        AddToWorkList(II);
+        ICI.setOperand(0, II->getOperand(1));
+        ICI.setOperand(1, ConstantInt::get(RHSV.byteSwap()));
+        return &ICI;
+      }
+    }
+  }
+  return 0;
+}
+
+/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
+/// We only handle extending casts so far.
+///
+Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
+  const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
+  Value *LHSCIOp        = LHSCI->getOperand(0);
+  const Type *SrcTy     = LHSCIOp->getType();
+  const Type *DestTy    = LHSCI->getType();
+  Value *RHSCIOp;
+
+  // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the 
+  // integer type is the same size as the pointer type.
+  if (LHSCI->getOpcode() == Instruction::PtrToInt &&
+      getTargetData().getPointerSizeInBits() == 
+         cast<IntegerType>(DestTy)->getBitWidth()) {
+    Value *RHSOp = 0;
+    if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
+      RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
+    } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
+      RHSOp = RHSC->getOperand(0);
+      // If the pointer types don't match, insert a bitcast.
+      if (LHSCIOp->getType() != RHSOp->getType())
+        RHSOp = InsertBitCastBefore(RHSOp, LHSCIOp->getType(), ICI);
+    }
+
+    if (RHSOp)
+      return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
+  }
+  
+  // The code below only handles extension cast instructions, so far.
+  // Enforce this.
+  if (LHSCI->getOpcode() != Instruction::ZExt &&
+      LHSCI->getOpcode() != Instruction::SExt)
+    return 0;
+
+  bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
+  bool isSignedCmp = ICI.isSignedPredicate();
+
+  if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
+    // Not an extension from the same type?
+    RHSCIOp = CI->getOperand(0);
+    if (RHSCIOp->getType() != LHSCIOp->getType()) 
+      return 0;
+    
+    // If the signedness of the two casts doesn't agree (i.e. one is a sext
+    // and the other is a zext), then we can't handle this.
+    if (CI->getOpcode() != LHSCI->getOpcode())
+      return 0;
+
+    // Deal with equality cases early.
+    if (ICI.isEquality())
+      return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
+
+    // A signed comparison of sign extended values simplifies into a
+    // signed comparison.
+    if (isSignedCmp && isSignedExt)
+      return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
+
+    // The other three cases all fold into an unsigned comparison.
+    return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
+  }
+
+  // If we aren't dealing with a constant on the RHS, exit early
+  ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
+  if (!CI)
+    return 0;
+
+  // Compute the constant that would happen if we truncated to SrcTy then
+  // reextended to DestTy.
+  Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
+  Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy);
+
+  // If the re-extended constant didn't change...
+  if (Res2 == CI) {
+    // Make sure that sign of the Cmp and the sign of the Cast are the same.
+    // For example, we might have:
+    //    %A = sext short %X to uint
+    //    %B = icmp ugt uint %A, 1330
+    // It is incorrect to transform this into 
+    //    %B = icmp ugt short %X, 1330 
+    // because %A may have negative value. 
+    //
+    // However, we allow this when the compare is EQ/NE, because they are
+    // signless.
+    if (isSignedExt == isSignedCmp || ICI.isEquality())
+      return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
+    return 0;
+  }
+
+  // The re-extended constant changed so the constant cannot be represented 
+  // in the shorter type. Consequently, we cannot emit a simple comparison.
+
+  // First, handle some easy cases. We know the result cannot be equal at this
+  // point so handle the ICI.isEquality() cases
+  if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+    return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+  if (ICI.getPredicate() == ICmpInst::ICMP_NE)
+    return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+
+  // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
+  // should have been folded away previously and not enter in here.
+  Value *Result;
+  if (isSignedCmp) {
+    // We're performing a signed comparison.
+    if (cast<ConstantInt>(CI)->getValue().isNegative())
+      Result = ConstantInt::getFalse();          // X < (small) --> false
+    else
+      Result = ConstantInt::getTrue();           // X < (large) --> true
+  } else {
+    // We're performing an unsigned comparison.
+    if (isSignedExt) {
+      // We're performing an unsigned comp with a sign extended value.
+      // This is true if the input is >= 0. [aka >s -1]
+      Constant *NegOne = ConstantInt::getAllOnesValue(SrcTy);
+      Result = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_SGT, LHSCIOp,
+                                   NegOne, ICI.getName()), ICI);
+    } else {
+      // Unsigned extend & unsigned compare -> always true.
+      Result = ConstantInt::getTrue();
+    }
+  }
+
+  // Finally, return the value computed.
+  if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
+      ICI.getPredicate() == ICmpInst::ICMP_SLT)
+    return ReplaceInstUsesWith(ICI, Result);
+
+  assert((ICI.getPredicate()==ICmpInst::ICMP_UGT || 
+          ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
+         "ICmp should be folded!");
+  if (Constant *CI = dyn_cast<Constant>(Result))
+    return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
+  return BinaryOperator::CreateNot(Result);
+}
+
+Instruction *InstCombiner::visitShl(BinaryOperator &I) {
+  return commonShiftTransforms(I);
+}
+
+Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
+  return commonShiftTransforms(I);
+}
+
+Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
+  if (Instruction *R = commonShiftTransforms(I))
+    return R;
+  
+  Value *Op0 = I.getOperand(0);
+  
+  // ashr int -1, X = -1   (for any arithmetic shift rights of ~0)
+  if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
+    if (CSI->isAllOnesValue())
+      return ReplaceInstUsesWith(I, CSI);
+  
+  // See if we can turn a signed shr into an unsigned shr.
+  if (!isa<VectorType>(I.getType())) {
+    if (MaskedValueIsZero(Op0,
+                      APInt::getSignBit(I.getType()->getPrimitiveSizeInBits())))
+      return BinaryOperator::CreateLShr(Op0, I.getOperand(1));
+
+    // Arithmetic shifting an all-sign-bit value is a no-op.
+    unsigned NumSignBits = ComputeNumSignBits(Op0);
+    if (NumSignBits == Op0->getType()->getPrimitiveSizeInBits())
+      return ReplaceInstUsesWith(I, Op0);
+  }
+
+  return 0;
+}
+
+Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
+  assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  // shl X, 0 == X and shr X, 0 == X
+  // shl 0, X == 0 and shr 0, X == 0
+  if (Op1 == Constant::getNullValue(Op1->getType()) ||
+      Op0 == Constant::getNullValue(Op0->getType()))
+    return ReplaceInstUsesWith(I, Op0);
+  
+  if (isa<UndefValue>(Op0)) {            
+    if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
+      return ReplaceInstUsesWith(I, Op0);
+    else                                    // undef << X -> 0, undef >>u X -> 0
+      return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+  }
+  if (isa<UndefValue>(Op1)) {
+    if (I.getOpcode() == Instruction::AShr)  // X >>s undef -> X
+      return ReplaceInstUsesWith(I, Op0);          
+    else                                     // X << undef, X >>u undef -> 0
+      return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+  }
+
+  // See if we can fold away this shift.
+  if (!isa<VectorType>(I.getType()) && SimplifyDemandedInstructionBits(I))
+    return &I;
+
+  // Try to fold constant and into select arguments.
+  if (isa<Constant>(Op0))
+    if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+      if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+        return R;
+
+  if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
+    if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
+      return Res;
+  return 0;
+}
+
+Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
+                                               BinaryOperator &I) {
+  bool isLeftShift = I.getOpcode() == Instruction::Shl;
+
+  // See if we can simplify any instructions used by the instruction whose sole 
+  // purpose is to compute bits we don't care about.
+  uint32_t TypeBits = Op0->getType()->getPrimitiveSizeInBits();
+  
+  // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
+  // of a signed value.
+  //
+  if (Op1->uge(TypeBits)) {
+    if (I.getOpcode() != Instruction::AShr)
+      return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
+    else {
+      I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
+      return &I;
+    }
+  }
+  
+  // ((X*C1) << C2) == (X * (C1 << C2))
+  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
+    if (BO->getOpcode() == Instruction::Mul && isLeftShift)
+      if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
+        return BinaryOperator::CreateMul(BO->getOperand(0),
+                                         ConstantExpr::getShl(BOOp, Op1));
+  
+  // Try to fold constant and into select arguments.
+  if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+    if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+      return R;
+  if (isa<PHINode>(Op0))
+    if (Instruction *NV = FoldOpIntoPhi(I))
+      return NV;
+  
+  // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
+  if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
+    Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
+    // If 'shift2' is an ashr, we would have to get the sign bit into a funny
+    // place.  Don't try to do this transformation in this case.  Also, we
+    // require that the input operand is a shift-by-constant so that we have
+    // confidence that the shifts will get folded together.  We could do this
+    // xform in more cases, but it is unlikely to be profitable.
+    if (TrOp && I.isLogicalShift() && TrOp->isShift() && 
+        isa<ConstantInt>(TrOp->getOperand(1))) {
+      // Okay, we'll do this xform.  Make the shift of shift.
+      Constant *ShAmt = ConstantExpr::getZExt(Op1, TrOp->getType());
+      Instruction *NSh = BinaryOperator::Create(I.getOpcode(), TrOp, ShAmt,
+                                                I.getName());
+      InsertNewInstBefore(NSh, I); // (shift2 (shift1 & 0x00FF), c2)
+
+      // For logical shifts, the truncation has the effect of making the high
+      // part of the register be zeros.  Emulate this by inserting an AND to
+      // clear the top bits as needed.  This 'and' will usually be zapped by
+      // other xforms later if dead.
+      unsigned SrcSize = TrOp->getType()->getPrimitiveSizeInBits();
+      unsigned DstSize = TI->getType()->getPrimitiveSizeInBits();
+      APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
+      
+      // The mask we constructed says what the trunc would do if occurring
+      // between the shifts.  We want to know the effect *after* the second
+      // shift.  We know that it is a logical shift by a constant, so adjust the
+      // mask as appropriate.
+      if (I.getOpcode() == Instruction::Shl)
+        MaskV <<= Op1->getZExtValue();
+      else {
+        assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
+        MaskV = MaskV.lshr(Op1->getZExtValue());
+      }
+
+      Instruction *And = BinaryOperator::CreateAnd(NSh, ConstantInt::get(MaskV),
+                                                   TI->getName());
+      InsertNewInstBefore(And, I); // shift1 & 0x00FF
+
+      // Return the value truncated to the interesting size.
+      return new TruncInst(And, I.getType());
+    }
+  }
+  
+  if (Op0->hasOneUse()) {
+    if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
+      // Turn ((X >> C) + Y) << C  ->  (X + (Y << C)) & (~0 << C)
+      Value *V1, *V2;
+      ConstantInt *CC;
+      switch (Op0BO->getOpcode()) {
+        default: break;
+        case Instruction::Add:
+        case Instruction::And:
+        case Instruction::Or:
+        case Instruction::Xor: {
+          // These operators commute.
+          // Turn (Y + (X >> C)) << C  ->  (X + (Y << C)) & (~0 << C)
+          if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
+              match(Op0BO->getOperand(1), m_Shr(m_Value(V1), m_Specific(Op1)))){
+            Instruction *YS = BinaryOperator::CreateShl(
+                                            Op0BO->getOperand(0), Op1,
+                                            Op0BO->getName());
+            InsertNewInstBefore(YS, I); // (Y << C)
+            Instruction *X = 
+              BinaryOperator::Create(Op0BO->getOpcode(), YS, V1,
+                                     Op0BO->getOperand(1)->getName());
+            InsertNewInstBefore(X, I);  // (X + (Y << C))
+            uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
+            return BinaryOperator::CreateAnd(X, ConstantInt::get(
+                       APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
+          }
+          
+          // Turn (Y + ((X >> C) & CC)) << C  ->  ((X & (CC << C)) + (Y << C))
+          Value *Op0BOOp1 = Op0BO->getOperand(1);
+          if (isLeftShift && Op0BOOp1->hasOneUse() &&
+              match(Op0BOOp1, 
+                    m_And(m_Shr(m_Value(V1), m_Specific(Op1)),
+                          m_ConstantInt(CC))) &&
+              cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse()) {
+            Instruction *YS = BinaryOperator::CreateShl(
+                                                     Op0BO->getOperand(0), Op1,
+                                                     Op0BO->getName());
+            InsertNewInstBefore(YS, I); // (Y << C)
+            Instruction *XM =
+              BinaryOperator::CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
+                                        V1->getName()+".mask");
+            InsertNewInstBefore(XM, I); // X & (CC << C)
+            
+            return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
+          }
+        }
+          
+        // FALL THROUGH.
+        case Instruction::Sub: {
+          // Turn ((X >> C) + Y) << C  ->  (X + (Y << C)) & (~0 << C)
+          if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
+              match(Op0BO->getOperand(0), m_Shr(m_Value(V1), m_Specific(Op1)))){
+            Instruction *YS = BinaryOperator::CreateShl(
+                                                     Op0BO->getOperand(1), Op1,
+                                                     Op0BO->getName());
+            InsertNewInstBefore(YS, I); // (Y << C)
+            Instruction *X =
+              BinaryOperator::Create(Op0BO->getOpcode(), V1, YS,
+                                     Op0BO->getOperand(0)->getName());
+            InsertNewInstBefore(X, I);  // (X + (Y << C))
+            uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
+            return BinaryOperator::CreateAnd(X, ConstantInt::get(
+                       APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
+          }
+          
+          // Turn (((X >> C)&CC) + Y) << C  ->  (X + (Y << C)) & (CC << C)
+          if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
+              match(Op0BO->getOperand(0),
+                    m_And(m_Shr(m_Value(V1), m_Value(V2)),
+                          m_ConstantInt(CC))) && V2 == Op1 &&
+              cast<BinaryOperator>(Op0BO->getOperand(0))
+                  ->getOperand(0)->hasOneUse()) {
+            Instruction *YS = BinaryOperator::CreateShl(
+                                                     Op0BO->getOperand(1), Op1,
+                                                     Op0BO->getName());
+            InsertNewInstBefore(YS, I); // (Y << C)
+            Instruction *XM =
+              BinaryOperator::CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
+                                        V1->getName()+".mask");
+            InsertNewInstBefore(XM, I); // X & (CC << C)
+            
+            return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
+          }
+          
+          break;
+        }
+      }
+      
+      
+      // If the operand is an bitwise operator with a constant RHS, and the
+      // shift is the only use, we can pull it out of the shift.
+      if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
+        bool isValid = true;     // Valid only for And, Or, Xor
+        bool highBitSet = false; // Transform if high bit of constant set?
+        
+        switch (Op0BO->getOpcode()) {
+          default: isValid = false; break;   // Do not perform transform!
+          case Instruction::Add:
+            isValid = isLeftShift;
+            break;
+          case Instruction::Or:
+          case Instruction::Xor:
+            highBitSet = false;
+            break;
+          case Instruction::And:
+            highBitSet = true;
+            break;
+        }
+        
+        // If this is a signed shift right, and the high bit is modified
+        // by the logical operation, do not perform the transformation.
+        // The highBitSet boolean indicates the value of the high bit of
+        // the constant which would cause it to be modified for this
+        // operation.
+        //
+        if (isValid && I.getOpcode() == Instruction::AShr)
+          isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
+        
+        if (isValid) {
+          Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
+          
+          Instruction *NewShift =
+            BinaryOperator::Create(I.getOpcode(), Op0BO->getOperand(0), Op1);
+          InsertNewInstBefore(NewShift, I);
+          NewShift->takeName(Op0BO);
+          
+          return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
+                                        NewRHS);
+        }
+      }
+    }
+  }
+  
+  // Find out if this is a shift of a shift by a constant.
+  BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
+  if (ShiftOp && !ShiftOp->isShift())
+    ShiftOp = 0;
+  
+  if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
+    ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
+    uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits);
+    uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits);
+    assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
+    if (ShiftAmt1 == 0) return 0;  // Will be simplified in the future.
+    Value *X = ShiftOp->getOperand(0);
+    
+    uint32_t AmtSum = ShiftAmt1+ShiftAmt2;   // Fold into one big shift.
+    
+    const IntegerType *Ty = cast<IntegerType>(I.getType());
+    
+    // Check for (X << c1) << c2  and  (X >> c1) >> c2
+    if (I.getOpcode() == ShiftOp->getOpcode()) {
+      // If this is oversized composite shift, then unsigned shifts get 0, ashr
+      // saturates.
+      if (AmtSum >= TypeBits) {
+        if (I.getOpcode() != Instruction::AShr)
+          return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+        AmtSum = TypeBits-1;  // Saturate to 31 for i32 ashr.
+      }
+      
+      return BinaryOperator::Create(I.getOpcode(), X,
+                                    ConstantInt::get(Ty, AmtSum));
+    } else if (ShiftOp->getOpcode() == Instruction::LShr &&
+               I.getOpcode() == Instruction::AShr) {
+      if (AmtSum >= TypeBits)
+        return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+      
+      // ((X >>u C1) >>s C2) -> (X >>u (C1+C2))  since C1 != 0.
+      return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum));
+    } else if (ShiftOp->getOpcode() == Instruction::AShr &&
+               I.getOpcode() == Instruction::LShr) {
+      // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
+      if (AmtSum >= TypeBits)
+        AmtSum = TypeBits-1;
+      
+      Instruction *Shift =
+        BinaryOperator::CreateAShr(X, ConstantInt::get(Ty, AmtSum));
+      InsertNewInstBefore(Shift, I);
+
+      APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
+      return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
+    }
+    
+    // Okay, if we get here, one shift must be left, and the other shift must be
+    // right.  See if the amounts are equal.
+    if (ShiftAmt1 == ShiftAmt2) {
+      // If we have ((X >>? C) << C), turn this into X & (-1 << C).
+      if (I.getOpcode() == Instruction::Shl) {
+        APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1));
+        return BinaryOperator::CreateAnd(X, ConstantInt::get(Mask));
+      }
+      // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
+      if (I.getOpcode() == Instruction::LShr) {
+        APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
+        return BinaryOperator::CreateAnd(X, ConstantInt::get(Mask));
+      }
+      // We can simplify ((X << C) >>s C) into a trunc + sext.
+      // NOTE: we could do this for any C, but that would make 'unusual' integer
+      // types.  For now, just stick to ones well-supported by the code
+      // generators.
+      const Type *SExtType = 0;
+      switch (Ty->getBitWidth() - ShiftAmt1) {
+      case 1  :
+      case 8  :
+      case 16 :
+      case 32 :
+      case 64 :
+      case 128:
+        SExtType = IntegerType::get(Ty->getBitWidth() - ShiftAmt1);
+        break;
+      default: break;
+      }
+      if (SExtType) {
+        Instruction *NewTrunc = new TruncInst(X, SExtType, "sext");
+        InsertNewInstBefore(NewTrunc, I);
+        return new SExtInst(NewTrunc, Ty);
+      }
+      // Otherwise, we can't handle it yet.
+    } else if (ShiftAmt1 < ShiftAmt2) {
+      uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;
+      
+      // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
+      if (I.getOpcode() == Instruction::Shl) {
+        assert(ShiftOp->getOpcode() == Instruction::LShr ||
+               ShiftOp->getOpcode() == Instruction::AShr);
+        Instruction *Shift =
+          BinaryOperator::CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
+        InsertNewInstBefore(Shift, I);
+        
+        APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
+        return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
+      }
+      
+      // (X << C1) >>u C2  --> X >>u (C2-C1) & (-1 >> C2)
+      if (I.getOpcode() == Instruction::LShr) {
+        assert(ShiftOp->getOpcode() == Instruction::Shl);
+        Instruction *Shift =
+          BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, ShiftDiff));
+        InsertNewInstBefore(Shift, I);
+        
+        APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
+        return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
+      }
+      
+      // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
+    } else {
+      assert(ShiftAmt2 < ShiftAmt1);
+      uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;
+
+      // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
+      if (I.getOpcode() == Instruction::Shl) {
+        assert(ShiftOp->getOpcode() == Instruction::LShr ||
+               ShiftOp->getOpcode() == Instruction::AShr);
+        Instruction *Shift =
+          BinaryOperator::Create(ShiftOp->getOpcode(), X,
+                                 ConstantInt::get(Ty, ShiftDiff));
+        InsertNewInstBefore(Shift, I);
+        
+        APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
+        return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
+      }
+      
+      // (X << C1) >>u C2  --> X << (C1-C2) & (-1 >> C2)
+      if (I.getOpcode() == Instruction::LShr) {
+        assert(ShiftOp->getOpcode() == Instruction::Shl);
+        Instruction *Shift =
+          BinaryOperator::CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
+        InsertNewInstBefore(Shift, I);
+        
+        APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
+        return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
+      }
+      
+      // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
+    }
+  }
+  return 0;
+}
+
+
+/// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
+/// expression.  If so, decompose it, returning some value X, such that Val is
+/// X*Scale+Offset.
+///
+static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
+                                        int &Offset) {
+  assert(Val->getType() == Type::Int32Ty && "Unexpected allocation size type!");
+  if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
+    Offset = CI->getZExtValue();
+    Scale  = 0;
+    return ConstantInt::get(Type::Int32Ty, 0);
+  } else if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
+    if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
+      if (I->getOpcode() == Instruction::Shl) {
+        // This is a value scaled by '1 << the shift amt'.
+        Scale = 1U << RHS->getZExtValue();
+        Offset = 0;
+        return I->getOperand(0);
+      } else if (I->getOpcode() == Instruction::Mul) {
+        // This value is scaled by 'RHS'.
+        Scale = RHS->getZExtValue();
+        Offset = 0;
+        return I->getOperand(0);
+      } else if (I->getOpcode() == Instruction::Add) {
+        // We have X+C.  Check to see if we really have (X*C2)+C1, 
+        // where C1 is divisible by C2.
+        unsigned SubScale;
+        Value *SubVal = 
+          DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
+        Offset += RHS->getZExtValue();
+        Scale = SubScale;
+        return SubVal;
+      }
+    }
+  }
+
+  // Otherwise, we can't look past this.
+  Scale = 1;
+  Offset = 0;
+  return Val;
+}
+
+
+/// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
+/// try to eliminate the cast by moving the type information into the alloc.
+Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
+                                                   AllocationInst &AI) {
+  const PointerType *PTy = cast<PointerType>(CI.getType());
+  
+  // Remove any uses of AI that are dead.
+  assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
+  
+  for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
+    Instruction *User = cast<Instruction>(*UI++);
+    if (isInstructionTriviallyDead(User)) {
+      while (UI != E && *UI == User)
+        ++UI; // If this instruction uses AI more than once, don't break UI.
+      
+      ++NumDeadInst;
+      DOUT << "IC: DCE: " << *User;
+      EraseInstFromFunction(*User);
+    }
+  }
+  
+  // Get the type really allocated and the type casted to.
+  const Type *AllocElTy = AI.getAllocatedType();
+  const Type *CastElTy = PTy->getElementType();
+  if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
+
+  unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
+  unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
+  if (CastElTyAlign < AllocElTyAlign) return 0;
+
+  // If the allocation has multiple uses, only promote it if we are strictly
+  // increasing the alignment of the resultant allocation.  If we keep it the
+  // same, we open the door to infinite loops of various kinds.  (A reference
+  // from a dbg.declare doesn't count as a use for this purpose.)
+  if (!AI.hasOneUse() && !hasOneUsePlusDeclare(&AI) &&
+      CastElTyAlign == AllocElTyAlign) return 0;
+
+  uint64_t AllocElTySize = TD->getTypeAllocSize(AllocElTy);
+  uint64_t CastElTySize = TD->getTypeAllocSize(CastElTy);
+  if (CastElTySize == 0 || AllocElTySize == 0) return 0;
+
+  // See if we can satisfy the modulus by pulling a scale out of the array
+  // size argument.
+  unsigned ArraySizeScale;
+  int ArrayOffset;
+  Value *NumElements = // See if the array size is a decomposable linear expr.
+    DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
+ 
+  // If we can now satisfy the modulus, by using a non-1 scale, we really can
+  // do the xform.
+  if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
+      (AllocElTySize*ArrayOffset   ) % CastElTySize != 0) return 0;
+
+  unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
+  Value *Amt = 0;
+  if (Scale == 1) {
+    Amt = NumElements;
+  } else {
+    // If the allocation size is constant, form a constant mul expression
+    Amt = ConstantInt::get(Type::Int32Ty, Scale);
+    if (isa<ConstantInt>(NumElements))
+      Amt = Multiply(cast<ConstantInt>(NumElements), cast<ConstantInt>(Amt));
+    // otherwise multiply the amount and the number of elements
+    else {
+      Instruction *Tmp = BinaryOperator::CreateMul(Amt, NumElements, "tmp");
+      Amt = InsertNewInstBefore(Tmp, AI);
+    }
+  }
+  
+  if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
+    Value *Off = ConstantInt::get(Type::Int32Ty, Offset, true);
+    Instruction *Tmp = BinaryOperator::CreateAdd(Amt, Off, "tmp");
+    Amt = InsertNewInstBefore(Tmp, AI);
+  }
+  
+  AllocationInst *New;
+  if (isa<MallocInst>(AI))
+    New = new MallocInst(CastElTy, Amt, AI.getAlignment());
+  else
+    New = new AllocaInst(CastElTy, Amt, AI.getAlignment());
+  InsertNewInstBefore(New, AI);
+  New->takeName(&AI);
+  
+  // If the allocation has one real use plus a dbg.declare, just remove the
+  // declare.
+  if (DbgDeclareInst *DI = hasOneUsePlusDeclare(&AI)) {
+    EraseInstFromFunction(*DI);
+  }
+  // If the allocation has multiple real uses, insert a cast and change all
+  // things that used it to use the new cast.  This will also hack on CI, but it
+  // will die soon.
+  else if (!AI.hasOneUse()) {
+    AddUsesToWorkList(AI);
+    // New is the allocation instruction, pointer typed. AI is the original
+    // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
+    CastInst *NewCast = new BitCastInst(New, AI.getType(), "tmpcast");
+    InsertNewInstBefore(NewCast, AI);
+    AI.replaceAllUsesWith(NewCast);
+  }
+  return ReplaceInstUsesWith(CI, New);
+}
+
+/// CanEvaluateInDifferentType - Return true if we can take the specified value
+/// and return it as type Ty without inserting any new casts and without
+/// changing the computed value.  This is used by code that tries to decide
+/// whether promoting or shrinking integer operations to wider or smaller types
+/// will allow us to eliminate a truncate or extend.
+///
+/// This is a truncation operation if Ty is smaller than V->getType(), or an
+/// extension operation if Ty is larger.
+///
+/// If CastOpc is a truncation, then Ty will be a type smaller than V.  We
+/// should return true if trunc(V) can be computed by computing V in the smaller
+/// type.  If V is an instruction, then trunc(inst(x,y)) can be computed as
+/// inst(trunc(x),trunc(y)), which only makes sense if x and y can be
+/// efficiently truncated.
+///
+/// If CastOpc is a sext or zext, we are asking if the low bits of the value can
+/// bit computed in a larger type, which is then and'd or sext_in_reg'd to get
+/// the final result.
+bool InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
+                                              unsigned CastOpc,
+                                              int &NumCastsRemoved){
+  // We can always evaluate constants in another type.
+  if (isa<ConstantInt>(V))
+    return true;
+  
+  Instruction *I = dyn_cast<Instruction>(V);
+  if (!I) return false;
+  
+  const IntegerType *OrigTy = cast<IntegerType>(V->getType());
+  
+  // If this is an extension or truncate, we can often eliminate it.
+  if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
+    // If this is a cast from the destination type, we can trivially eliminate
+    // it, and this will remove a cast overall.
+    if (I->getOperand(0)->getType() == Ty) {
+      // If the first operand is itself a cast, and is eliminable, do not count
+      // this as an eliminable cast.  We would prefer to eliminate those two
+      // casts first.
+      if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse())
+        ++NumCastsRemoved;
+      return true;
+    }
+  }
+
+  // We can't extend or shrink something that has multiple uses: doing so would
+  // require duplicating the instruction in general, which isn't profitable.
+  if (!I->hasOneUse()) return false;
+
+  unsigned Opc = I->getOpcode();
+  switch (Opc) {
+  case Instruction::Add:
+  case Instruction::Sub:
+  case Instruction::Mul:
+  case Instruction::And:
+  case Instruction::Or:
+  case Instruction::Xor:
+    // These operators can all arbitrarily be extended or truncated.
+    return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+                                      NumCastsRemoved) &&
+           CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
+                                      NumCastsRemoved);
+
+  case Instruction::Shl:
+    // If we are truncating the result of this SHL, and if it's a shift of a
+    // constant amount, we can always perform a SHL in a smaller type.
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+      uint32_t BitWidth = Ty->getBitWidth();
+      if (BitWidth < OrigTy->getBitWidth() && 
+          CI->getLimitedValue(BitWidth) < BitWidth)
+        return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+                                          NumCastsRemoved);
+    }
+    break;
+  case Instruction::LShr:
+    // If this is a truncate of a logical shr, we can truncate it to a smaller
+    // lshr iff we know that the bits we would otherwise be shifting in are
+    // already zeros.
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+      uint32_t OrigBitWidth = OrigTy->getBitWidth();
+      uint32_t BitWidth = Ty->getBitWidth();
+      if (BitWidth < OrigBitWidth &&
+          MaskedValueIsZero(I->getOperand(0),
+            APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
+          CI->getLimitedValue(BitWidth) < BitWidth) {
+        return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+                                          NumCastsRemoved);
+      }
+    }
+    break;
+  case Instruction::ZExt:
+  case Instruction::SExt:
+  case Instruction::Trunc:
+    // If this is the same kind of case as our original (e.g. zext+zext), we
+    // can safely replace it.  Note that replacing it does not reduce the number
+    // of casts in the input.
+    if (Opc == CastOpc)
+      return true;
+
+    // sext (zext ty1), ty2 -> zext ty2
+    if (CastOpc == Instruction::SExt && Opc == Instruction::ZExt)
+      return true;
+    break;
+  case Instruction::Select: {
+    SelectInst *SI = cast<SelectInst>(I);
+    return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
+                                      NumCastsRemoved) &&
+           CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
+                                      NumCastsRemoved);
+  }
+  case Instruction::PHI: {
+    // We can change a phi if we can change all operands.
+    PHINode *PN = cast<PHINode>(I);
+    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+      if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc,
+                                      NumCastsRemoved))
+        return false;
+    return true;
+  }
+  default:
+    // TODO: Can handle more cases here.
+    break;
+  }
+  
+  return false;
+}
+
+/// EvaluateInDifferentType - Given an expression that 
+/// CanEvaluateInDifferentType returns true for, actually insert the code to
+/// evaluate the expression.
+Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty, 
+                                             bool isSigned) {
+  if (Constant *C = dyn_cast<Constant>(V))
+    return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
+
+  // Otherwise, it must be an instruction.
+  Instruction *I = cast<Instruction>(V);
+  Instruction *Res = 0;
+  unsigned Opc = I->getOpcode();
+  switch (Opc) {
+  case Instruction::Add:
+  case Instruction::Sub:
+  case Instruction::Mul:
+  case Instruction::And:
+  case Instruction::Or:
+  case Instruction::Xor:
+  case Instruction::AShr:
+  case Instruction::LShr:
+  case Instruction::Shl: {
+    Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
+    Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
+    Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
+    break;
+  }    
+  case Instruction::Trunc:
+  case Instruction::ZExt:
+  case Instruction::SExt:
+    // If the source type of the cast is the type we're trying for then we can
+    // just return the source.  There's no need to insert it because it is not
+    // new.
+    if (I->getOperand(0)->getType() == Ty)
+      return I->getOperand(0);
+    
+    // Otherwise, must be the same type of cast, so just reinsert a new one.
+    Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
+                           Ty);
+    break;
+  case Instruction::Select: {
+    Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
+    Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
+    Res = SelectInst::Create(I->getOperand(0), True, False);
+    break;
+  }
+  case Instruction::PHI: {
+    PHINode *OPN = cast<PHINode>(I);
+    PHINode *NPN = PHINode::Create(Ty);
+    for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
+      Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
+      NPN->addIncoming(V, OPN->getIncomingBlock(i));
+    }
+    Res = NPN;
+    break;
+  }
+  default: 
+    // TODO: Can handle more cases here.
+    assert(0 && "Unreachable!");
+    break;
+  }
+  
+  Res->takeName(I);
+  return InsertNewInstBefore(Res, *I);
+}
+
+/// @brief Implement the transforms common to all CastInst visitors.
+Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
+  Value *Src = CI.getOperand(0);
+
+  // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
+  // eliminate it now.
+  if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {   // A->B->C cast
+    if (Instruction::CastOps opc = 
+        isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
+      // The first cast (CSrc) is eliminable so we need to fix up or replace
+      // the second cast (CI). CSrc will then have a good chance of being dead.
+      return CastInst::Create(opc, CSrc->getOperand(0), CI.getType());
+    }
+  }
+
+  // If we are casting a select then fold the cast into the select
+  if (SelectInst *SI = dyn_cast<SelectInst>(Src))
+    if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
+      return NV;
+
+  // If we are casting a PHI then fold the cast into the PHI
+  if (isa<PHINode>(Src))
+    if (Instruction *NV = FoldOpIntoPhi(CI))
+      return NV;
+  
+  return 0;
+}
+
+/// FindElementAtOffset - Given a type and a constant offset, determine whether
+/// or not there is a sequence of GEP indices into the type that will land us at
+/// the specified offset.  If so, fill them into NewIndices and return the
+/// resultant element type, otherwise return null.
+static const Type *FindElementAtOffset(const Type *Ty, int64_t Offset, 
+                                       SmallVectorImpl<Value*> &NewIndices,
+                                       const TargetData *TD) {
+  if (!Ty->isSized()) return 0;
+  
+  // Start with the index over the outer type.  Note that the type size
+  // might be zero (even if the offset isn't zero) if the indexed type
+  // is something like [0 x {int, int}]
+  const Type *IntPtrTy = TD->getIntPtrType();
+  int64_t FirstIdx = 0;
+  if (int64_t TySize = TD->getTypeAllocSize(Ty)) {
+    FirstIdx = Offset/TySize;
+    Offset -= FirstIdx*TySize;
+    
+    // Handle hosts where % returns negative instead of values [0..TySize).
+    if (Offset < 0) {
+      --FirstIdx;
+      Offset += TySize;
+      assert(Offset >= 0);
+    }
+    assert((uint64_t)Offset < (uint64_t)TySize && "Out of range offset");
+  }
+  
+  NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
+    
+  // Index into the types.  If we fail, set OrigBase to null.
+  while (Offset) {
+    // Indexing into tail padding between struct/array elements.
+    if (uint64_t(Offset*8) >= TD->getTypeSizeInBits(Ty))
+      return 0;
+    
+    if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+      const StructLayout *SL = TD->getStructLayout(STy);
+      assert(Offset < (int64_t)SL->getSizeInBytes() &&
+             "Offset must stay within the indexed type");
+      
+      unsigned Elt = SL->getElementContainingOffset(Offset);
+      NewIndices.push_back(ConstantInt::get(Type::Int32Ty, Elt));
+      
+      Offset -= SL->getElementOffset(Elt);
+      Ty = STy->getElementType(Elt);
+    } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
+      uint64_t EltSize = TD->getTypeAllocSize(AT->getElementType());
+      assert(EltSize && "Cannot index into a zero-sized array");
+      NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
+      Offset %= EltSize;
+      Ty = AT->getElementType();
+    } else {
+      // Otherwise, we can't index into the middle of this atomic type, bail.
+      return 0;
+    }
+  }
+  
+  return Ty;
+}
+
+/// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
+Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
+  Value *Src = CI.getOperand(0);
+  
+  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
+    // If casting the result of a getelementptr instruction with no offset, turn
+    // this into a cast of the original pointer!
+    if (GEP->hasAllZeroIndices()) {
+      // Changing the cast operand is usually not a good idea but it is safe
+      // here because the pointer operand is being replaced with another 
+      // pointer operand so the opcode doesn't need to change.
+      AddToWorkList(GEP);
+      CI.setOperand(0, GEP->getOperand(0));
+      return &CI;
+    }
+    
+    // If the GEP has a single use, and the base pointer is a bitcast, and the
+    // GEP computes a constant offset, see if we can convert these three
+    // instructions into fewer.  This typically happens with unions and other
+    // non-type-safe code.
+    if (GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
+      if (GEP->hasAllConstantIndices()) {
+        // We are guaranteed to get a constant from EmitGEPOffset.
+        ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP, CI, *this));
+        int64_t Offset = OffsetV->getSExtValue();
+        
+        // Get the base pointer input of the bitcast, and the type it points to.
+        Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
+        const Type *GEPIdxTy =
+          cast<PointerType>(OrigBase->getType())->getElementType();
+        SmallVector<Value*, 8> NewIndices;
+        if (FindElementAtOffset(GEPIdxTy, Offset, NewIndices, TD)) {
+          // If we were able to index down into an element, create the GEP
+          // and bitcast the result.  This eliminates one bitcast, potentially
+          // two.
+          Instruction *NGEP = GetElementPtrInst::Create(OrigBase, 
+                                                        NewIndices.begin(),
+                                                        NewIndices.end(), "");
+          InsertNewInstBefore(NGEP, CI);
+          NGEP->takeName(GEP);
+          
+          if (isa<BitCastInst>(CI))
+            return new BitCastInst(NGEP, CI.getType());
+          assert(isa<PtrToIntInst>(CI));
+          return new PtrToIntInst(NGEP, CI.getType());
+        }
+      }      
+    }
+  }
+    
+  return commonCastTransforms(CI);
+}
+
+/// isSafeIntegerType - Return true if this is a basic integer type, not a crazy
+/// type like i42.  We don't want to introduce operations on random non-legal
+/// integer types where they don't already exist in the code.  In the future,
+/// we should consider making this based off target-data, so that 32-bit targets
+/// won't get i64 operations etc.
+static bool isSafeIntegerType(const Type *Ty) {
+  switch (Ty->getPrimitiveSizeInBits()) {
+  case 8:
+  case 16:
+  case 32:
+  case 64:
+    return true;
+  default: 
+    return false;
+  }
+}
+
+/// Only the TRUNC, ZEXT, SEXT, and BITCAST can both operand and result as
+/// integer types. This function implements the common transforms for all those
+/// cases.
+/// @brief Implement the transforms common to CastInst with integer operands
+Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
+  if (Instruction *Result = commonCastTransforms(CI))
+    return Result;
+
+  Value *Src = CI.getOperand(0);
+  const Type *SrcTy = Src->getType();
+  const Type *DestTy = CI.getType();
+  uint32_t SrcBitSize = SrcTy->getPrimitiveSizeInBits();
+  uint32_t DestBitSize = DestTy->getPrimitiveSizeInBits();
+
+  // See if we can simplify any instructions used by the LHS whose sole 
+  // purpose is to compute bits we don't care about.
+  if (SimplifyDemandedInstructionBits(CI))
+    return &CI;
+
+  // If the source isn't an instruction or has more than one use then we
+  // can't do anything more. 
+  Instruction *SrcI = dyn_cast<Instruction>(Src);
+  if (!SrcI || !Src->hasOneUse())
+    return 0;
+
+  // Attempt to propagate the cast into the instruction for int->int casts.
+  int NumCastsRemoved = 0;
+  if (!isa<BitCastInst>(CI) &&
+      // Only do this if the dest type is a simple type, don't convert the
+      // expression tree to something weird like i93 unless the source is also
+      // strange.
+      (isSafeIntegerType(DestTy) || !isSafeIntegerType(SrcI->getType())) &&
+      CanEvaluateInDifferentType(SrcI, cast<IntegerType>(DestTy),
+                                 CI.getOpcode(), NumCastsRemoved)) {
+    // If this cast is a truncate, evaluting in a different type always
+    // eliminates the cast, so it is always a win.  If this is a zero-extension,
+    // we need to do an AND to maintain the clear top-part of the computation,
+    // so we require that the input have eliminated at least one cast.  If this
+    // is a sign extension, we insert two new casts (to do the extension) so we
+    // require that two casts have been eliminated.
+    bool DoXForm = false;
+    bool JustReplace = false;
+    switch (CI.getOpcode()) {
+    default:
+      // All the others use floating point so we shouldn't actually 
+      // get here because of the check above.
+      assert(0 && "Unknown cast type");
+    case Instruction::Trunc:
+      DoXForm = true;
+      break;
+    case Instruction::ZExt: {
+      DoXForm = NumCastsRemoved >= 1;
+      if (!DoXForm && 0) {
+        // If it's unnecessary to issue an AND to clear the high bits, it's
+        // always profitable to do this xform.
+        Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, false);
+        APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
+        if (MaskedValueIsZero(TryRes, Mask))
+          return ReplaceInstUsesWith(CI, TryRes);
+        
+        if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
+          if (TryI->use_empty())
+            EraseInstFromFunction(*TryI);
+      }
+      break;
+    }
+    case Instruction::SExt: {
+      DoXForm = NumCastsRemoved >= 2;
+      if (!DoXForm && !isa<TruncInst>(SrcI) && 0) {
+        // If we do not have to emit the truncate + sext pair, then it's always
+        // profitable to do this xform.
+        //
+        // It's not safe to eliminate the trunc + sext pair if one of the
+        // eliminated cast is a truncate. e.g.
+        // t2 = trunc i32 t1 to i16
+        // t3 = sext i16 t2 to i32
+        // !=
+        // i32 t1
+        Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, true);
+        unsigned NumSignBits = ComputeNumSignBits(TryRes);
+        if (NumSignBits > (DestBitSize - SrcBitSize))
+          return ReplaceInstUsesWith(CI, TryRes);
+        
+        if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
+          if (TryI->use_empty())
+            EraseInstFromFunction(*TryI);
+      }
+      break;
+    }
+    }
+    
+    if (DoXForm) {
+      DOUT << "ICE: EvaluateInDifferentType converting expression type to avoid"
+           << " cast: " << CI;
+      Value *Res = EvaluateInDifferentType(SrcI, DestTy, 
+                                           CI.getOpcode() == Instruction::SExt);
+      if (JustReplace)
+        // Just replace this cast with the result.
+        return ReplaceInstUsesWith(CI, Res);
+
+      assert(Res->getType() == DestTy);
+      switch (CI.getOpcode()) {
+      default: assert(0 && "Unknown cast type!");
+      case Instruction::Trunc:
+      case Instruction::BitCast:
+        // Just replace this cast with the result.
+        return ReplaceInstUsesWith(CI, Res);
+      case Instruction::ZExt: {
+        assert(SrcBitSize < DestBitSize && "Not a zext?");
+
+        // If the high bits are already zero, just replace this cast with the
+        // result.
+        APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
+        if (MaskedValueIsZero(Res, Mask))
+          return ReplaceInstUsesWith(CI, Res);
+
+        // We need to emit an AND to clear the high bits.
+        Constant *C = ConstantInt::get(APInt::getLowBitsSet(DestBitSize,
+                                                            SrcBitSize));
+        return BinaryOperator::CreateAnd(Res, C);
+      }
+      case Instruction::SExt: {
+        // If the high bits are already filled with sign bit, just replace this
+        // cast with the result.
+        unsigned NumSignBits = ComputeNumSignBits(Res);
+        if (NumSignBits > (DestBitSize - SrcBitSize))
+          return ReplaceInstUsesWith(CI, Res);
+
+        // We need to emit a cast to truncate, then a cast to sext.
+        return CastInst::Create(Instruction::SExt,
+            InsertCastBefore(Instruction::Trunc, Res, Src->getType(), 
+                             CI), DestTy);
+      }
+      }
+    }
+  }
+  
+  Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
+  Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
+
+  switch (SrcI->getOpcode()) {
+  case Instruction::Add:
+  case Instruction::Mul:
+  case Instruction::And:
+  case Instruction::Or:
+  case Instruction::Xor:
+    // If we are discarding information, rewrite.
+    if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
+      // Don't insert two casts if they cannot be eliminated.  We allow 
+      // two casts to be inserted if the sizes are the same.  This could 
+      // only be converting signedness, which is a noop.
+      if (DestBitSize == SrcBitSize || 
+          !ValueRequiresCast(CI.getOpcode(), Op1, DestTy,TD) ||
+          !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
+        Instruction::CastOps opcode = CI.getOpcode();
+        Value *Op0c = InsertCastBefore(opcode, Op0, DestTy, *SrcI);
+        Value *Op1c = InsertCastBefore(opcode, Op1, DestTy, *SrcI);
+        return BinaryOperator::Create(
+            cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
+      }
+    }
+
+    // cast (xor bool X, true) to int  --> xor (cast bool X to int), 1
+    if (isa<ZExtInst>(CI) && SrcBitSize == 1 && 
+        SrcI->getOpcode() == Instruction::Xor &&
+        Op1 == ConstantInt::getTrue() &&
+        (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
+      Value *New = InsertCastBefore(Instruction::ZExt, Op0, DestTy, CI);
+      return BinaryOperator::CreateXor(New, ConstantInt::get(CI.getType(), 1));
+    }
+    break;
+  case Instruction::SDiv:
+  case Instruction::UDiv:
+  case Instruction::SRem:
+  case Instruction::URem:
+    // If we are just changing the sign, rewrite.
+    if (DestBitSize == SrcBitSize) {
+      // Don't insert two casts if they cannot be eliminated.  We allow 
+      // two casts to be inserted if the sizes are the same.  This could 
+      // only be converting signedness, which is a noop.
+      if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) || 
+          !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
+        Value *Op0c = InsertCastBefore(Instruction::BitCast, 
+                                       Op0, DestTy, *SrcI);
+        Value *Op1c = InsertCastBefore(Instruction::BitCast, 
+                                       Op1, DestTy, *SrcI);
+        return BinaryOperator::Create(
+          cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
+      }
+    }
+    break;
+
+  case Instruction::Shl:
+    // Allow changing the sign of the source operand.  Do not allow 
+    // changing the size of the shift, UNLESS the shift amount is a 
+    // constant.  We must not change variable sized shifts to a smaller 
+    // size, because it is undefined to shift more bits out than exist 
+    // in the value.
+    if (DestBitSize == SrcBitSize ||
+        (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
+      Instruction::CastOps opcode = (DestBitSize == SrcBitSize ?
+          Instruction::BitCast : Instruction::Trunc);
+      Value *Op0c = InsertCastBefore(opcode, Op0, DestTy, *SrcI);
+      Value *Op1c = InsertCastBefore(opcode, Op1, DestTy, *SrcI);
+      return BinaryOperator::CreateShl(Op0c, Op1c);
+    }
+    break;
+  case Instruction::AShr:
+    // If this is a signed shr, and if all bits shifted in are about to be
+    // truncated off, turn it into an unsigned shr to allow greater
+    // simplifications.
+    if (DestBitSize < SrcBitSize &&
+        isa<ConstantInt>(Op1)) {
+      uint32_t ShiftAmt = cast<ConstantInt>(Op1)->getLimitedValue(SrcBitSize);
+      if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
+        // Insert the new logical shift right.
+        return BinaryOperator::CreateLShr(Op0, Op1);
+      }
+    }
+    break;
+  }
+  return 0;
+}
+
+Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
+  if (Instruction *Result = commonIntCastTransforms(CI))
+    return Result;
+  
+  Value *Src = CI.getOperand(0);
+  const Type *Ty = CI.getType();
+  uint32_t DestBitWidth = Ty->getPrimitiveSizeInBits();
+  uint32_t SrcBitWidth = cast<IntegerType>(Src->getType())->getBitWidth();
+
+  // Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0)
+  if (DestBitWidth == 1) {
+    Constant *One = ConstantInt::get(Src->getType(), 1);
+    Src = InsertNewInstBefore(BinaryOperator::CreateAnd(Src, One, "tmp"), CI);
+    Value *Zero = Constant::getNullValue(Src->getType());
+    return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero);
+  }
+  
+  // Optimize trunc(lshr(), c) to pull the shift through the truncate.
+  ConstantInt *ShAmtV = 0;
+  Value *ShiftOp = 0;
+  if (Src->hasOneUse() &&
+      match(Src, m_LShr(m_Value(ShiftOp), m_ConstantInt(ShAmtV)))) {
+    uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
+    
+    // Get a mask for the bits shifting in.
+    APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
+    if (MaskedValueIsZero(ShiftOp, Mask)) {
+      if (ShAmt >= DestBitWidth)        // All zeros.
+        return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
+      
+      // Okay, we can shrink this.  Truncate the input, then return a new
+      // shift.
+      Value *V1 = InsertCastBefore(Instruction::Trunc, ShiftOp, Ty, CI);
+      Value *V2 = ConstantExpr::getTrunc(ShAmtV, Ty);
+      return BinaryOperator::CreateLShr(V1, V2);
+    }
+  }
+  
+  return 0;
+}
+
+/// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations
+/// in order to eliminate the icmp.
+Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
+                                             bool DoXform) {
+  // If we are just checking for a icmp eq of a single bit and zext'ing it
+  // to an integer, then shift the bit to the appropriate place and then
+  // cast to integer to avoid the comparison.
+  if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
+    const APInt &Op1CV = Op1C->getValue();
+      
+    // zext (x <s  0) to i32 --> x>>u31      true if signbit set.
+    // zext (x >s -1) to i32 --> (x>>u31)^1  true if signbit clear.
+    if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
+        (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
+      if (!DoXform) return ICI;
+
+      Value *In = ICI->getOperand(0);
+      Value *Sh = ConstantInt::get(In->getType(),
+                                   In->getType()->getPrimitiveSizeInBits()-1);
+      In = InsertNewInstBefore(BinaryOperator::CreateLShr(In, Sh,
+                                                        In->getName()+".lobit"),
+                               CI);
+      if (In->getType() != CI.getType())
+        In = CastInst::CreateIntegerCast(In, CI.getType(),
+                                         false/*ZExt*/, "tmp", &CI);
+
+      if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
+        Constant *One = ConstantInt::get(In->getType(), 1);
+        In = InsertNewInstBefore(BinaryOperator::CreateXor(In, One,
+                                                         In->getName()+".not"),
+                                 CI);
+      }
+
+      return ReplaceInstUsesWith(CI, In);
+    }
+      
+      
+      
+    // zext (X == 0) to i32 --> X^1      iff X has only the low bit set.
+    // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
+    // zext (X == 1) to i32 --> X        iff X has only the low bit set.
+    // zext (X == 2) to i32 --> X>>1     iff X has only the 2nd bit set.
+    // zext (X != 0) to i32 --> X        iff X has only the low bit set.
+    // zext (X != 0) to i32 --> X>>1     iff X has only the 2nd bit set.
+    // zext (X != 1) to i32 --> X^1      iff X has only the low bit set.
+    // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
+    if ((Op1CV == 0 || Op1CV.isPowerOf2()) && 
+        // This only works for EQ and NE
+        ICI->isEquality()) {
+      // If Op1C some other power of two, convert:
+      uint32_t BitWidth = Op1C->getType()->getBitWidth();
+      APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+      APInt TypeMask(APInt::getAllOnesValue(BitWidth));
+      ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
+        
+      APInt KnownZeroMask(~KnownZero);
+      if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
+        if (!DoXform) return ICI;
+
+        bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
+        if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
+          // (X&4) == 2 --> false
+          // (X&4) != 2 --> true
+          Constant *Res = ConstantInt::get(Type::Int1Ty, isNE);
+          Res = ConstantExpr::getZExt(Res, CI.getType());
+          return ReplaceInstUsesWith(CI, Res);
+        }
+          
+        uint32_t ShiftAmt = KnownZeroMask.logBase2();
+        Value *In = ICI->getOperand(0);
+        if (ShiftAmt) {
+          // Perform a logical shr by shiftamt.
+          // Insert the shift to put the result in the low bit.
+          In = InsertNewInstBefore(BinaryOperator::CreateLShr(In,
+                                  ConstantInt::get(In->getType(), ShiftAmt),
+                                                   In->getName()+".lobit"), CI);
+        }
+          
+        if ((Op1CV != 0) == isNE) { // Toggle the low bit.
+          Constant *One = ConstantInt::get(In->getType(), 1);
+          In = BinaryOperator::CreateXor(In, One, "tmp");
+          InsertNewInstBefore(cast<Instruction>(In), CI);
+        }
+          
+        if (CI.getType() == In->getType())
+          return ReplaceInstUsesWith(CI, In);
+        else
+          return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
+      }
+    }
+  }
+
+  return 0;
+}
+
+Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
+  // If one of the common conversion will work ..
+  if (Instruction *Result = commonIntCastTransforms(CI))
+    return Result;
+
+  Value *Src = CI.getOperand(0);
+
+  // If this is a TRUNC followed by a ZEXT then we are dealing with integral
+  // types and if the sizes are just right we can convert this into a logical
+  // 'and' which will be much cheaper than the pair of casts.
+  if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) {   // A->B->C cast
+    // Get the sizes of the types involved.  We know that the intermediate type
+    // will be smaller than A or C, but don't know the relation between A and C.
+    Value *A = CSrc->getOperand(0);
+    unsigned SrcSize = A->getType()->getPrimitiveSizeInBits();
+    unsigned MidSize = CSrc->getType()->getPrimitiveSizeInBits();
+    unsigned DstSize = CI.getType()->getPrimitiveSizeInBits();
+    // If we're actually extending zero bits, then if
+    // SrcSize <  DstSize: zext(a & mask)
+    // SrcSize == DstSize: a & mask
+    // SrcSize  > DstSize: trunc(a) & mask
+    if (SrcSize < DstSize) {
+      APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
+      Constant *AndConst = ConstantInt::get(AndValue);
+      Instruction *And =
+        BinaryOperator::CreateAnd(A, AndConst, CSrc->getName()+".mask");
+      InsertNewInstBefore(And, CI);
+      return new ZExtInst(And, CI.getType());
+    } else if (SrcSize == DstSize) {
+      APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
+      return BinaryOperator::CreateAnd(A, ConstantInt::get(AndValue));
+    } else if (SrcSize > DstSize) {
+      Instruction *Trunc = new TruncInst(A, CI.getType(), "tmp");
+      InsertNewInstBefore(Trunc, CI);
+      APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
+      return BinaryOperator::CreateAnd(Trunc, ConstantInt::get(AndValue));
+    }
+  }
+
+  if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
+    return transformZExtICmp(ICI, CI);
+
+  BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
+  if (SrcI && SrcI->getOpcode() == Instruction::Or) {
+    // zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one
+    // of the (zext icmp) will be transformed.
+    ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
+    ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
+    if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
+        (transformZExtICmp(LHS, CI, false) ||
+         transformZExtICmp(RHS, CI, false))) {
+      Value *LCast = InsertCastBefore(Instruction::ZExt, LHS, CI.getType(), CI);
+      Value *RCast = InsertCastBefore(Instruction::ZExt, RHS, CI.getType(), CI);
+      return BinaryOperator::Create(Instruction::Or, LCast, RCast);
+    }
+  }
+
+  return 0;
+}
+
+Instruction *InstCombiner::visitSExt(SExtInst &CI) {
+  if (Instruction *I = commonIntCastTransforms(CI))
+    return I;
+  
+  Value *Src = CI.getOperand(0);
+  
+  // Canonicalize sign-extend from i1 to a select.
+  if (Src->getType() == Type::Int1Ty)
+    return SelectInst::Create(Src,
+                              ConstantInt::getAllOnesValue(CI.getType()),
+                              Constant::getNullValue(CI.getType()));
+
+  // See if the value being truncated is already sign extended.  If so, just
+  // eliminate the trunc/sext pair.
+  if (getOpcode(Src) == Instruction::Trunc) {
+    Value *Op = cast<User>(Src)->getOperand(0);
+    unsigned OpBits   = cast<IntegerType>(Op->getType())->getBitWidth();
+    unsigned MidBits  = cast<IntegerType>(Src->getType())->getBitWidth();
+    unsigned DestBits = cast<IntegerType>(CI.getType())->getBitWidth();
+    unsigned NumSignBits = ComputeNumSignBits(Op);
+
+    if (OpBits == DestBits) {
+      // Op is i32, Mid is i8, and Dest is i32.  If Op has more than 24 sign
+      // bits, it is already ready.
+      if (NumSignBits > DestBits-MidBits)
+        return ReplaceInstUsesWith(CI, Op);
+    } else if (OpBits < DestBits) {
+      // Op is i32, Mid is i8, and Dest is i64.  If Op has more than 24 sign
+      // bits, just sext from i32.
+      if (NumSignBits > OpBits-MidBits)
+        return new SExtInst(Op, CI.getType(), "tmp");
+    } else {
+      // Op is i64, Mid is i8, and Dest is i32.  If Op has more than 56 sign
+      // bits, just truncate to i32.
+      if (NumSignBits > OpBits-MidBits)
+        return new TruncInst(Op, CI.getType(), "tmp");
+    }
+  }
+
+  // If the input is a shl/ashr pair of a same constant, then this is a sign
+  // extension from a smaller value.  If we could trust arbitrary bitwidth
+  // integers, we could turn this into a truncate to the smaller bit and then
+  // use a sext for the whole extension.  Since we don't, look deeper and check
+  // for a truncate.  If the source and dest are the same type, eliminate the
+  // trunc and extend and just do shifts.  For example, turn:
+  //   %a = trunc i32 %i to i8
+  //   %b = shl i8 %a, 6
+  //   %c = ashr i8 %b, 6
+  //   %d = sext i8 %c to i32
+  // into:
+  //   %a = shl i32 %i, 30
+  //   %d = ashr i32 %a, 30
+  Value *A = 0;
+  ConstantInt *BA = 0, *CA = 0;
+  if (match(Src, m_AShr(m_Shl(m_Value(A), m_ConstantInt(BA)),
+                        m_ConstantInt(CA))) &&
+      BA == CA && isa<TruncInst>(A)) {
+    Value *I = cast<TruncInst>(A)->getOperand(0);
+    if (I->getType() == CI.getType()) {
+      unsigned MidSize = Src->getType()->getPrimitiveSizeInBits();
+      unsigned SrcDstSize = CI.getType()->getPrimitiveSizeInBits();
+      unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
+      Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
+      I = InsertNewInstBefore(BinaryOperator::CreateShl(I, ShAmtV,
+                                                        CI.getName()), CI);
+      return BinaryOperator::CreateAShr(I, ShAmtV);
+    }
+  }
+  
+  return 0;
+}
+
+/// FitsInFPType - Return a Constant* for the specified FP constant if it fits
+/// in the specified FP type without changing its value.
+static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
+  bool losesInfo;
+  APFloat F = CFP->getValueAPF();
+  (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
+  if (!losesInfo)
+    return ConstantFP::get(F);
+  return 0;
+}
+
+/// LookThroughFPExtensions - If this is an fp extension instruction, look
+/// through it until we get the source value.
+static Value *LookThroughFPExtensions(Value *V) {
+  if (Instruction *I = dyn_cast<Instruction>(V))
+    if (I->getOpcode() == Instruction::FPExt)
+      return LookThroughFPExtensions(I->getOperand(0));
+  
+  // If this value is a constant, return the constant in the smallest FP type
+  // that can accurately represent it.  This allows us to turn
+  // (float)((double)X+2.0) into x+2.0f.
+  if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
+    if (CFP->getType() == Type::PPC_FP128Ty)
+      return V;  // No constant folding of this.
+    // See if the value can be truncated to float and then reextended.
+    if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle))
+      return V;
+    if (CFP->getType() == Type::DoubleTy)
+      return V;  // Won't shrink.
+    if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble))
+      return V;
+    // Don't try to shrink to various long double types.
+  }
+  
+  return V;
+}
+
+Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
+  if (Instruction *I = commonCastTransforms(CI))
+    return I;
+  
+  // If we have fptrunc(add (fpextend x), (fpextend y)), where x and y are
+  // smaller than the destination type, we can eliminate the truncate by doing
+  // the add as the smaller type.  This applies to add/sub/mul/div as well as
+  // many builtins (sqrt, etc).
+  BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0));
+  if (OpI && OpI->hasOneUse()) {
+    switch (OpI->getOpcode()) {
+    default: break;
+    case Instruction::Add:
+    case Instruction::Sub:
+    case Instruction::Mul:
+    case Instruction::FDiv:
+    case Instruction::FRem:
+      const Type *SrcTy = OpI->getType();
+      Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0));
+      Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1));
+      if (LHSTrunc->getType() != SrcTy && 
+          RHSTrunc->getType() != SrcTy) {
+        unsigned DstSize = CI.getType()->getPrimitiveSizeInBits();
+        // If the source types were both smaller than the destination type of
+        // the cast, do this xform.
+        if (LHSTrunc->getType()->getPrimitiveSizeInBits() <= DstSize &&
+            RHSTrunc->getType()->getPrimitiveSizeInBits() <= DstSize) {
+          LHSTrunc = InsertCastBefore(Instruction::FPExt, LHSTrunc,
+                                      CI.getType(), CI);
+          RHSTrunc = InsertCastBefore(Instruction::FPExt, RHSTrunc,
+                                      CI.getType(), CI);
+          return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc);
+        }
+      }
+      break;  
+    }
+  }
+  return 0;
+}
+
+Instruction *InstCombiner::visitFPExt(CastInst &CI) {
+  return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
+  Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
+  if (OpI == 0)
+    return commonCastTransforms(FI);
+
+  // fptoui(uitofp(X)) --> X
+  // fptoui(sitofp(X)) --> X
+  // This is safe if the intermediate type has enough bits in its mantissa to
+  // accurately represent all values of X.  For example, do not do this with
+  // i64->float->i64.  This is also safe for sitofp case, because any negative
+  // 'X' value would cause an undefined result for the fptoui. 
+  if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
+      OpI->getOperand(0)->getType() == FI.getType() &&
+      (int)FI.getType()->getPrimitiveSizeInBits() < /*extra bit for sign */
+                    OpI->getType()->getFPMantissaWidth())
+    return ReplaceInstUsesWith(FI, OpI->getOperand(0));
+
+  return commonCastTransforms(FI);
+}
+
+Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
+  Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
+  if (OpI == 0)
+    return commonCastTransforms(FI);
+  
+  // fptosi(sitofp(X)) --> X
+  // fptosi(uitofp(X)) --> X
+  // This is safe if the intermediate type has enough bits in its mantissa to
+  // accurately represent all values of X.  For example, do not do this with
+  // i64->float->i64.  This is also safe for sitofp case, because any negative
+  // 'X' value would cause an undefined result for the fptoui. 
+  if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
+      OpI->getOperand(0)->getType() == FI.getType() &&
+      (int)FI.getType()->getPrimitiveSizeInBits() <= 
+                    OpI->getType()->getFPMantissaWidth())
+    return ReplaceInstUsesWith(FI, OpI->getOperand(0));
+  
+  return commonCastTransforms(FI);
+}
+
+Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
+  return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
+  return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) {
+  // If the destination integer type is smaller than the intptr_t type for
+  // this target, do a ptrtoint to intptr_t then do a trunc.  This allows the
+  // trunc to be exposed to other transforms.  Don't do this for extending
+  // ptrtoint's, because we don't know if the target sign or zero extends its
+  // pointers.
+  if (CI.getType()->getPrimitiveSizeInBits() < TD->getPointerSizeInBits()) {
+    Value *P = InsertNewInstBefore(new PtrToIntInst(CI.getOperand(0),
+                                                    TD->getIntPtrType(),
+                                                    "tmp"), CI);
+    return new TruncInst(P, CI.getType());
+  }
+  
+  return commonPointerCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
+  // If the source integer type is larger than the intptr_t type for
+  // this target, do a trunc to the intptr_t type, then inttoptr of it.  This
+  // allows the trunc to be exposed to other transforms.  Don't do this for
+  // extending inttoptr's, because we don't know if the target sign or zero
+  // extends to pointers.
+  if (CI.getOperand(0)->getType()->getPrimitiveSizeInBits() >
+      TD->getPointerSizeInBits()) {
+    Value *P = InsertNewInstBefore(new TruncInst(CI.getOperand(0),
+                                                 TD->getIntPtrType(),
+                                                 "tmp"), CI);
+    return new IntToPtrInst(P, CI.getType());
+  }
+  
+  if (Instruction *I = commonCastTransforms(CI))
+    return I;
+  
+  const Type *DestPointee = cast<PointerType>(CI.getType())->getElementType();
+  if (!DestPointee->isSized()) return 0;
+
+  // If this is inttoptr(add (ptrtoint x), cst), try to turn this into a GEP.
+  ConstantInt *Cst;
+  Value *X;
+  if (match(CI.getOperand(0), m_Add(m_Cast<PtrToIntInst>(m_Value(X)),
+                                    m_ConstantInt(Cst)))) {
+    // If the source and destination operands have the same type, see if this
+    // is a single-index GEP.
+    if (X->getType() == CI.getType()) {
+      // Get the size of the pointee type.
+      uint64_t Size = TD->getTypeAllocSize(DestPointee);
+
+      // Convert the constant to intptr type.
+      APInt Offset = Cst->getValue();
+      Offset.sextOrTrunc(TD->getPointerSizeInBits());
+
+      // If Offset is evenly divisible by Size, we can do this xform.
+      if (Size && !APIntOps::srem(Offset, APInt(Offset.getBitWidth(), Size))){
+        Offset = APIntOps::sdiv(Offset, APInt(Offset.getBitWidth(), Size));
+        return GetElementPtrInst::Create(X, ConstantInt::get(Offset));
+      }
+    }
+    // TODO: Could handle other cases, e.g. where add is indexing into field of
+    // struct etc.
+  } else if (CI.getOperand(0)->hasOneUse() &&
+             match(CI.getOperand(0), m_Add(m_Value(X), m_ConstantInt(Cst)))) {
+    // Otherwise, if this is inttoptr(add x, cst), try to turn this into an
+    // "inttoptr+GEP" instead of "add+intptr".
+    
+    // Get the size of the pointee type.
+    uint64_t Size = TD->getTypeAllocSize(DestPointee);
+    
+    // Convert the constant to intptr type.
+    APInt Offset = Cst->getValue();
+    Offset.sextOrTrunc(TD->getPointerSizeInBits());
+    
+    // If Offset is evenly divisible by Size, we can do this xform.
+    if (Size && !APIntOps::srem(Offset, APInt(Offset.getBitWidth(), Size))){
+      Offset = APIntOps::sdiv(Offset, APInt(Offset.getBitWidth(), Size));
+      
+      Instruction *P = InsertNewInstBefore(new IntToPtrInst(X, CI.getType(),
+                                                            "tmp"), CI);
+      return GetElementPtrInst::Create(P, ConstantInt::get(Offset), "tmp");
+    }
+  }
+  return 0;
+}
+
+Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
+  // If the operands are integer typed then apply the integer transforms,
+  // otherwise just apply the common ones.
+  Value *Src = CI.getOperand(0);
+  const Type *SrcTy = Src->getType();
+  const Type *DestTy = CI.getType();
+
+  if (SrcTy->isInteger() && DestTy->isInteger()) {
+    if (Instruction *Result = commonIntCastTransforms(CI))
+      return Result;
+  } else if (isa<PointerType>(SrcTy)) {
+    if (Instruction *I = commonPointerCastTransforms(CI))
+      return I;
+  } else {
+    if (Instruction *Result = commonCastTransforms(CI))
+      return Result;
+  }
+
+
+  // Get rid of casts from one type to the same type. These are useless and can
+  // be replaced by the operand.
+  if (DestTy == Src->getType())
+    return ReplaceInstUsesWith(CI, Src);
+
+  if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
+    const PointerType *SrcPTy = cast<PointerType>(SrcTy);
+    const Type *DstElTy = DstPTy->getElementType();
+    const Type *SrcElTy = SrcPTy->getElementType();
+    
+    // If the address spaces don't match, don't eliminate the bitcast, which is
+    // required for changing types.
+    if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace())
+      return 0;
+    
+    // If we are casting a malloc or alloca to a pointer to a type of the same
+    // size, rewrite the allocation instruction to allocate the "right" type.
+    if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
+      if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
+        return V;
+    
+    // If the source and destination are pointers, and this cast is equivalent
+    // to a getelementptr X, 0, 0, 0...  turn it into the appropriate gep.
+    // This can enhance SROA and other transforms that want type-safe pointers.
+    Constant *ZeroUInt = Constant::getNullValue(Type::Int32Ty);
+    unsigned NumZeros = 0;
+    while (SrcElTy != DstElTy && 
+           isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
+           SrcElTy->getNumContainedTypes() /* not "{}" */) {
+      SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
+      ++NumZeros;
+    }
+
+    // If we found a path from the src to dest, create the getelementptr now.
+    if (SrcElTy == DstElTy) {
+      SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
+      return GetElementPtrInst::Create(Src, Idxs.begin(), Idxs.end(), "", 
+                                       ((Instruction*) NULL));
+    }
+  }
+
+  if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
+    if (SVI->hasOneUse()) {
+      // Okay, we have (bitconvert (shuffle ..)).  Check to see if this is
+      // a bitconvert to a vector with the same # elts.
+      if (isa<VectorType>(DestTy) && 
+          cast<VectorType>(DestTy)->getNumElements() ==
+                SVI->getType()->getNumElements() &&
+          SVI->getType()->getNumElements() ==
+            cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) {
+        CastInst *Tmp;
+        // If either of the operands is a cast from CI.getType(), then
+        // evaluating the shuffle in the casted destination's type will allow
+        // us to eliminate at least one cast.
+        if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) && 
+             Tmp->getOperand(0)->getType() == DestTy) ||
+            ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) && 
+             Tmp->getOperand(0)->getType() == DestTy)) {
+          Value *LHS = InsertCastBefore(Instruction::BitCast,
+                                        SVI->getOperand(0), DestTy, CI);
+          Value *RHS = InsertCastBefore(Instruction::BitCast,
+                                        SVI->getOperand(1), DestTy, CI);
+          // Return a new shuffle vector.  Use the same element ID's, as we
+          // know the vector types match #elts.
+          return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
+        }
+      }
+    }
+  }
+  return 0;
+}
+
+/// GetSelectFoldableOperands - We want to turn code that looks like this:
+///   %C = or %A, %B
+///   %D = select %cond, %C, %A
+/// into:
+///   %C = select %cond, %B, 0
+///   %D = or %A, %C
+///
+/// Assuming that the specified instruction is an operand to the select, return
+/// a bitmask indicating which operands of this instruction are foldable if they
+/// equal the other incoming value of the select.
+///
+static unsigned GetSelectFoldableOperands(Instruction *I) {
+  switch (I->getOpcode()) {
+  case Instruction::Add:
+  case Instruction::Mul:
+  case Instruction::And:
+  case Instruction::Or:
+  case Instruction::Xor:
+    return 3;              // Can fold through either operand.
+  case Instruction::Sub:   // Can only fold on the amount subtracted.
+  case Instruction::Shl:   // Can only fold on the shift amount.
+  case Instruction::LShr:
+  case Instruction::AShr:
+    return 1;
+  default:
+    return 0;              // Cannot fold
+  }
+}
+
+/// GetSelectFoldableConstant - For the same transformation as the previous
+/// function, return the identity constant that goes into the select.
+static Constant *GetSelectFoldableConstant(Instruction *I) {
+  switch (I->getOpcode()) {
+  default: assert(0 && "This cannot happen!"); abort();
+  case Instruction::Add:
+  case Instruction::Sub:
+  case Instruction::Or:
+  case Instruction::Xor:
+  case Instruction::Shl:
+  case Instruction::LShr:
+  case Instruction::AShr:
+    return Constant::getNullValue(I->getType());
+  case Instruction::And:
+    return Constant::getAllOnesValue(I->getType());
+  case Instruction::Mul:
+    return ConstantInt::get(I->getType(), 1);
+  }
+}
+
+/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
+/// have the same opcode and only one use each.  Try to simplify this.
+Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
+                                          Instruction *FI) {
+  if (TI->getNumOperands() == 1) {
+    // If this is a non-volatile load or a cast from the same type,
+    // merge.
+    if (TI->isCast()) {
+      if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
+        return 0;
+    } else {
+      return 0;  // unknown unary op.
+    }
+
+    // Fold this by inserting a select from the input values.
+    SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0),
+                                           FI->getOperand(0), SI.getName()+".v");
+    InsertNewInstBefore(NewSI, SI);
+    return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI, 
+                            TI->getType());
+  }
+
+  // Only handle binary operators here.
+  if (!isa<BinaryOperator>(TI))
+    return 0;
+
+  // Figure out if the operations have any operands in common.
+  Value *MatchOp, *OtherOpT, *OtherOpF;
+  bool MatchIsOpZero;
+  if (TI->getOperand(0) == FI->getOperand(0)) {
+    MatchOp  = TI->getOperand(0);
+    OtherOpT = TI->getOperand(1);
+    OtherOpF = FI->getOperand(1);
+    MatchIsOpZero = true;
+  } else if (TI->getOperand(1) == FI->getOperand(1)) {
+    MatchOp  = TI->getOperand(1);
+    OtherOpT = TI->getOperand(0);
+    OtherOpF = FI->getOperand(0);
+    MatchIsOpZero = false;
+  } else if (!TI->isCommutative()) {
+    return 0;
+  } else if (TI->getOperand(0) == FI->getOperand(1)) {
+    MatchOp  = TI->getOperand(0);
+    OtherOpT = TI->getOperand(1);
+    OtherOpF = FI->getOperand(0);
+    MatchIsOpZero = true;
+  } else if (TI->getOperand(1) == FI->getOperand(0)) {
+    MatchOp  = TI->getOperand(1);
+    OtherOpT = TI->getOperand(0);
+    OtherOpF = FI->getOperand(1);
+    MatchIsOpZero = true;
+  } else {
+    return 0;
+  }
+
+  // If we reach here, they do have operations in common.
+  SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT,
+                                         OtherOpF, SI.getName()+".v");
+  InsertNewInstBefore(NewSI, SI);
+
+  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
+    if (MatchIsOpZero)
+      return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI);
+    else
+      return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
+  }
+  assert(0 && "Shouldn't get here");
+  return 0;
+}
+
+static bool isSelect01(Constant *C1, Constant *C2) {
+  ConstantInt *C1I = dyn_cast<ConstantInt>(C1);
+  if (!C1I)
+    return false;
+  ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
+  if (!C2I)
+    return false;
+  return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne());
+}
+
+/// FoldSelectIntoOp - Try fold the select into one of the operands to
+/// facilitate further optimization.
+Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
+                                            Value *FalseVal) {
+  // See the comment above GetSelectFoldableOperands for a description of the
+  // transformation we are doing here.
+  if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) {
+    if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
+        !isa<Constant>(FalseVal)) {
+      if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
+        unsigned OpToFold = 0;
+        if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
+          OpToFold = 1;
+        } else  if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
+          OpToFold = 2;
+        }
+
+        if (OpToFold) {
+          Constant *C = GetSelectFoldableConstant(TVI);
+          Value *OOp = TVI->getOperand(2-OpToFold);
+          // Avoid creating select between 2 constants unless it's selecting
+          // between 0 and 1.
+          if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
+            Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C);
+            InsertNewInstBefore(NewSel, SI);
+            NewSel->takeName(TVI);
+            if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
+              return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel);
+            assert(0 && "Unknown instruction!!");
+          }
+        }
+      }
+    }
+  }
+
+  if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) {
+    if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
+        !isa<Constant>(TrueVal)) {
+      if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
+        unsigned OpToFold = 0;
+        if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
+          OpToFold = 1;
+        } else  if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
+          OpToFold = 2;
+        }
+
+        if (OpToFold) {
+          Constant *C = GetSelectFoldableConstant(FVI);
+          Value *OOp = FVI->getOperand(2-OpToFold);
+          // Avoid creating select between 2 constants unless it's selecting
+          // between 0 and 1.
+          if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
+            Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp);
+            InsertNewInstBefore(NewSel, SI);
+            NewSel->takeName(FVI);
+            if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
+              return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel);
+            assert(0 && "Unknown instruction!!");
+          }
+        }
+      }
+    }
+  }
+
+  return 0;
+}
+
+/// visitSelectInstWithICmp - Visit a SelectInst that has an
+/// ICmpInst as its first operand.
+///
+Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
+                                                   ICmpInst *ICI) {
+  bool Changed = false;
+  ICmpInst::Predicate Pred = ICI->getPredicate();
+  Value *CmpLHS = ICI->getOperand(0);
+  Value *CmpRHS = ICI->getOperand(1);
+  Value *TrueVal = SI.getTrueValue();
+  Value *FalseVal = SI.getFalseValue();
+
+  // Check cases where the comparison is with a constant that
+  // can be adjusted to fit the min/max idiom. We may edit ICI in
+  // place here, so make sure the select is the only user.
+  if (ICI->hasOneUse())
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
+      switch (Pred) {
+      default: break;
+      case ICmpInst::ICMP_ULT:
+      case ICmpInst::ICMP_SLT: {
+        // X < MIN ? T : F  -->  F
+        if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT))
+          return ReplaceInstUsesWith(SI, FalseVal);
+        // X < C ? X : C-1  -->  X > C-1 ? C-1 : X
+        Constant *AdjustedRHS = SubOne(CI);
+        if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
+            (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
+          Pred = ICmpInst::getSwappedPredicate(Pred);
+          CmpRHS = AdjustedRHS;
+          std::swap(FalseVal, TrueVal);
+          ICI->setPredicate(Pred);
+          ICI->setOperand(1, CmpRHS);
+          SI.setOperand(1, TrueVal);
+          SI.setOperand(2, FalseVal);
+          Changed = true;
+        }
+        break;
+      }
+      case ICmpInst::ICMP_UGT:
+      case ICmpInst::ICMP_SGT: {
+        // X > MAX ? T : F  -->  F
+        if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT))
+          return ReplaceInstUsesWith(SI, FalseVal);
+        // X > C ? X : C+1  -->  X < C+1 ? C+1 : X
+        Constant *AdjustedRHS = AddOne(CI);
+        if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
+            (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
+          Pred = ICmpInst::getSwappedPredicate(Pred);
+          CmpRHS = AdjustedRHS;
+          std::swap(FalseVal, TrueVal);
+          ICI->setPredicate(Pred);
+          ICI->setOperand(1, CmpRHS);
+          SI.setOperand(1, TrueVal);
+          SI.setOperand(2, FalseVal);
+          Changed = true;
+        }
+        break;
+      }
+      }
+
+      // (x <s 0) ? -1 : 0 -> ashr x, 31   -> all ones if signed
+      // (x >s -1) ? -1 : 0 -> ashr x, 31  -> all ones if not signed
+      CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE;
+      if (match(TrueVal, m_ConstantInt<-1>()) &&
+          match(FalseVal, m_ConstantInt<0>()))
+        Pred = ICI->getPredicate();
+      else if (match(TrueVal, m_ConstantInt<0>()) &&
+               match(FalseVal, m_ConstantInt<-1>()))
+        Pred = CmpInst::getInversePredicate(ICI->getPredicate());
+      
+      if (Pred != CmpInst::BAD_ICMP_PREDICATE) {
+        // If we are just checking for a icmp eq of a single bit and zext'ing it
+        // to an integer, then shift the bit to the appropriate place and then
+        // cast to integer to avoid the comparison.
+        const APInt &Op1CV = CI->getValue();
+    
+        // sext (x <s  0) to i32 --> x>>s31      true if signbit set.
+        // sext (x >s -1) to i32 --> (x>>s31)^-1  true if signbit clear.
+        if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) ||
+            (Pred == ICmpInst::ICMP_SGT && Op1CV.isAllOnesValue())) {
+          Value *In = ICI->getOperand(0);
+          Value *Sh = ConstantInt::get(In->getType(),
+                                       In->getType()->getPrimitiveSizeInBits()-1);
+          In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh,
+                                                          In->getName()+".lobit"),
+                                   *ICI);
+          if (In->getType() != SI.getType())
+            In = CastInst::CreateIntegerCast(In, SI.getType(),
+                                             true/*SExt*/, "tmp", ICI);
+    
+          if (Pred == ICmpInst::ICMP_SGT)
+            In = InsertNewInstBefore(BinaryOperator::CreateNot(In,
+                                       In->getName()+".not"), *ICI);
+    
+          return ReplaceInstUsesWith(SI, In);
+        }
+      }
+    }
+
+  if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
+    // Transform (X == Y) ? X : Y  -> Y
+    if (Pred == ICmpInst::ICMP_EQ)
+      return ReplaceInstUsesWith(SI, FalseVal);
+    // Transform (X != Y) ? X : Y  -> X
+    if (Pred == ICmpInst::ICMP_NE)
+      return ReplaceInstUsesWith(SI, TrueVal);
+    /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
+
+  } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) {
+    // Transform (X == Y) ? Y : X  -> X
+    if (Pred == ICmpInst::ICMP_EQ)
+      return ReplaceInstUsesWith(SI, FalseVal);
+    // Transform (X != Y) ? Y : X  -> Y
+    if (Pred == ICmpInst::ICMP_NE)
+      return ReplaceInstUsesWith(SI, TrueVal);
+    /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
+  }
+
+  /// NOTE: if we wanted to, this is where to detect integer ABS
+
+  return Changed ? &SI : 0;
+}
+
+Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
+  Value *CondVal = SI.getCondition();
+  Value *TrueVal = SI.getTrueValue();
+  Value *FalseVal = SI.getFalseValue();
+
+  // select true, X, Y  -> X
+  // select false, X, Y -> Y
+  if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
+    return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
+
+  // select C, X, X -> X
+  if (TrueVal == FalseVal)
+    return ReplaceInstUsesWith(SI, TrueVal);
+
+  if (isa<UndefValue>(TrueVal))   // select C, undef, X -> X
+    return ReplaceInstUsesWith(SI, FalseVal);
+  if (isa<UndefValue>(FalseVal))   // select C, X, undef -> X
+    return ReplaceInstUsesWith(SI, TrueVal);
+  if (isa<UndefValue>(CondVal)) {  // select undef, X, Y -> X or Y
+    if (isa<Constant>(TrueVal))
+      return ReplaceInstUsesWith(SI, TrueVal);
+    else
+      return ReplaceInstUsesWith(SI, FalseVal);
+  }
+
+  if (SI.getType() == Type::Int1Ty) {
+    if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
+      if (C->getZExtValue()) {
+        // Change: A = select B, true, C --> A = or B, C
+        return BinaryOperator::CreateOr(CondVal, FalseVal);
+      } else {
+        // Change: A = select B, false, C --> A = and !B, C
+        Value *NotCond =
+          InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
+                                             "not."+CondVal->getName()), SI);
+        return BinaryOperator::CreateAnd(NotCond, FalseVal);
+      }
+    } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
+      if (C->getZExtValue() == false) {
+        // Change: A = select B, C, false --> A = and B, C
+        return BinaryOperator::CreateAnd(CondVal, TrueVal);
+      } else {
+        // Change: A = select B, C, true --> A = or !B, C
+        Value *NotCond =
+          InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
+                                             "not."+CondVal->getName()), SI);
+        return BinaryOperator::CreateOr(NotCond, TrueVal);
+      }
+    }
+    
+    // select a, b, a  -> a&b
+    // select a, a, b  -> a|b
+    if (CondVal == TrueVal)
+      return BinaryOperator::CreateOr(CondVal, FalseVal);
+    else if (CondVal == FalseVal)
+      return BinaryOperator::CreateAnd(CondVal, TrueVal);
+  }
+
+  // Selecting between two integer constants?
+  if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
+    if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
+      // select C, 1, 0 -> zext C to int
+      if (FalseValC->isZero() && TrueValC->getValue() == 1) {
+        return CastInst::Create(Instruction::ZExt, CondVal, SI.getType());
+      } else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
+        // select C, 0, 1 -> zext !C to int
+        Value *NotCond =
+          InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
+                                               "not."+CondVal->getName()), SI);
+        return CastInst::Create(Instruction::ZExt, NotCond, SI.getType());
+      }
+
+      if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
+
+        // (x <s 0) ? -1 : 0 -> ashr x, 31
+        if (TrueValC->isAllOnesValue() && FalseValC->isZero())
+          if (ConstantInt *CmpCst = dyn_cast<ConstantInt>(IC->getOperand(1))) {
+            if (IC->getPredicate() == ICmpInst::ICMP_SLT && CmpCst->isZero()) {
+              // The comparison constant and the result are not neccessarily the
+              // same width. Make an all-ones value by inserting a AShr.
+              Value *X = IC->getOperand(0);
+              uint32_t Bits = X->getType()->getPrimitiveSizeInBits();
+              Constant *ShAmt = ConstantInt::get(X->getType(), Bits-1);
+              Instruction *SRA = BinaryOperator::Create(Instruction::AShr, X,
+                                                        ShAmt, "ones");
+              InsertNewInstBefore(SRA, SI);
+
+              // Then cast to the appropriate width.
+              return CastInst::CreateIntegerCast(SRA, SI.getType(), true);
+            }
+          }
+
+
+        // If one of the constants is zero (we know they can't both be) and we
+        // have an icmp instruction with zero, and we have an 'and' with the
+        // non-constant value, eliminate this whole mess.  This corresponds to
+        // cases like this: ((X & 27) ? 27 : 0)
+        if (TrueValC->isZero() || FalseValC->isZero())
+          if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
+              cast<Constant>(IC->getOperand(1))->isNullValue())
+            if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
+              if (ICA->getOpcode() == Instruction::And &&
+                  isa<ConstantInt>(ICA->getOperand(1)) &&
+                  (ICA->getOperand(1) == TrueValC ||
+                   ICA->getOperand(1) == FalseValC) &&
+                  isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
+                // Okay, now we know that everything is set up, we just don't
+                // know whether we have a icmp_ne or icmp_eq and whether the 
+                // true or false val is the zero.
+                bool ShouldNotVal = !TrueValC->isZero();
+                ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
+                Value *V = ICA;
+                if (ShouldNotVal)
+                  V = InsertNewInstBefore(BinaryOperator::Create(
+                                  Instruction::Xor, V, ICA->getOperand(1)), SI);
+                return ReplaceInstUsesWith(SI, V);
+              }
+      }
+    }
+
+  // See if we are selecting two values based on a comparison of the two values.
+  if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
+    if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
+      // Transform (X == Y) ? X : Y  -> Y
+      if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
+        // This is not safe in general for floating point:  
+        // consider X== -0, Y== +0.
+        // It becomes safe if either operand is a nonzero constant.
+        ConstantFP *CFPt, *CFPf;
+        if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
+              !CFPt->getValueAPF().isZero()) ||
+            ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
+             !CFPf->getValueAPF().isZero()))
+        return ReplaceInstUsesWith(SI, FalseVal);
+      }
+      // Transform (X != Y) ? X : Y  -> X
+      if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
+        return ReplaceInstUsesWith(SI, TrueVal);
+      // NOTE: if we wanted to, this is where to detect MIN/MAX
+
+    } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
+      // Transform (X == Y) ? Y : X  -> X
+      if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
+        // This is not safe in general for floating point:  
+        // consider X== -0, Y== +0.
+        // It becomes safe if either operand is a nonzero constant.
+        ConstantFP *CFPt, *CFPf;
+        if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
+              !CFPt->getValueAPF().isZero()) ||
+            ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
+             !CFPf->getValueAPF().isZero()))
+          return ReplaceInstUsesWith(SI, FalseVal);
+      }
+      // Transform (X != Y) ? Y : X  -> Y
+      if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
+        return ReplaceInstUsesWith(SI, TrueVal);
+      // NOTE: if we wanted to, this is where to detect MIN/MAX
+    }
+    // NOTE: if we wanted to, this is where to detect ABS
+  }
+
+  // See if we are selecting two values based on a comparison of the two values.
+  if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
+    if (Instruction *Result = visitSelectInstWithICmp(SI, ICI))
+      return Result;
+
+  if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
+    if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
+      if (TI->hasOneUse() && FI->hasOneUse()) {
+        Instruction *AddOp = 0, *SubOp = 0;
+
+        // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
+        if (TI->getOpcode() == FI->getOpcode())
+          if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
+            return IV;
+
+        // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))).  This is
+        // even legal for FP.
+        if (TI->getOpcode() == Instruction::Sub &&
+            FI->getOpcode() == Instruction::Add) {
+          AddOp = FI; SubOp = TI;
+        } else if (FI->getOpcode() == Instruction::Sub &&
+                   TI->getOpcode() == Instruction::Add) {
+          AddOp = TI; SubOp = FI;
+        }
+
+        if (AddOp) {
+          Value *OtherAddOp = 0;
+          if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
+            OtherAddOp = AddOp->getOperand(1);
+          } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
+            OtherAddOp = AddOp->getOperand(0);
+          }
+
+          if (OtherAddOp) {
+            // So at this point we know we have (Y -> OtherAddOp):
+            //        select C, (add X, Y), (sub X, Z)
+            Value *NegVal;  // Compute -Z
+            if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
+              NegVal = ConstantExpr::getNeg(C);
+            } else {
+              NegVal = InsertNewInstBefore(
+                    BinaryOperator::CreateNeg(SubOp->getOperand(1), "tmp"), SI);
+            }
+
+            Value *NewTrueOp = OtherAddOp;
+            Value *NewFalseOp = NegVal;
+            if (AddOp != TI)
+              std::swap(NewTrueOp, NewFalseOp);
+            Instruction *NewSel =
+              SelectInst::Create(CondVal, NewTrueOp,
+                                 NewFalseOp, SI.getName() + ".p");
+
+            NewSel = InsertNewInstBefore(NewSel, SI);
+            return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
+          }
+        }
+      }
+
+  // See if we can fold the select into one of our operands.
+  if (SI.getType()->isInteger()) {
+    Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal);
+    if (FoldI)
+      return FoldI;
+  }
+
+  if (BinaryOperator::isNot(CondVal)) {
+    SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
+    SI.setOperand(1, FalseVal);
+    SI.setOperand(2, TrueVal);
+    return &SI;
+  }
+
+  return 0;
+}
+
+/// EnforceKnownAlignment - If the specified pointer points to an object that
+/// we control, modify the object's alignment to PrefAlign. This isn't
+/// often possible though. If alignment is important, a more reliable approach
+/// is to simply align all global variables and allocation instructions to
+/// their preferred alignment from the beginning.
+///
+static unsigned EnforceKnownAlignment(Value *V,
+                                      unsigned Align, unsigned PrefAlign) {
+
+  User *U = dyn_cast<User>(V);
+  if (!U) return Align;
+
+  switch (getOpcode(U)) {
+  default: break;
+  case Instruction::BitCast:
+    return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
+  case Instruction::GetElementPtr: {
+    // If all indexes are zero, it is just the alignment of the base pointer.
+    bool AllZeroOperands = true;
+    for (User::op_iterator i = U->op_begin() + 1, e = U->op_end(); i != e; ++i)
+      if (!isa<Constant>(*i) ||
+          !cast<Constant>(*i)->isNullValue()) {
+        AllZeroOperands = false;
+        break;
+      }
+
+    if (AllZeroOperands) {
+      // Treat this like a bitcast.
+      return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
+    }
+    break;
+  }
+  }
+
+  if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
+    // If there is a large requested alignment and we can, bump up the alignment
+    // of the global.
+    if (!GV->isDeclaration()) {
+      if (GV->getAlignment() >= PrefAlign)
+        Align = GV->getAlignment();
+      else {
+        GV->setAlignment(PrefAlign);
+        Align = PrefAlign;
+      }
+    }
+  } else if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) {
+    // If there is a requested alignment and if this is an alloca, round up.  We
+    // don't do this for malloc, because some systems can't respect the request.
+    if (isa<AllocaInst>(AI)) {
+      if (AI->getAlignment() >= PrefAlign)
+        Align = AI->getAlignment();
+      else {
+        AI->setAlignment(PrefAlign);
+        Align = PrefAlign;
+      }
+    }
+  }
+
+  return Align;
+}
+
+/// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
+/// we can determine, return it, otherwise return 0.  If PrefAlign is specified,
+/// and it is more than the alignment of the ultimate object, see if we can
+/// increase the alignment of the ultimate object, making this check succeed.
+unsigned InstCombiner::GetOrEnforceKnownAlignment(Value *V,
+                                                  unsigned PrefAlign) {
+  unsigned BitWidth = TD ? TD->getTypeSizeInBits(V->getType()) :
+                      sizeof(PrefAlign) * CHAR_BIT;
+  APInt Mask = APInt::getAllOnesValue(BitWidth);
+  APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+  ComputeMaskedBits(V, Mask, KnownZero, KnownOne);
+  unsigned TrailZ = KnownZero.countTrailingOnes();
+  unsigned Align = 1u << std::min(BitWidth - 1, TrailZ);
+
+  if (PrefAlign > Align)
+    Align = EnforceKnownAlignment(V, Align, PrefAlign);
+  
+    // We don't need to make any adjustment.
+  return Align;
+}
+
+Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
+  unsigned DstAlign = GetOrEnforceKnownAlignment(MI->getOperand(1));
+  unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getOperand(2));
+  unsigned MinAlign = std::min(DstAlign, SrcAlign);
+  unsigned CopyAlign = MI->getAlignment();
+
+  if (CopyAlign < MinAlign) {
+    MI->setAlignment(MinAlign);
+    return MI;
+  }
+  
+  // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
+  // load/store.
+  ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getOperand(3));
+  if (MemOpLength == 0) return 0;
+  
+  // Source and destination pointer types are always "i8*" for intrinsic.  See
+  // if the size is something we can handle with a single primitive load/store.
+  // A single load+store correctly handles overlapping memory in the memmove
+  // case.
+  unsigned Size = MemOpLength->getZExtValue();
+  if (Size == 0) return MI;  // Delete this mem transfer.
+  
+  if (Size > 8 || (Size&(Size-1)))
+    return 0;  // If not 1/2/4/8 bytes, exit.
+  
+  // Use an integer load+store unless we can find something better.
+  Type *NewPtrTy = PointerType::getUnqual(IntegerType::get(Size<<3));
+  
+  // Memcpy forces the use of i8* for the source and destination.  That means
+  // that if you're using memcpy to move one double around, you'll get a cast
+  // from double* to i8*.  We'd much rather use a double load+store rather than
+  // an i64 load+store, here because this improves the odds that the source or
+  // dest address will be promotable.  See if we can find a better type than the
+  // integer datatype.
+  if (Value *Op = getBitCastOperand(MI->getOperand(1))) {
+    const Type *SrcETy = cast<PointerType>(Op->getType())->getElementType();
+    if (SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) {
+      // The SrcETy might be something like {{{double}}} or [1 x double].  Rip
+      // down through these levels if so.
+      while (!SrcETy->isSingleValueType()) {
+        if (const StructType *STy = dyn_cast<StructType>(SrcETy)) {
+          if (STy->getNumElements() == 1)
+            SrcETy = STy->getElementType(0);
+          else
+            break;
+        } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcETy)) {
+          if (ATy->getNumElements() == 1)
+            SrcETy = ATy->getElementType();
+          else
+            break;
+        } else
+          break;
+      }
+      
+      if (SrcETy->isSingleValueType())
+        NewPtrTy = PointerType::getUnqual(SrcETy);
+    }
+  }
+  
+  
+  // If the memcpy/memmove provides better alignment info than we can
+  // infer, use it.
+  SrcAlign = std::max(SrcAlign, CopyAlign);
+  DstAlign = std::max(DstAlign, CopyAlign);
+  
+  Value *Src = InsertBitCastBefore(MI->getOperand(2), NewPtrTy, *MI);
+  Value *Dest = InsertBitCastBefore(MI->getOperand(1), NewPtrTy, *MI);
+  Instruction *L = new LoadInst(Src, "tmp", false, SrcAlign);
+  InsertNewInstBefore(L, *MI);
+  InsertNewInstBefore(new StoreInst(L, Dest, false, DstAlign), *MI);
+
+  // Set the size of the copy to 0, it will be deleted on the next iteration.
+  MI->setOperand(3, Constant::getNullValue(MemOpLength->getType()));
+  return MI;
+}
+
+Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
+  unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest());
+  if (MI->getAlignment() < Alignment) {
+    MI->setAlignment(Alignment);
+    return MI;
+  }
+  
+  // Extract the length and alignment and fill if they are constant.
+  ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
+  ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
+  if (!LenC || !FillC || FillC->getType() != Type::Int8Ty)
+    return 0;
+  uint64_t Len = LenC->getZExtValue();
+  Alignment = MI->getAlignment();
+  
+  // If the length is zero, this is a no-op
+  if (Len == 0) return MI; // memset(d,c,0,a) -> noop
+  
+  // memset(s,c,n) -> store s, c (for n=1,2,4,8)
+  if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
+    const Type *ITy = IntegerType::get(Len*8);  // n=1 -> i8.
+    
+    Value *Dest = MI->getDest();
+    Dest = InsertBitCastBefore(Dest, PointerType::getUnqual(ITy), *MI);
+
+    // Alignment 0 is identity for alignment 1 for memset, but not store.
+    if (Alignment == 0) Alignment = 1;
+    
+    // Extract the fill value and store.
+    uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
+    InsertNewInstBefore(new StoreInst(ConstantInt::get(ITy, Fill), Dest, false,
+                                      Alignment), *MI);
+    
+    // Set the size of the copy to 0, it will be deleted on the next iteration.
+    MI->setLength(Constant::getNullValue(LenC->getType()));
+    return MI;
+  }
+
+  return 0;
+}
+
+
+/// visitCallInst - CallInst simplification.  This mostly only handles folding 
+/// of intrinsic instructions.  For normal calls, it allows visitCallSite to do
+/// the heavy lifting.
+///
+Instruction *InstCombiner::visitCallInst(CallInst &CI) {
+  // If the caller function is nounwind, mark the call as nounwind, even if the
+  // callee isn't.
+  if (CI.getParent()->getParent()->doesNotThrow() &&
+      !CI.doesNotThrow()) {
+    CI.setDoesNotThrow();
+    return &CI;
+  }
+  
+  
+  
+  IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
+  if (!II) return visitCallSite(&CI);
+  
+  // Intrinsics cannot occur in an invoke, so handle them here instead of in
+  // visitCallSite.
+  if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
+    bool Changed = false;
+
+    // memmove/cpy/set of zero bytes is a noop.
+    if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
+      if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
+
+      if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
+        if (CI->getZExtValue() == 1) {
+          // Replace the instruction with just byte operations.  We would
+          // transform other cases to loads/stores, but we don't know if
+          // alignment is sufficient.
+        }
+    }
+
+    // If we have a memmove and the source operation is a constant global,
+    // then the source and dest pointers can't alias, so we can change this
+    // into a call to memcpy.
+    if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
+      if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
+        if (GVSrc->isConstant()) {
+          Module *M = CI.getParent()->getParent()->getParent();
+          Intrinsic::ID MemCpyID = Intrinsic::memcpy;
+          const Type *Tys[1];
+          Tys[0] = CI.getOperand(3)->getType();
+          CI.setOperand(0, 
+                        Intrinsic::getDeclaration(M, MemCpyID, Tys, 1));
+          Changed = true;
+        }
+
+      // memmove(x,x,size) -> noop.
+      if (MMI->getSource() == MMI->getDest())
+        return EraseInstFromFunction(CI);
+    }
+
+    // If we can determine a pointer alignment that is bigger than currently
+    // set, update the alignment.
+    if (isa<MemTransferInst>(MI)) {
+      if (Instruction *I = SimplifyMemTransfer(MI))
+        return I;
+    } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
+      if (Instruction *I = SimplifyMemSet(MSI))
+        return I;
+    }
+          
+    if (Changed) return II;
+  }
+  
+  switch (II->getIntrinsicID()) {
+  default: break;
+  case Intrinsic::bswap:
+    // bswap(bswap(x)) -> x
+    if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getOperand(1)))
+      if (Operand->getIntrinsicID() == Intrinsic::bswap)
+        return ReplaceInstUsesWith(CI, Operand->getOperand(1));
+    break;
+  case Intrinsic::ppc_altivec_lvx:
+  case Intrinsic::ppc_altivec_lvxl:
+  case Intrinsic::x86_sse_loadu_ps:
+  case Intrinsic::x86_sse2_loadu_pd:
+  case Intrinsic::x86_sse2_loadu_dq:
+    // Turn PPC lvx     -> load if the pointer is known aligned.
+    // Turn X86 loadups -> load if the pointer is known aligned.
+    if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
+      Value *Ptr = InsertBitCastBefore(II->getOperand(1),
+                                       PointerType::getUnqual(II->getType()),
+                                       CI);
+      return new LoadInst(Ptr);
+    }
+    break;
+  case Intrinsic::ppc_altivec_stvx:
+  case Intrinsic::ppc_altivec_stvxl:
+    // Turn stvx -> store if the pointer is known aligned.
+    if (GetOrEnforceKnownAlignment(II->getOperand(2), 16) >= 16) {
+      const Type *OpPtrTy = 
+        PointerType::getUnqual(II->getOperand(1)->getType());
+      Value *Ptr = InsertBitCastBefore(II->getOperand(2), OpPtrTy, CI);
+      return new StoreInst(II->getOperand(1), Ptr);
+    }
+    break;
+  case Intrinsic::x86_sse_storeu_ps:
+  case Intrinsic::x86_sse2_storeu_pd:
+  case Intrinsic::x86_sse2_storeu_dq:
+    // Turn X86 storeu -> store if the pointer is known aligned.
+    if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
+      const Type *OpPtrTy = 
+        PointerType::getUnqual(II->getOperand(2)->getType());
+      Value *Ptr = InsertBitCastBefore(II->getOperand(1), OpPtrTy, CI);
+      return new StoreInst(II->getOperand(2), Ptr);
+    }
+    break;
+    
+  case Intrinsic::x86_sse_cvttss2si: {
+    // These intrinsics only demands the 0th element of its input vector.  If
+    // we can simplify the input based on that, do so now.
+    unsigned VWidth =
+      cast<VectorType>(II->getOperand(1)->getType())->getNumElements();
+    APInt DemandedElts(VWidth, 1);
+    APInt UndefElts(VWidth, 0);
+    if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
+                                              UndefElts)) {
+      II->setOperand(1, V);
+      return II;
+    }
+    break;
+  }
+    
+  case Intrinsic::ppc_altivec_vperm:
+    // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
+    if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
+      assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
+      
+      // Check that all of the elements are integer constants or undefs.
+      bool AllEltsOk = true;
+      for (unsigned i = 0; i != 16; ++i) {
+        if (!isa<ConstantInt>(Mask->getOperand(i)) && 
+            !isa<UndefValue>(Mask->getOperand(i))) {
+          AllEltsOk = false;
+          break;
+        }
+      }
+      
+      if (AllEltsOk) {
+        // Cast the input vectors to byte vectors.
+        Value *Op0 =InsertBitCastBefore(II->getOperand(1),Mask->getType(),CI);
+        Value *Op1 =InsertBitCastBefore(II->getOperand(2),Mask->getType(),CI);
+        Value *Result = UndefValue::get(Op0->getType());
+        
+        // Only extract each element once.
+        Value *ExtractedElts[32];
+        memset(ExtractedElts, 0, sizeof(ExtractedElts));
+        
+        for (unsigned i = 0; i != 16; ++i) {
+          if (isa<UndefValue>(Mask->getOperand(i)))
+            continue;
+          unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
+          Idx &= 31;  // Match the hardware behavior.
+          
+          if (ExtractedElts[Idx] == 0) {
+            Instruction *Elt = 
+              new ExtractElementInst(Idx < 16 ? Op0 : Op1, Idx&15, "tmp");
+            InsertNewInstBefore(Elt, CI);
+            ExtractedElts[Idx] = Elt;
+          }
+        
+          // Insert this value into the result vector.
+          Result = InsertElementInst::Create(Result, ExtractedElts[Idx],
+                                             i, "tmp");
+          InsertNewInstBefore(cast<Instruction>(Result), CI);
+        }
+        return CastInst::Create(Instruction::BitCast, Result, CI.getType());
+      }
+    }
+    break;
+
+  case Intrinsic::stackrestore: {
+    // If the save is right next to the restore, remove the restore.  This can
+    // happen when variable allocas are DCE'd.
+    if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
+      if (SS->getIntrinsicID() == Intrinsic::stacksave) {
+        BasicBlock::iterator BI = SS;
+        if (&*++BI == II)
+          return EraseInstFromFunction(CI);
+      }
+    }
+    
+    // Scan down this block to see if there is another stack restore in the
+    // same block without an intervening call/alloca.
+    BasicBlock::iterator BI = II;
+    TerminatorInst *TI = II->getParent()->getTerminator();
+    bool CannotRemove = false;
+    for (++BI; &*BI != TI; ++BI) {
+      if (isa<AllocaInst>(BI)) {
+        CannotRemove = true;
+        break;
+      }
+      if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
+        if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
+          // If there is a stackrestore below this one, remove this one.
+          if (II->getIntrinsicID() == Intrinsic::stackrestore)
+            return EraseInstFromFunction(CI);
+          // Otherwise, ignore the intrinsic.
+        } else {
+          // If we found a non-intrinsic call, we can't remove the stack
+          // restore.
+          CannotRemove = true;
+          break;
+        }
+      }
+    }
+    
+    // If the stack restore is in a return/unwind block and if there are no
+    // allocas or calls between the restore and the return, nuke the restore.
+    if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)))
+      return EraseInstFromFunction(CI);
+    break;
+  }
+  }
+
+  return visitCallSite(II);
+}
+
+// InvokeInst simplification
+//
+Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
+  return visitCallSite(&II);
+}
+
+/// isSafeToEliminateVarargsCast - If this cast does not affect the value 
+/// passed through the varargs area, we can eliminate the use of the cast.
+static bool isSafeToEliminateVarargsCast(const CallSite CS,
+                                         const CastInst * const CI,
+                                         const TargetData * const TD,
+                                         const int ix) {
+  if (!CI->isLosslessCast())
+    return false;
+
+  // The size of ByVal arguments is derived from the type, so we
+  // can't change to a type with a different size.  If the size were
+  // passed explicitly we could avoid this check.
+  if (!CS.paramHasAttr(ix, Attribute::ByVal))
+    return true;
+
+  const Type* SrcTy = 
+            cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
+  const Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
+  if (!SrcTy->isSized() || !DstTy->isSized())
+    return false;
+  if (TD->getTypeAllocSize(SrcTy) != TD->getTypeAllocSize(DstTy))
+    return false;
+  return true;
+}
+
+// visitCallSite - Improvements for call and invoke instructions.
+//
+Instruction *InstCombiner::visitCallSite(CallSite CS) {
+  bool Changed = false;
+
+  // If the callee is a constexpr cast of a function, attempt to move the cast
+  // to the arguments of the call/invoke.
+  if (transformConstExprCastCall(CS)) return 0;
+
+  Value *Callee = CS.getCalledValue();
+
+  if (Function *CalleeF = dyn_cast<Function>(Callee))
+    if (CalleeF->getCallingConv() != CS.getCallingConv()) {
+      Instruction *OldCall = CS.getInstruction();
+      // If the call and callee calling conventions don't match, this call must
+      // be unreachable, as the call is undefined.
+      new StoreInst(ConstantInt::getTrue(),
+                    UndefValue::get(PointerType::getUnqual(Type::Int1Ty)), 
+                                    OldCall);
+      if (!OldCall->use_empty())
+        OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
+      if (isa<CallInst>(OldCall))   // Not worth removing an invoke here.
+        return EraseInstFromFunction(*OldCall);
+      return 0;
+    }
+
+  if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
+    // This instruction is not reachable, just remove it.  We insert a store to
+    // undef so that we know that this code is not reachable, despite the fact
+    // that we can't modify the CFG here.
+    new StoreInst(ConstantInt::getTrue(),
+                  UndefValue::get(PointerType::getUnqual(Type::Int1Ty)),
+                  CS.getInstruction());
+
+    if (!CS.getInstruction()->use_empty())
+      CS.getInstruction()->
+        replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
+
+    if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
+      // Don't break the CFG, insert a dummy cond branch.
+      BranchInst::Create(II->getNormalDest(), II->getUnwindDest(),
+                         ConstantInt::getTrue(), II);
+    }
+    return EraseInstFromFunction(*CS.getInstruction());
+  }
+
+  if (BitCastInst *BC = dyn_cast<BitCastInst>(Callee))
+    if (IntrinsicInst *In = dyn_cast<IntrinsicInst>(BC->getOperand(0)))
+      if (In->getIntrinsicID() == Intrinsic::init_trampoline)
+        return transformCallThroughTrampoline(CS);
+
+  const PointerType *PTy = cast<PointerType>(Callee->getType());
+  const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
+  if (FTy->isVarArg()) {
+    int ix = FTy->getNumParams() + (isa<InvokeInst>(Callee) ? 3 : 1);
+    // See if we can optimize any arguments passed through the varargs area of
+    // the call.
+    for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
+           E = CS.arg_end(); I != E; ++I, ++ix) {
+      CastInst *CI = dyn_cast<CastInst>(*I);
+      if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) {
+        *I = CI->getOperand(0);
+        Changed = true;
+      }
+    }
+  }
+
+  if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
+    // Inline asm calls cannot throw - mark them 'nounwind'.
+    CS.setDoesNotThrow();
+    Changed = true;
+  }
+
+  return Changed ? CS.getInstruction() : 0;
+}
+
+// transformConstExprCastCall - If the callee is a constexpr cast of a function,
+// attempt to move the cast to the arguments of the call/invoke.
+//
+bool InstCombiner::transformConstExprCastCall(CallSite CS) {
+  if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
+  ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
+  if (CE->getOpcode() != Instruction::BitCast || 
+      !isa<Function>(CE->getOperand(0)))
+    return false;
+  Function *Callee = cast<Function>(CE->getOperand(0));
+  Instruction *Caller = CS.getInstruction();
+  const AttrListPtr &CallerPAL = CS.getAttributes();
+
+  // Okay, this is a cast from a function to a different type.  Unless doing so
+  // would cause a type conversion of one of our arguments, change this call to
+  // be a direct call with arguments casted to the appropriate types.
+  //
+  const FunctionType *FT = Callee->getFunctionType();
+  const Type *OldRetTy = Caller->getType();
+  const Type *NewRetTy = FT->getReturnType();
+
+  if (isa<StructType>(NewRetTy))
+    return false; // TODO: Handle multiple return values.
+
+  // Check to see if we are changing the return type...
+  if (OldRetTy != NewRetTy) {
+    if (Callee->isDeclaration() &&
+        // Conversion is ok if changing from one pointer type to another or from
+        // a pointer to an integer of the same size.
+        !((isa<PointerType>(OldRetTy) || OldRetTy == TD->getIntPtrType()) &&
+          (isa<PointerType>(NewRetTy) || NewRetTy == TD->getIntPtrType())))
+      return false;   // Cannot transform this return value.
+
+    if (!Caller->use_empty() &&
+        // void -> non-void is handled specially
+        NewRetTy != Type::VoidTy && !CastInst::isCastable(NewRetTy, OldRetTy))
+      return false;   // Cannot transform this return value.
+
+    if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
+      Attributes RAttrs = CallerPAL.getRetAttributes();
+      if (RAttrs & Attribute::typeIncompatible(NewRetTy))
+        return false;   // Attribute not compatible with transformed value.
+    }
+
+    // If the callsite is an invoke instruction, and the return value is used by
+    // a PHI node in a successor, we cannot change the return type of the call
+    // because there is no place to put the cast instruction (without breaking
+    // the critical edge).  Bail out in this case.
+    if (!Caller->use_empty())
+      if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
+        for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
+             UI != E; ++UI)
+          if (PHINode *PN = dyn_cast<PHINode>(*UI))
+            if (PN->getParent() == II->getNormalDest() ||
+                PN->getParent() == II->getUnwindDest())
+              return false;
+  }
+
+  unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
+  unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
+
+  CallSite::arg_iterator AI = CS.arg_begin();
+  for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
+    const Type *ParamTy = FT->getParamType(i);
+    const Type *ActTy = (*AI)->getType();
+
+    if (!CastInst::isCastable(ActTy, ParamTy))
+      return false;   // Cannot transform this parameter value.
+
+    if (CallerPAL.getParamAttributes(i + 1) 
+        & Attribute::typeIncompatible(ParamTy))
+      return false;   // Attribute not compatible with transformed value.
+
+    // Converting from one pointer type to another or between a pointer and an
+    // integer of the same size is safe even if we do not have a body.
+    bool isConvertible = ActTy == ParamTy ||
+      ((isa<PointerType>(ParamTy) || ParamTy == TD->getIntPtrType()) &&
+       (isa<PointerType>(ActTy) || ActTy == TD->getIntPtrType()));
+    if (Callee->isDeclaration() && !isConvertible) return false;
+  }
+
+  if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
+      Callee->isDeclaration())
+    return false;   // Do not delete arguments unless we have a function body.
+
+  if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
+      !CallerPAL.isEmpty())
+    // In this case we have more arguments than the new function type, but we
+    // won't be dropping them.  Check that these extra arguments have attributes
+    // that are compatible with being a vararg call argument.
+    for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
+      if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams())
+        break;
+      Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs;
+      if (PAttrs & Attribute::VarArgsIncompatible)
+        return false;
+    }
+
+  // Okay, we decided that this is a safe thing to do: go ahead and start
+  // inserting cast instructions as necessary...
+  std::vector<Value*> Args;
+  Args.reserve(NumActualArgs);
+  SmallVector<AttributeWithIndex, 8> attrVec;
+  attrVec.reserve(NumCommonArgs);
+
+  // Get any return attributes.
+  Attributes RAttrs = CallerPAL.getRetAttributes();
+
+  // If the return value is not being used, the type may not be compatible
+  // with the existing attributes.  Wipe out any problematic attributes.
+  RAttrs &= ~Attribute::typeIncompatible(NewRetTy);
+
+  // Add the new return attributes.
+  if (RAttrs)
+    attrVec.push_back(AttributeWithIndex::get(0, RAttrs));
+
+  AI = CS.arg_begin();
+  for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
+    const Type *ParamTy = FT->getParamType(i);
+    if ((*AI)->getType() == ParamTy) {
+      Args.push_back(*AI);
+    } else {
+      Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
+          false, ParamTy, false);
+      CastInst *NewCast = CastInst::Create(opcode, *AI, ParamTy, "tmp");
+      Args.push_back(InsertNewInstBefore(NewCast, *Caller));
+    }
+
+    // Add any parameter attributes.
+    if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
+      attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
+  }
+
+  // If the function takes more arguments than the call was taking, add them
+  // now...
+  for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
+    Args.push_back(Constant::getNullValue(FT->getParamType(i)));
+
+  // If we are removing arguments to the function, emit an obnoxious warning...
+  if (FT->getNumParams() < NumActualArgs) {
+    if (!FT->isVarArg()) {
+      cerr << "WARNING: While resolving call to function '"
+           << Callee->getName() << "' arguments were dropped!\n";
+    } else {
+      // Add all of the arguments in their promoted form to the arg list...
+      for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
+        const Type *PTy = getPromotedType((*AI)->getType());
+        if (PTy != (*AI)->getType()) {
+          // Must promote to pass through va_arg area!
+          Instruction::CastOps opcode = CastInst::getCastOpcode(*AI, false, 
+                                                                PTy, false);
+          Instruction *Cast = CastInst::Create(opcode, *AI, PTy, "tmp");
+          InsertNewInstBefore(Cast, *Caller);
+          Args.push_back(Cast);
+        } else {
+          Args.push_back(*AI);
+        }
+
+        // Add any parameter attributes.
+        if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
+          attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
+      }
+    }
+  }
+
+  if (Attributes FnAttrs =  CallerPAL.getFnAttributes())
+    attrVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
+
+  if (NewRetTy == Type::VoidTy)
+    Caller->setName("");   // Void type should not have a name.
+
+  const AttrListPtr &NewCallerPAL = AttrListPtr::get(attrVec.begin(),attrVec.end());
+
+  Instruction *NC;
+  if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
+    NC = InvokeInst::Create(Callee, II->getNormalDest(), II->getUnwindDest(),
+                            Args.begin(), Args.end(),
+                            Caller->getName(), Caller);
+    cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
+    cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
+  } else {
+    NC = CallInst::Create(Callee, Args.begin(), Args.end(),
+                          Caller->getName(), Caller);
+    CallInst *CI = cast<CallInst>(Caller);
+    if (CI->isTailCall())
+      cast<CallInst>(NC)->setTailCall();
+    cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
+    cast<CallInst>(NC)->setAttributes(NewCallerPAL);
+  }
+
+  // Insert a cast of the return type as necessary.
+  Value *NV = NC;
+  if (OldRetTy != NV->getType() && !Caller->use_empty()) {
+    if (NV->getType() != Type::VoidTy) {
+      Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false, 
+                                                            OldRetTy, false);
+      NV = NC = CastInst::Create(opcode, NC, OldRetTy, "tmp");
+
+      // If this is an invoke instruction, we should insert it after the first
+      // non-phi, instruction in the normal successor block.
+      if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
+        BasicBlock::iterator I = II->getNormalDest()->getFirstNonPHI();
+        InsertNewInstBefore(NC, *I);
+      } else {
+        // Otherwise, it's a call, just insert cast right after the call instr
+        InsertNewInstBefore(NC, *Caller);
+      }
+      AddUsersToWorkList(*Caller);
+    } else {
+      NV = UndefValue::get(Caller->getType());
+    }
+  }
+
+  if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
+    Caller->replaceAllUsesWith(NV);
+  Caller->eraseFromParent();
+  RemoveFromWorkList(Caller);
+  return true;
+}
+
+// transformCallThroughTrampoline - Turn a call to a function created by the
+// init_trampoline intrinsic into a direct call to the underlying function.
+//
+Instruction *InstCombiner::transformCallThroughTrampoline(CallSite CS) {
+  Value *Callee = CS.getCalledValue();
+  const PointerType *PTy = cast<PointerType>(Callee->getType());
+  const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
+  const AttrListPtr &Attrs = CS.getAttributes();
+
+  // If the call already has the 'nest' attribute somewhere then give up -
+  // otherwise 'nest' would occur twice after splicing in the chain.
+  if (Attrs.hasAttrSomewhere(Attribute::Nest))
+    return 0;
+
+  IntrinsicInst *Tramp =
+    cast<IntrinsicInst>(cast<BitCastInst>(Callee)->getOperand(0));
+
+  Function *NestF = cast<Function>(Tramp->getOperand(2)->stripPointerCasts());
+  const PointerType *NestFPTy = cast<PointerType>(NestF->getType());
+  const FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
+
+  const AttrListPtr &NestAttrs = NestF->getAttributes();
+  if (!NestAttrs.isEmpty()) {
+    unsigned NestIdx = 1;
+    const Type *NestTy = 0;
+    Attributes NestAttr = Attribute::None;
+
+    // Look for a parameter marked with the 'nest' attribute.
+    for (FunctionType::param_iterator I = NestFTy->param_begin(),
+         E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
+      if (NestAttrs.paramHasAttr(NestIdx, Attribute::Nest)) {
+        // Record the parameter type and any other attributes.
+        NestTy = *I;
+        NestAttr = NestAttrs.getParamAttributes(NestIdx);
+        break;
+      }
+
+    if (NestTy) {
+      Instruction *Caller = CS.getInstruction();
+      std::vector<Value*> NewArgs;
+      NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
+
+      SmallVector<AttributeWithIndex, 8> NewAttrs;
+      NewAttrs.reserve(Attrs.getNumSlots() + 1);
+
+      // Insert the nest argument into the call argument list, which may
+      // mean appending it.  Likewise for attributes.
+
+      // Add any result attributes.
+      if (Attributes Attr = Attrs.getRetAttributes())
+        NewAttrs.push_back(AttributeWithIndex::get(0, Attr));
+
+      {
+        unsigned Idx = 1;
+        CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
+        do {
+          if (Idx == NestIdx) {
+            // Add the chain argument and attributes.
+            Value *NestVal = Tramp->getOperand(3);
+            if (NestVal->getType() != NestTy)
+              NestVal = new BitCastInst(NestVal, NestTy, "nest", Caller);
+            NewArgs.push_back(NestVal);
+            NewAttrs.push_back(AttributeWithIndex::get(NestIdx, NestAttr));
+          }
+
+          if (I == E)
+            break;
+
+          // Add the original argument and attributes.
+          NewArgs.push_back(*I);
+          if (Attributes Attr = Attrs.getParamAttributes(Idx))
+            NewAttrs.push_back
+              (AttributeWithIndex::get(Idx + (Idx >= NestIdx), Attr));
+
+          ++Idx, ++I;
+        } while (1);
+      }
+
+      // Add any function attributes.
+      if (Attributes Attr = Attrs.getFnAttributes())
+        NewAttrs.push_back(AttributeWithIndex::get(~0, Attr));
+
+      // The trampoline may have been bitcast to a bogus type (FTy).
+      // Handle this by synthesizing a new function type, equal to FTy
+      // with the chain parameter inserted.
+
+      std::vector<const Type*> NewTypes;
+      NewTypes.reserve(FTy->getNumParams()+1);
+
+      // Insert the chain's type into the list of parameter types, which may
+      // mean appending it.
+      {
+        unsigned Idx = 1;
+        FunctionType::param_iterator I = FTy->param_begin(),
+          E = FTy->param_end();
+
+        do {
+          if (Idx == NestIdx)
+            // Add the chain's type.
+            NewTypes.push_back(NestTy);
+
+          if (I == E)
+            break;
+
+          // Add the original type.
+          NewTypes.push_back(*I);
+
+          ++Idx, ++I;
+        } while (1);
+      }
+
+      // Replace the trampoline call with a direct call.  Let the generic
+      // code sort out any function type mismatches.
+      FunctionType *NewFTy =
+        FunctionType::get(FTy->getReturnType(), NewTypes, FTy->isVarArg());
+      Constant *NewCallee = NestF->getType() == PointerType::getUnqual(NewFTy) ?
+        NestF : ConstantExpr::getBitCast(NestF, PointerType::getUnqual(NewFTy));
+      const AttrListPtr &NewPAL = AttrListPtr::get(NewAttrs.begin(),NewAttrs.end());
+
+      Instruction *NewCaller;
+      if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
+        NewCaller = InvokeInst::Create(NewCallee,
+                                       II->getNormalDest(), II->getUnwindDest(),
+                                       NewArgs.begin(), NewArgs.end(),
+                                       Caller->getName(), Caller);
+        cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
+        cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
+      } else {
+        NewCaller = CallInst::Create(NewCallee, NewArgs.begin(), NewArgs.end(),
+                                     Caller->getName(), Caller);
+        if (cast<CallInst>(Caller)->isTailCall())
+          cast<CallInst>(NewCaller)->setTailCall();
+        cast<CallInst>(NewCaller)->
+          setCallingConv(cast<CallInst>(Caller)->getCallingConv());
+        cast<CallInst>(NewCaller)->setAttributes(NewPAL);
+      }
+      if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
+        Caller->replaceAllUsesWith(NewCaller);
+      Caller->eraseFromParent();
+      RemoveFromWorkList(Caller);
+      return 0;
+    }
+  }
+
+  // Replace the trampoline call with a direct call.  Since there is no 'nest'
+  // parameter, there is no need to adjust the argument list.  Let the generic
+  // code sort out any function type mismatches.
+  Constant *NewCallee =
+    NestF->getType() == PTy ? NestF : ConstantExpr::getBitCast(NestF, PTy);
+  CS.setCalledFunction(NewCallee);
+  return CS.getInstruction();
+}
+
+/// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(c,d)]
+/// and if a/b/c/d and the add's all have a single use, turn this into two phi's
+/// and a single binop.
+Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
+  Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
+  assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst));
+  unsigned Opc = FirstInst->getOpcode();
+  Value *LHSVal = FirstInst->getOperand(0);
+  Value *RHSVal = FirstInst->getOperand(1);
+    
+  const Type *LHSType = LHSVal->getType();
+  const Type *RHSType = RHSVal->getType();
+  
+  // Scan to see if all operands are the same opcode, all have one use, and all
+  // kill their operands (i.e. the operands have one use).
+  for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
+    Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
+    if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
+        // Verify type of the LHS matches so we don't fold cmp's of different
+        // types or GEP's with different index types.
+        I->getOperand(0)->getType() != LHSType ||
+        I->getOperand(1)->getType() != RHSType)
+      return 0;
+
+    // If they are CmpInst instructions, check their predicates
+    if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
+      if (cast<CmpInst>(I)->getPredicate() !=
+          cast<CmpInst>(FirstInst)->getPredicate())
+        return 0;
+    
+    // Keep track of which operand needs a phi node.
+    if (I->getOperand(0) != LHSVal) LHSVal = 0;
+    if (I->getOperand(1) != RHSVal) RHSVal = 0;
+  }
+  
+  // Otherwise, this is safe to transform!
+  
+  Value *InLHS = FirstInst->getOperand(0);
+  Value *InRHS = FirstInst->getOperand(1);
+  PHINode *NewLHS = 0, *NewRHS = 0;
+  if (LHSVal == 0) {
+    NewLHS = PHINode::Create(LHSType,
+                             FirstInst->getOperand(0)->getName() + ".pn");
+    NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
+    NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
+    InsertNewInstBefore(NewLHS, PN);
+    LHSVal = NewLHS;
+  }
+  
+  if (RHSVal == 0) {
+    NewRHS = PHINode::Create(RHSType,
+                             FirstInst->getOperand(1)->getName() + ".pn");
+    NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
+    NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
+    InsertNewInstBefore(NewRHS, PN);
+    RHSVal = NewRHS;
+  }
+  
+  // Add all operands to the new PHIs.
+  if (NewLHS || NewRHS) {
+    for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+      Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i));
+      if (NewLHS) {
+        Value *NewInLHS = InInst->getOperand(0);
+        NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
+      }
+      if (NewRHS) {
+        Value *NewInRHS = InInst->getOperand(1);
+        NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
+      }
+    }
+  }
+    
+  if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
+    return BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
+  CmpInst *CIOp = cast<CmpInst>(FirstInst);
+  return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(), LHSVal,
+                         RHSVal);
+}
+
+Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
+  GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0));
+  
+  SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(), 
+                                        FirstInst->op_end());
+  // This is true if all GEP bases are allocas and if all indices into them are
+  // constants.
+  bool AllBasePointersAreAllocas = true;
+  
+  // Scan to see if all operands are the same opcode, all have one use, and all
+  // kill their operands (i.e. the operands have one use).
+  for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
+    GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i));
+    if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() ||
+      GEP->getNumOperands() != FirstInst->getNumOperands())
+      return 0;
+
+    // Keep track of whether or not all GEPs are of alloca pointers.
+    if (AllBasePointersAreAllocas &&
+        (!isa<AllocaInst>(GEP->getOperand(0)) ||
+         !GEP->hasAllConstantIndices()))
+      AllBasePointersAreAllocas = false;
+    
+    // Compare the operand lists.
+    for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) {
+      if (FirstInst->getOperand(op) == GEP->getOperand(op))
+        continue;
+      
+      // Don't merge two GEPs when two operands differ (introducing phi nodes)
+      // if one of the PHIs has a constant for the index.  The index may be
+      // substantially cheaper to compute for the constants, so making it a
+      // variable index could pessimize the path.  This also handles the case
+      // for struct indices, which must always be constant.
+      if (isa<ConstantInt>(FirstInst->getOperand(op)) ||
+          isa<ConstantInt>(GEP->getOperand(op)))
+        return 0;
+      
+      if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType())
+        return 0;
+      FixedOperands[op] = 0;  // Needs a PHI.
+    }
+  }
+  
+  // If all of the base pointers of the PHI'd GEPs are from allocas, don't
+  // bother doing this transformation.  At best, this will just save a bit of
+  // offset calculation, but all the predecessors will have to materialize the
+  // stack address into a register anyway.  We'd actually rather *clone* the
+  // load up into the predecessors so that we have a load of a gep of an alloca,
+  // which can usually all be folded into the load.
+  if (AllBasePointersAreAllocas)
+    return 0;
+  
+  // Otherwise, this is safe to transform.  Insert PHI nodes for each operand
+  // that is variable.
+  SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size());
+  
+  bool HasAnyPHIs = false;
+  for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) {
+    if (FixedOperands[i]) continue;  // operand doesn't need a phi.
+    Value *FirstOp = FirstInst->getOperand(i);
+    PHINode *NewPN = PHINode::Create(FirstOp->getType(),
+                                     FirstOp->getName()+".pn");
+    InsertNewInstBefore(NewPN, PN);
+    
+    NewPN->reserveOperandSpace(e);
+    NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0));
+    OperandPhis[i] = NewPN;
+    FixedOperands[i] = NewPN;
+    HasAnyPHIs = true;
+  }
+
+  
+  // Add all operands to the new PHIs.
+  if (HasAnyPHIs) {
+    for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+      GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i));
+      BasicBlock *InBB = PN.getIncomingBlock(i);
+      
+      for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op)
+        if (PHINode *OpPhi = OperandPhis[op])
+          OpPhi->addIncoming(InGEP->getOperand(op), InBB);
+    }
+  }
+  
+  Value *Base = FixedOperands[0];
+  return GetElementPtrInst::Create(Base, FixedOperands.begin()+1,
+                                   FixedOperands.end());
+}
+
+
+/// isSafeAndProfitableToSinkLoad - Return true if we know that it is safe to
+/// sink the load out of the block that defines it.  This means that it must be
+/// obvious the value of the load is not changed from the point of the load to
+/// the end of the block it is in.
+///
+/// Finally, it is safe, but not profitable, to sink a load targetting a
+/// non-address-taken alloca.  Doing so will cause us to not promote the alloca
+/// to a register.
+static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
+  BasicBlock::iterator BBI = L, E = L->getParent()->end();
+  
+  for (++BBI; BBI != E; ++BBI)
+    if (BBI->mayWriteToMemory())
+      return false;
+  
+  // Check for non-address taken alloca.  If not address-taken already, it isn't
+  // profitable to do this xform.
+  if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
+    bool isAddressTaken = false;
+    for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
+         UI != E; ++UI) {
+      if (isa<LoadInst>(UI)) continue;
+      if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
+        // If storing TO the alloca, then the address isn't taken.
+        if (SI->getOperand(1) == AI) continue;
+      }
+      isAddressTaken = true;
+      break;
+    }
+    
+    if (!isAddressTaken && AI->isStaticAlloca())
+      return false;
+  }
+  
+  // If this load is a load from a GEP with a constant offset from an alloca,
+  // then we don't want to sink it.  In its present form, it will be
+  // load [constant stack offset].  Sinking it will cause us to have to
+  // materialize the stack addresses in each predecessor in a register only to
+  // do a shared load from register in the successor.
+  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0)))
+    if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0)))
+      if (AI->isStaticAlloca() && GEP->hasAllConstantIndices())
+        return false;
+  
+  return true;
+}
+
+
+// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
+// operator and they all are only used by the PHI, PHI together their
+// inputs, and do the operation once, to the result of the PHI.
+Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
+  Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
+
+  // Scan the instruction, looking for input operations that can be folded away.
+  // If all input operands to the phi are the same instruction (e.g. a cast from
+  // the same type or "+42") we can pull the operation through the PHI, reducing
+  // code size and simplifying code.
+  Constant *ConstantOp = 0;
+  const Type *CastSrcTy = 0;
+  bool isVolatile = false;
+  if (isa<CastInst>(FirstInst)) {
+    CastSrcTy = FirstInst->getOperand(0)->getType();
+  } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
+    // Can fold binop, compare or shift here if the RHS is a constant, 
+    // otherwise call FoldPHIArgBinOpIntoPHI.
+    ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
+    if (ConstantOp == 0)
+      return FoldPHIArgBinOpIntoPHI(PN);
+  } else if (LoadInst *LI = dyn_cast<LoadInst>(FirstInst)) {
+    isVolatile = LI->isVolatile();
+    // We can't sink the load if the loaded value could be modified between the
+    // load and the PHI.
+    if (LI->getParent() != PN.getIncomingBlock(0) ||
+        !isSafeAndProfitableToSinkLoad(LI))
+      return 0;
+    
+    // If the PHI is of volatile loads and the load block has multiple
+    // successors, sinking it would remove a load of the volatile value from
+    // the path through the other successor.
+    if (isVolatile &&
+        LI->getParent()->getTerminator()->getNumSuccessors() != 1)
+      return 0;
+    
+  } else if (isa<GetElementPtrInst>(FirstInst)) {
+    return FoldPHIArgGEPIntoPHI(PN);
+  } else {
+    return 0;  // Cannot fold this operation.
+  }
+
+  // Check to see if all arguments are the same operation.
+  for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+    if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
+    Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
+    if (!I->hasOneUse() || !I->isSameOperationAs(FirstInst))
+      return 0;
+    if (CastSrcTy) {
+      if (I->getOperand(0)->getType() != CastSrcTy)
+        return 0;  // Cast operation must match.
+    } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+      // We can't sink the load if the loaded value could be modified between 
+      // the load and the PHI.
+      if (LI->isVolatile() != isVolatile ||
+          LI->getParent() != PN.getIncomingBlock(i) ||
+          !isSafeAndProfitableToSinkLoad(LI))
+        return 0;
+      
+      // If the PHI is of volatile loads and the load block has multiple
+      // successors, sinking it would remove a load of the volatile value from
+      // the path through the other successor.
+      if (isVolatile &&
+          LI->getParent()->getTerminator()->getNumSuccessors() != 1)
+        return 0;
+      
+    } else if (I->getOperand(1) != ConstantOp) {
+      return 0;
+    }
+  }
+
+  // Okay, they are all the same operation.  Create a new PHI node of the
+  // correct type, and PHI together all of the LHS's of the instructions.
+  PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(),
+                                   PN.getName()+".in");
+  NewPN->reserveOperandSpace(PN.getNumOperands()/2);
+
+  Value *InVal = FirstInst->getOperand(0);
+  NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
+
+  // Add all operands to the new PHI.
+  for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+    Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
+    if (NewInVal != InVal)
+      InVal = 0;
+    NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
+  }
+
+  Value *PhiVal;
+  if (InVal) {
+    // The new PHI unions all of the same values together.  This is really
+    // common, so we handle it intelligently here for compile-time speed.
+    PhiVal = InVal;
+    delete NewPN;
+  } else {
+    InsertNewInstBefore(NewPN, PN);
+    PhiVal = NewPN;
+  }
+
+  // Insert and return the new operation.
+  if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst))
+    return CastInst::Create(FirstCI->getOpcode(), PhiVal, PN.getType());
+  if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
+    return BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
+  if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
+    return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(), 
+                           PhiVal, ConstantOp);
+  assert(isa<LoadInst>(FirstInst) && "Unknown operation");
+  
+  // If this was a volatile load that we are merging, make sure to loop through
+  // and mark all the input loads as non-volatile.  If we don't do this, we will
+  // insert a new volatile load and the old ones will not be deletable.
+  if (isVolatile)
+    for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
+      cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
+  
+  return new LoadInst(PhiVal, "", isVolatile);
+}
+
+/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
+/// that is dead.
+static bool DeadPHICycle(PHINode *PN,
+                         SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
+  if (PN->use_empty()) return true;
+  if (!PN->hasOneUse()) return false;
+
+  // Remember this node, and if we find the cycle, return.
+  if (!PotentiallyDeadPHIs.insert(PN))
+    return true;
+  
+  // Don't scan crazily complex things.
+  if (PotentiallyDeadPHIs.size() == 16)
+    return false;
+
+  if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
+    return DeadPHICycle(PU, PotentiallyDeadPHIs);
+
+  return false;
+}
+
+/// PHIsEqualValue - Return true if this phi node is always equal to
+/// NonPhiInVal.  This happens with mutually cyclic phi nodes like:
+///   z = some value; x = phi (y, z); y = phi (x, z)
+static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal, 
+                           SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) {
+  // See if we already saw this PHI node.
+  if (!ValueEqualPHIs.insert(PN))
+    return true;
+  
+  // Don't scan crazily complex things.
+  if (ValueEqualPHIs.size() == 16)
+    return false;
+ 
+  // Scan the operands to see if they are either phi nodes or are equal to
+  // the value.
+  for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+    Value *Op = PN->getIncomingValue(i);
+    if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
+      if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
+        return false;
+    } else if (Op != NonPhiInVal)
+      return false;
+  }
+  
+  return true;
+}
+
+
+// PHINode simplification
+//
+Instruction *InstCombiner::visitPHINode(PHINode &PN) {
+  // If LCSSA is around, don't mess with Phi nodes
+  if (MustPreserveLCSSA) return 0;
+  
+  if (Value *V = PN.hasConstantValue())
+    return ReplaceInstUsesWith(PN, V);
+
+  // If all PHI operands are the same operation, pull them through the PHI,
+  // reducing code size.
+  if (isa<Instruction>(PN.getIncomingValue(0)) &&
+      isa<Instruction>(PN.getIncomingValue(1)) &&
+      cast<Instruction>(PN.getIncomingValue(0))->getOpcode() ==
+      cast<Instruction>(PN.getIncomingValue(1))->getOpcode() &&
+      // FIXME: The hasOneUse check will fail for PHIs that use the value more
+      // than themselves more than once.
+      PN.getIncomingValue(0)->hasOneUse())
+    if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
+      return Result;
+
+  // If this is a trivial cycle in the PHI node graph, remove it.  Basically, if
+  // this PHI only has a single use (a PHI), and if that PHI only has one use (a
+  // PHI)... break the cycle.
+  if (PN.hasOneUse()) {
+    Instruction *PHIUser = cast<Instruction>(PN.use_back());
+    if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
+      SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
+      PotentiallyDeadPHIs.insert(&PN);
+      if (DeadPHICycle(PU, PotentiallyDeadPHIs))
+        return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
+    }
+   
+    // If this phi has a single use, and if that use just computes a value for
+    // the next iteration of a loop, delete the phi.  This occurs with unused
+    // induction variables, e.g. "for (int j = 0; ; ++j);".  Detecting this
+    // common case here is good because the only other things that catch this
+    // are induction variable analysis (sometimes) and ADCE, which is only run
+    // late.
+    if (PHIUser->hasOneUse() &&
+        (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
+        PHIUser->use_back() == &PN) {
+      return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
+    }
+  }
+
+  // We sometimes end up with phi cycles that non-obviously end up being the
+  // same value, for example:
+  //   z = some value; x = phi (y, z); y = phi (x, z)
+  // where the phi nodes don't necessarily need to be in the same block.  Do a
+  // quick check to see if the PHI node only contains a single non-phi value, if
+  // so, scan to see if the phi cycle is actually equal to that value.
+  {
+    unsigned InValNo = 0, NumOperandVals = PN.getNumIncomingValues();
+    // Scan for the first non-phi operand.
+    while (InValNo != NumOperandVals && 
+           isa<PHINode>(PN.getIncomingValue(InValNo)))
+      ++InValNo;
+
+    if (InValNo != NumOperandVals) {
+      Value *NonPhiInVal = PN.getOperand(InValNo);
+      
+      // Scan the rest of the operands to see if there are any conflicts, if so
+      // there is no need to recursively scan other phis.
+      for (++InValNo; InValNo != NumOperandVals; ++InValNo) {
+        Value *OpVal = PN.getIncomingValue(InValNo);
+        if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
+          break;
+      }
+      
+      // If we scanned over all operands, then we have one unique value plus
+      // phi values.  Scan PHI nodes to see if they all merge in each other or
+      // the value.
+      if (InValNo == NumOperandVals) {
+        SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
+        if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
+          return ReplaceInstUsesWith(PN, NonPhiInVal);
+      }
+    }
+  }
+  return 0;
+}
+
+static Value *InsertCastToIntPtrTy(Value *V, const Type *DTy,
+                                   Instruction *InsertPoint,
+                                   InstCombiner *IC) {
+  unsigned PtrSize = DTy->getPrimitiveSizeInBits();
+  unsigned VTySize = V->getType()->getPrimitiveSizeInBits();
+  // We must cast correctly to the pointer type. Ensure that we
+  // sign extend the integer value if it is smaller as this is
+  // used for address computation.
+  Instruction::CastOps opcode = 
+     (VTySize < PtrSize ? Instruction::SExt :
+      (VTySize == PtrSize ? Instruction::BitCast : Instruction::Trunc));
+  return IC->InsertCastBefore(opcode, V, DTy, *InsertPoint);
+}
+
+
+Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
+  Value *PtrOp = GEP.getOperand(0);
+  // Is it 'getelementptr %P, i32 0'  or 'getelementptr %P'
+  // If so, eliminate the noop.
+  if (GEP.getNumOperands() == 1)
+    return ReplaceInstUsesWith(GEP, PtrOp);
+
+  if (isa<UndefValue>(GEP.getOperand(0)))
+    return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
+
+  bool HasZeroPointerIndex = false;
+  if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
+    HasZeroPointerIndex = C->isNullValue();
+
+  if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
+    return ReplaceInstUsesWith(GEP, PtrOp);
+
+  // Eliminate unneeded casts for indices.
+  bool MadeChange = false;
+  
+  gep_type_iterator GTI = gep_type_begin(GEP);
+  for (User::op_iterator i = GEP.op_begin() + 1, e = GEP.op_end();
+       i != e; ++i, ++GTI) {
+    if (isa<SequentialType>(*GTI)) {
+      if (CastInst *CI = dyn_cast<CastInst>(*i)) {
+        if (CI->getOpcode() == Instruction::ZExt ||
+            CI->getOpcode() == Instruction::SExt) {
+          const Type *SrcTy = CI->getOperand(0)->getType();
+          // We can eliminate a cast from i32 to i64 iff the target 
+          // is a 32-bit pointer target.
+          if (SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
+            MadeChange = true;
+            *i = CI->getOperand(0);
+          }
+        }
+      }
+      // If we are using a wider index than needed for this platform, shrink it
+      // to what we need.  If narrower, sign-extend it to what we need.
+      // If the incoming value needs a cast instruction,
+      // insert it.  This explicit cast can make subsequent optimizations more
+      // obvious.
+      Value *Op = *i;
+      if (TD->getTypeSizeInBits(Op->getType()) > TD->getPointerSizeInBits()) {
+        if (Constant *C = dyn_cast<Constant>(Op)) {
+          *i = ConstantExpr::getTrunc(C, TD->getIntPtrType());
+          MadeChange = true;
+        } else {
+          Op = InsertCastBefore(Instruction::Trunc, Op, TD->getIntPtrType(),
+                                GEP);
+          *i = Op;
+          MadeChange = true;
+        }
+      } else if (TD->getTypeSizeInBits(Op->getType()) < TD->getPointerSizeInBits()) {
+        if (Constant *C = dyn_cast<Constant>(Op)) {
+          *i = ConstantExpr::getSExt(C, TD->getIntPtrType());
+          MadeChange = true;
+        } else {
+          Op = InsertCastBefore(Instruction::SExt, Op, TD->getIntPtrType(),
+                                GEP);
+          *i = Op;
+          MadeChange = true;
+        }
+      }
+    }
+  }
+  if (MadeChange) return &GEP;
+
+  // Combine Indices - If the source pointer to this getelementptr instruction
+  // is a getelementptr instruction, combine the indices of the two
+  // getelementptr instructions into a single instruction.
+  //
+  SmallVector<Value*, 8> SrcGEPOperands;
+  if (User *Src = dyn_castGetElementPtr(PtrOp))
+    SrcGEPOperands.append(Src->op_begin(), Src->op_end());
+
+  if (!SrcGEPOperands.empty()) {
+    // Note that if our source is a gep chain itself that we wait for that
+    // chain to be resolved before we perform this transformation.  This
+    // avoids us creating a TON of code in some cases.
+    //
+    if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
+        cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
+      return 0;   // Wait until our source is folded to completion.
+
+    SmallVector<Value*, 8> Indices;
+
+    // Find out whether the last index in the source GEP is a sequential idx.
+    bool EndsWithSequential = false;
+    for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
+           E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
+      EndsWithSequential = !isa<StructType>(*I);
+
+    // Can we combine the two pointer arithmetics offsets?
+    if (EndsWithSequential) {
+      // Replace: gep (gep %P, long B), long A, ...
+      // With:    T = long A+B; gep %P, T, ...
+      //
+      Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
+      if (SO1 == Constant::getNullValue(SO1->getType())) {
+        Sum = GO1;
+      } else if (GO1 == Constant::getNullValue(GO1->getType())) {
+        Sum = SO1;
+      } else {
+        // If they aren't the same type, convert both to an integer of the
+        // target's pointer size.
+        if (SO1->getType() != GO1->getType()) {
+          if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
+            SO1 = ConstantExpr::getIntegerCast(SO1C, GO1->getType(), true);
+          } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
+            GO1 = ConstantExpr::getIntegerCast(GO1C, SO1->getType(), true);
+          } else {
+            unsigned PS = TD->getPointerSizeInBits();
+            if (TD->getTypeSizeInBits(SO1->getType()) == PS) {
+              // Convert GO1 to SO1's type.
+              GO1 = InsertCastToIntPtrTy(GO1, SO1->getType(), &GEP, this);
+
+            } else if (TD->getTypeSizeInBits(GO1->getType()) == PS) {
+              // Convert SO1 to GO1's type.
+              SO1 = InsertCastToIntPtrTy(SO1, GO1->getType(), &GEP, this);
+            } else {
+              const Type *PT = TD->getIntPtrType();
+              SO1 = InsertCastToIntPtrTy(SO1, PT, &GEP, this);
+              GO1 = InsertCastToIntPtrTy(GO1, PT, &GEP, this);
+            }
+          }
+        }
+        if (isa<Constant>(SO1) && isa<Constant>(GO1))
+          Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
+        else {
+          Sum = BinaryOperator::CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
+          InsertNewInstBefore(cast<Instruction>(Sum), GEP);
+        }
+      }
+
+      // Recycle the GEP we already have if possible.
+      if (SrcGEPOperands.size() == 2) {
+        GEP.setOperand(0, SrcGEPOperands[0]);
+        GEP.setOperand(1, Sum);
+        return &GEP;
+      } else {
+        Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
+                       SrcGEPOperands.end()-1);
+        Indices.push_back(Sum);
+        Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
+      }
+    } else if (isa<Constant>(*GEP.idx_begin()) &&
+               cast<Constant>(*GEP.idx_begin())->isNullValue() &&
+               SrcGEPOperands.size() != 1) {
+      // Otherwise we can do the fold if the first index of the GEP is a zero
+      Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
+                     SrcGEPOperands.end());
+      Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
+    }
+
+    if (!Indices.empty())
+      return GetElementPtrInst::Create(SrcGEPOperands[0], Indices.begin(),
+                                       Indices.end(), GEP.getName());
+
+  } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
+    // GEP of global variable.  If all of the indices for this GEP are
+    // constants, we can promote this to a constexpr instead of an instruction.
+
+    // Scan for nonconstants...
+    SmallVector<Constant*, 8> Indices;
+    User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
+    for (; I != E && isa<Constant>(*I); ++I)
+      Indices.push_back(cast<Constant>(*I));
+
+    if (I == E) {  // If they are all constants...
+      Constant *CE = ConstantExpr::getGetElementPtr(GV,
+                                                    &Indices[0],Indices.size());
+
+      // Replace all uses of the GEP with the new constexpr...
+      return ReplaceInstUsesWith(GEP, CE);
+    }
+  } else if (Value *X = getBitCastOperand(PtrOp)) {  // Is the operand a cast?
+    if (!isa<PointerType>(X->getType())) {
+      // Not interesting.  Source pointer must be a cast from pointer.
+    } else if (HasZeroPointerIndex) {
+      // transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
+      // into     : GEP [10 x i8]* X, i32 0, ...
+      //
+      // Likewise, transform: GEP (bitcast i8* X to [0 x i8]*), i32 0, ...
+      //           into     : GEP i8* X, ...
+      // 
+      // This occurs when the program declares an array extern like "int X[];"
+      const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
+      const PointerType *XTy = cast<PointerType>(X->getType());
+      if (const ArrayType *CATy =
+          dyn_cast<ArrayType>(CPTy->getElementType())) {
+        // GEP (bitcast i8* X to [0 x i8]*), i32 0, ... ?
+        if (CATy->getElementType() == XTy->getElementType()) {
+          // -> GEP i8* X, ...
+          SmallVector<Value*, 8> Indices(GEP.idx_begin()+1, GEP.idx_end());
+          return GetElementPtrInst::Create(X, Indices.begin(), Indices.end(),
+                                           GEP.getName());
+        } else if (const ArrayType *XATy =
+                 dyn_cast<ArrayType>(XTy->getElementType())) {
+          // GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... ?
+          if (CATy->getElementType() == XATy->getElementType()) {
+            // -> GEP [10 x i8]* X, i32 0, ...
+            // At this point, we know that the cast source type is a pointer
+            // to an array of the same type as the destination pointer
+            // array.  Because the array type is never stepped over (there
+            // is a leading zero) we can fold the cast into this GEP.
+            GEP.setOperand(0, X);
+            return &GEP;
+          }
+        }
+      }
+    } else if (GEP.getNumOperands() == 2) {
+      // Transform things like:
+      // %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
+      // into:  %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
+      const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
+      const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
+      if (isa<ArrayType>(SrcElTy) &&
+          TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
+          TD->getTypeAllocSize(ResElTy)) {
+        Value *Idx[2];
+        Idx[0] = Constant::getNullValue(Type::Int32Ty);
+        Idx[1] = GEP.getOperand(1);
+        Value *V = InsertNewInstBefore(
+               GetElementPtrInst::Create(X, Idx, Idx + 2, GEP.getName()), GEP);
+        // V and GEP are both pointer types --> BitCast
+        return new BitCastInst(V, GEP.getType());
+      }
+      
+      // Transform things like:
+      // getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
+      //   (where tmp = 8*tmp2) into:
+      // getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
+      
+      if (isa<ArrayType>(SrcElTy) && ResElTy == Type::Int8Ty) {
+        uint64_t ArrayEltSize =
+            TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType());
+        
+        // Check to see if "tmp" is a scale by a multiple of ArrayEltSize.  We
+        // allow either a mul, shift, or constant here.
+        Value *NewIdx = 0;
+        ConstantInt *Scale = 0;
+        if (ArrayEltSize == 1) {
+          NewIdx = GEP.getOperand(1);
+          Scale = ConstantInt::get(NewIdx->getType(), 1);
+        } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
+          NewIdx = ConstantInt::get(CI->getType(), 1);
+          Scale = CI;
+        } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
+          if (Inst->getOpcode() == Instruction::Shl &&
+              isa<ConstantInt>(Inst->getOperand(1))) {
+            ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1));
+            uint32_t ShAmtVal = ShAmt->getLimitedValue(64);
+            Scale = ConstantInt::get(Inst->getType(), 1ULL << ShAmtVal);
+            NewIdx = Inst->getOperand(0);
+          } else if (Inst->getOpcode() == Instruction::Mul &&
+                     isa<ConstantInt>(Inst->getOperand(1))) {
+            Scale = cast<ConstantInt>(Inst->getOperand(1));
+            NewIdx = Inst->getOperand(0);
+          }
+        }
+        
+        // If the index will be to exactly the right offset with the scale taken
+        // out, perform the transformation. Note, we don't know whether Scale is
+        // signed or not. We'll use unsigned version of division/modulo
+        // operation after making sure Scale doesn't have the sign bit set.
+        if (ArrayEltSize && Scale && Scale->getSExtValue() >= 0LL &&
+            Scale->getZExtValue() % ArrayEltSize == 0) {
+          Scale = ConstantInt::get(Scale->getType(),
+                                   Scale->getZExtValue() / ArrayEltSize);
+          if (Scale->getZExtValue() != 1) {
+            Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
+                                                       false /*ZExt*/);
+            Instruction *Sc = BinaryOperator::CreateMul(NewIdx, C, "idxscale");
+            NewIdx = InsertNewInstBefore(Sc, GEP);
+          }
+
+          // Insert the new GEP instruction.
+          Value *Idx[2];
+          Idx[0] = Constant::getNullValue(Type::Int32Ty);
+          Idx[1] = NewIdx;
+          Instruction *NewGEP =
+            GetElementPtrInst::Create(X, Idx, Idx + 2, GEP.getName());
+          NewGEP = InsertNewInstBefore(NewGEP, GEP);
+          // The NewGEP must be pointer typed, so must the old one -> BitCast
+          return new BitCastInst(NewGEP, GEP.getType());
+        }
+      }
+    }
+  }
+  
+  /// See if we can simplify:
+  ///   X = bitcast A to B*
+  ///   Y = gep X, <...constant indices...>
+  /// into a gep of the original struct.  This is important for SROA and alias
+  /// analysis of unions.  If "A" is also a bitcast, wait for A/X to be merged.
+  if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
+    if (!isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) {
+      // Determine how much the GEP moves the pointer.  We are guaranteed to get
+      // a constant back from EmitGEPOffset.
+      ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP, GEP, *this));
+      int64_t Offset = OffsetV->getSExtValue();
+      
+      // If this GEP instruction doesn't move the pointer, just replace the GEP
+      // with a bitcast of the real input to the dest type.
+      if (Offset == 0) {
+        // If the bitcast is of an allocation, and the allocation will be
+        // converted to match the type of the cast, don't touch this.
+        if (isa<AllocationInst>(BCI->getOperand(0))) {
+          // See if the bitcast simplifies, if so, don't nuke this GEP yet.
+          if (Instruction *I = visitBitCast(*BCI)) {
+            if (I != BCI) {
+              I->takeName(BCI);
+              BCI->getParent()->getInstList().insert(BCI, I);
+              ReplaceInstUsesWith(*BCI, I);
+            }
+            return &GEP;
+          }
+        }
+        return new BitCastInst(BCI->getOperand(0), GEP.getType());
+      }
+      
+      // Otherwise, if the offset is non-zero, we need to find out if there is a
+      // field at Offset in 'A's type.  If so, we can pull the cast through the
+      // GEP.
+      SmallVector<Value*, 8> NewIndices;
+      const Type *InTy =
+        cast<PointerType>(BCI->getOperand(0)->getType())->getElementType();
+      if (FindElementAtOffset(InTy, Offset, NewIndices, TD)) {
+        Instruction *NGEP =
+           GetElementPtrInst::Create(BCI->getOperand(0), NewIndices.begin(),
+                                     NewIndices.end());
+        if (NGEP->getType() == GEP.getType()) return NGEP;
+        InsertNewInstBefore(NGEP, GEP);
+        NGEP->takeName(&GEP);
+        return new BitCastInst(NGEP, GEP.getType());
+      }
+    }
+  }    
+    
+  return 0;
+}
+
+Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
+  // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
+  if (AI.isArrayAllocation()) {  // Check C != 1
+    if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
+      const Type *NewTy = 
+        ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
+      AllocationInst *New = 0;
+
+      // Create and insert the replacement instruction...
+      if (isa<MallocInst>(AI))
+        New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
+      else {
+        assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
+        New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
+      }
+
+      InsertNewInstBefore(New, AI);
+
+      // Scan to the end of the allocation instructions, to skip over a block of
+      // allocas if possible...also skip interleaved debug info
+      //
+      BasicBlock::iterator It = New;
+      while (isa<AllocationInst>(*It) || isa<DbgInfoIntrinsic>(*It)) ++It;
+
+      // Now that I is pointing to the first non-allocation-inst in the block,
+      // insert our getelementptr instruction...
+      //
+      Value *NullIdx = Constant::getNullValue(Type::Int32Ty);
+      Value *Idx[2];
+      Idx[0] = NullIdx;
+      Idx[1] = NullIdx;
+      Value *V = GetElementPtrInst::Create(New, Idx, Idx + 2,
+                                           New->getName()+".sub", It);
+
+      // Now make everything use the getelementptr instead of the original
+      // allocation.
+      return ReplaceInstUsesWith(AI, V);
+    } else if (isa<UndefValue>(AI.getArraySize())) {
+      return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
+    }
+  }
+
+  if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized()) {
+    // If alloca'ing a zero byte object, replace the alloca with a null pointer.
+    // Note that we only do this for alloca's, because malloc should allocate
+    // and return a unique pointer, even for a zero byte allocation.
+    if (TD->getTypeAllocSize(AI.getAllocatedType()) == 0)
+      return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
+
+    // If the alignment is 0 (unspecified), assign it the preferred alignment.
+    if (AI.getAlignment() == 0)
+      AI.setAlignment(TD->getPrefTypeAlignment(AI.getAllocatedType()));
+  }
+
+  return 0;
+}
+
+Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
+  Value *Op = FI.getOperand(0);
+
+  // free undef -> unreachable.
+  if (isa<UndefValue>(Op)) {
+    // Insert a new store to null because we cannot modify the CFG here.
+    new StoreInst(ConstantInt::getTrue(),
+                  UndefValue::get(PointerType::getUnqual(Type::Int1Ty)), &FI);
+    return EraseInstFromFunction(FI);
+  }
+  
+  // If we have 'free null' delete the instruction.  This can happen in stl code
+  // when lots of inlining happens.
+  if (isa<ConstantPointerNull>(Op))
+    return EraseInstFromFunction(FI);
+  
+  // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
+  if (BitCastInst *CI = dyn_cast<BitCastInst>(Op)) {
+    FI.setOperand(0, CI->getOperand(0));
+    return &FI;
+  }
+  
+  // Change free (gep X, 0,0,0,0) into free(X)
+  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
+    if (GEPI->hasAllZeroIndices()) {
+      AddToWorkList(GEPI);
+      FI.setOperand(0, GEPI->getOperand(0));
+      return &FI;
+    }
+  }
+  
+  // Change free(malloc) into nothing, if the malloc has a single use.
+  if (MallocInst *MI = dyn_cast<MallocInst>(Op))
+    if (MI->hasOneUse()) {
+      EraseInstFromFunction(FI);
+      return EraseInstFromFunction(*MI);
+    }
+
+  return 0;
+}
+
+
+/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
+static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
+                                        const TargetData *TD) {
+  User *CI = cast<User>(LI.getOperand(0));
+  Value *CastOp = CI->getOperand(0);
+
+  if (TD) {
+    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(CI)) {
+      // Instead of loading constant c string, use corresponding integer value
+      // directly if string length is small enough.
+      std::string Str;
+      if (GetConstantStringInfo(CE->getOperand(0), Str) && !Str.empty()) {
+        unsigned len = Str.length();
+        const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
+        unsigned numBits = Ty->getPrimitiveSizeInBits();
+        // Replace LI with immediate integer store.
+        if ((numBits >> 3) == len + 1) {
+          APInt StrVal(numBits, 0);
+          APInt SingleChar(numBits, 0);
+          if (TD->isLittleEndian()) {
+            for (signed i = len-1; i >= 0; i--) {
+              SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
+              StrVal = (StrVal << 8) | SingleChar;
+            }
+          } else {
+            for (unsigned i = 0; i < len; i++) {
+              SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
+              StrVal = (StrVal << 8) | SingleChar;
+            }
+            // Append NULL at the end.
+            SingleChar = 0;
+            StrVal = (StrVal << 8) | SingleChar;
+          }
+          Value *NL = ConstantInt::get(StrVal);
+          return IC.ReplaceInstUsesWith(LI, NL);
+        }
+      }
+    }
+  }
+
+  const PointerType *DestTy = cast<PointerType>(CI->getType());
+  const Type *DestPTy = DestTy->getElementType();
+  if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
+
+    // If the address spaces don't match, don't eliminate the cast.
+    if (DestTy->getAddressSpace() != SrcTy->getAddressSpace())
+      return 0;
+
+    const Type *SrcPTy = SrcTy->getElementType();
+
+    if (DestPTy->isInteger() || isa<PointerType>(DestPTy) || 
+         isa<VectorType>(DestPTy)) {
+      // If the source is an array, the code below will not succeed.  Check to
+      // see if a trivial 'gep P, 0, 0' will help matters.  Only do this for
+      // constants.
+      if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
+        if (Constant *CSrc = dyn_cast<Constant>(CastOp))
+          if (ASrcTy->getNumElements() != 0) {
+            Value *Idxs[2];
+            Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
+            CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
+            SrcTy = cast<PointerType>(CastOp->getType());
+            SrcPTy = SrcTy->getElementType();
+          }
+
+      if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy) || 
+            isa<VectorType>(SrcPTy)) &&
+          // Do not allow turning this into a load of an integer, which is then
+          // casted to a pointer, this pessimizes pointer analysis a lot.
+          (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
+          IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
+               IC.getTargetData().getTypeSizeInBits(DestPTy)) {
+
+        // Okay, we are casting from one integer or pointer type to another of
+        // the same size.  Instead of casting the pointer before the load, cast
+        // the result of the loaded value.
+        Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
+                                                             CI->getName(),
+                                                         LI.isVolatile()),LI);
+        // Now cast the result of the load.
+        return new BitCastInst(NewLoad, LI.getType());
+      }
+    }
+  }
+  return 0;
+}
+
+/// isSafeToLoadUnconditionally - Return true if we know that executing a load
+/// from this value cannot trap.  If it is not obviously safe to load from the
+/// specified pointer, we do a quick local scan of the basic block containing
+/// ScanFrom, to determine if the address is already accessed.
+static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
+  // If it is an alloca it is always safe to load from.
+  if (isa<AllocaInst>(V)) return true;
+
+  // If it is a global variable it is mostly safe to load from.
+  if (const GlobalValue *GV = dyn_cast<GlobalVariable>(V))
+    // Don't try to evaluate aliases.  External weak GV can be null.
+    return !isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage();
+
+  // Otherwise, be a little bit agressive by scanning the local block where we
+  // want to check to see if the pointer is already being loaded or stored
+  // from/to.  If so, the previous load or store would have already trapped,
+  // so there is no harm doing an extra load (also, CSE will later eliminate
+  // the load entirely).
+  BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
+
+  while (BBI != E) {
+    --BBI;
+
+    // If we see a free or a call (which might do a free) the pointer could be
+    // marked invalid.
+    if (isa<FreeInst>(BBI) || 
+        (isa<CallInst>(BBI) && !isa<DbgInfoIntrinsic>(BBI)))
+      return false;
+    
+    if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
+      if (LI->getOperand(0) == V) return true;
+    } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
+      if (SI->getOperand(1) == V) return true;
+    }
+
+  }
+  return false;
+}
+
+Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
+  Value *Op = LI.getOperand(0);
+
+  // Attempt to improve the alignment.
+  unsigned KnownAlign =
+    GetOrEnforceKnownAlignment(Op, TD->getPrefTypeAlignment(LI.getType()));
+  if (KnownAlign >
+      (LI.getAlignment() == 0 ? TD->getABITypeAlignment(LI.getType()) :
+                                LI.getAlignment()))
+    LI.setAlignment(KnownAlign);
+
+  // load (cast X) --> cast (load X) iff safe
+  if (isa<CastInst>(Op))
+    if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
+      return Res;
+
+  // None of the following transforms are legal for volatile loads.
+  if (LI.isVolatile()) return 0;
+  
+  // Do really simple store-to-load forwarding and load CSE, to catch cases
+  // where there are several consequtive memory accesses to the same location,
+  // separated by a few arithmetic operations.
+  BasicBlock::iterator BBI = &LI;
+  if (Value *AvailableVal = FindAvailableLoadedValue(Op, LI.getParent(), BBI,6))
+    return ReplaceInstUsesWith(LI, AvailableVal);
+
+  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
+    const Value *GEPI0 = GEPI->getOperand(0);
+    // TODO: Consider a target hook for valid address spaces for this xform.
+    if (isa<ConstantPointerNull>(GEPI0) &&
+        cast<PointerType>(GEPI0->getType())->getAddressSpace() == 0) {
+      // Insert a new store to null instruction before the load to indicate
+      // that this code is not reachable.  We do this instead of inserting
+      // an unreachable instruction directly because we cannot modify the
+      // CFG.
+      new StoreInst(UndefValue::get(LI.getType()),
+                    Constant::getNullValue(Op->getType()), &LI);
+      return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+    }
+  } 
+
+  if (Constant *C = dyn_cast<Constant>(Op)) {
+    // load null/undef -> undef
+    // TODO: Consider a target hook for valid address spaces for this xform.
+    if (isa<UndefValue>(C) || (C->isNullValue() && 
+        cast<PointerType>(Op->getType())->getAddressSpace() == 0)) {
+      // Insert a new store to null instruction before the load to indicate that
+      // this code is not reachable.  We do this instead of inserting an
+      // unreachable instruction directly because we cannot modify the CFG.
+      new StoreInst(UndefValue::get(LI.getType()),
+                    Constant::getNullValue(Op->getType()), &LI);
+      return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+    }
+
+    // Instcombine load (constant global) into the value loaded.
+    if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
+      if (GV->isConstant() && GV->hasDefinitiveInitializer())
+        return ReplaceInstUsesWith(LI, GV->getInitializer());
+
+    // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
+    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op)) {
+      if (CE->getOpcode() == Instruction::GetElementPtr) {
+        if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
+          if (GV->isConstant() && GV->hasDefinitiveInitializer())
+            if (Constant *V = 
+               ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
+              return ReplaceInstUsesWith(LI, V);
+        if (CE->getOperand(0)->isNullValue()) {
+          // Insert a new store to null instruction before the load to indicate
+          // that this code is not reachable.  We do this instead of inserting
+          // an unreachable instruction directly because we cannot modify the
+          // CFG.
+          new StoreInst(UndefValue::get(LI.getType()),
+                        Constant::getNullValue(Op->getType()), &LI);
+          return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+        }
+
+      } else if (CE->isCast()) {
+        if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
+          return Res;
+      }
+    }
+  }
+    
+  // If this load comes from anywhere in a constant global, and if the global
+  // is all undef or zero, we know what it loads.
+  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op->getUnderlyingObject())){
+    if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
+      if (GV->getInitializer()->isNullValue())
+        return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
+      else if (isa<UndefValue>(GV->getInitializer()))
+        return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+    }
+  }
+
+  if (Op->hasOneUse()) {
+    // Change select and PHI nodes to select values instead of addresses: this
+    // helps alias analysis out a lot, allows many others simplifications, and
+    // exposes redundancy in the code.
+    //
+    // Note that we cannot do the transformation unless we know that the
+    // introduced loads cannot trap!  Something like this is valid as long as
+    // the condition is always false: load (select bool %C, int* null, int* %G),
+    // but it would not be valid if we transformed it to load from null
+    // unconditionally.
+    //
+    if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
+      // load (select (Cond, &V1, &V2))  --> select(Cond, load &V1, load &V2).
+      if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
+          isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
+        Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
+                                     SI->getOperand(1)->getName()+".val"), LI);
+        Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
+                                     SI->getOperand(2)->getName()+".val"), LI);
+        return SelectInst::Create(SI->getCondition(), V1, V2);
+      }
+
+      // load (select (cond, null, P)) -> load P
+      if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
+        if (C->isNullValue()) {
+          LI.setOperand(0, SI->getOperand(2));
+          return &LI;
+        }
+
+      // load (select (cond, P, null)) -> load P
+      if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
+        if (C->isNullValue()) {
+          LI.setOperand(0, SI->getOperand(1));
+          return &LI;
+        }
+    }
+  }
+  return 0;
+}
+
+/// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
+/// when possible.  This makes it generally easy to do alias analysis and/or
+/// SROA/mem2reg of the memory object.
+static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
+  User *CI = cast<User>(SI.getOperand(1));
+  Value *CastOp = CI->getOperand(0);
+
+  const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
+  const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType());
+  if (SrcTy == 0) return 0;
+  
+  const Type *SrcPTy = SrcTy->getElementType();
+
+  if (!DestPTy->isInteger() && !isa<PointerType>(DestPTy))
+    return 0;
+  
+  /// NewGEPIndices - If SrcPTy is an aggregate type, we can emit a "noop gep"
+  /// to its first element.  This allows us to handle things like:
+  ///   store i32 xxx, (bitcast {foo*, float}* %P to i32*)
+  /// on 32-bit hosts.
+  SmallVector<Value*, 4> NewGEPIndices;
+  
+  // If the source is an array, the code below will not succeed.  Check to
+  // see if a trivial 'gep P, 0, 0' will help matters.  Only do this for
+  // constants.
+  if (isa<ArrayType>(SrcPTy) || isa<StructType>(SrcPTy)) {
+    // Index through pointer.
+    Constant *Zero = Constant::getNullValue(Type::Int32Ty);
+    NewGEPIndices.push_back(Zero);
+    
+    while (1) {
+      if (const StructType *STy = dyn_cast<StructType>(SrcPTy)) {
+        if (!STy->getNumElements()) /* Struct can be empty {} */
+          break;
+        NewGEPIndices.push_back(Zero);
+        SrcPTy = STy->getElementType(0);
+      } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcPTy)) {
+        NewGEPIndices.push_back(Zero);
+        SrcPTy = ATy->getElementType();
+      } else {
+        break;
+      }
+    }
+    
+    SrcTy = PointerType::get(SrcPTy, SrcTy->getAddressSpace());
+  }
+
+  if (!SrcPTy->isInteger() && !isa<PointerType>(SrcPTy))
+    return 0;
+  
+  // If the pointers point into different address spaces or if they point to
+  // values with different sizes, we can't do the transformation.
+  if (SrcTy->getAddressSpace() != 
+        cast<PointerType>(CI->getType())->getAddressSpace() ||
+      IC.getTargetData().getTypeSizeInBits(SrcPTy) !=
+      IC.getTargetData().getTypeSizeInBits(DestPTy))
+    return 0;
+
+  // Okay, we are casting from one integer or pointer type to another of
+  // the same size.  Instead of casting the pointer before 
+  // the store, cast the value to be stored.
+  Value *NewCast;
+  Value *SIOp0 = SI.getOperand(0);
+  Instruction::CastOps opcode = Instruction::BitCast;
+  const Type* CastSrcTy = SIOp0->getType();
+  const Type* CastDstTy = SrcPTy;
+  if (isa<PointerType>(CastDstTy)) {
+    if (CastSrcTy->isInteger())
+      opcode = Instruction::IntToPtr;
+  } else if (isa<IntegerType>(CastDstTy)) {
+    if (isa<PointerType>(SIOp0->getType()))
+      opcode = Instruction::PtrToInt;
+  }
+  
+  // SIOp0 is a pointer to aggregate and this is a store to the first field,
+  // emit a GEP to index into its first field.
+  if (!NewGEPIndices.empty()) {
+    if (Constant *C = dyn_cast<Constant>(CastOp))
+      CastOp = ConstantExpr::getGetElementPtr(C, &NewGEPIndices[0], 
+                                              NewGEPIndices.size());
+    else
+      CastOp = IC.InsertNewInstBefore(
+              GetElementPtrInst::Create(CastOp, NewGEPIndices.begin(),
+                                        NewGEPIndices.end()), SI);
+  }
+  
+  if (Constant *C = dyn_cast<Constant>(SIOp0))
+    NewCast = ConstantExpr::getCast(opcode, C, CastDstTy);
+  else
+    NewCast = IC.InsertNewInstBefore(
+      CastInst::Create(opcode, SIOp0, CastDstTy, SIOp0->getName()+".c"), 
+      SI);
+  return new StoreInst(NewCast, CastOp);
+}
+
+/// equivalentAddressValues - Test if A and B will obviously have the same
+/// value. This includes recognizing that %t0 and %t1 will have the same
+/// value in code like this:
+///   %t0 = getelementptr \@a, 0, 3
+///   store i32 0, i32* %t0
+///   %t1 = getelementptr \@a, 0, 3
+///   %t2 = load i32* %t1
+///
+static bool equivalentAddressValues(Value *A, Value *B) {
+  // Test if the values are trivially equivalent.
+  if (A == B) return true;
+  
+  // Test if the values come form identical arithmetic instructions.
+  if (isa<BinaryOperator>(A) ||
+      isa<CastInst>(A) ||
+      isa<PHINode>(A) ||
+      isa<GetElementPtrInst>(A))
+    if (Instruction *BI = dyn_cast<Instruction>(B))
+      if (cast<Instruction>(A)->isIdenticalTo(BI))
+        return true;
+  
+  // Otherwise they may not be equivalent.
+  return false;
+}
+
+// If this instruction has two uses, one of which is a llvm.dbg.declare,
+// return the llvm.dbg.declare.
+DbgDeclareInst *InstCombiner::hasOneUsePlusDeclare(Value *V) {
+  if (!V->hasNUses(2))
+    return 0;
+  for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
+       UI != E; ++UI) {
+    if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI))
+      return DI;
+    if (isa<BitCastInst>(UI) && UI->hasOneUse()) {
+      if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI->use_begin()))
+        return DI;
+      }
+  }
+  return 0;
+}
+
+Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
+  Value *Val = SI.getOperand(0);
+  Value *Ptr = SI.getOperand(1);
+
+  if (isa<UndefValue>(Ptr)) {     // store X, undef -> noop (even if volatile)
+    EraseInstFromFunction(SI);
+    ++NumCombined;
+    return 0;
+  }
+  
+  // If the RHS is an alloca with a single use, zapify the store, making the
+  // alloca dead.
+  // If the RHS is an alloca with a two uses, the other one being a 
+  // llvm.dbg.declare, zapify the store and the declare, making the
+  // alloca dead.  We must do this to prevent declare's from affecting
+  // codegen.
+  if (!SI.isVolatile()) {
+    if (Ptr->hasOneUse()) {
+      if (isa<AllocaInst>(Ptr)) {
+        EraseInstFromFunction(SI);
+        ++NumCombined;
+        return 0;
+      }
+      if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
+        if (isa<AllocaInst>(GEP->getOperand(0))) {
+          if (GEP->getOperand(0)->hasOneUse()) {
+            EraseInstFromFunction(SI);
+            ++NumCombined;
+            return 0;
+          }
+          if (DbgDeclareInst *DI = hasOneUsePlusDeclare(GEP->getOperand(0))) {
+            EraseInstFromFunction(*DI);
+            EraseInstFromFunction(SI);
+            ++NumCombined;
+            return 0;
+          }
+        }
+      }
+    }
+    if (DbgDeclareInst *DI = hasOneUsePlusDeclare(Ptr)) {
+      EraseInstFromFunction(*DI);
+      EraseInstFromFunction(SI);
+      ++NumCombined;
+      return 0;
+    }
+  }
+
+  // Attempt to improve the alignment.
+  unsigned KnownAlign =
+    GetOrEnforceKnownAlignment(Ptr, TD->getPrefTypeAlignment(Val->getType()));
+  if (KnownAlign >
+      (SI.getAlignment() == 0 ? TD->getABITypeAlignment(Val->getType()) :
+                                SI.getAlignment()))
+    SI.setAlignment(KnownAlign);
+
+  // Do really simple DSE, to catch cases where there are several consecutive
+  // stores to the same location, separated by a few arithmetic operations. This
+  // situation often occurs with bitfield accesses.
+  BasicBlock::iterator BBI = &SI;
+  for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
+       --ScanInsts) {
+    --BBI;
+    // Don't count debug info directives, lest they affect codegen,
+    // and we skip pointer-to-pointer bitcasts, which are NOPs.
+    // It is necessary for correctness to skip those that feed into a
+    // llvm.dbg.declare, as these are not present when debugging is off.
+    if (isa<DbgInfoIntrinsic>(BBI) ||
+        (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
+      ScanInsts++;
+      continue;
+    }    
+    
+    if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
+      // Prev store isn't volatile, and stores to the same location?
+      if (!PrevSI->isVolatile() &&equivalentAddressValues(PrevSI->getOperand(1),
+                                                          SI.getOperand(1))) {
+        ++NumDeadStore;
+        ++BBI;
+        EraseInstFromFunction(*PrevSI);
+        continue;
+      }
+      break;
+    }
+    
+    // If this is a load, we have to stop.  However, if the loaded value is from
+    // the pointer we're loading and is producing the pointer we're storing,
+    // then *this* store is dead (X = load P; store X -> P).
+    if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
+      if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) &&
+          !SI.isVolatile()) {
+        EraseInstFromFunction(SI);
+        ++NumCombined;
+        return 0;
+      }
+      // Otherwise, this is a load from some other location.  Stores before it
+      // may not be dead.
+      break;
+    }
+    
+    // Don't skip over loads or things that can modify memory.
+    if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory())
+      break;
+  }
+  
+  
+  if (SI.isVolatile()) return 0;  // Don't hack volatile stores.
+
+  // store X, null    -> turns into 'unreachable' in SimplifyCFG
+  if (isa<ConstantPointerNull>(Ptr)) {
+    if (!isa<UndefValue>(Val)) {
+      SI.setOperand(0, UndefValue::get(Val->getType()));
+      if (Instruction *U = dyn_cast<Instruction>(Val))
+        AddToWorkList(U);  // Dropped a use.
+      ++NumCombined;
+    }
+    return 0;  // Do not modify these!
+  }
+
+  // store undef, Ptr -> noop
+  if (isa<UndefValue>(Val)) {
+    EraseInstFromFunction(SI);
+    ++NumCombined;
+    return 0;
+  }
+
+  // If the pointer destination is a cast, see if we can fold the cast into the
+  // source instead.
+  if (isa<CastInst>(Ptr))
+    if (Instruction *Res = InstCombineStoreToCast(*this, SI))
+      return Res;
+  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+    if (CE->isCast())
+      if (Instruction *Res = InstCombineStoreToCast(*this, SI))
+        return Res;
+
+  
+  // If this store is the last instruction in the basic block (possibly
+  // excepting debug info instructions and the pointer bitcasts that feed
+  // into them), and if the block ends with an unconditional branch, try
+  // to move it to the successor block.
+  BBI = &SI; 
+  do {
+    ++BBI;
+  } while (isa<DbgInfoIntrinsic>(BBI) ||
+           (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType())));
+  if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
+    if (BI->isUnconditional())
+      if (SimplifyStoreAtEndOfBlock(SI))
+        return 0;  // xform done!
+  
+  return 0;
+}
+
+/// SimplifyStoreAtEndOfBlock - Turn things like:
+///   if () { *P = v1; } else { *P = v2 }
+/// into a phi node with a store in the successor.
+///
+/// Simplify things like:
+///   *P = v1; if () { *P = v2; }
+/// into a phi node with a store in the successor.
+///
+bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
+  BasicBlock *StoreBB = SI.getParent();
+  
+  // Check to see if the successor block has exactly two incoming edges.  If
+  // so, see if the other predecessor contains a store to the same location.
+  // if so, insert a PHI node (if needed) and move the stores down.
+  BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
+  
+  // Determine whether Dest has exactly two predecessors and, if so, compute
+  // the other predecessor.
+  pred_iterator PI = pred_begin(DestBB);
+  BasicBlock *OtherBB = 0;
+  if (*PI != StoreBB)
+    OtherBB = *PI;
+  ++PI;
+  if (PI == pred_end(DestBB))
+    return false;
+  
+  if (*PI != StoreBB) {
+    if (OtherBB)
+      return false;
+    OtherBB = *PI;
+  }
+  if (++PI != pred_end(DestBB))
+    return false;
+
+  // Bail out if all the relevant blocks aren't distinct (this can happen,
+  // for example, if SI is in an infinite loop)
+  if (StoreBB == DestBB || OtherBB == DestBB)
+    return false;
+
+  // Verify that the other block ends in a branch and is not otherwise empty.
+  BasicBlock::iterator BBI = OtherBB->getTerminator();
+  BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
+  if (!OtherBr || BBI == OtherBB->begin())
+    return false;
+  
+  // If the other block ends in an unconditional branch, check for the 'if then
+  // else' case.  there is an instruction before the branch.
+  StoreInst *OtherStore = 0;
+  if (OtherBr->isUnconditional()) {
+    --BBI;
+    // Skip over debugging info.
+    while (isa<DbgInfoIntrinsic>(BBI) ||
+           (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
+      if (BBI==OtherBB->begin())
+        return false;
+      --BBI;
+    }
+    // If this isn't a store, or isn't a store to the same location, bail out.
+    OtherStore = dyn_cast<StoreInst>(BBI);
+    if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1))
+      return false;
+  } else {
+    // Otherwise, the other block ended with a conditional branch. If one of the
+    // destinations is StoreBB, then we have the if/then case.
+    if (OtherBr->getSuccessor(0) != StoreBB && 
+        OtherBr->getSuccessor(1) != StoreBB)
+      return false;
+    
+    // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
+    // if/then triangle.  See if there is a store to the same ptr as SI that
+    // lives in OtherBB.
+    for (;; --BBI) {
+      // Check to see if we find the matching store.
+      if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
+        if (OtherStore->getOperand(1) != SI.getOperand(1))
+          return false;
+        break;
+      }
+      // If we find something that may be using or overwriting the stored
+      // value, or if we run out of instructions, we can't do the xform.
+      if (BBI->mayReadFromMemory() || BBI->mayWriteToMemory() ||
+          BBI == OtherBB->begin())
+        return false;
+    }
+    
+    // In order to eliminate the store in OtherBr, we have to
+    // make sure nothing reads or overwrites the stored value in
+    // StoreBB.
+    for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
+      // FIXME: This should really be AA driven.
+      if (I->mayReadFromMemory() || I->mayWriteToMemory())
+        return false;
+    }
+  }
+  
+  // Insert a PHI node now if we need it.
+  Value *MergedVal = OtherStore->getOperand(0);
+  if (MergedVal != SI.getOperand(0)) {
+    PHINode *PN = PHINode::Create(MergedVal->getType(), "storemerge");
+    PN->reserveOperandSpace(2);
+    PN->addIncoming(SI.getOperand(0), SI.getParent());
+    PN->addIncoming(OtherStore->getOperand(0), OtherBB);
+    MergedVal = InsertNewInstBefore(PN, DestBB->front());
+  }
+  
+  // Advance to a place where it is safe to insert the new store and
+  // insert it.
+  BBI = DestBB->getFirstNonPHI();
+  InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
+                                    OtherStore->isVolatile()), *BBI);
+  
+  // Nuke the old stores.
+  EraseInstFromFunction(SI);
+  EraseInstFromFunction(*OtherStore);
+  ++NumCombined;
+  return true;
+}
+
+
+Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
+  // Change br (not X), label True, label False to: br X, label False, True
+  Value *X = 0;
+  BasicBlock *TrueDest;
+  BasicBlock *FalseDest;
+  if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
+      !isa<Constant>(X)) {
+    // Swap Destinations and condition...
+    BI.setCondition(X);
+    BI.setSuccessor(0, FalseDest);
+    BI.setSuccessor(1, TrueDest);
+    return &BI;
+  }
+
+  // Cannonicalize fcmp_one -> fcmp_oeq
+  FCmpInst::Predicate FPred; Value *Y;
+  if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)), 
+                             TrueDest, FalseDest)))
+    if ((FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
+         FPred == FCmpInst::FCMP_OGE) && BI.getCondition()->hasOneUse()) {
+      FCmpInst *I = cast<FCmpInst>(BI.getCondition());
+      FCmpInst::Predicate NewPred = FCmpInst::getInversePredicate(FPred);
+      Instruction *NewSCC = new FCmpInst(NewPred, X, Y, "", I);
+      NewSCC->takeName(I);
+      // Swap Destinations and condition...
+      BI.setCondition(NewSCC);
+      BI.setSuccessor(0, FalseDest);
+      BI.setSuccessor(1, TrueDest);
+      RemoveFromWorkList(I);
+      I->eraseFromParent();
+      AddToWorkList(NewSCC);
+      return &BI;
+    }
+
+  // Cannonicalize icmp_ne -> icmp_eq
+  ICmpInst::Predicate IPred;
+  if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
+                      TrueDest, FalseDest)))
+    if ((IPred == ICmpInst::ICMP_NE  || IPred == ICmpInst::ICMP_ULE ||
+         IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
+         IPred == ICmpInst::ICMP_SGE) && BI.getCondition()->hasOneUse()) {
+      ICmpInst *I = cast<ICmpInst>(BI.getCondition());
+      ICmpInst::Predicate NewPred = ICmpInst::getInversePredicate(IPred);
+      Instruction *NewSCC = new ICmpInst(NewPred, X, Y, "", I);
+      NewSCC->takeName(I);
+      // Swap Destinations and condition...
+      BI.setCondition(NewSCC);
+      BI.setSuccessor(0, FalseDest);
+      BI.setSuccessor(1, TrueDest);
+      RemoveFromWorkList(I);
+      I->eraseFromParent();;
+      AddToWorkList(NewSCC);
+      return &BI;
+    }
+
+  return 0;
+}
+
+Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
+  Value *Cond = SI.getCondition();
+  if (Instruction *I = dyn_cast<Instruction>(Cond)) {
+    if (I->getOpcode() == Instruction::Add)
+      if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
+        // change 'switch (X+4) case 1:' into 'switch (X) case -3'
+        for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
+          SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
+                                                AddRHS));
+        SI.setOperand(0, I->getOperand(0));
+        AddToWorkList(I);
+        return &SI;
+      }
+  }
+  return 0;
+}
+
+Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
+  Value *Agg = EV.getAggregateOperand();
+
+  if (!EV.hasIndices())
+    return ReplaceInstUsesWith(EV, Agg);
+
+  if (Constant *C = dyn_cast<Constant>(Agg)) {
+    if (isa<UndefValue>(C))
+      return ReplaceInstUsesWith(EV, UndefValue::get(EV.getType()));
+      
+    if (isa<ConstantAggregateZero>(C))
+      return ReplaceInstUsesWith(EV, Constant::getNullValue(EV.getType()));
+
+    if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) {
+      // Extract the element indexed by the first index out of the constant
+      Value *V = C->getOperand(*EV.idx_begin());
+      if (EV.getNumIndices() > 1)
+        // Extract the remaining indices out of the constant indexed by the
+        // first index
+        return ExtractValueInst::Create(V, EV.idx_begin() + 1, EV.idx_end());
+      else
+        return ReplaceInstUsesWith(EV, V);
+    }
+    return 0; // Can't handle other constants
+  } 
+  if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
+    // We're extracting from an insertvalue instruction, compare the indices
+    const unsigned *exti, *exte, *insi, *inse;
+    for (exti = EV.idx_begin(), insi = IV->idx_begin(),
+         exte = EV.idx_end(), inse = IV->idx_end();
+         exti != exte && insi != inse;
+         ++exti, ++insi) {
+      if (*insi != *exti)
+        // The insert and extract both reference distinctly different elements.
+        // This means the extract is not influenced by the insert, and we can
+        // replace the aggregate operand of the extract with the aggregate
+        // operand of the insert. i.e., replace
+        // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
+        // %E = extractvalue { i32, { i32 } } %I, 0
+        // with
+        // %E = extractvalue { i32, { i32 } } %A, 0
+        return ExtractValueInst::Create(IV->getAggregateOperand(),
+                                        EV.idx_begin(), EV.idx_end());
+    }
+    if (exti == exte && insi == inse)
+      // Both iterators are at the end: Index lists are identical. Replace
+      // %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
+      // %C = extractvalue { i32, { i32 } } %B, 1, 0
+      // with "i32 42"
+      return ReplaceInstUsesWith(EV, IV->getInsertedValueOperand());
+    if (exti == exte) {
+      // The extract list is a prefix of the insert list. i.e. replace
+      // %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
+      // %E = extractvalue { i32, { i32 } } %I, 1
+      // with
+      // %X = extractvalue { i32, { i32 } } %A, 1
+      // %E = insertvalue { i32 } %X, i32 42, 0
+      // by switching the order of the insert and extract (though the
+      // insertvalue should be left in, since it may have other uses).
+      Value *NewEV = InsertNewInstBefore(
+        ExtractValueInst::Create(IV->getAggregateOperand(),
+                                 EV.idx_begin(), EV.idx_end()),
+        EV);
+      return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(),
+                                     insi, inse);
+    }
+    if (insi == inse)
+      // The insert list is a prefix of the extract list
+      // We can simply remove the common indices from the extract and make it
+      // operate on the inserted value instead of the insertvalue result.
+      // i.e., replace
+      // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
+      // %E = extractvalue { i32, { i32 } } %I, 1, 0
+      // with
+      // %E extractvalue { i32 } { i32 42 }, 0
+      return ExtractValueInst::Create(IV->getInsertedValueOperand(), 
+                                      exti, exte);
+  }
+  // Can't simplify extracts from other values. Note that nested extracts are
+  // already simplified implicitely by the above (extract ( extract (insert) )
+  // will be translated into extract ( insert ( extract ) ) first and then just
+  // the value inserted, if appropriate).
+  return 0;
+}
+
+/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
+/// is to leave as a vector operation.
+static bool CheapToScalarize(Value *V, bool isConstant) {
+  if (isa<ConstantAggregateZero>(V)) 
+    return true;
+  if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
+    if (isConstant) return true;
+    // If all elts are the same, we can extract.
+    Constant *Op0 = C->getOperand(0);
+    for (unsigned i = 1; i < C->getNumOperands(); ++i)
+      if (C->getOperand(i) != Op0)
+        return false;
+    return true;
+  }
+  Instruction *I = dyn_cast<Instruction>(V);
+  if (!I) return false;
+  
+  // Insert element gets simplified to the inserted element or is deleted if
+  // this is constant idx extract element and its a constant idx insertelt.
+  if (I->getOpcode() == Instruction::InsertElement && isConstant &&
+      isa<ConstantInt>(I->getOperand(2)))
+    return true;
+  if (I->getOpcode() == Instruction::Load && I->hasOneUse())
+    return true;
+  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
+    if (BO->hasOneUse() &&
+        (CheapToScalarize(BO->getOperand(0), isConstant) ||
+         CheapToScalarize(BO->getOperand(1), isConstant)))
+      return true;
+  if (CmpInst *CI = dyn_cast<CmpInst>(I))
+    if (CI->hasOneUse() &&
+        (CheapToScalarize(CI->getOperand(0), isConstant) ||
+         CheapToScalarize(CI->getOperand(1), isConstant)))
+      return true;
+  
+  return false;
+}
+
+/// Read and decode a shufflevector mask.
+///
+/// It turns undef elements into values that are larger than the number of
+/// elements in the input.
+static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
+  unsigned NElts = SVI->getType()->getNumElements();
+  if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
+    return std::vector<unsigned>(NElts, 0);
+  if (isa<UndefValue>(SVI->getOperand(2)))
+    return std::vector<unsigned>(NElts, 2*NElts);
+
+  std::vector<unsigned> Result;
+  const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
+  for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
+    if (isa<UndefValue>(*i))
+      Result.push_back(NElts*2);  // undef -> 8
+    else
+      Result.push_back(cast<ConstantInt>(*i)->getZExtValue());
+  return Result;
+}
+
+/// FindScalarElement - Given a vector and an element number, see if the scalar
+/// value is already around as a register, for example if it were inserted then
+/// extracted from the vector.
+static Value *FindScalarElement(Value *V, unsigned EltNo) {
+  assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
+  const VectorType *PTy = cast<VectorType>(V->getType());
+  unsigned Width = PTy->getNumElements();
+  if (EltNo >= Width)  // Out of range access.
+    return UndefValue::get(PTy->getElementType());
+  
+  if (isa<UndefValue>(V))
+    return UndefValue::get(PTy->getElementType());
+  else if (isa<ConstantAggregateZero>(V))
+    return Constant::getNullValue(PTy->getElementType());
+  else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
+    return CP->getOperand(EltNo);
+  else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
+    // If this is an insert to a variable element, we don't know what it is.
+    if (!isa<ConstantInt>(III->getOperand(2))) 
+      return 0;
+    unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
+    
+    // If this is an insert to the element we are looking for, return the
+    // inserted value.
+    if (EltNo == IIElt) 
+      return III->getOperand(1);
+    
+    // Otherwise, the insertelement doesn't modify the value, recurse on its
+    // vector input.
+    return FindScalarElement(III->getOperand(0), EltNo);
+  } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
+    unsigned LHSWidth =
+      cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
+    unsigned InEl = getShuffleMask(SVI)[EltNo];
+    if (InEl < LHSWidth)
+      return FindScalarElement(SVI->getOperand(0), InEl);
+    else if (InEl < LHSWidth*2)
+      return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
+    else
+      return UndefValue::get(PTy->getElementType());
+  }
+  
+  // Otherwise, we don't know.
+  return 0;
+}
+
+Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
+  // If vector val is undef, replace extract with scalar undef.
+  if (isa<UndefValue>(EI.getOperand(0)))
+    return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+
+  // If vector val is constant 0, replace extract with scalar 0.
+  if (isa<ConstantAggregateZero>(EI.getOperand(0)))
+    return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
+  
+  if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
+    // If vector val is constant with all elements the same, replace EI with
+    // that element. When the elements are not identical, we cannot replace yet
+    // (we do that below, but only when the index is constant).
+    Constant *op0 = C->getOperand(0);
+    for (unsigned i = 1; i < C->getNumOperands(); ++i)
+      if (C->getOperand(i) != op0) {
+        op0 = 0; 
+        break;
+      }
+    if (op0)
+      return ReplaceInstUsesWith(EI, op0);
+  }
+  
+  // If extracting a specified index from the vector, see if we can recursively
+  // find a previously computed scalar that was inserted into the vector.
+  if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
+    unsigned IndexVal = IdxC->getZExtValue();
+    unsigned VectorWidth = 
+      cast<VectorType>(EI.getOperand(0)->getType())->getNumElements();
+      
+    // If this is extracting an invalid index, turn this into undef, to avoid
+    // crashing the code below.
+    if (IndexVal >= VectorWidth)
+      return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+    
+    // This instruction only demands the single element from the input vector.
+    // If the input vector has a single use, simplify it based on this use
+    // property.
+    if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
+      APInt UndefElts(VectorWidth, 0);
+      APInt DemandedMask(VectorWidth, 1 << IndexVal);
+      if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
+                                                DemandedMask, UndefElts)) {
+        EI.setOperand(0, V);
+        return &EI;
+      }
+    }
+    
+    if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
+      return ReplaceInstUsesWith(EI, Elt);
+    
+    // If the this extractelement is directly using a bitcast from a vector of
+    // the same number of elements, see if we can find the source element from
+    // it.  In this case, we will end up needing to bitcast the scalars.
+    if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
+      if (const VectorType *VT = 
+              dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
+        if (VT->getNumElements() == VectorWidth)
+          if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
+            return new BitCastInst(Elt, EI.getType());
+    }
+  }
+  
+  if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
+    if (I->hasOneUse()) {
+      // Push extractelement into predecessor operation if legal and
+      // profitable to do so
+      if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
+        bool isConstantElt = isa<ConstantInt>(EI.getOperand(1));
+        if (CheapToScalarize(BO, isConstantElt)) {
+          ExtractElementInst *newEI0 = 
+            new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
+                                   EI.getName()+".lhs");
+          ExtractElementInst *newEI1 =
+            new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
+                                   EI.getName()+".rhs");
+          InsertNewInstBefore(newEI0, EI);
+          InsertNewInstBefore(newEI1, EI);
+          return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1);
+        }
+      } else if (isa<LoadInst>(I)) {
+        unsigned AS = 
+          cast<PointerType>(I->getOperand(0)->getType())->getAddressSpace();
+        Value *Ptr = InsertBitCastBefore(I->getOperand(0),
+                                         PointerType::get(EI.getType(), AS),EI);
+        GetElementPtrInst *GEP =
+          GetElementPtrInst::Create(Ptr, EI.getOperand(1), I->getName()+".gep");
+        InsertNewInstBefore(GEP, EI);
+        return new LoadInst(GEP);
+      }
+    }
+    if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
+      // Extracting the inserted element?
+      if (IE->getOperand(2) == EI.getOperand(1))
+        return ReplaceInstUsesWith(EI, IE->getOperand(1));
+      // If the inserted and extracted elements are constants, they must not
+      // be the same value, extract from the pre-inserted value instead.
+      if (isa<Constant>(IE->getOperand(2)) &&
+          isa<Constant>(EI.getOperand(1))) {
+        AddUsesToWorkList(EI);
+        EI.setOperand(0, IE->getOperand(0));
+        return &EI;
+      }
+    } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
+      // If this is extracting an element from a shufflevector, figure out where
+      // it came from and extract from the appropriate input element instead.
+      if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
+        unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
+        Value *Src;
+        unsigned LHSWidth =
+          cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
+
+        if (SrcIdx < LHSWidth)
+          Src = SVI->getOperand(0);
+        else if (SrcIdx < LHSWidth*2) {
+          SrcIdx -= LHSWidth;
+          Src = SVI->getOperand(1);
+        } else {
+          return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+        }
+        return new ExtractElementInst(Src, SrcIdx);
+      }
+    }
+  }
+  return 0;
+}
+
+/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
+/// elements from either LHS or RHS, return the shuffle mask and true. 
+/// Otherwise, return false.
+static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
+                                         std::vector<Constant*> &Mask) {
+  assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
+         "Invalid CollectSingleShuffleElements");
+  unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
+
+  if (isa<UndefValue>(V)) {
+    Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
+    return true;
+  } else if (V == LHS) {
+    for (unsigned i = 0; i != NumElts; ++i)
+      Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
+    return true;
+  } else if (V == RHS) {
+    for (unsigned i = 0; i != NumElts; ++i)
+      Mask.push_back(ConstantInt::get(Type::Int32Ty, i+NumElts));
+    return true;
+  } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
+    // If this is an insert of an extract from some other vector, include it.
+    Value *VecOp    = IEI->getOperand(0);
+    Value *ScalarOp = IEI->getOperand(1);
+    Value *IdxOp    = IEI->getOperand(2);
+    
+    if (!isa<ConstantInt>(IdxOp))
+      return false;
+    unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
+    
+    if (isa<UndefValue>(ScalarOp)) {  // inserting undef into vector.
+      // Okay, we can handle this if the vector we are insertinting into is
+      // transitively ok.
+      if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
+        // If so, update the mask to reflect the inserted undef.
+        Mask[InsertedIdx] = UndefValue::get(Type::Int32Ty);
+        return true;
+      }      
+    } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
+      if (isa<ConstantInt>(EI->getOperand(1)) &&
+          EI->getOperand(0)->getType() == V->getType()) {
+        unsigned ExtractedIdx =
+          cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+        
+        // This must be extracting from either LHS or RHS.
+        if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
+          // Okay, we can handle this if the vector we are insertinting into is
+          // transitively ok.
+          if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
+            // If so, update the mask to reflect the inserted value.
+            if (EI->getOperand(0) == LHS) {
+              Mask[InsertedIdx % NumElts] = 
+                 ConstantInt::get(Type::Int32Ty, ExtractedIdx);
+            } else {
+              assert(EI->getOperand(0) == RHS);
+              Mask[InsertedIdx % NumElts] = 
+                ConstantInt::get(Type::Int32Ty, ExtractedIdx+NumElts);
+              
+            }
+            return true;
+          }
+        }
+      }
+    }
+  }
+  // TODO: Handle shufflevector here!
+  
+  return false;
+}
+
+/// CollectShuffleElements - We are building a shuffle of V, using RHS as the
+/// RHS of the shuffle instruction, if it is not null.  Return a shuffle mask
+/// that computes V and the LHS value of the shuffle.
+static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
+                                     Value *&RHS) {
+  assert(isa<VectorType>(V->getType()) && 
+         (RHS == 0 || V->getType() == RHS->getType()) &&
+         "Invalid shuffle!");
+  unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
+
+  if (isa<UndefValue>(V)) {
+    Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
+    return V;
+  } else if (isa<ConstantAggregateZero>(V)) {
+    Mask.assign(NumElts, ConstantInt::get(Type::Int32Ty, 0));
+    return V;
+  } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
+    // If this is an insert of an extract from some other vector, include it.
+    Value *VecOp    = IEI->getOperand(0);
+    Value *ScalarOp = IEI->getOperand(1);
+    Value *IdxOp    = IEI->getOperand(2);
+    
+    if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
+      if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
+          EI->getOperand(0)->getType() == V->getType()) {
+        unsigned ExtractedIdx =
+          cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+        unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
+        
+        // Either the extracted from or inserted into vector must be RHSVec,
+        // otherwise we'd end up with a shuffle of three inputs.
+        if (EI->getOperand(0) == RHS || RHS == 0) {
+          RHS = EI->getOperand(0);
+          Value *V = CollectShuffleElements(VecOp, Mask, RHS);
+          Mask[InsertedIdx % NumElts] = 
+            ConstantInt::get(Type::Int32Ty, NumElts+ExtractedIdx);
+          return V;
+        }
+        
+        if (VecOp == RHS) {
+          Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
+          // Everything but the extracted element is replaced with the RHS.
+          for (unsigned i = 0; i != NumElts; ++i) {
+            if (i != InsertedIdx)
+              Mask[i] = ConstantInt::get(Type::Int32Ty, NumElts+i);
+          }
+          return V;
+        }
+        
+        // If this insertelement is a chain that comes from exactly these two
+        // vectors, return the vector and the effective shuffle.
+        if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
+          return EI->getOperand(0);
+        
+      }
+    }
+  }
+  // TODO: Handle shufflevector here!
+  
+  // Otherwise, can't do anything fancy.  Return an identity vector.
+  for (unsigned i = 0; i != NumElts; ++i)
+    Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
+  return V;
+}
+
+Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
+  Value *VecOp    = IE.getOperand(0);
+  Value *ScalarOp = IE.getOperand(1);
+  Value *IdxOp    = IE.getOperand(2);
+  
+  // Inserting an undef or into an undefined place, remove this.
+  if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
+    ReplaceInstUsesWith(IE, VecOp);
+  
+  // If the inserted element was extracted from some other vector, and if the 
+  // indexes are constant, try to turn this into a shufflevector operation.
+  if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
+    if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
+        EI->getOperand(0)->getType() == IE.getType()) {
+      unsigned NumVectorElts = IE.getType()->getNumElements();
+      unsigned ExtractedIdx =
+        cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+      unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
+      
+      if (ExtractedIdx >= NumVectorElts) // Out of range extract.
+        return ReplaceInstUsesWith(IE, VecOp);
+      
+      if (InsertedIdx >= NumVectorElts)  // Out of range insert.
+        return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
+      
+      // If we are extracting a value from a vector, then inserting it right
+      // back into the same place, just use the input vector.
+      if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
+        return ReplaceInstUsesWith(IE, VecOp);      
+      
+      // We could theoretically do this for ANY input.  However, doing so could
+      // turn chains of insertelement instructions into a chain of shufflevector
+      // instructions, and right now we do not merge shufflevectors.  As such,
+      // only do this in a situation where it is clear that there is benefit.
+      if (isa<UndefValue>(VecOp) || isa<ConstantAggregateZero>(VecOp)) {
+        // Turn this into shuffle(EIOp0, VecOp, Mask).  The result has all of
+        // the values of VecOp, except then one read from EIOp0.
+        // Build a new shuffle mask.
+        std::vector<Constant*> Mask;
+        if (isa<UndefValue>(VecOp))
+          Mask.assign(NumVectorElts, UndefValue::get(Type::Int32Ty));
+        else {
+          assert(isa<ConstantAggregateZero>(VecOp) && "Unknown thing");
+          Mask.assign(NumVectorElts, ConstantInt::get(Type::Int32Ty,
+                                                       NumVectorElts));
+        } 
+        Mask[InsertedIdx] = ConstantInt::get(Type::Int32Ty, ExtractedIdx);
+        return new ShuffleVectorInst(EI->getOperand(0), VecOp,
+                                     ConstantVector::get(Mask));
+      }
+      
+      // If this insertelement isn't used by some other insertelement, turn it
+      // (and any insertelements it points to), into one big shuffle.
+      if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
+        std::vector<Constant*> Mask;
+        Value *RHS = 0;
+        Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
+        if (RHS == 0) RHS = UndefValue::get(LHS->getType());
+        // We now have a shuffle of LHS, RHS, Mask.
+        return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Mask));
+      }
+    }
+  }
+
+  return 0;
+}
+
+
+Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
+  Value *LHS = SVI.getOperand(0);
+  Value *RHS = SVI.getOperand(1);
+  std::vector<unsigned> Mask = getShuffleMask(&SVI);
+
+  bool MadeChange = false;
+
+  // Undefined shuffle mask -> undefined value.
+  if (isa<UndefValue>(SVI.getOperand(2)))
+    return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
+
+  unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
+
+  if (VWidth != cast<VectorType>(LHS->getType())->getNumElements())
+    return 0;
+
+  APInt UndefElts(VWidth, 0);
+  APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
+  if (SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
+    LHS = SVI.getOperand(0);
+    RHS = SVI.getOperand(1);
+    MadeChange = true;
+  }
+  
+  // Canonicalize shuffle(x    ,x,mask) -> shuffle(x, undef,mask')
+  // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
+  if (LHS == RHS || isa<UndefValue>(LHS)) {
+    if (isa<UndefValue>(LHS) && LHS == RHS) {
+      // shuffle(undef,undef,mask) -> undef.
+      return ReplaceInstUsesWith(SVI, LHS);
+    }
+    
+    // Remap any references to RHS to use LHS.
+    std::vector<Constant*> Elts;
+    for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+      if (Mask[i] >= 2*e)
+        Elts.push_back(UndefValue::get(Type::Int32Ty));
+      else {
+        if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
+            (Mask[i] <  e && isa<UndefValue>(LHS))) {
+          Mask[i] = 2*e;     // Turn into undef.
+          Elts.push_back(UndefValue::get(Type::Int32Ty));
+        } else {
+          Mask[i] = Mask[i] % e;  // Force to LHS.
+          Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
+        }
+      }
+    }
+    SVI.setOperand(0, SVI.getOperand(1));
+    SVI.setOperand(1, UndefValue::get(RHS->getType()));
+    SVI.setOperand(2, ConstantVector::get(Elts));
+    LHS = SVI.getOperand(0);
+    RHS = SVI.getOperand(1);
+    MadeChange = true;
+  }
+  
+  // Analyze the shuffle, are the LHS or RHS and identity shuffles?
+  bool isLHSID = true, isRHSID = true;
+    
+  for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+    if (Mask[i] >= e*2) continue;  // Ignore undef values.
+    // Is this an identity shuffle of the LHS value?
+    isLHSID &= (Mask[i] == i);
+      
+    // Is this an identity shuffle of the RHS value?
+    isRHSID &= (Mask[i]-e == i);
+  }
+
+  // Eliminate identity shuffles.
+  if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
+  if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
+  
+  // If the LHS is a shufflevector itself, see if we can combine it with this
+  // one without producing an unusual shuffle.  Here we are really conservative:
+  // we are absolutely afraid of producing a shuffle mask not in the input
+  // program, because the code gen may not be smart enough to turn a merged
+  // shuffle into two specific shuffles: it may produce worse code.  As such,
+  // we only merge two shuffles if the result is one of the two input shuffle
+  // masks.  In this case, merging the shuffles just removes one instruction,
+  // which we know is safe.  This is good for things like turning:
+  // (splat(splat)) -> splat.
+  if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
+    if (isa<UndefValue>(RHS)) {
+      std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
+
+      std::vector<unsigned> NewMask;
+      for (unsigned i = 0, e = Mask.size(); i != e; ++i)
+        if (Mask[i] >= 2*e)
+          NewMask.push_back(2*e);
+        else
+          NewMask.push_back(LHSMask[Mask[i]]);
+      
+      // If the result mask is equal to the src shuffle or this shuffle mask, do
+      // the replacement.
+      if (NewMask == LHSMask || NewMask == Mask) {
+        unsigned LHSInNElts =
+          cast<VectorType>(LHSSVI->getOperand(0)->getType())->getNumElements();
+        std::vector<Constant*> Elts;
+        for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
+          if (NewMask[i] >= LHSInNElts*2) {
+            Elts.push_back(UndefValue::get(Type::Int32Ty));
+          } else {
+            Elts.push_back(ConstantInt::get(Type::Int32Ty, NewMask[i]));
+          }
+        }
+        return new ShuffleVectorInst(LHSSVI->getOperand(0),
+                                     LHSSVI->getOperand(1),
+                                     ConstantVector::get(Elts));
+      }
+    }
+  }
+
+  return MadeChange ? &SVI : 0;
+}
+
+
+
+
+/// TryToSinkInstruction - Try to move the specified instruction from its
+/// current block into the beginning of DestBlock, which can only happen if it's
+/// safe to move the instruction past all of the instructions between it and the
+/// end of its block.
+static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
+  assert(I->hasOneUse() && "Invariants didn't hold!");
+
+  // Cannot move control-flow-involving, volatile loads, vaarg, etc.
+  if (isa<PHINode>(I) || I->mayHaveSideEffects() || isa<TerminatorInst>(I))
+    return false;
+
+  // Do not sink alloca instructions out of the entry block.
+  if (isa<AllocaInst>(I) && I->getParent() ==
+        &DestBlock->getParent()->getEntryBlock())
+    return false;
+
+  // We can only sink load instructions if there is nothing between the load and
+  // the end of block that could change the value.
+  if (I->mayReadFromMemory()) {
+    for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
+         Scan != E; ++Scan)
+      if (Scan->mayWriteToMemory())
+        return false;
+  }
+
+  BasicBlock::iterator InsertPos = DestBlock->getFirstNonPHI();
+
+  CopyPrecedingStopPoint(I, InsertPos);
+  I->moveBefore(InsertPos);
+  ++NumSunkInst;
+  return true;
+}
+
+
+/// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
+/// all reachable code to the worklist.
+///
+/// This has a couple of tricks to make the code faster and more powerful.  In
+/// particular, we constant fold and DCE instructions as we go, to avoid adding
+/// them to the worklist (this significantly speeds up instcombine on code where
+/// many instructions are dead or constant).  Additionally, if we find a branch
+/// whose condition is a known constant, we only visit the reachable successors.
+///
+static void AddReachableCodeToWorklist(BasicBlock *BB, 
+                                       SmallPtrSet<BasicBlock*, 64> &Visited,
+                                       InstCombiner &IC,
+                                       const TargetData *TD) {
+  SmallVector<BasicBlock*, 256> Worklist;
+  Worklist.push_back(BB);
+
+  while (!Worklist.empty()) {
+    BB = Worklist.back();
+    Worklist.pop_back();
+    
+    // We have now visited this block!  If we've already been here, ignore it.
+    if (!Visited.insert(BB)) continue;
+
+    DbgInfoIntrinsic *DBI_Prev = NULL;
+    for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
+      Instruction *Inst = BBI++;
+      
+      // DCE instruction if trivially dead.
+      if (isInstructionTriviallyDead(Inst)) {
+        ++NumDeadInst;
+        DOUT << "IC: DCE: " << *Inst;
+        Inst->eraseFromParent();
+        continue;
+      }
+      
+      // ConstantProp instruction if trivially constant.
+      if (Constant *C = ConstantFoldInstruction(Inst, TD)) {
+        DOUT << "IC: ConstFold to: " << *C << " from: " << *Inst;
+        Inst->replaceAllUsesWith(C);
+        ++NumConstProp;
+        Inst->eraseFromParent();
+        continue;
+      }
+     
+      // If there are two consecutive llvm.dbg.stoppoint calls then
+      // it is likely that the optimizer deleted code in between these
+      // two intrinsics. 
+      DbgInfoIntrinsic *DBI_Next = dyn_cast<DbgInfoIntrinsic>(Inst);
+      if (DBI_Next) {
+        if (DBI_Prev
+            && DBI_Prev->getIntrinsicID() == llvm::Intrinsic::dbg_stoppoint
+            && DBI_Next->getIntrinsicID() == llvm::Intrinsic::dbg_stoppoint) {
+          IC.RemoveFromWorkList(DBI_Prev);
+          DBI_Prev->eraseFromParent();
+        }
+        DBI_Prev = DBI_Next;
+      } else {
+        DBI_Prev = 0;
+      }
+
+      IC.AddToWorkList(Inst);
+    }
+
+    // Recursively visit successors.  If this is a branch or switch on a
+    // constant, only visit the reachable successor.
+    TerminatorInst *TI = BB->getTerminator();
+    if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
+      if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
+        bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
+        BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
+        Worklist.push_back(ReachableBB);
+        continue;
+      }
+    } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+      if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
+        // See if this is an explicit destination.
+        for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
+          if (SI->getCaseValue(i) == Cond) {
+            BasicBlock *ReachableBB = SI->getSuccessor(i);
+            Worklist.push_back(ReachableBB);
+            continue;
+          }
+        
+        // Otherwise it is the default destination.
+        Worklist.push_back(SI->getSuccessor(0));
+        continue;
+      }
+    }
+    
+    for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+      Worklist.push_back(TI->getSuccessor(i));
+  }
+}
+
+bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
+  bool Changed = false;
+  TD = &getAnalysis<TargetData>();
+  
+  DEBUG(DOUT << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
+             << F.getNameStr() << "\n");
+
+  {
+    // Do a depth-first traversal of the function, populate the worklist with
+    // the reachable instructions.  Ignore blocks that are not reachable.  Keep
+    // track of which blocks we visit.
+    SmallPtrSet<BasicBlock*, 64> Visited;
+    AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
+
+    // Do a quick scan over the function.  If we find any blocks that are
+    // unreachable, remove any instructions inside of them.  This prevents
+    // the instcombine code from having to deal with some bad special cases.
+    for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+      if (!Visited.count(BB)) {
+        Instruction *Term = BB->getTerminator();
+        while (Term != BB->begin()) {   // Remove instrs bottom-up
+          BasicBlock::iterator I = Term; --I;
+
+          DOUT << "IC: DCE: " << *I;
+          // A debug intrinsic shouldn't force another iteration if we weren't
+          // going to do one without it.
+          if (!isa<DbgInfoIntrinsic>(I)) {
+            ++NumDeadInst;
+            Changed = true;
+          }
+          if (!I->use_empty())
+            I->replaceAllUsesWith(UndefValue::get(I->getType()));
+          I->eraseFromParent();
+        }
+      }
+  }
+
+  while (!Worklist.empty()) {
+    Instruction *I = RemoveOneFromWorkList();
+    if (I == 0) continue;  // skip null values.
+
+    // Check to see if we can DCE the instruction.
+    if (isInstructionTriviallyDead(I)) {
+      // Add operands to the worklist.
+      if (I->getNumOperands() < 4)
+        AddUsesToWorkList(*I);
+      ++NumDeadInst;
+
+      DOUT << "IC: DCE: " << *I;
+
+      I->eraseFromParent();
+      RemoveFromWorkList(I);
+      Changed = true;
+      continue;
+    }
+
+    // Instruction isn't dead, see if we can constant propagate it.
+    if (Constant *C = ConstantFoldInstruction(I, TD)) {
+      DOUT << "IC: ConstFold to: " << *C << " from: " << *I;
+
+      // Add operands to the worklist.
+      AddUsesToWorkList(*I);
+      ReplaceInstUsesWith(*I, C);
+
+      ++NumConstProp;
+      I->eraseFromParent();
+      RemoveFromWorkList(I);
+      Changed = true;
+      continue;
+    }
+
+    if (TD &&
+        (I->getType()->getTypeID() == Type::VoidTyID ||
+         I->isTrapping())) {
+      // See if we can constant fold its operands.
+      for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i)
+        if (ConstantExpr *CE = dyn_cast<ConstantExpr>(i))
+          if (Constant *NewC = ConstantFoldConstantExpression(CE, TD))
+            if (NewC != CE) {
+              i->set(NewC);
+              Changed = true;
+            }
+    }
+
+    // See if we can trivially sink this instruction to a successor basic block.
+    if (I->hasOneUse()) {
+      BasicBlock *BB = I->getParent();
+      BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
+      if (UserParent != BB) {
+        bool UserIsSuccessor = false;
+        // See if the user is one of our successors.
+        for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
+          if (*SI == UserParent) {
+            UserIsSuccessor = true;
+            break;
+          }
+
+        // If the user is one of our immediate successors, and if that successor
+        // only has us as a predecessors (we'd have to split the critical edge
+        // otherwise), we can keep going.
+        if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
+            next(pred_begin(UserParent)) == pred_end(UserParent))
+          // Okay, the CFG is simple enough, try to sink this instruction.
+          Changed |= TryToSinkInstruction(I, UserParent);
+      }
+    }
+
+    // Now that we have an instruction, try combining it to simplify it...
+#ifndef NDEBUG
+    std::string OrigI;
+#endif
+    DEBUG(std::ostringstream SS; I->print(SS); OrigI = SS.str(););
+    if (Instruction *Result = visit(*I)) {
+      ++NumCombined;
+      // Should we replace the old instruction with a new one?
+      if (Result != I) {
+        DOUT << "IC: Old = " << *I
+             << "    New = " << *Result;
+
+        // Everything uses the new instruction now.
+        I->replaceAllUsesWith(Result);
+
+        // Push the new instruction and any users onto the worklist.
+        AddToWorkList(Result);
+        AddUsersToWorkList(*Result);
+
+        // Move the name to the new instruction first.
+        Result->takeName(I);
+
+        // Insert the new instruction into the basic block...
+        BasicBlock *InstParent = I->getParent();
+        BasicBlock::iterator InsertPos = I;
+
+        if (!isa<PHINode>(Result))        // If combining a PHI, don't insert
+          while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
+            ++InsertPos;
+
+        InstParent->getInstList().insert(InsertPos, Result);
+
+        // Make sure that we reprocess all operands now that we reduced their
+        // use counts.
+        AddUsesToWorkList(*I);
+
+        // Instructions can end up on the worklist more than once.  Make sure
+        // we do not process an instruction that has been deleted.
+        RemoveFromWorkList(I);
+
+        // Erase the old instruction.
+        InstParent->getInstList().erase(I);
+      } else {
+#ifndef NDEBUG
+        DOUT << "IC: Mod = " << OrigI
+             << "    New = " << *I;
+#endif
+
+        // If the instruction was modified, it's possible that it is now dead.
+        // if so, remove it.
+        if (isInstructionTriviallyDead(I)) {
+          // Make sure we process all operands now that we are reducing their
+          // use counts.
+          AddUsesToWorkList(*I);
+
+          // Instructions may end up in the worklist more than once.  Erase all
+          // occurrences of this instruction.
+          RemoveFromWorkList(I);
+          I->eraseFromParent();
+        } else {
+          AddToWorkList(I);
+          AddUsersToWorkList(*I);
+        }
+      }
+      Changed = true;
+    }
+  }
+
+  assert(WorklistMap.empty() && "Worklist empty, but map not?");
+    
+  // Do an explicit clear, this shrinks the map if needed.
+  WorklistMap.clear();
+  return Changed;
+}
+
+
+bool InstCombiner::runOnFunction(Function &F) {
+  MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
+  
+  bool EverMadeChange = false;
+
+  // Iterate while there is work to do.
+  unsigned Iteration = 0;
+  while (DoOneIteration(F, Iteration++))
+    EverMadeChange = true;
+  return EverMadeChange;
+}
+
+FunctionPass *llvm::createInstructionCombiningPass() {
+  return new InstCombiner();
+}