Update LLVM to r90226.

16 files changed, 1123 insertions, 841 deletions

diff --git a/lib/Analysis/AliasAnalysis.cpp b/lib/Analysis/AliasAnalysis.cpp
index 0234965..dee9b53 100644
--- a/lib/Analysis/AliasAnalysis.cpp
+++ b/lib/Analysis/AliasAnalysis.cpp
@@ -49,21 +49,11 @@ AliasAnalysis::alias(const Value *V1, unsigned V1Size,
   return AA->alias(V1, V1Size, V2, V2Size);
 }
 
-void AliasAnalysis::getMustAliases(Value *P, std::vector<Value*> &RetVals) {
-  assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
-  return AA->getMustAliases(P, RetVals);
-}
-
 bool AliasAnalysis::pointsToConstantMemory(const Value *P) {
   assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
   return AA->pointsToConstantMemory(P);
 }
 
-bool AliasAnalysis::hasNoModRefInfoForCalls() const {
-  assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
-  return AA->hasNoModRefInfoForCalls();
-}
-
 void AliasAnalysis::deleteValue(Value *V) {
   assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
   AA->deleteValue(V);
@@ -137,17 +127,18 @@ AliasAnalysis::getModRefBehavior(Function *F,
 
 AliasAnalysis::ModRefResult
 AliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
-  ModRefResult Mask = ModRef;
   ModRefBehavior MRB = getModRefBehavior(CS);
   if (MRB == DoesNotAccessMemory)
     return NoModRef;
-  else if (MRB == OnlyReadsMemory)
+  
+  ModRefResult Mask = ModRef;
+  if (MRB == OnlyReadsMemory)
     Mask = Ref;
   else if (MRB == AliasAnalysis::AccessesArguments) {
     bool doesAlias = false;
     for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
          AI != AE; ++AI)
-      if (alias(*AI, ~0U, P, Size) != NoAlias) {
+      if (!isNoAlias(*AI, ~0U, P, Size)) {
         doesAlias = true;
         break;
       }
diff --git a/lib/Analysis/AliasDebugger.cpp b/lib/Analysis/AliasDebugger.cpp
index cf4727f..6868e3f 100644
--- a/lib/Analysis/AliasDebugger.cpp
+++ b/lib/Analysis/AliasDebugger.cpp
@@ -90,11 +90,6 @@ namespace {
       return AliasAnalysis::getModRefInfo(CS1,CS2);
     }
     
-    void getMustAliases(Value *P, std::vector<Value*> &RetVals) {
-      assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
-      return AliasAnalysis::getMustAliases(P, RetVals);
-    }
-
     bool pointsToConstantMemory(const Value *P) {
       assert(Vals.find(P) != Vals.end() && "Never seen value in AA before");
       return AliasAnalysis::pointsToConstantMemory(P);
diff --git a/lib/Analysis/AliasSetTracker.cpp b/lib/Analysis/AliasSetTracker.cpp
index c037c8d..6634600 100644
--- a/lib/Analysis/AliasSetTracker.cpp
+++ b/lib/Analysis/AliasSetTracker.cpp
@@ -153,9 +153,6 @@ bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
 
   // Check the call sites list and invoke list...
   if (!CallSites.empty()) {
-    if (AA.hasNoModRefInfoForCalls())
-      return true;
-
     for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
       if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size)
                    != AliasAnalysis::NoModRef)
@@ -169,9 +166,6 @@ bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
   if (AA.doesNotAccessMemory(CS))
     return false;
 
-  if (AA.hasNoModRefInfoForCalls())
-    return true;
-
   for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
     if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef ||
         AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef)
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index b8d69f4..b2983c7 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -14,8 +14,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/CaptureTracking.h"
-#include "llvm/Analysis/MemoryBuiltins.h"
 #include "llvm/Analysis/Passes.h"
 #include "llvm/Constants.h"
 #include "llvm/DerivedTypes.h"
@@ -25,12 +23,13 @@
 #include "llvm/IntrinsicInst.h"
 #include "llvm/Operator.h"
 #include "llvm/Pass.h"
+#include "llvm/Analysis/CaptureTracking.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Target/TargetData.h"
-#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
 #include <algorithm>
 using namespace llvm;
 
@@ -38,26 +37,6 @@ using namespace llvm;
 // Useful predicates
 //===----------------------------------------------------------------------===//
 
-static const Value *GetGEPOperands(const Value *V, 
-                                   SmallVector<Value*, 16> &GEPOps) {
-  assert(GEPOps.empty() && "Expect empty list to populate!");
-  GEPOps.insert(GEPOps.end(), cast<User>(V)->op_begin()+1,
-                cast<User>(V)->op_end());
-
-  // Accumulate all of the chained indexes into the operand array
-  V = cast<User>(V)->getOperand(0);
-
-  while (const GEPOperator *G = dyn_cast<GEPOperator>(V)) {
-    if (!isa<Constant>(GEPOps[0]) || isa<GlobalValue>(GEPOps[0]) ||
-        !cast<Constant>(GEPOps[0])->isNullValue())
-      break;  // Don't handle folding arbitrary pointer offsets yet...
-    GEPOps.erase(GEPOps.begin());   // Drop the zero index
-    GEPOps.insert(GEPOps.begin(), G->op_begin()+1, G->op_end());
-    V = G->getOperand(0);
-  }
-  return V;
-}
-
 /// isKnownNonNull - Return true if we know that the specified value is never
 /// null.
 static bool isKnownNonNull(const Value *V) {
@@ -79,7 +58,12 @@ static bool isKnownNonNull(const Value *V) {
 static bool isNonEscapingLocalObject(const Value *V) {
   // If this is a local allocation, check to see if it escapes.
   if (isa<AllocaInst>(V) || isNoAliasCall(V))
-    return !PointerMayBeCaptured(V, false);
+    // Set StoreCaptures to True so that we can assume in our callers that the
+    // pointer is not the result of a load instruction. Currently
+    // PointerMayBeCaptured doesn't have any special analysis for the
+    // StoreCaptures=false case; if it did, our callers could be refined to be
+    // more precise.
+    return !PointerMayBeCaptured(V, false, /*StoreCaptures=*/true);
 
   // If this is an argument that corresponds to a byval or noalias argument,
   // then it has not escaped before entering the function.  Check if it escapes
@@ -89,7 +73,7 @@ static bool isNonEscapingLocalObject(const Value *V) {
       // Don't bother analyzing arguments already known not to escape.
       if (A->hasNoCaptureAttr())
         return true;
-      return !PointerMayBeCaptured(V, false);
+      return !PointerMayBeCaptured(V, false, /*StoreCaptures=*/true);
     }
   return false;
 }
@@ -159,7 +143,6 @@ namespace {
       llvm_unreachable("This method may not be called on this function!");
     }
 
-    virtual void getMustAliases(Value *P, std::vector<Value*> &RetVals) { }
     virtual bool pointsToConstantMemory(const Value *P) { return false; }
     virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) {
       return ModRef;
@@ -167,7 +150,6 @@ namespace {
     virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
       return ModRef;
     }
-    virtual bool hasNoModRefInfoForCalls() const { return true; }
 
     virtual void deleteValue(Value *V) {}
     virtual void copyValue(Value *From, Value *To) {}
@@ -206,10 +188,6 @@ namespace {
     ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
     ModRefResult getModRefInfo(CallSite CS1, CallSite CS2);
 
-    /// hasNoModRefInfoForCalls - We can provide mod/ref information against
-    /// non-escaping allocations.
-    virtual bool hasNoModRefInfoForCalls() const { return false; }
-
     /// pointsToConstantMemory - Chase pointers until we find a (constant
     /// global) or not.
     bool pointsToConstantMemory(const Value *P);
@@ -218,13 +196,14 @@ namespace {
     // VisitedPHIs - Track PHI nodes visited by a aliasCheck() call.
     SmallPtrSet<const Value*, 16> VisitedPHIs;
 
-    // aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP instruction
-    // against another.
-    AliasResult aliasGEP(const Value *V1, unsigned V1Size,
-                         const Value *V2, unsigned V2Size);
+    // aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP
+    // instruction against another.
+    AliasResult aliasGEP(const GEPOperator *V1, unsigned V1Size,
+                         const Value *V2, unsigned V2Size,
+                         const Value *UnderlyingV1, const Value *UnderlyingV2);
 
-    // aliasPHI - Provide a bunch of ad-hoc rules to disambiguate a PHI instruction
-    // against another.
+    // aliasPHI - Provide a bunch of ad-hoc rules to disambiguate a PHI
+    // instruction against another.
     AliasResult aliasPHI(const PHINode *PN, unsigned PNSize,
                          const Value *V2, unsigned V2Size);
 
@@ -234,15 +213,6 @@ namespace {
 
     AliasResult aliasCheck(const Value *V1, unsigned V1Size,
                            const Value *V2, unsigned V2Size);
-
-    // CheckGEPInstructions - Check two GEP instructions with known
-    // must-aliasing base pointers.  This checks to see if the index expressions
-    // preclude the pointers from aliasing...
-    AliasResult
-    CheckGEPInstructions(const Type* BasePtr1Ty,
-                         Value **GEP1Ops, unsigned NumGEP1Ops, unsigned G1Size,
-                         const Type *BasePtr2Ty,
-                         Value **GEP2Ops, unsigned NumGEP2Ops, unsigned G2Size);
   };
 }  // End of anonymous namespace
 
@@ -264,107 +234,124 @@ ImmutablePass *llvm::createBasicAliasAnalysisPass() {
 bool BasicAliasAnalysis::pointsToConstantMemory(const Value *P) {
   if (const GlobalVariable *GV = 
         dyn_cast<GlobalVariable>(P->getUnderlyingObject()))
+    // Note: this doesn't require GV to be "ODR" because it isn't legal for a
+    // global to be marked constant in some modules and non-constant in others.
+    // GV may even be a declaration, not a definition.
     return GV->isConstant();
   return false;
 }
 
 
-// getModRefInfo - Check to see if the specified callsite can clobber the
-// specified memory object.  Since we only look at local properties of this
-// function, we really can't say much about this query.  We do, however, use
-// simple "address taken" analysis on local objects.
-//
+/// getModRefInfo - Check to see if the specified callsite can clobber the
+/// specified memory object.  Since we only look at local properties of this
+/// function, we really can't say much about this query.  We do, however, use
+/// simple "address taken" analysis on local objects.
 AliasAnalysis::ModRefResult
 BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
-  if (!isa<Constant>(P)) {
-    const Value *Object = P->getUnderlyingObject();
-    
-    // If this is a tail call and P points to a stack location, we know that
-    // the tail call cannot access or modify the local stack.
-    // We cannot exclude byval arguments here; these belong to the caller of
-    // the current function not to the current function, and a tail callee
-    // may reference them.
-    if (isa<AllocaInst>(Object))
-      if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction()))
-        if (CI->isTailCall())
-          return NoModRef;
-    
-    // If the pointer is to a locally allocated object that does not escape,
-    // then the call can not mod/ref the pointer unless the call takes the
-    // argument without capturing it.
-    if (isNonEscapingLocalObject(Object) && CS.getInstruction() != Object) {
-      bool passedAsArg = false;
-      // TODO: Eventually only check 'nocapture' arguments.
-      for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
-           CI != CE; ++CI)
-        if (isa<PointerType>((*CI)->getType()) &&
-            alias(cast<Value>(CI), ~0U, P, ~0U) != NoAlias)
-          passedAsArg = true;
-      
-      if (!passedAsArg)
+  const Value *Object = P->getUnderlyingObject();
+  
+  // If this is a tail call and P points to a stack location, we know that
+  // the tail call cannot access or modify the local stack.
+  // We cannot exclude byval arguments here; these belong to the caller of
+  // the current function not to the current function, and a tail callee
+  // may reference them.
+  if (isa<AllocaInst>(Object))
+    if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction()))
+      if (CI->isTailCall())
         return NoModRef;
-    }
-
-    if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
-      switch (II->getIntrinsicID()) {
-      default: break;
-      case Intrinsic::memcpy:
-      case Intrinsic::memmove: {
-        unsigned Len = ~0U;
-        if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getOperand(3)))
-          Len = LenCI->getZExtValue();
-        Value *Dest = II->getOperand(1);
-        Value *Src = II->getOperand(2);
-        if (alias(Dest, Len, P, Size) == NoAlias) {
-          if (alias(Src, Len, P, Size) == NoAlias)
-            return NoModRef;
-          return Ref;
-        }
-        }
-        break;
-      case Intrinsic::memset:
-        if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getOperand(3))) {
-          unsigned Len = LenCI->getZExtValue();
-          Value *Dest = II->getOperand(1);
-          if (alias(Dest, Len, P, Size) == NoAlias)
-            return NoModRef;
-        }
-        break;
-      case Intrinsic::atomic_cmp_swap:
-      case Intrinsic::atomic_swap:
-      case Intrinsic::atomic_load_add:
-      case Intrinsic::atomic_load_sub:
-      case Intrinsic::atomic_load_and:
-      case Intrinsic::atomic_load_nand:
-      case Intrinsic::atomic_load_or:
-      case Intrinsic::atomic_load_xor:
-      case Intrinsic::atomic_load_max:
-      case Intrinsic::atomic_load_min:
-      case Intrinsic::atomic_load_umax:
-      case Intrinsic::atomic_load_umin:
-        if (TD) {
-          Value *Op1 = II->getOperand(1);
-          unsigned Op1Size = TD->getTypeStoreSize(Op1->getType());
-          if (alias(Op1, Op1Size, P, Size) == NoAlias)
-            return NoModRef;
-        }
+  
+  // If the pointer is to a locally allocated object that does not escape,
+  // then the call can not mod/ref the pointer unless the call takes the pointer
+  // as an argument, and itself doesn't capture it.
+  if (!isa<Constant>(Object) && CS.getInstruction() != Object &&
+      isNonEscapingLocalObject(Object)) {
+    bool PassedAsArg = false;
+    unsigned ArgNo = 0;
+    for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
+         CI != CE; ++CI, ++ArgNo) {
+      // Only look at the no-capture pointer arguments.
+      if (!isa<PointerType>((*CI)->getType()) ||
+          !CS.paramHasAttr(ArgNo+1, Attribute::NoCapture))
+        continue;
+      
+      // If  this is a no-capture pointer argument, see if we can tell that it
+      // is impossible to alias the pointer we're checking.  If not, we have to
+      // assume that the call could touch the pointer, even though it doesn't
+      // escape.
+      if (!isNoAlias(cast<Value>(CI), ~0U, P, ~0U)) {
+        PassedAsArg = true;
         break;
-      case Intrinsic::lifetime_start:
-      case Intrinsic::lifetime_end:
-      case Intrinsic::invariant_start: {
-        unsigned PtrSize = cast<ConstantInt>(II->getOperand(1))->getZExtValue();
-        if (alias(II->getOperand(2), PtrSize, P, Size) == NoAlias)
-          return NoModRef;
-      }
-      break;
-      case Intrinsic::invariant_end: {
-        unsigned PtrSize = cast<ConstantInt>(II->getOperand(2))->getZExtValue();
-        if (alias(II->getOperand(3), PtrSize, P, Size) == NoAlias)
-          return NoModRef;
-      }
-      break;
       }
     }
+    
+    if (!PassedAsArg)
+      return NoModRef;
+  }
+
+  // Finally, handle specific knowledge of intrinsics.
+  IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction());
+  if (II == 0)
+    return AliasAnalysis::getModRefInfo(CS, P, Size);
+
+  switch (II->getIntrinsicID()) {
+  default: break;
+  case Intrinsic::memcpy:
+  case Intrinsic::memmove: {
+    unsigned Len = ~0U;
+    if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getOperand(3)))
+      Len = LenCI->getZExtValue();
+    Value *Dest = II->getOperand(1);
+    Value *Src = II->getOperand(2);
+    if (isNoAlias(Dest, Len, P, Size)) {
+      if (isNoAlias(Src, Len, P, Size))
+        return NoModRef;
+      return Ref;
+    }
+    break;
+  }
+  case Intrinsic::memset:
+    // Since memset is 'accesses arguments' only, the AliasAnalysis base class
+    // will handle it for the variable length case.
+    if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getOperand(3))) {
+      unsigned Len = LenCI->getZExtValue();
+      Value *Dest = II->getOperand(1);
+      if (isNoAlias(Dest, Len, P, Size))
+        return NoModRef;
+    }
+    break;
+  case Intrinsic::atomic_cmp_swap:
+  case Intrinsic::atomic_swap:
+  case Intrinsic::atomic_load_add:
+  case Intrinsic::atomic_load_sub:
+  case Intrinsic::atomic_load_and:
+  case Intrinsic::atomic_load_nand:
+  case Intrinsic::atomic_load_or:
+  case Intrinsic::atomic_load_xor:
+  case Intrinsic::atomic_load_max:
+  case Intrinsic::atomic_load_min:
+  case Intrinsic::atomic_load_umax:
+  case Intrinsic::atomic_load_umin:
+    if (TD) {
+      Value *Op1 = II->getOperand(1);
+      unsigned Op1Size = TD->getTypeStoreSize(Op1->getType());
+      if (isNoAlias(Op1, Op1Size, P, Size))
+        return NoModRef;
+    }
+    break;
+  case Intrinsic::lifetime_start:
+  case Intrinsic::lifetime_end:
+  case Intrinsic::invariant_start: {
+    unsigned PtrSize = cast<ConstantInt>(II->getOperand(1))->getZExtValue();
+    if (isNoAlias(II->getOperand(2), PtrSize, P, Size))
+      return NoModRef;
+    break;
+  }
+  case Intrinsic::invariant_end: {
+    unsigned PtrSize = cast<ConstantInt>(II->getOperand(2))->getZExtValue();
+    if (isNoAlias(II->getOperand(3), PtrSize, P, Size))
+      return NoModRef;
+    break;
+  }
   }
 
   // The AliasAnalysis base class has some smarts, lets use them.
@@ -389,141 +376,157 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS1, CallSite CS2) {
   return NoAA::getModRefInfo(CS1, CS2);
 }
 
-// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP instruction
-// against another.
-//
+/// GetIndiceDifference - Dest and Src are the variable indices from two
+/// decomposed GetElementPtr instructions GEP1 and GEP2 which have common base
+/// pointers.  Subtract the GEP2 indices from GEP1 to find the symbolic
+/// difference between the two pointers. 
+static void GetIndiceDifference(
+                      SmallVectorImpl<std::pair<const Value*, int64_t> > &Dest,
+                const SmallVectorImpl<std::pair<const Value*, int64_t> > &Src) {
+  if (Src.empty()) return;
+
+  for (unsigned i = 0, e = Src.size(); i != e; ++i) {
+    const Value *V = Src[i].first;
+    int64_t Scale = Src[i].second;
+    
+    // Find V in Dest.  This is N^2, but pointer indices almost never have more
+    // than a few variable indexes.
+    for (unsigned j = 0, e = Dest.size(); j != e; ++j) {
+      if (Dest[j].first != V) continue;
+      
+      // If we found it, subtract off Scale V's from the entry in Dest.  If it
+      // goes to zero, remove the entry.
+      if (Dest[j].second != Scale)
+        Dest[j].second -= Scale;
+      else
+        Dest.erase(Dest.begin()+j);
+      Scale = 0;
+      break;
+    }
+    
+    // If we didn't consume this entry, add it to the end of the Dest list.
+    if (Scale)
+      Dest.push_back(std::make_pair(V, -Scale));
+  }
+}
+
+/// aliasGEP - Provide a bunch of ad-hoc rules to disambiguate a GEP instruction
+/// against another pointer.  We know that V1 is a GEP, but we don't know
+/// anything about V2.  UnderlyingV1 is GEP1->getUnderlyingObject(),
+/// UnderlyingV2 is the same for V2.
+///
 AliasAnalysis::AliasResult
-BasicAliasAnalysis::aliasGEP(const Value *V1, unsigned V1Size,
-                             const Value *V2, unsigned V2Size) {
+BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, unsigned V1Size,
+                             const Value *V2, unsigned V2Size,
+                             const Value *UnderlyingV1,
+                             const Value *UnderlyingV2) {
+  int64_t GEP1BaseOffset;
+  SmallVector<std::pair<const Value*, int64_t>, 4> GEP1VariableIndices;
+
   // If we have two gep instructions with must-alias'ing base pointers, figure
   // out if the indexes to the GEP tell us anything about the derived pointer.
-  // Note that we also handle chains of getelementptr instructions as well as
-  // constant expression getelementptrs here.
-  //
-  if (isa<GEPOperator>(V1) && isa<GEPOperator>(V2)) {
-    const User *GEP1 = cast<User>(V1);
-    const User *GEP2 = cast<User>(V2);
+  if (const GEPOperator *GEP2 = dyn_cast<GEPOperator>(V2)) {
+    // Do the base pointers alias?
+    AliasResult BaseAlias = aliasCheck(UnderlyingV1, ~0U, UnderlyingV2, ~0U);
     
-    // If V1 and V2 are identical GEPs, just recurse down on both of them.
-    // This allows us to analyze things like:
-    //   P = gep A, 0, i, 1
-    //   Q = gep B, 0, i, 1
-    // by just analyzing A and B.  This is even safe for variable indices.
-    if (GEP1->getType() == GEP2->getType() &&
-        GEP1->getNumOperands() == GEP2->getNumOperands() &&
-        GEP1->getOperand(0)->getType() == GEP2->getOperand(0)->getType() &&
-        // All operands are the same, ignoring the base.
-        std::equal(GEP1->op_begin()+1, GEP1->op_end(), GEP2->op_begin()+1))
-      return aliasCheck(GEP1->getOperand(0), V1Size,
-                        GEP2->getOperand(0), V2Size);
+    // If we get a No or May, then return it immediately, no amount of analysis
+    // will improve this situation.
+    if (BaseAlias != MustAlias) return BaseAlias;
     
-    // Drill down into the first non-gep value, to test for must-aliasing of
-    // the base pointers.
-    while (isa<GEPOperator>(GEP1->getOperand(0)) &&
-           GEP1->getOperand(1) ==
-           Constant::getNullValue(GEP1->getOperand(1)->getType()))
-      GEP1 = cast<User>(GEP1->getOperand(0));
-    const Value *BasePtr1 = GEP1->getOperand(0);
-
-    while (isa<GEPOperator>(GEP2->getOperand(0)) &&
-           GEP2->getOperand(1) ==
-           Constant::getNullValue(GEP2->getOperand(1)->getType()))
-      GEP2 = cast<User>(GEP2->getOperand(0));
-    const Value *BasePtr2 = GEP2->getOperand(0);
-
-    // Do the base pointers alias?
-    AliasResult BaseAlias = aliasCheck(BasePtr1, ~0U, BasePtr2, ~0U);
-    if (BaseAlias == NoAlias) return NoAlias;
-    if (BaseAlias == MustAlias) {
-      // If the base pointers alias each other exactly, check to see if we can
-      // figure out anything about the resultant pointers, to try to prove
-      // non-aliasing.
-
-      // Collect all of the chained GEP operands together into one simple place
-      SmallVector<Value*, 16> GEP1Ops, GEP2Ops;
-      BasePtr1 = GetGEPOperands(V1, GEP1Ops);
-      BasePtr2 = GetGEPOperands(V2, GEP2Ops);
-
-      // If GetGEPOperands were able to fold to the same must-aliased pointer,
-      // do the comparison.
-      if (BasePtr1 == BasePtr2) {
-        AliasResult GAlias =
-          CheckGEPInstructions(BasePtr1->getType(),
-                               &GEP1Ops[0], GEP1Ops.size(), V1Size,
-                               BasePtr2->getType(),
-                               &GEP2Ops[0], GEP2Ops.size(), V2Size);
-        if (GAlias != MayAlias)
-          return GAlias;
-      }
+    // Otherwise, we have a MustAlias.  Since the base pointers alias each other
+    // exactly, see if the computed offset from the common pointer tells us
+    // about the relation of the resulting pointer.
+    const Value *GEP1BasePtr =
+      DecomposeGEPExpression(GEP1, GEP1BaseOffset, GEP1VariableIndices, TD);
+    
+    int64_t GEP2BaseOffset;
+    SmallVector<std::pair<const Value*, int64_t>, 4> GEP2VariableIndices;
+    const Value *GEP2BasePtr =
+      DecomposeGEPExpression(GEP2, GEP2BaseOffset, GEP2VariableIndices, TD);
+    
+    // If DecomposeGEPExpression isn't able to look all the way through the
+    // addressing operation, we must not have TD and this is too complex for us
+    // to handle without it.
+    if (GEP1BasePtr != UnderlyingV1 || GEP2BasePtr != UnderlyingV2) {
+      assert(TD == 0 &&
+             "DecomposeGEPExpression and getUnderlyingObject disagree!");
+      return MayAlias;
     }
-  }
+    
+    // Subtract the GEP2 pointer from the GEP1 pointer to find out their
+    // symbolic difference.
+    GEP1BaseOffset -= GEP2BaseOffset;
+    GetIndiceDifference(GEP1VariableIndices, GEP2VariableIndices);
+    
+  } else {
+    // Check to see if these two pointers are related by the getelementptr
+    // instruction.  If one pointer is a GEP with a non-zero index of the other
+    // pointer, we know they cannot alias.
 
-  // Check to see if these two pointers are related by a getelementptr
-  // instruction.  If one pointer is a GEP with a non-zero index of the other
-  // pointer, we know they cannot alias.
-  //
-  if (V1Size == ~0U || V2Size == ~0U)
-    return MayAlias;
+    // If both accesses are unknown size, we can't do anything useful here.
+    if (V1Size == ~0U && V2Size == ~0U)
+      return MayAlias;
 
-  SmallVector<Value*, 16> GEPOperands;
-  const Value *BasePtr = GetGEPOperands(V1, GEPOperands);
-
-  AliasResult R = aliasCheck(BasePtr, ~0U, V2, V2Size);
-  if (R != MustAlias)
-    // If V2 may alias GEP base pointer, conservatively returns MayAlias.
-    // If V2 is known not to alias GEP base pointer, then the two values
-    // cannot alias per GEP semantics: "A pointer value formed from a
-    // getelementptr instruction is associated with the addresses associated
-    // with the first operand of the getelementptr".
-    return R;
-
-  // If there is at least one non-zero constant index, we know they cannot
-  // alias.
-  bool ConstantFound = false;
-  bool AllZerosFound = true;
-  for (unsigned i = 0, e = GEPOperands.size(); i != e; ++i)
-    if (const Constant *C = dyn_cast<Constant>(GEPOperands[i])) {
-      if (!C->isNullValue()) {
-        ConstantFound = true;
-        AllZerosFound = false;
-        break;
-      }
-    } else {
-      AllZerosFound = false;
+    AliasResult R = aliasCheck(UnderlyingV1, ~0U, V2, V2Size);
+    if (R != MustAlias)
+      // If V2 may alias GEP base pointer, conservatively returns MayAlias.
+      // If V2 is known not to alias GEP base pointer, then the two values
+      // cannot alias per GEP semantics: "A pointer value formed from a
+      // getelementptr instruction is associated with the addresses associated
+      // with the first operand of the getelementptr".
+      return R;
+
+    const Value *GEP1BasePtr =
+      DecomposeGEPExpression(GEP1, GEP1BaseOffset, GEP1VariableIndices, TD);
+    
+    // If DecomposeGEPExpression isn't able to look all the way through the
+    // addressing operation, we must not have TD and this is too complex for us
+    // to handle without it.
+    if (GEP1BasePtr != UnderlyingV1) {
+      assert(TD == 0 &&
+             "DecomposeGEPExpression and getUnderlyingObject disagree!");
+      return MayAlias;
     }
-
-  // If we have getelementptr <ptr>, 0, 0, 0, 0, ... and V2 must aliases
-  // the ptr, the end result is a must alias also.
-  if (AllZerosFound)
+  }
+  
+  // In the two GEP Case, if there is no difference in the offsets of the
+  // computed pointers, the resultant pointers are a must alias.  This
+  // hapens when we have two lexically identical GEP's (for example).
+  //
+  // In the other case, if we have getelementptr <ptr>, 0, 0, 0, 0, ... and V2
+  // must aliases the GEP, the end result is a must alias also.
+  if (GEP1BaseOffset == 0 && GEP1VariableIndices.empty())
     return MustAlias;
 
-  if (ConstantFound) {
-    if (V2Size <= 1 && V1Size <= 1)  // Just pointer check?
+  // If we have a known constant offset, see if this offset is larger than the
+  // access size being queried.  If so, and if no variable indices can remove
+  // pieces of this constant, then we know we have a no-alias.  For example,
+  //   &A[100] != &A.
+  
+  // In order to handle cases like &A[100][i] where i is an out of range
+  // subscript, we have to ignore all constant offset pieces that are a multiple
+  // of a scaled index.  Do this by removing constant offsets that are a
+  // multiple of any of our variable indices.  This allows us to transform
+  // things like &A[i][1] because i has a stride of (e.g.) 8 bytes but the 1
+  // provides an offset of 4 bytes (assuming a <= 4 byte access).
+  for (unsigned i = 0, e = GEP1VariableIndices.size();
+       i != e && GEP1BaseOffset;++i)
+    if (int64_t RemovedOffset = GEP1BaseOffset/GEP1VariableIndices[i].second)
+      GEP1BaseOffset -= RemovedOffset*GEP1VariableIndices[i].second;
+  
+  // If our known offset is bigger than the access size, we know we don't have
+  // an alias.
+  if (GEP1BaseOffset) {
+    if (GEP1BaseOffset >= (int64_t)V2Size ||
+        GEP1BaseOffset <= -(int64_t)V1Size)
       return NoAlias;
-
-    // Otherwise we have to check to see that the distance is more than
-    // the size of the argument... build an index vector that is equal to
-    // the arguments provided, except substitute 0's for any variable
-    // indexes we find...
-    if (TD &&
-        cast<PointerType>(BasePtr->getType())->getElementType()->isSized()) {
-      for (unsigned i = 0; i != GEPOperands.size(); ++i)
-        if (!isa<ConstantInt>(GEPOperands[i]))
-          GEPOperands[i] = Constant::getNullValue(GEPOperands[i]->getType());
-      int64_t Offset = TD->getIndexedOffset(BasePtr->getType(),
-                                            &GEPOperands[0],
-                                            GEPOperands.size());
-
-      if (Offset >= (int64_t)V2Size || Offset <= -(int64_t)V1Size)
-        return NoAlias;
-    }
   }
-
+  
   return MayAlias;
 }
 
-// aliasSelect - Provide a bunch of ad-hoc rules to disambiguate a Select instruction
-// against another.
+/// aliasSelect - Provide a bunch of ad-hoc rules to disambiguate a Select
+/// instruction against another.
 AliasAnalysis::AliasResult
 BasicAliasAnalysis::aliasSelect(const SelectInst *SI, unsigned SISize,
                                 const Value *V2, unsigned V2Size) {
@@ -683,22 +686,31 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, unsigned V1Size,
         (V2Size != ~0U && isObjectSmallerThan(O1, V2Size, *TD)))
       return NoAlias;
   
-  // If one pointer is the result of a call/invoke and the other is a
+  // If one pointer is the result of a call/invoke or load and the other is a
   // non-escaping local object, then we know the object couldn't escape to a
-  // point where the call could return it.
-  if ((isa<CallInst>(O1) || isa<InvokeInst>(O1)) &&
-      isNonEscapingLocalObject(O2) && O1 != O2)
-    return NoAlias;
-  if ((isa<CallInst>(O2) || isa<InvokeInst>(O2)) &&
-      isNonEscapingLocalObject(O1) && O1 != O2)
-    return NoAlias;
+  // point where the call could return it. The load case works because
+  // isNonEscapingLocalObject considers all stores to be escapes (it
+  // passes true for the StoreCaptures argument to PointerMayBeCaptured).
+  if (O1 != O2) {
+    if ((isa<CallInst>(O1) || isa<InvokeInst>(O1) || isa<LoadInst>(O1) ||
+         isa<Argument>(O1)) &&
+        isNonEscapingLocalObject(O2))
+      return NoAlias;
+    if ((isa<CallInst>(O2) || isa<InvokeInst>(O2) || isa<LoadInst>(O2) ||
+         isa<Argument>(O2)) &&
+        isNonEscapingLocalObject(O1))
+      return NoAlias;
+  }
 
+  // FIXME: This isn't aggressively handling alias(GEP, PHI) for example: if the
+  // GEP can't simplify, we don't even look at the PHI cases.
   if (!isa<GEPOperator>(V1) && isa<GEPOperator>(V2)) {
     std::swap(V1, V2);
     std::swap(V1Size, V2Size);
+    std::swap(O1, O2);
   }
-  if (isa<GEPOperator>(V1))
-    return aliasGEP(V1, V1Size, V2, V2Size);
+  if (const GEPOperator *GV1 = dyn_cast<GEPOperator>(V1))
+    return aliasGEP(GV1, V1Size, V2, V2Size, O1, O2);
 
   if (isa<PHINode>(V2) && !isa<PHINode>(V1)) {
     std::swap(V1, V2);
@@ -717,351 +729,5 @@ BasicAliasAnalysis::aliasCheck(const Value *V1, unsigned V1Size,
   return MayAlias;
 }
 
-// This function is used to determine if the indices of two GEP instructions are
-// equal. V1 and V2 are the indices.
-static bool IndexOperandsEqual(Value *V1, Value *V2) {
-  if (V1->getType() == V2->getType())
-    return V1 == V2;
-  if (Constant *C1 = dyn_cast<Constant>(V1))
-    if (Constant *C2 = dyn_cast<Constant>(V2)) {
-      // Sign extend the constants to long types, if necessary
-      if (C1->getType() != Type::getInt64Ty(C1->getContext()))
-        C1 = ConstantExpr::getSExt(C1, Type::getInt64Ty(C1->getContext()));
-      if (C2->getType() != Type::getInt64Ty(C1->getContext())) 
-        C2 = ConstantExpr::getSExt(C2, Type::getInt64Ty(C1->getContext()));
-      return C1 == C2;
-    }
-  return false;
-}
-
-/// CheckGEPInstructions - Check two GEP instructions with known must-aliasing
-/// base pointers.  This checks to see if the index expressions preclude the
-/// pointers from aliasing...
-AliasAnalysis::AliasResult 
-BasicAliasAnalysis::CheckGEPInstructions(
-  const Type* BasePtr1Ty, Value **GEP1Ops, unsigned NumGEP1Ops, unsigned G1S,
-  const Type *BasePtr2Ty, Value **GEP2Ops, unsigned NumGEP2Ops, unsigned G2S) {
-  // We currently can't handle the case when the base pointers have different
-  // primitive types.  Since this is uncommon anyway, we are happy being
-  // extremely conservative.
-  if (BasePtr1Ty != BasePtr2Ty)
-    return MayAlias;
-
-  const PointerType *GEPPointerTy = cast<PointerType>(BasePtr1Ty);
-
-  // Find the (possibly empty) initial sequence of equal values... which are not
-  // necessarily constants.
-  unsigned NumGEP1Operands = NumGEP1Ops, NumGEP2Operands = NumGEP2Ops;
-  unsigned MinOperands = std::min(NumGEP1Operands, NumGEP2Operands);
-  unsigned MaxOperands = std::max(NumGEP1Operands, NumGEP2Operands);
-  unsigned UnequalOper = 0;
-  while (UnequalOper != MinOperands &&
-         IndexOperandsEqual(GEP1Ops[UnequalOper], GEP2Ops[UnequalOper])) {
-    // Advance through the type as we go...
-    ++UnequalOper;
-    if (const CompositeType *CT = dyn_cast<CompositeType>(BasePtr1Ty))
-      BasePtr1Ty = CT->getTypeAtIndex(GEP1Ops[UnequalOper-1]);
-    else {
-      // If all operands equal each other, then the derived pointers must
-      // alias each other...
-      BasePtr1Ty = 0;
-      assert(UnequalOper == NumGEP1Operands && UnequalOper == NumGEP2Operands &&
-             "Ran out of type nesting, but not out of operands?");
-      return MustAlias;
-    }
-  }
-
-  // If we have seen all constant operands, and run out of indexes on one of the
-  // getelementptrs, check to see if the tail of the leftover one is all zeros.
-  // If so, return mustalias.
-  if (UnequalOper == MinOperands) {
-    if (NumGEP1Ops < NumGEP2Ops) {
-      std::swap(GEP1Ops, GEP2Ops);
-      std::swap(NumGEP1Ops, NumGEP2Ops);
-    }
-
-    bool AllAreZeros = true;
-    for (unsigned i = UnequalOper; i != MaxOperands; ++i)
-      if (!isa<Constant>(GEP1Ops[i]) ||
-          !cast<Constant>(GEP1Ops[i])->isNullValue()) {
-        AllAreZeros = false;
-        break;
-      }
-    if (AllAreZeros) return MustAlias;
-  }
-
-
-  // So now we know that the indexes derived from the base pointers,
-  // which are known to alias, are different.  We can still determine a
-  // no-alias result if there are differing constant pairs in the index
-  // chain.  For example:
-  //        A[i][0] != A[j][1] iff (&A[0][1]-&A[0][0] >= std::max(G1S, G2S))
-  //
-  // We have to be careful here about array accesses.  In particular, consider:
-  //        A[1][0] vs A[0][i]
-  // In this case, we don't *know* that the array will be accessed in bounds:
-  // the index could even be negative.  Because of this, we have to
-  // conservatively *give up* and return may alias.  We disregard differing
-  // array subscripts that are followed by a variable index without going
-  // through a struct.
-  //
-  unsigned SizeMax = std::max(G1S, G2S);
-  if (SizeMax == ~0U) return MayAlias; // Avoid frivolous work.
-
-  // Scan for the first operand that is constant and unequal in the
-  // two getelementptrs...
-  unsigned FirstConstantOper = UnequalOper;
-  for (; FirstConstantOper != MinOperands; ++FirstConstantOper) {
-    const Value *G1Oper = GEP1Ops[FirstConstantOper];
-    const Value *G2Oper = GEP2Ops[FirstConstantOper];
-
-    if (G1Oper != G2Oper)   // Found non-equal constant indexes...
-      if (Constant *G1OC = dyn_cast<ConstantInt>(const_cast<Value*>(G1Oper)))
-        if (Constant *G2OC = dyn_cast<ConstantInt>(const_cast<Value*>(G2Oper))){
-          if (G1OC->getType() != G2OC->getType()) {
-            // Sign extend both operands to long.
-            const Type *Int64Ty = Type::getInt64Ty(G1OC->getContext());
-            if (G1OC->getType() != Int64Ty)
-              G1OC = ConstantExpr::getSExt(G1OC, Int64Ty);
-            if (G2OC->getType() != Int64Ty) 
-              G2OC = ConstantExpr::getSExt(G2OC, Int64Ty);
-            GEP1Ops[FirstConstantOper] = G1OC;
-            GEP2Ops[FirstConstantOper] = G2OC;
-          }
-          
-          if (G1OC != G2OC) {
-            // Handle the "be careful" case above: if this is an array/vector
-            // subscript, scan for a subsequent variable array index.
-            if (const SequentialType *STy =
-                  dyn_cast<SequentialType>(BasePtr1Ty)) {
-              const Type *NextTy = STy;
-              bool isBadCase = false;
-              
-              for (unsigned Idx = FirstConstantOper;
-                   Idx != MinOperands && isa<SequentialType>(NextTy); ++Idx) {
-                const Value *V1 = GEP1Ops[Idx], *V2 = GEP2Ops[Idx];
-                if (!isa<Constant>(V1) || !isa<Constant>(V2)) {
-                  isBadCase = true;
-                  break;
-                }
-                // If the array is indexed beyond the bounds of the static type
-                // at this level, it will also fall into the "be careful" case.
-                // It would theoretically be possible to analyze these cases,
-                // but for now just be conservatively correct.
-                if (const ArrayType *ATy = dyn_cast<ArrayType>(STy))
-                  if (cast<ConstantInt>(G1OC)->getZExtValue() >=
-                        ATy->getNumElements() ||
-                      cast<ConstantInt>(G2OC)->getZExtValue() >=
-                        ATy->getNumElements()) {
-                    isBadCase = true;
-                    break;
-                  }
-                if (const VectorType *VTy = dyn_cast<VectorType>(STy))
-                  if (cast<ConstantInt>(G1OC)->getZExtValue() >=
-                        VTy->getNumElements() ||
-                      cast<ConstantInt>(G2OC)->getZExtValue() >=
-                        VTy->getNumElements()) {
-                    isBadCase = true;
-                    break;
-                  }
-                STy = cast<SequentialType>(NextTy);
-                NextTy = cast<SequentialType>(NextTy)->getElementType();
-              }
-              
-              if (isBadCase) G1OC = 0;
-            }
-
-            // Make sure they are comparable (ie, not constant expressions), and
-            // make sure the GEP with the smaller leading constant is GEP1.
-            if (G1OC) {
-              Constant *Compare = ConstantExpr::getICmp(ICmpInst::ICMP_SGT, 
-                                                        G1OC, G2OC);
-              if (ConstantInt *CV = dyn_cast<ConstantInt>(Compare)) {
-                if (CV->getZExtValue()) {  // If they are comparable and G2 > G1
-                  std::swap(GEP1Ops, GEP2Ops);  // Make GEP1 < GEP2
-                  std::swap(NumGEP1Ops, NumGEP2Ops);
-                }
-                break;
-              }
-            }
-          }
-        }
-    BasePtr1Ty = cast<CompositeType>(BasePtr1Ty)->getTypeAtIndex(G1Oper);
-  }
-
-  // No shared constant operands, and we ran out of common operands.  At this
-  // point, the GEP instructions have run through all of their operands, and we
-  // haven't found evidence that there are any deltas between the GEP's.
-  // However, one GEP may have more operands than the other.  If this is the
-  // case, there may still be hope.  Check this now.
-  if (FirstConstantOper == MinOperands) {
-    // Without TargetData, we won't know what the offsets are.
-    if (!TD)
-      return MayAlias;
-
-    // Make GEP1Ops be the longer one if there is a longer one.
-    if (NumGEP1Ops < NumGEP2Ops) {
-      std::swap(GEP1Ops, GEP2Ops);
-      std::swap(NumGEP1Ops, NumGEP2Ops);
-    }
-
-    // Is there anything to check?
-    if (NumGEP1Ops > MinOperands) {
-      for (unsigned i = FirstConstantOper; i != MaxOperands; ++i)
-        if (isa<ConstantInt>(GEP1Ops[i]) && 
-            !cast<ConstantInt>(GEP1Ops[i])->isZero()) {
-          // Yup, there's a constant in the tail.  Set all variables to
-          // constants in the GEP instruction to make it suitable for
-          // TargetData::getIndexedOffset.
-          for (i = 0; i != MaxOperands; ++i)
-            if (!isa<ConstantInt>(GEP1Ops[i]))
-              GEP1Ops[i] = Constant::getNullValue(GEP1Ops[i]->getType());
-          // Okay, now get the offset.  This is the relative offset for the full
-          // instruction.
-          int64_t Offset1 = TD->getIndexedOffset(GEPPointerTy, GEP1Ops,
-                                                 NumGEP1Ops);
-
-          // Now check without any constants at the end.
-          int64_t Offset2 = TD->getIndexedOffset(GEPPointerTy, GEP1Ops,
-                                                 MinOperands);
-
-          // Make sure we compare the absolute difference.
-          if (Offset1 > Offset2)
-            std::swap(Offset1, Offset2);
-
-          // If the tail provided a bit enough offset, return noalias!
-          if ((uint64_t)(Offset2-Offset1) >= SizeMax)
-            return NoAlias;
-          // Otherwise break - we don't look for another constant in the tail.
-          break;
-        }
-    }
-
-    // Couldn't find anything useful.
-    return MayAlias;
-  }
-
-  // If there are non-equal constants arguments, then we can figure
-  // out a minimum known delta between the two index expressions... at
-  // this point we know that the first constant index of GEP1 is less
-  // than the first constant index of GEP2.
-
-  // Advance BasePtr[12]Ty over this first differing constant operand.
-  BasePtr2Ty = cast<CompositeType>(BasePtr1Ty)->
-      getTypeAtIndex(GEP2Ops[FirstConstantOper]);
-  BasePtr1Ty = cast<CompositeType>(BasePtr1Ty)->
-      getTypeAtIndex(GEP1Ops[FirstConstantOper]);
-
-  // We are going to be using TargetData::getIndexedOffset to determine the
-  // offset that each of the GEP's is reaching.  To do this, we have to convert
-  // all variable references to constant references.  To do this, we convert the
-  // initial sequence of array subscripts into constant zeros to start with.
-  const Type *ZeroIdxTy = GEPPointerTy;
-  for (unsigned i = 0; i != FirstConstantOper; ++i) {
-    if (!isa<StructType>(ZeroIdxTy))
-      GEP1Ops[i] = GEP2Ops[i] = 
-              Constant::getNullValue(Type::getInt32Ty(ZeroIdxTy->getContext()));
-
-    if (const CompositeType *CT = dyn_cast<CompositeType>(ZeroIdxTy))
-      ZeroIdxTy = CT->getTypeAtIndex(GEP1Ops[i]);
-  }
-
-  // We know that GEP1Ops[FirstConstantOper] & GEP2Ops[FirstConstantOper] are ok
-
-  // Loop over the rest of the operands...
-  for (unsigned i = FirstConstantOper+1; i != MaxOperands; ++i) {
-    const Value *Op1 = i < NumGEP1Ops ? GEP1Ops[i] : 0;
-    const Value *Op2 = i < NumGEP2Ops ? GEP2Ops[i] : 0;
-    // If they are equal, use a zero index...
-    if (Op1 == Op2 && BasePtr1Ty == BasePtr2Ty) {
-      if (!isa<ConstantInt>(Op1))
-        GEP1Ops[i] = GEP2Ops[i] = Constant::getNullValue(Op1->getType());
-      // Otherwise, just keep the constants we have.
-    } else {
-      if (Op1) {
-        if (const ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
-          // If this is an array index, make sure the array element is in range.
-          if (const ArrayType *AT = dyn_cast<ArrayType>(BasePtr1Ty)) {
-            if (Op1C->getZExtValue() >= AT->getNumElements())
-              return MayAlias;  // Be conservative with out-of-range accesses
-          } else if (const VectorType *VT = dyn_cast<VectorType>(BasePtr1Ty)) {
-            if (Op1C->getZExtValue() >= VT->getNumElements())
-              return MayAlias;  // Be conservative with out-of-range accesses
-          }
-          
-        } else {
-          // GEP1 is known to produce a value less than GEP2.  To be
-          // conservatively correct, we must assume the largest possible
-          // constant is used in this position.  This cannot be the initial
-          // index to the GEP instructions (because we know we have at least one
-          // element before this one with the different constant arguments), so
-          // we know that the current index must be into either a struct or
-          // array.  Because we know it's not constant, this cannot be a
-          // structure index.  Because of this, we can calculate the maximum
-          // value possible.
-          //
-          if (const ArrayType *AT = dyn_cast<ArrayType>(BasePtr1Ty))
-            GEP1Ops[i] =
-                  ConstantInt::get(Type::getInt64Ty(AT->getContext()), 
-                                   AT->getNumElements()-1);
-          else if (const VectorType *VT = dyn_cast<VectorType>(BasePtr1Ty))
-            GEP1Ops[i] = 
-                  ConstantInt::get(Type::getInt64Ty(VT->getContext()),
-                                   VT->getNumElements()-1);
-        }
-      }
-
-      if (Op2) {
-        if (const ConstantInt *Op2C = dyn_cast<ConstantInt>(Op2)) {
-          // If this is an array index, make sure the array element is in range.
-          if (const ArrayType *AT = dyn_cast<ArrayType>(BasePtr2Ty)) {
-            if (Op2C->getZExtValue() >= AT->getNumElements())
-              return MayAlias;  // Be conservative with out-of-range accesses
-          } else if (const VectorType *VT = dyn_cast<VectorType>(BasePtr2Ty)) {
-            if (Op2C->getZExtValue() >= VT->getNumElements())
-              return MayAlias;  // Be conservative with out-of-range accesses
-          }
-        } else {  // Conservatively assume the minimum value for this index
-          GEP2Ops[i] = Constant::getNullValue(Op2->getType());
-        }
-      }
-    }
-
-    if (BasePtr1Ty && Op1) {
-      if (const CompositeType *CT = dyn_cast<CompositeType>(BasePtr1Ty))
-        BasePtr1Ty = CT->getTypeAtIndex(GEP1Ops[i]);
-      else
-        BasePtr1Ty = 0;
-    }
-
-    if (BasePtr2Ty && Op2) {
-      if (const CompositeType *CT = dyn_cast<CompositeType>(BasePtr2Ty))
-        BasePtr2Ty = CT->getTypeAtIndex(GEP2Ops[i]);
-      else
-        BasePtr2Ty = 0;
-    }
-  }
-
-  if (TD && GEPPointerTy->getElementType()->isSized()) {
-    int64_t Offset1 =
-      TD->getIndexedOffset(GEPPointerTy, GEP1Ops, NumGEP1Ops);
-    int64_t Offset2 = 
-      TD->getIndexedOffset(GEPPointerTy, GEP2Ops, NumGEP2Ops);
-    assert(Offset1 != Offset2 &&
-           "There is at least one different constant here!");
-    
-    // Make sure we compare the absolute difference.
-    if (Offset1 > Offset2)
-      std::swap(Offset1, Offset2);
-    
-    if ((uint64_t)(Offset2-Offset1) >= SizeMax) {
-      //cerr << "Determined that these two GEP's don't alias ["
-      //     << SizeMax << " bytes]: \n" << *GEP1 << *GEP2;
-      return NoAlias;
-    }
-  }
-  return MayAlias;
-}
-
-// Make sure that anything that uses AliasAnalysis pulls in this file...
+// Make sure that anything that uses AliasAnalysis pulls in this file.
 DEFINING_FILE_FOR(BasicAliasAnalysis)
diff --git a/lib/Analysis/CaptureTracking.cpp b/lib/Analysis/CaptureTracking.cpp
index f615881..a276c64 100644
--- a/lib/Analysis/CaptureTracking.cpp
+++ b/lib/Analysis/CaptureTracking.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Analysis/CaptureTracking.h"
 #include "llvm/Instructions.h"
 #include "llvm/Value.h"
+#include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/CallSite.h"
@@ -28,8 +29,11 @@ using namespace llvm;
 /// by the enclosing function (which is required to exist).  This routine can
 /// be expensive, so consider caching the results.  The boolean ReturnCaptures
 /// specifies whether returning the value (or part of it) from the function
+/// counts as capturing it or not.  The boolean StoreCaptures specified whether
+/// storing the value (or part of it) into memory anywhere automatically
 /// counts as capturing it or not.
-bool llvm::PointerMayBeCaptured(const Value *V, bool ReturnCaptures) {
+bool llvm::PointerMayBeCaptured(const Value *V,
+                                bool ReturnCaptures, bool StoreCaptures) {
   assert(isa<PointerType>(V->getType()) && "Capture is for pointers only!");
   SmallVector<Use*, 16> Worklist;
   SmallSet<Use*, 16> Visited;
@@ -53,8 +57,7 @@ bool llvm::PointerMayBeCaptured(const Value *V, bool ReturnCaptures) {
       // Not captured if the callee is readonly, doesn't return a copy through
       // its return value and doesn't unwind (a readonly function can leak bits
       // by throwing an exception or not depending on the input value).
-      if (CS.onlyReadsMemory() && CS.doesNotThrow() &&
-          I->getType() == Type::getVoidTy(V->getContext()))
+      if (CS.onlyReadsMemory() && CS.doesNotThrow() && I->getType()->isVoidTy())
         break;
 
       // Not captured if only passed via 'nocapture' arguments.  Note that
@@ -82,7 +85,11 @@ bool llvm::PointerMayBeCaptured(const Value *V, bool ReturnCaptures) {
       break;
     case Instruction::Store:
       if (V == I->getOperand(0))
-        // Stored the pointer - it may be captured.
+        // Stored the pointer - conservatively assume it may be captured.
+        // TODO: If StoreCaptures is not true, we could do Fancy analysis
+        // to determine whether this store is not actually an escape point.
+        // In that case, BasicAliasAnalysis should be updated as well to
+        // take advantage of this.
         return true;
       // Storing to the pointee does not cause the pointer to be captured.
       break;
@@ -98,6 +105,18 @@ bool llvm::PointerMayBeCaptured(const Value *V, bool ReturnCaptures) {
           Worklist.push_back(U);
       }
       break;
+    case Instruction::ICmp:
+      // Don't count comparisons of a no-alias return value against null as
+      // captures. This allows us to ignore comparisons of malloc results
+      // with null, for example.
+      if (isNoAliasCall(V->stripPointerCasts()))
+        if (ConstantPointerNull *CPN =
+              dyn_cast<ConstantPointerNull>(I->getOperand(1)))
+          if (CPN->getType()->getAddressSpace() == 0)
+            break;
+      // Otherwise, be conservative. There are crazy ways to capture pointers
+      // using comparisons.
+      return true;
     default:
       // Something else - be conservative and say it is captured.
       return true;
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 1cdadbf..96f738e 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -564,6 +564,7 @@ static Constant *SymbolicallyEvaluateGEP(Constant *const *Ops, unsigned NumOps,
   // we eliminate over-indexing of the notional static type array bounds.
   // This makes it easy to determine if the getelementptr is "inbounds".
   // Also, this helps GlobalOpt do SROA on GlobalVariables.
+  Ptr = cast<Constant>(Ptr->stripPointerCasts());
   const Type *Ty = Ptr->getType();
   SmallVector<Constant*, 32> NewIdxs;
   do {
@@ -671,8 +672,13 @@ Constant *llvm::ConstantFoldInstruction(Instruction *I, const TargetData *TD) {
 Constant *llvm::ConstantFoldConstantExpression(ConstantExpr *CE,
                                                const TargetData *TD) {
   SmallVector<Constant*, 8> Ops;
-  for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i)
-    Ops.push_back(cast<Constant>(*i));
+  for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i) {
+    Constant *NewC = cast<Constant>(*i);
+    // Recursively fold the ConstantExpr's operands.
+    if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(NewC))
+      NewC = ConstantFoldConstantExpression(NewCE, TD);
+    Ops.push_back(NewC);
+  }
 
   if (CE->isCompare())
     return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1],
@@ -687,6 +693,10 @@ Constant *llvm::ConstantFoldConstantExpression(ConstantExpr *CE,
 /// attempting to fold instructions like loads and stores, which have no
 /// constant expression form.
 ///
+/// TODO: This function neither utilizes nor preserves nsw/nuw/inbounds/etc
+/// information, due to only being passed an opcode and operands. Constant
+/// folding using this function strips this information.
+///
 Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy, 
                                          Constant* const* Ops, unsigned NumOps,
                                          const TargetData *TD) {
diff --git a/lib/Analysis/DebugInfo.cpp b/lib/Analysis/DebugInfo.cpp
index 8f62245..41d803c 100644
--- a/lib/Analysis/DebugInfo.cpp
+++ b/lib/Analysis/DebugInfo.cpp
@@ -78,19 +78,16 @@ DIDescriptor::DIDescriptor(MDNode *N, unsigned RequiredTag) {
   }
 }
 
-const char *
+StringRef 
 DIDescriptor::getStringField(unsigned Elt) const {
   if (DbgNode == 0)
-    return NULL;
+    return StringRef();
 
   if (Elt < DbgNode->getNumElements())
-    if (MDString *MDS = dyn_cast_or_null<MDString>(DbgNode->getElement(Elt))) {
-      if (MDS->getLength() == 0)
-        return NULL;
-      return MDS->getString().data();
-    }
+    if (MDString *MDS = dyn_cast_or_null<MDString>(DbgNode->getElement(Elt)))
+      return MDS->getString();
 
-  return NULL;
+  return StringRef();
 }
 
 uint64_t DIDescriptor::getUInt64Field(unsigned Elt) const {
@@ -310,8 +307,8 @@ void DIDerivedType::replaceAllUsesWith(DIDescriptor &D) {
 bool DICompileUnit::Verify() const {
   if (isNull())
     return false;
-  const char *N = getFilename();
-  if (!N)
+  StringRef N = getFilename();
+  if (N.empty())
     return false;
   // It is possible that directory and produce string is empty.
   return true;
@@ -366,7 +363,7 @@ bool DIGlobalVariable::Verify() const {
   if (isNull())
     return false;
 
-  if (!getDisplayName())
+  if (getDisplayName().empty())
     return false;
 
   if (getContext().isNull())
@@ -426,15 +423,15 @@ uint64_t DIDerivedType::getOriginalTypeSize() const {
 /// information for the function F.
 bool DISubprogram::describes(const Function *F) {
   assert (F && "Invalid function");
-  const char *Name = getLinkageName();
-  if (!Name)
+  StringRef Name = getLinkageName();
+  if (Name.empty())
     Name = getName();
-  if (strcmp(F->getName().data(), Name) == 0)
+  if (F->getName() == Name)
     return true;
   return false;
 }
 
-const char *DIScope::getFilename() const {
+StringRef DIScope::getFilename() const {
   if (isLexicalBlock()) 
     return DILexicalBlock(DbgNode).getFilename();
   else if (isSubprogram())
@@ -443,10 +440,10 @@ const char *DIScope::getFilename() const {
     return DICompileUnit(DbgNode).getFilename();
   else 
     assert (0 && "Invalid DIScope!");
-  return NULL;
+  return StringRef();
 }
 
-const char *DIScope::getDirectory() const {
+StringRef DIScope::getDirectory() const {
   if (isLexicalBlock()) 
     return DILexicalBlock(DbgNode).getDirectory();
   else if (isSubprogram())
@@ -455,7 +452,7 @@ const char *DIScope::getDirectory() const {
     return DICompileUnit(DbgNode).getDirectory();
   else 
     assert (0 && "Invalid DIScope!");
-  return NULL;
+  return StringRef();
 }
 
 //===----------------------------------------------------------------------===//
@@ -481,7 +478,8 @@ void DICompileUnit::dump() const {
 void DIType::dump() const {
   if (isNull()) return;
 
-  if (const char *Res = getName())
+  StringRef Res = getName();
+  if (!Res.empty())
     errs() << " [" << Res << "] ";
 
   unsigned Tag = getTag();
@@ -538,7 +536,8 @@ void DICompositeType::dump() const {
 
 /// dump - Print global.
 void DIGlobal::dump() const {
-  if (const char *Res = getName())
+  StringRef Res = getName();
+  if (!Res.empty())
     errs() << " [" << Res << "] ";
 
   unsigned Tag = getTag();
@@ -562,7 +561,8 @@ void DIGlobal::dump() const {
 
 /// dump - Print subprogram.
 void DISubprogram::dump() const {
-  if (const char *Res = getName())
+  StringRef Res = getName();
+  if (!Res.empty())
     errs() << " [" << Res << "] ";
 
   unsigned Tag = getTag();
@@ -590,7 +590,8 @@ void DIGlobalVariable::dump() const {
 
 /// dump - Print variable.
 void DIVariable::dump() const {
-  if (const char *Res = getName())
+  StringRef Res = getName();
+  if (!Res.empty())
     errs() << " [" << Res << "] ";
 
   getCompileUnit().dump();
@@ -651,12 +652,12 @@ DISubrange DIFactory::GetOrCreateSubrange(int64_t Lo, int64_t Hi) {
 /// CreateCompileUnit - Create a new descriptor for the specified compile
 /// unit.  Note that this does not unique compile units within the module.
 DICompileUnit DIFactory::CreateCompileUnit(unsigned LangID,
-                                           const char * Filename,
-                                           const char * Directory,
-                                           const char * Producer,
+                                           StringRef Filename,
+                                           StringRef Directory,
+                                           StringRef Producer,
                                            bool isMain,
                                            bool isOptimized,
-                                           const char *Flags,
+                                           StringRef Flags,
                                            unsigned RunTimeVer) {
   Value *Elts[] = {
     GetTagConstant(dwarf::DW_TAG_compile_unit),
@@ -675,7 +676,7 @@ DICompileUnit DIFactory::CreateCompileUnit(unsigned LangID,
 }
 
 /// CreateEnumerator - Create a single enumerator value.
-DIEnumerator DIFactory::CreateEnumerator(const char * Name, uint64_t Val){
+DIEnumerator DIFactory::CreateEnumerator(StringRef Name, uint64_t Val){
   Value *Elts[] = {
     GetTagConstant(dwarf::DW_TAG_enumerator),
     MDString::get(VMContext, Name),
@@ -687,7 +688,7 @@ DIEnumerator DIFactory::CreateEnumerator(const char * Name, uint64_t Val){
 
 /// CreateBasicType - Create a basic type like int, float, etc.
 DIBasicType DIFactory::CreateBasicType(DIDescriptor Context,
-                                       const char * Name,
+                                       StringRef Name,
                                        DICompileUnit CompileUnit,
                                        unsigned LineNumber,
                                        uint64_t SizeInBits,
@@ -712,7 +713,7 @@ DIBasicType DIFactory::CreateBasicType(DIDescriptor Context,
 
 /// CreateBasicType - Create a basic type like int, float, etc.
 DIBasicType DIFactory::CreateBasicTypeEx(DIDescriptor Context,
-                                         const char * Name,
+                                         StringRef Name,
                                          DICompileUnit CompileUnit,
                                          unsigned LineNumber,
                                          Constant *SizeInBits,
@@ -739,7 +740,7 @@ DIBasicType DIFactory::CreateBasicTypeEx(DIDescriptor Context,
 /// pointer, typedef, etc.
 DIDerivedType DIFactory::CreateDerivedType(unsigned Tag,
                                            DIDescriptor Context,
-                                           const char * Name,
+                                           StringRef Name,
                                            DICompileUnit CompileUnit,
                                            unsigned LineNumber,
                                            uint64_t SizeInBits,
@@ -767,7 +768,7 @@ DIDerivedType DIFactory::CreateDerivedType(unsigned Tag,
 /// pointer, typedef, etc.
 DIDerivedType DIFactory::CreateDerivedTypeEx(unsigned Tag,
                                              DIDescriptor Context,
-                                             const char * Name,
+                                             StringRef Name,
                                              DICompileUnit CompileUnit,
                                              unsigned LineNumber,
                                              Constant *SizeInBits,
@@ -794,7 +795,7 @@ DIDerivedType DIFactory::CreateDerivedTypeEx(unsigned Tag,
 /// CreateCompositeType - Create a composite type like array, struct, etc.
 DICompositeType DIFactory::CreateCompositeType(unsigned Tag,
                                                DIDescriptor Context,
-                                               const char * Name,
+                                               StringRef Name,
                                                DICompileUnit CompileUnit,
                                                unsigned LineNumber,
                                                uint64_t SizeInBits,
@@ -826,7 +827,7 @@ DICompositeType DIFactory::CreateCompositeType(unsigned Tag,
 /// CreateCompositeType - Create a composite type like array, struct, etc.
 DICompositeType DIFactory::CreateCompositeTypeEx(unsigned Tag,
                                                  DIDescriptor Context,
-                                                 const char * Name,
+                                                 StringRef Name,
                                                  DICompileUnit CompileUnit,
                                                  unsigned LineNumber,
                                                  Constant *SizeInBits,
@@ -859,9 +860,9 @@ DICompositeType DIFactory::CreateCompositeTypeEx(unsigned Tag,
 /// See comments in DISubprogram for descriptions of these fields.  This
 /// method does not unique the generated descriptors.
 DISubprogram DIFactory::CreateSubprogram(DIDescriptor Context,
-                                         const char * Name,
-                                         const char * DisplayName,
-                                         const char * LinkageName,
+                                         StringRef Name,
+                                         StringRef DisplayName,
+                                         StringRef LinkageName,
                                          DICompileUnit CompileUnit,
                                          unsigned LineNo, DIType Type,
                                          bool isLocalToUnit,
@@ -885,9 +886,9 @@ DISubprogram DIFactory::CreateSubprogram(DIDescriptor Context,
 
 /// CreateGlobalVariable - Create a new descriptor for the specified global.
 DIGlobalVariable
-DIFactory::CreateGlobalVariable(DIDescriptor Context, const char * Name,
-                                const char * DisplayName,
-                                const char * LinkageName,
+DIFactory::CreateGlobalVariable(DIDescriptor Context, StringRef Name,
+                                StringRef DisplayName,
+                                StringRef LinkageName,
                                 DICompileUnit CompileUnit,
                                 unsigned LineNo, DIType Type,bool isLocalToUnit,
                                 bool isDefinition, llvm::GlobalVariable *Val) {
@@ -919,7 +920,7 @@ DIFactory::CreateGlobalVariable(DIDescriptor Context, const char * Name,
 
 /// CreateVariable - Create a new descriptor for the specified variable.
 DIVariable DIFactory::CreateVariable(unsigned Tag, DIDescriptor Context,
-                                     const char * Name,
+                                     StringRef Name,
                                      DICompileUnit CompileUnit, unsigned LineNo,
                                      DIType Type) {
   Value *Elts[] = {
@@ -976,6 +977,17 @@ DILocation DIFactory::CreateLocation(unsigned LineNo, unsigned ColumnNo,
   return DILocation(MDNode::get(VMContext, &Elts[0], 4));
 }
 
+/// CreateLocation - Creates a debug info location.
+DILocation DIFactory::CreateLocation(unsigned LineNo, unsigned ColumnNo,
+                                     DIScope S, MDNode *OrigLoc) {
+ Value *Elts[] = {
+    ConstantInt::get(Type::getInt32Ty(VMContext), LineNo),
+    ConstantInt::get(Type::getInt32Ty(VMContext), ColumnNo),
+    S.getNode(),
+    OrigLoc
+  };
+  return DILocation(MDNode::get(VMContext, &Elts[0], 4));
+}
 
 //===----------------------------------------------------------------------===//
 // DIFactory: Routines for inserting code into a function
@@ -1263,7 +1275,8 @@ bool getLocationInfo(const Value *V, std::string &DisplayName,
       if (!DIGV) return false;
       DIGlobalVariable Var(cast<MDNode>(DIGV));
 
-      if (const char *D = Var.getDisplayName())
+      StringRef D = Var.getDisplayName();
+      if (!D.empty())
         DisplayName = D;
       LineNo = Var.getLineNumber();
       Unit = Var.getCompileUnit();
@@ -1273,18 +1286,22 @@ bool getLocationInfo(const Value *V, std::string &DisplayName,
       if (!DDI) return false;
       DIVariable Var(cast<MDNode>(DDI->getVariable()));
 
-      if (const char *D = Var.getName())
+      StringRef D = Var.getName();
+      if (!D.empty())
         DisplayName = D;
       LineNo = Var.getLineNumber();
       Unit = Var.getCompileUnit();
       TypeD = Var.getType();
     }
 
-    if (const char *T = TypeD.getName())
+    StringRef T = TypeD.getName();
+    if (!T.empty())
       Type = T;
-    if (const char *F = Unit.getFilename())
+    StringRef F = Unit.getFilename();
+    if (!F.empty())
       File = F;
-    if (const char *D = Unit.getDirectory())
+    StringRef D = Unit.getDirectory();
+    if (!D.empty())
       Dir = D;
     return true;
   }
@@ -1398,4 +1415,36 @@ bool getLocationInfo(const Value *V, std::string &DisplayName,
 
     return DebugLoc::get(Id);
   }
+
+  /// getDISubprogram - Find subprogram that is enclosing this scope.
+  DISubprogram getDISubprogram(MDNode *Scope) {
+    DIDescriptor D(Scope);
+    if (D.isNull())
+      return DISubprogram();
+    
+    if (D.isCompileUnit())
+      return DISubprogram();
+    
+    if (D.isSubprogram())
+      return DISubprogram(Scope);
+    
+    if (D.isLexicalBlock())
+      return getDISubprogram(DILexicalBlock(Scope).getContext().getNode());
+    
+    return DISubprogram();
+  }
+
+  /// getDICompositeType - Find underlying composite type.
+  DICompositeType getDICompositeType(DIType T) {
+    if (T.isNull())
+      return DICompositeType();
+    
+    if (T.isCompositeType())
+      return DICompositeType(T.getNode());
+    
+    if (T.isDerivedType())
+      return getDICompositeType(DIDerivedType(T.getNode()).getTypeDerivedFrom());
+    
+    return DICompositeType();
+  }
 }
diff --git a/lib/Analysis/DomPrinter.cpp b/lib/Analysis/DomPrinter.cpp
index f1b44d0..32b8994 100644
--- a/lib/Analysis/DomPrinter.cpp
+++ b/lib/Analysis/DomPrinter.cpp
@@ -30,46 +30,55 @@ using namespace llvm;
 namespace llvm {
 template<>
 struct DOTGraphTraits<DomTreeNode*> : public DefaultDOTGraphTraits {
-  static std::string getNodeLabel(DomTreeNode *Node, DomTreeNode *Graph,
-                                  bool ShortNames) {
+
+  DOTGraphTraits (bool isSimple=false)
+    : DefaultDOTGraphTraits(isSimple) {}
+
+  std::string getNodeLabel(DomTreeNode *Node, DomTreeNode *Graph) {
 
     BasicBlock *BB = Node->getBlock();
 
     if (!BB)
       return "Post dominance root node";
 
-    return DOTGraphTraits<const Function*>::getNodeLabel(BB, BB->getParent(),
-                                                         ShortNames);
+
+    if (isSimple())
+      return DOTGraphTraits<const Function*>
+	       ::getSimpleNodeLabel(BB, BB->getParent());
+    else
+      return DOTGraphTraits<const Function*>
+	       ::getCompleteNodeLabel(BB, BB->getParent());
   }
 };
 
 template<>
 struct DOTGraphTraits<DominatorTree*> : public DOTGraphTraits<DomTreeNode*> {
 
+  DOTGraphTraits (bool isSimple=false)
+    : DOTGraphTraits<DomTreeNode*>(isSimple) {}
+
   static std::string getGraphName(DominatorTree *DT) {
     return "Dominator tree";
   }
 
-  static std::string getNodeLabel(DomTreeNode *Node,
-                                  DominatorTree *G,
-                                  bool ShortNames) {
-    return DOTGraphTraits<DomTreeNode*>::getNodeLabel(Node, G->getRootNode(),
-                                                      ShortNames);
+  std::string getNodeLabel(DomTreeNode *Node, DominatorTree *G) {
+    return DOTGraphTraits<DomTreeNode*>::getNodeLabel(Node, G->getRootNode());
   }
 };
 
 template<>
 struct DOTGraphTraits<PostDominatorTree*>
   : public DOTGraphTraits<DomTreeNode*> {
+
+  DOTGraphTraits (bool isSimple=false)
+    : DOTGraphTraits<DomTreeNode*>(isSimple) {}
+
   static std::string getGraphName(PostDominatorTree *DT) {
     return "Post dominator tree";
   }
-  static std::string getNodeLabel(DomTreeNode *Node,
-                                  PostDominatorTree *G,
-                                  bool ShortNames) {
-    return DOTGraphTraits<DomTreeNode*>::getNodeLabel(Node,
-                                                      G->getRootNode(),
-                                                      ShortNames);
+
+  std::string getNodeLabel(DomTreeNode *Node, PostDominatorTree *G ) {
+    return DOTGraphTraits<DomTreeNode*>::getNodeLabel(Node, G->getRootNode());
   }
 };
 }
@@ -85,9 +94,11 @@ struct GenericGraphViewer : public FunctionPass {
 
   virtual bool runOnFunction(Function &F) {
     Analysis *Graph;
-
+    std::string Title, GraphName;
     Graph = &getAnalysis<Analysis>();
-    ViewGraph(Graph, Name, OnlyBBS);
+    GraphName = DOTGraphTraits<Analysis*>::getGraphName(Graph);
+    Title = GraphName + " for '" + F.getNameStr() + "' function";
+    ViewGraph(Graph, Name, OnlyBBS, Title);
 
     return false;
   }
@@ -163,8 +174,12 @@ struct GenericGraphPrinter : public FunctionPass {
     raw_fd_ostream File(Filename.c_str(), ErrorInfo);
     Graph = &getAnalysis<Analysis>();
 
+    std::string Title, GraphName;
+    GraphName = DOTGraphTraits<Analysis*>::getGraphName(Graph);
+    Title = GraphName + " for '" + F.getNameStr() + "' function";
+
     if (ErrorInfo.empty())
-      WriteGraph(File, Graph, OnlyBBS);
+      WriteGraph(File, Graph, OnlyBBS, Name, Title);
     else
       errs() << "  error opening file for writing!";
     errs() << "\n";
diff --git a/lib/Analysis/IPA/Andersens.cpp b/lib/Analysis/IPA/Andersens.cpp
index 40a8cd5..e12db81 100644
--- a/lib/Analysis/IPA/Andersens.cpp
+++ b/lib/Analysis/IPA/Andersens.cpp
@@ -484,7 +484,6 @@ namespace {
                       const Value *V2, unsigned V2Size);
     virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
     virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2);
-    void getMustAliases(Value *P, std::vector<Value*> &RetVals);
     bool pointsToConstantMemory(const Value *P);
 
     virtual void deleteValue(Value *V) {
@@ -680,32 +679,6 @@ Andersens::getModRefInfo(CallSite CS1, CallSite CS2) {
   return AliasAnalysis::getModRefInfo(CS1,CS2);
 }
 
-/// getMustAlias - We can provide must alias information if we know that a
-/// pointer can only point to a specific function or the null pointer.
-/// Unfortunately we cannot determine must-alias information for global
-/// variables or any other memory memory objects because we do not track whether
-/// a pointer points to the beginning of an object or a field of it.
-void Andersens::getMustAliases(Value *P, std::vector<Value*> &RetVals) {
-  Node *N = &GraphNodes[FindNode(getNode(P))];
-  if (N->PointsTo->count() == 1) {
-    Node *Pointee = &GraphNodes[N->PointsTo->find_first()];
-    // If a function is the only object in the points-to set, then it must be
-    // the destination.  Note that we can't handle global variables here,
-    // because we don't know if the pointer is actually pointing to a field of
-    // the global or to the beginning of it.
-    if (Value *V = Pointee->getValue()) {
-      if (Function *F = dyn_cast<Function>(V))
-        RetVals.push_back(F);
-    } else {
-      // If the object in the points-to set is the null object, then the null
-      // pointer is a must alias.
-      if (Pointee == &GraphNodes[NullObject])
-        RetVals.push_back(Constant::getNullValue(P->getType()));
-    }
-  }
-  AliasAnalysis::getMustAliases(P, RetVals);
-}
-
 /// pointsToConstantMemory - If we can determine that this pointer only points
 /// to constant memory, return true.  In practice, this means that if the
 /// pointer can only point to constant globals, functions, or the null pointer,
diff --git a/lib/Analysis/IPA/GlobalsModRef.cpp b/lib/Analysis/IPA/GlobalsModRef.cpp
index ddd6ff9..a979a99 100644
--- a/lib/Analysis/IPA/GlobalsModRef.cpp
+++ b/lib/Analysis/IPA/GlobalsModRef.cpp
@@ -111,7 +111,6 @@ namespace {
     ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
       return AliasAnalysis::getModRefInfo(CS1,CS2);
     }
-    bool hasNoModRefInfoForCalls() const { return false; }
 
     /// getModRefBehavior - Return the behavior of the specified function if
     /// called from the specified call site.  The call site may be null in which
diff --git a/lib/Analysis/IVUsers.cpp b/lib/Analysis/IVUsers.cpp
index efe40e4..37747b6 100644
--- a/lib/Analysis/IVUsers.cpp
+++ b/lib/Analysis/IVUsers.cpp
@@ -24,7 +24,6 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/Support/CommandLine.h"
 #include <algorithm>
 using namespace llvm;
 
@@ -32,10 +31,6 @@ char IVUsers::ID = 0;
 static RegisterPass<IVUsers>
 X("iv-users", "Induction Variable Users", false, true);
 
-static cl::opt<bool>
-SimplifyIVUsers("simplify-iv-users", cl::Hidden, cl::init(false),
-          cl::desc("Restrict IV Users to loop-invariant strides"));
-
 Pass *llvm::createIVUsersPass() {
   return new IVUsers();
 }
@@ -214,8 +209,7 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
     return false;  // Non-reducible symbolic expression, bail out.
 
   // Keep things simple. Don't touch loop-variant strides.
-  if (SimplifyIVUsers && !Stride->isLoopInvariant(L)
-      && L->contains(I->getParent()))
+  if (!Stride->isLoopInvariant(L) && L->contains(I->getParent()))
     return false;
 
   SmallPtrSet<Instruction *, 4> UniqueUsers;
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index f9953e3..b53ac13 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -21,13 +21,41 @@
 using namespace llvm;
 using namespace llvm::PatternMatch;
 
-/// SimplifyAndInst - Given operands for an And, see if we can
+/// SimplifyAddInst - Given operands for an Add, see if we can
 /// fold the result.  If not, this returns null.
-Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1,
+Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
                              const TargetData *TD) {
   if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
     if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
       Constant *Ops[] = { CLHS, CRHS };
+      return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
+                                      Ops, 2, TD);
+    }
+    
+    // Canonicalize the constant to the RHS.
+    std::swap(Op0, Op1);
+  }
+  
+  if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+    // X + undef -> undef
+    if (isa<UndefValue>(Op1C))
+      return Op1C;
+    
+    // X + 0 --> X
+    if (Op1C->isNullValue())
+      return Op0;
+  }
+  
+  // FIXME: Could pull several more out of instcombine.
+  return 0;
+}
+
+/// SimplifyAndInst - Given operands for an And, see if we can
+/// fold the result.  If not, this returns null.
+Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD) {
+  if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+    if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+      Constant *Ops[] = { CLHS, CRHS };
       return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
                                       Ops, 2, TD);
     }
@@ -83,8 +111,7 @@ Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1,
 
 /// SimplifyOrInst - Given operands for an Or, see if we can
 /// fold the result.  If not, this returns null.
-Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1,
-                            const TargetData *TD) {
+Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD) {
   if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
     if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
       Constant *Ops[] = { CLHS, CRHS };
@@ -142,8 +169,6 @@ Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1,
 }
 
 
-
-
 static const Type *GetCompareTy(Value *Op) {
   return CmpInst::makeCmpResultType(Op->getType());
 }
@@ -264,6 +289,34 @@ Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
   return 0;
 }
 
+/// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
+/// fold the result.  If not, this returns null.
+Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
+                             const TargetData *TD) {
+  // getelementptr P -> P.
+  if (NumOps == 1)
+    return Ops[0];
+
+  // TODO.
+  //if (isa<UndefValue>(Ops[0]))
+  //  return UndefValue::get(GEP.getType());
+
+  // getelementptr P, 0 -> P.
+  if (NumOps == 2)
+    if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
+      if (C->isZero())
+        return Ops[0];
+  
+  // Check to see if this is constant foldable.
+  for (unsigned i = 0; i != NumOps; ++i)
+    if (!isa<Constant>(Ops[i]))
+      return 0;
+  
+  return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
+                                        (Constant *const*)Ops+1, NumOps-1);
+}
+
+
 //=== Helper functions for higher up the class hierarchy.
 
 /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
@@ -299,6 +352,10 @@ Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD) {
   switch (I->getOpcode()) {
   default:
     return ConstantFoldInstruction(I, TD);
+  case Instruction::Add:
+    return SimplifyAddInst(I->getOperand(0), I->getOperand(1),
+                           cast<BinaryOperator>(I)->hasNoSignedWrap(),
+                           cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD);
   case Instruction::And:
     return SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD);
   case Instruction::Or:
@@ -309,6 +366,10 @@ Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD) {
   case Instruction::FCmp:
     return SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
                             I->getOperand(0), I->getOperand(1), TD);
+  case Instruction::GetElementPtr: {
+    SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
+    return SimplifyGEPInst(&Ops[0], Ops.size(), TD);
+  }
   }
 }
 
diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp
index 1c614b0..4de756c 100644
--- a/lib/Analysis/LoopInfo.cpp
+++ b/lib/Analysis/LoopInfo.cpp
@@ -243,6 +243,11 @@ unsigned Loop::getSmallConstantTripMultiple() const {
         case BinaryOperator::Mul:
           Result = dyn_cast<ConstantInt>(BO->getOperand(1));
           break;
+        case BinaryOperator::Shl:
+          if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1)))
+            if (CI->getValue().getActiveBits() <= 5)
+              return 1u << CI->getZExtValue();
+          break;
         default:
           break;
         }
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index 0ec0e74..ae6f970 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -20,6 +20,8 @@
 #include "llvm/IntrinsicInst.h"
 #include "llvm/Function.h"
 #include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/MemoryBuiltins.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/STLExtras.h"
@@ -117,10 +119,6 @@ getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall,
       Pointer = Inst->getOperand(1);
       // calls to free() erase the entire structure
       PointerSize = ~0ULL;
-    } else if (isFreeCall(Inst)) {
-      Pointer = Inst->getOperand(0);
-      // calls to free() erase the entire structure
-      PointerSize = ~0ULL;
     } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
       // Debug intrinsics don't cause dependences.
       if (isa<DbgInfoIntrinsic>(Inst)) continue;
@@ -174,7 +172,7 @@ MemDepResult MemoryDependenceAnalysis::
 getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad, 
                          BasicBlock::iterator ScanIt, BasicBlock *BB) {
 
-  Value* invariantTag = 0;
+  Value *invariantTag = 0;
 
   // Walk backwards through the basic block, looking for dependencies.
   while (ScanIt != BB->begin()) {
@@ -185,12 +183,12 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
     if (invariantTag == Inst) {
       invariantTag = 0;
       continue;
-    } else if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(Inst)) {
+    } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
       // If we pass an invariant-end marker, then we've just entered an
       // invariant region and can start ignoring dependencies.
       if (II->getIntrinsicID() == Intrinsic::invariant_end) {
         uint64_t invariantSize = ~0ULL;
-        if (ConstantInt* CI = dyn_cast<ConstantInt>(II->getOperand(2)))
+        if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(2)))
           invariantSize = CI->getZExtValue();
         
         AliasAnalysis::AliasResult R =
@@ -203,9 +201,9 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
       // If we reach a lifetime begin or end marker, then the query ends here
       // because the value is undefined.
       } else if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
-                   II->getIntrinsicID() == Intrinsic::lifetime_end) {
+                 II->getIntrinsicID() == Intrinsic::lifetime_end) {
         uint64_t invariantSize = ~0ULL;
-        if (ConstantInt* CI = dyn_cast<ConstantInt>(II->getOperand(1)))
+        if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(1)))
           invariantSize = CI->getZExtValue();
 
         AliasAnalysis::AliasResult R =
@@ -371,20 +369,41 @@ MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) {
     // calls to free() erase the entire structure, not just a field.
     MemSize = ~0UL;
   } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
-    CallSite QueryCS = CallSite::get(QueryInst);
-    bool isReadOnly = AA->onlyReadsMemory(QueryCS);
-    LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos,
-                                           QueryParent);
+    int IntrinsicID = 0;  // Intrinsic IDs start at 1.
+    if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(QueryInst))
+      IntrinsicID = II->getIntrinsicID();
+
+    switch (IntrinsicID) {
+      case Intrinsic::lifetime_start:
+      case Intrinsic::lifetime_end:
+      case Intrinsic::invariant_start:
+        MemPtr = QueryInst->getOperand(2);
+        MemSize = cast<ConstantInt>(QueryInst->getOperand(1))->getZExtValue();
+        break;
+      case Intrinsic::invariant_end:
+        MemPtr = QueryInst->getOperand(3);
+        MemSize = cast<ConstantInt>(QueryInst->getOperand(2))->getZExtValue();
+        break;
+      default:
+        CallSite QueryCS = CallSite::get(QueryInst);
+        bool isReadOnly = AA->onlyReadsMemory(QueryCS);
+        LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos,
+                                               QueryParent);
+    }
   } else {
     // Non-memory instruction.
     LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
   }
   
   // If we need to do a pointer scan, make it happen.
-  if (MemPtr)
-    LocalCache = getPointerDependencyFrom(MemPtr, MemSize, 
-                                          isa<LoadInst>(QueryInst),
-                                          ScanPos, QueryParent);
+  if (MemPtr) {
+    bool isLoad = !QueryInst->mayWriteToMemory();
+    if (IntrinsicInst *II = dyn_cast<MemoryUseIntrinsic>(QueryInst)) {
+      isLoad |= II->getIntrinsicID() == Intrinsic::lifetime_end;
+    }
+    LocalCache = getPointerDependencyFrom(MemPtr, MemSize, isLoad, ScanPos,
+                                          QueryParent);
+  }
   
   // Remember the result!
   if (Instruction *I = LocalCache.getInst())
@@ -688,6 +707,274 @@ SortNonLocalDepInfoCache(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
   }
 }
 
+/// isPHITranslatable - Return true if the specified computation is derived from
+/// a PHI node in the current block and if it is simple enough for us to handle.
+static bool isPHITranslatable(Instruction *Inst) {
+  if (isa<PHINode>(Inst))
+    return true;
+  
+  // We can handle bitcast of a PHI, but the PHI needs to be in the same block
+  // as the bitcast.
+  if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
+    Instruction *OpI = dyn_cast<Instruction>(BC->getOperand(0));
+    if (OpI == 0 || OpI->getParent() != Inst->getParent())
+      return true;
+    return isPHITranslatable(OpI);
+  }
+  
+  // We can translate a GEP if all of its operands defined in this block are phi
+  // translatable. 
+  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
+    for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
+      Instruction *OpI = dyn_cast<Instruction>(GEP->getOperand(i));
+      if (OpI == 0 || OpI->getParent() != Inst->getParent())
+        continue;
+      
+      if (!isPHITranslatable(OpI))
+        return false;
+    }
+    return true;
+  }
+  
+  if (Inst->getOpcode() == Instruction::Add &&
+      isa<ConstantInt>(Inst->getOperand(1))) {
+    Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0));
+    if (OpI == 0 || OpI->getParent() != Inst->getParent())
+      return true;
+    return isPHITranslatable(OpI);
+  }
+
+  //   cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
+  //   if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
+  //     cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
+  
+  return false;
+}
+
+/// GetPHITranslatedValue - Given a computation that satisfied the
+/// isPHITranslatable predicate, see if we can translate the computation into
+/// the specified predecessor block.  If so, return that value.
+Value *MemoryDependenceAnalysis::
+GetPHITranslatedValue(Value *InVal, BasicBlock *CurBB, BasicBlock *Pred,
+                      const TargetData *TD) const {  
+  // If the input value is not an instruction, or if it is not defined in CurBB,
+  // then we don't need to phi translate it.
+  Instruction *Inst = dyn_cast<Instruction>(InVal);
+  if (Inst == 0 || Inst->getParent() != CurBB)
+    return InVal;
+  
+  if (PHINode *PN = dyn_cast<PHINode>(Inst))
+    return PN->getIncomingValueForBlock(Pred);
+  
+  // Handle bitcast of PHI.
+  if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
+    // PHI translate the input operand.
+    Value *PHIIn = GetPHITranslatedValue(BC->getOperand(0), CurBB, Pred, TD);
+    if (PHIIn == 0) return 0;
+    
+    // Constants are trivial to phi translate.
+    if (Constant *C = dyn_cast<Constant>(PHIIn))
+      return ConstantExpr::getBitCast(C, BC->getType());
+    
+    // Otherwise we have to see if a bitcasted version of the incoming pointer
+    // is available.  If so, we can use it, otherwise we have to fail.
+    for (Value::use_iterator UI = PHIIn->use_begin(), E = PHIIn->use_end();
+         UI != E; ++UI) {
+      if (BitCastInst *BCI = dyn_cast<BitCastInst>(*UI))
+        if (BCI->getType() == BC->getType())
+          return BCI;
+    }
+    return 0;
+  }
+
+  // Handle getelementptr with at least one PHI translatable operand.
+  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
+    SmallVector<Value*, 8> GEPOps;
+    BasicBlock *CurBB = GEP->getParent();
+    for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
+      Value *GEPOp = GEP->getOperand(i);
+      // No PHI translation is needed of operands whose values are live in to
+      // the predecessor block.
+      if (!isa<Instruction>(GEPOp) ||
+          cast<Instruction>(GEPOp)->getParent() != CurBB) {
+        GEPOps.push_back(GEPOp);
+        continue;
+      }
+      
+      // If the operand is a phi node, do phi translation.
+      Value *InOp = GetPHITranslatedValue(GEPOp, CurBB, Pred, TD);
+      if (InOp == 0) return 0;
+      
+      GEPOps.push_back(InOp);
+    }
+    
+    // Simplify the GEP to handle 'gep x, 0' -> x etc.
+    if (Value *V = SimplifyGEPInst(&GEPOps[0], GEPOps.size(), TD))
+      return V;
+
+    // Scan to see if we have this GEP available.
+    Value *APHIOp = GEPOps[0];
+    for (Value::use_iterator UI = APHIOp->use_begin(), E = APHIOp->use_end();
+         UI != E; ++UI) {
+      if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI))
+        if (GEPI->getType() == GEP->getType() &&
+            GEPI->getNumOperands() == GEPOps.size() &&
+            GEPI->getParent()->getParent() == CurBB->getParent()) {
+          bool Mismatch = false;
+          for (unsigned i = 0, e = GEPOps.size(); i != e; ++i)
+            if (GEPI->getOperand(i) != GEPOps[i]) {
+              Mismatch = true;
+              break;
+            }
+          if (!Mismatch)
+            return GEPI;
+        }
+    }
+    return 0;
+  }
+  
+  // Handle add with a constant RHS.
+  if (Inst->getOpcode() == Instruction::Add &&
+      isa<ConstantInt>(Inst->getOperand(1))) {
+    // PHI translate the LHS.
+    Value *LHS;
+    Constant *RHS = cast<ConstantInt>(Inst->getOperand(1));
+    Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0));
+    bool isNSW = cast<BinaryOperator>(Inst)->hasNoSignedWrap();
+    bool isNUW = cast<BinaryOperator>(Inst)->hasNoUnsignedWrap();
+    
+    if (OpI == 0 || OpI->getParent() != Inst->getParent())
+      LHS = Inst->getOperand(0);
+    else {
+      LHS = GetPHITranslatedValue(Inst->getOperand(0), CurBB, Pred, TD);
+      if (LHS == 0)
+        return 0;
+    }
+    
+    // If the PHI translated LHS is an add of a constant, fold the immediates.
+    if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(LHS))
+      if (BOp->getOpcode() == Instruction::Add)
+        if (ConstantInt *CI = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
+          LHS = BOp->getOperand(0);
+          RHS = ConstantExpr::getAdd(RHS, CI);
+          isNSW = isNUW = false;
+        }
+    
+    // See if the add simplifies away.
+    if (Value *Res = SimplifyAddInst(LHS, RHS, isNSW, isNUW, TD))
+      return Res;
+    
+    // Otherwise, see if we have this add available somewhere.
+    for (Value::use_iterator UI = LHS->use_begin(), E = LHS->use_end();
+         UI != E; ++UI) {
+      if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*UI))
+        if (BO->getOperand(0) == LHS && BO->getOperand(1) == RHS &&
+            BO->getParent()->getParent() == CurBB->getParent())
+          return BO;
+    }
+    
+    return 0;
+  }
+  
+  return 0;
+}
+
+/// GetAvailablePHITranslatePointer - Return the value computed by
+/// PHITranslatePointer if it dominates PredBB, otherwise return null.
+Value *MemoryDependenceAnalysis::
+GetAvailablePHITranslatedValue(Value *V,
+                               BasicBlock *CurBB, BasicBlock *PredBB,
+                               const TargetData *TD,
+                               const DominatorTree &DT) const {
+  // See if PHI translation succeeds.
+  V = GetPHITranslatedValue(V, CurBB, PredBB, TD);
+  if (V == 0) return 0;
+  
+  // Make sure the value is live in the predecessor.
+  if (Instruction *Inst = dyn_cast_or_null<Instruction>(V))
+    if (!DT.dominates(Inst->getParent(), PredBB))
+      return 0;
+  return V;
+}
+
+
+/// InsertPHITranslatedPointer - Insert a computation of the PHI translated
+/// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
+/// block.  All newly created instructions are added to the NewInsts list.
+///
+Value *MemoryDependenceAnalysis::
+InsertPHITranslatedPointer(Value *InVal, BasicBlock *CurBB,
+                           BasicBlock *PredBB, const TargetData *TD,
+                           const DominatorTree &DT,
+                           SmallVectorImpl<Instruction*> &NewInsts) const {
+  // See if we have a version of this value already available and dominating
+  // PredBB.  If so, there is no need to insert a new copy.
+  if (Value *Res = GetAvailablePHITranslatedValue(InVal, CurBB, PredBB, TD, DT))
+    return Res;
+  
+  // If we don't have an available version of this value, it must be an
+  // instruction.
+  Instruction *Inst = cast<Instruction>(InVal);
+  
+  // Handle bitcast of PHI translatable value.
+  if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
+    Value *OpVal = InsertPHITranslatedPointer(BC->getOperand(0),
+                                              CurBB, PredBB, TD, DT, NewInsts);
+    if (OpVal == 0) return 0;
+      
+    // Otherwise insert a bitcast at the end of PredBB.
+    BitCastInst *New = new BitCastInst(OpVal, InVal->getType(),
+                                       InVal->getName()+".phi.trans.insert",
+                                       PredBB->getTerminator());
+    NewInsts.push_back(New);
+    return New;
+  }
+  
+  // Handle getelementptr with at least one PHI operand.
+  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
+    SmallVector<Value*, 8> GEPOps;
+    BasicBlock *CurBB = GEP->getParent();
+    for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
+      Value *OpVal = InsertPHITranslatedPointer(GEP->getOperand(i),
+                                                CurBB, PredBB, TD, DT, NewInsts);
+      if (OpVal == 0) return 0;
+      GEPOps.push_back(OpVal);
+    }
+    
+    GetElementPtrInst *Result = 
+      GetElementPtrInst::Create(GEPOps[0], GEPOps.begin()+1, GEPOps.end(),
+                                InVal->getName()+".phi.trans.insert",
+                                PredBB->getTerminator());
+    Result->setIsInBounds(GEP->isInBounds());
+    NewInsts.push_back(Result);
+    return Result;
+  }
+  
+#if 0
+  // FIXME: This code works, but it is unclear that we actually want to insert
+  // a big chain of computation in order to make a value available in a block.
+  // This needs to be evaluated carefully to consider its cost trade offs.
+  
+  // Handle add with a constant RHS.
+  if (Inst->getOpcode() == Instruction::Add &&
+      isa<ConstantInt>(Inst->getOperand(1))) {
+    // PHI translate the LHS.
+    Value *OpVal = InsertPHITranslatedPointer(Inst->getOperand(0),
+                                              CurBB, PredBB, TD, DT, NewInsts);
+    if (OpVal == 0) return 0;
+    
+    BinaryOperator *Res = BinaryOperator::CreateAdd(OpVal, Inst->getOperand(1),
+                                           InVal->getName()+".phi.trans.insert",
+                                                    PredBB->getTerminator());
+    Res->setHasNoSignedWrap(cast<BinaryOperator>(Inst)->hasNoSignedWrap());
+    Res->setHasNoUnsignedWrap(cast<BinaryOperator>(Inst)->hasNoUnsignedWrap());
+    NewInsts.push_back(Res);
+    return Res;
+  }
+#endif
+  
+  return 0;
+}
 
 /// getNonLocalPointerDepFromBB - Perform a dependency query based on
 /// pointer/pointeesize starting at the end of StartBB.  Add any clobber/def
@@ -831,66 +1118,107 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
       NumSortedEntries = Cache->size();
     }
     
-    // If this is directly a PHI node, just use the incoming values for each
-    // pred as the phi translated version.
-    if (PHINode *PtrPHI = dyn_cast<PHINode>(PtrInst)) {
-      Cache = 0;
-      
-      for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
-        BasicBlock *Pred = *PI;
-        Value *PredPtr = PtrPHI->getIncomingValueForBlock(Pred);
-        
-        // Check to see if we have already visited this pred block with another
-        // pointer.  If so, we can't do this lookup.  This failure can occur
-        // with PHI translation when a critical edge exists and the PHI node in
-        // the successor translates to a pointer value different than the
-        // pointer the block was first analyzed with.
-        std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
-          InsertRes = Visited.insert(std::make_pair(Pred, PredPtr));
+    // If this is a computation derived from a PHI node, use the suitably
+    // translated incoming values for each pred as the phi translated version.
+    if (!isPHITranslatable(PtrInst))
+      goto PredTranslationFailure;
 
-        if (!InsertRes.second) {
-          // If the predecessor was visited with PredPtr, then we already did
-          // the analysis and can ignore it.
-          if (InsertRes.first->second == PredPtr)
-            continue;
-          
-          // Otherwise, the block was previously analyzed with a different
-          // pointer.  We can't represent the result of this case, so we just
-          // treat this as a phi translation failure.
-          goto PredTranslationFailure;
-        }
+    Cache = 0;
+      
+    for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
+      BasicBlock *Pred = *PI;
+      // Get the PHI translated pointer in this predecessor.  This can fail and
+      // return null if not translatable.
+      Value *PredPtr = GetPHITranslatedValue(PtrInst, BB, Pred, TD);
+      
+      // Check to see if we have already visited this pred block with another
+      // pointer.  If so, we can't do this lookup.  This failure can occur
+      // with PHI translation when a critical edge exists and the PHI node in
+      // the successor translates to a pointer value different than the
+      // pointer the block was first analyzed with.
+      std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
+        InsertRes = Visited.insert(std::make_pair(Pred, PredPtr));
 
-        // FIXME: it is entirely possible that PHI translating will end up with
-        // the same value.  Consider PHI translating something like:
-        // X = phi [x, bb1], [y, bb2].  PHI translating for bb1 doesn't *need*
-        // to recurse here, pedantically speaking.
+      if (!InsertRes.second) {
+        // If the predecessor was visited with PredPtr, then we already did
+        // the analysis and can ignore it.
+        if (InsertRes.first->second == PredPtr)
+          continue;
         
-        // If we have a problem phi translating, fall through to the code below
-        // to handle the failure condition.
-        if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred,
-                                        Result, Visited))
-          goto PredTranslationFailure;
+        // Otherwise, the block was previously analyzed with a different
+        // pointer.  We can't represent the result of this case, so we just
+        // treat this as a phi translation failure.
+        goto PredTranslationFailure;
       }
       
-      // Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
-      CacheInfo = &NonLocalPointerDeps[CacheKey];
-      Cache = &CacheInfo->second;
-      NumSortedEntries = Cache->size();
+      // If PHI translation was unable to find an available pointer in this
+      // predecessor, then we have to assume that the pointer is clobbered in
+      // that predecessor.  We can still do PRE of the load, which would insert
+      // a computation of the pointer in this predecessor.
+      if (PredPtr == 0) {
+        // Add the entry to the Result list.
+        NonLocalDepEntry Entry(Pred,
+                               MemDepResult::getClobber(Pred->getTerminator()));
+        Result.push_back(Entry);
+
+        // Add it to the cache for this CacheKey so that subsequent queries get
+        // this result.
+        Cache = &NonLocalPointerDeps[CacheKey].second;
+        MemoryDependenceAnalysis::NonLocalDepInfo::iterator It =
+          std::upper_bound(Cache->begin(), Cache->end(), Entry);
+        
+        if (It != Cache->begin() && prior(It)->first == Pred)
+          --It;
+
+        if (It == Cache->end() || It->first != Pred) {
+          Cache->insert(It, Entry);
+          // Add it to the reverse map.
+          ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey);
+        } else if (!It->second.isDirty()) {
+          // noop
+        } else if (It->second.getInst() == Pred->getTerminator()) {
+          // Same instruction, clear the dirty marker.
+          It->second = Entry.second;
+        } else if (It->second.getInst() == 0) {
+          // Dirty, with no instruction, just add this.
+          It->second = Entry.second;
+          ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey);
+        } else {
+          // Otherwise, dirty with a different instruction.
+          RemoveFromReverseMap(ReverseNonLocalPtrDeps, It->second.getInst(),
+                               CacheKey);
+          It->second = Entry.second;
+          ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey);
+        }
+        Cache = 0;
+        continue;
+      }
+
+      // FIXME: it is entirely possible that PHI translating will end up with
+      // the same value.  Consider PHI translating something like:
+      // X = phi [x, bb1], [y, bb2].  PHI translating for bb1 doesn't *need*
+      // to recurse here, pedantically speaking.
       
-      // Since we did phi translation, the "Cache" set won't contain all of the
-      // results for the query.  This is ok (we can still use it to accelerate
-      // specific block queries) but we can't do the fastpath "return all
-      // results from the set"  Clear out the indicator for this.
-      CacheInfo->first = BBSkipFirstBlockPair();
-      SkipFirstBlock = false;
-      continue;
+      // If we have a problem phi translating, fall through to the code below
+      // to handle the failure condition.
+      if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred,
+                                      Result, Visited))
+        goto PredTranslationFailure;
     }
     
-    // TODO: BITCAST, GEP.
+    // Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
+    CacheInfo = &NonLocalPointerDeps[CacheKey];
+    Cache = &CacheInfo->second;
+    NumSortedEntries = Cache->size();
     
-    //   cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
-    //   if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
-    //     cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
+    // Since we did phi translation, the "Cache" set won't contain all of the
+    // results for the query.  This is ok (we can still use it to accelerate
+    // specific block queries) but we can't do the fastpath "return all
+    // results from the set"  Clear out the indicator for this.
+    CacheInfo->first = BBSkipFirstBlockPair();
+    SkipFirstBlock = false;
+    continue;
+
   PredTranslationFailure:
     
     if (Cache == 0) {
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index ea4af40..c6835ef 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -3644,7 +3644,7 @@ EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
 /// the addressed element of the initializer or null if the index expression is
 /// invalid.
 static Constant *
-GetAddressedElementFromGlobal(LLVMContext &Context, GlobalVariable *GV,
+GetAddressedElementFromGlobal(GlobalVariable *GV,
                               const std::vector<ConstantInt*> &Indices) {
   Constant *Init = GV->getInitializer();
   for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
@@ -3732,7 +3732,7 @@ ScalarEvolution::ComputeLoadConstantCompareBackedgeTakenCount(
     // Form the GEP offset.
     Indexes[VarIdxNum] = Val;
 
-    Constant *Result = GetAddressedElementFromGlobal(getContext(), GV, Indexes);
+    Constant *Result = GetAddressedElementFromGlobal(GV, Indexes);
     if (Result == 0) break;  // Cannot compute!
 
     // Evaluate the condition for this iteration.
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index b0e6900..31d3ccc 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -325,7 +325,7 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
       APInt Mask2(Mask.shl(ShiftAmt));
       ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero,KnownOne, TD,
                         Depth+1);
-      assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); 
+      assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 
       KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
       KnownOne  = APIntOps::lshr(KnownOne, ShiftAmt);
       // high bits known zero.
@@ -343,7 +343,7 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
       APInt Mask2(Mask.shl(ShiftAmt));
       ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD,
                         Depth+1);
-      assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); 
+      assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 
       KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
       KnownOne  = APIntOps::lshr(KnownOne, ShiftAmt);
         
@@ -380,7 +380,7 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
   }
   // fall through
   case Instruction::Add: {
-    // If one of the operands has trailing zeros, than the bits that the
+    // If one of the operands has trailing zeros, then the bits that the
     // other operand has in those bit positions will be preserved in the
     // result. For an add, this works with either operand. For a subtract,
     // this only works if the known zeros are in the right operand.
@@ -436,7 +436,7 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
 
         KnownZero |= KnownZero2 & Mask;
 
-        assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); 
+        assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 
       }
     }
     break;
@@ -449,7 +449,7 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
         KnownZero |= ~LowBits & Mask;
         ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD,
                           Depth+1);
-        assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
+        assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
         break;
       }
     }
@@ -833,14 +833,12 @@ bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple,
 
   switch (I->getOpcode()) {
   default: break;
-  case Instruction::SExt: {
+  case Instruction::SExt:
     if (!LookThroughSExt) return false;
     // otherwise fall through to ZExt
-  }
-  case Instruction::ZExt: {
+  case Instruction::ZExt:
     return ComputeMultiple(I->getOperand(0), Base, Multiple,
                            LookThroughSExt, Depth+1);
-  }
   case Instruction::Shl:
   case Instruction::Mul: {
     Value *Op0 = I->getOperand(0);
@@ -950,6 +948,195 @@ bool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) {
   return false;
 }
 
+
+/// GetLinearExpression - Analyze the specified value as a linear expression:
+/// "A*V + B", where A and B are constant integers.  Return the scale and offset
+/// values as APInts and return V as a Value*.  The incoming Value is known to
+/// have IntegerType.  Note that this looks through extends, so the high bits
+/// may not be represented in the result.
+static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset,
+                                  const TargetData *TD, unsigned Depth) {
+  assert(isa<IntegerType>(V->getType()) && "Not an integer value");
+
+  // Limit our recursion depth.
+  if (Depth == 6) {
+    Scale = 1;
+    Offset = 0;
+    return V;
+  }
+  
+  if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(V)) {
+    if (ConstantInt *RHSC = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
+      switch (BOp->getOpcode()) {
+      default: break;
+      case Instruction::Or:
+        // X|C == X+C if all the bits in C are unset in X.  Otherwise we can't
+        // analyze it.
+        if (!MaskedValueIsZero(BOp->getOperand(0), RHSC->getValue(), TD))
+          break;
+        // FALL THROUGH.
+      case Instruction::Add:
+        V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD, Depth+1);
+        Offset += RHSC->getValue();
+        return V;
+      case Instruction::Mul:
+        V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD, Depth+1);
+        Offset *= RHSC->getValue();
+        Scale *= RHSC->getValue();
+        return V;
+      case Instruction::Shl:
+        V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD, Depth+1);
+        Offset <<= RHSC->getValue().getLimitedValue();
+        Scale <<= RHSC->getValue().getLimitedValue();
+        return V;
+      }
+    }
+  }
+  
+  // Since clients don't care about the high bits of the value, just scales and
+  // offsets, we can look through extensions.
+  if (isa<SExtInst>(V) || isa<ZExtInst>(V)) {
+    Value *CastOp = cast<CastInst>(V)->getOperand(0);
+    unsigned OldWidth = Scale.getBitWidth();
+    unsigned SmallWidth = CastOp->getType()->getPrimitiveSizeInBits();
+    Scale.trunc(SmallWidth);
+    Offset.trunc(SmallWidth);
+    Value *Result = GetLinearExpression(CastOp, Scale, Offset, TD, Depth+1);
+    Scale.zext(OldWidth);
+    Offset.zext(OldWidth);
+    return Result;
+  }
+  
+  Scale = 1;
+  Offset = 0;
+  return V;
+}
+
+/// DecomposeGEPExpression - If V is a symbolic pointer expression, decompose it
+/// into a base pointer with a constant offset and a number of scaled symbolic
+/// offsets.
+///
+/// The scaled symbolic offsets (represented by pairs of a Value* and a scale in
+/// the VarIndices vector) are Value*'s that are known to be scaled by the
+/// specified amount, but which may have other unrepresented high bits. As such,
+/// the gep cannot necessarily be reconstructed from its decomposed form.
+///
+/// When TargetData is around, this function is capable of analyzing everything
+/// that Value::getUnderlyingObject() can look through.  When not, it just looks
+/// through pointer casts.
+///
+const Value *llvm::DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
+                 SmallVectorImpl<std::pair<const Value*, int64_t> > &VarIndices,
+                                          const TargetData *TD) {
+  // Limit recursion depth to limit compile time in crazy cases.
+  unsigned MaxLookup = 6;
+  
+  BaseOffs = 0;
+  do {
+    // See if this is a bitcast or GEP.
+    const Operator *Op = dyn_cast<Operator>(V);
+    if (Op == 0) {
+      // The only non-operator case we can handle are GlobalAliases.
+      if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
+        if (!GA->mayBeOverridden()) {
+          V = GA->getAliasee();
+          continue;
+        }
+      }
+      return V;
+    }
+    
+    if (Op->getOpcode() == Instruction::BitCast) {
+      V = Op->getOperand(0);
+      continue;
+    }
+    
+    const GEPOperator *GEPOp = dyn_cast<GEPOperator>(Op);
+    if (GEPOp == 0)
+      return V;
+    
+    // Don't attempt to analyze GEPs over unsized objects.
+    if (!cast<PointerType>(GEPOp->getOperand(0)->getType())
+        ->getElementType()->isSized())
+      return V;
+    
+    // If we are lacking TargetData information, we can't compute the offets of
+    // elements computed by GEPs.  However, we can handle bitcast equivalent
+    // GEPs.
+    if (!TD) {
+      if (!GEPOp->hasAllZeroIndices())
+        return V;
+      V = GEPOp->getOperand(0);
+      continue;
+    }
+    
+    // Walk the indices of the GEP, accumulating them into BaseOff/VarIndices.
+    gep_type_iterator GTI = gep_type_begin(GEPOp);
+    for (User::const_op_iterator I = GEPOp->op_begin()+1,
+         E = GEPOp->op_end(); I != E; ++I) {
+      Value *Index = *I;
+      // Compute the (potentially symbolic) offset in bytes for this index.
+      if (const StructType *STy = dyn_cast<StructType>(*GTI++)) {
+        // For a struct, add the member offset.
+        unsigned FieldNo = cast<ConstantInt>(Index)->getZExtValue();
+        if (FieldNo == 0) continue;
+        
+        BaseOffs += TD->getStructLayout(STy)->getElementOffset(FieldNo);
+        continue;
+      }
+      
+      // For an array/pointer, add the element offset, explicitly scaled.
+      if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Index)) {
+        if (CIdx->isZero()) continue;
+        BaseOffs += TD->getTypeAllocSize(*GTI)*CIdx->getSExtValue();
+        continue;
+      }
+      
+      uint64_t Scale = TD->getTypeAllocSize(*GTI);
+      
+      // Use GetLinearExpression to decompose the index into a C1*V+C2 form.
+      unsigned Width = cast<IntegerType>(Index->getType())->getBitWidth();
+      APInt IndexScale(Width, 0), IndexOffset(Width, 0);
+      Index = GetLinearExpression(Index, IndexScale, IndexOffset, TD, 0);
+      
+      // The GEP index scale ("Scale") scales C1*V+C2, yielding (C1*V+C2)*Scale.
+      // This gives us an aggregate computation of (C1*Scale)*V + C2*Scale.
+      BaseOffs += IndexOffset.getZExtValue()*Scale;
+      Scale *= IndexScale.getZExtValue();
+      
+      
+      // If we already had an occurrance of this index variable, merge this
+      // scale into it.  For example, we want to handle:
+      //   A[x][x] -> x*16 + x*4 -> x*20
+      // This also ensures that 'x' only appears in the index list once.
+      for (unsigned i = 0, e = VarIndices.size(); i != e; ++i) {
+        if (VarIndices[i].first == Index) {
+          Scale += VarIndices[i].second;
+          VarIndices.erase(VarIndices.begin()+i);
+          break;
+        }
+      }
+      
+      // Make sure that we have a scale that makes sense for this target's
+      // pointer size.
+      if (unsigned ShiftBits = 64-TD->getPointerSizeInBits()) {
+        Scale <<= ShiftBits;
+        Scale >>= ShiftBits;
+      }
+      
+      if (Scale)
+        VarIndices.push_back(std::make_pair(Index, Scale));
+    }
+    
+    // Analyze the base pointer next.
+    V = GEPOp->getOperand(0);
+  } while (--MaxLookup);
+  
+  // If the chain of expressions is too deep, just return early.
+  return V;
+}
+
+
 // This is the recursive version of BuildSubAggregate. It takes a few different
 // arguments. Idxs is the index within the nested struct From that we are
 // looking at now (which is of type IndexedType). IdxSkip is the number of
@@ -959,7 +1146,6 @@ bool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) {
 static Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
                                 SmallVector<unsigned, 10> &Idxs,
                                 unsigned IdxSkip,
-                                LLVMContext &Context,
                                 Instruction *InsertBefore) {
   const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType);
   if (STy) {
@@ -971,7 +1157,7 @@ static Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
       Idxs.push_back(i);
       Value *PrevTo = To;
       To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip,
-                             Context, InsertBefore);
+                             InsertBefore);
       Idxs.pop_back();
       if (!To) {
         // Couldn't find any inserted value for this index? Cleanup
@@ -994,7 +1180,7 @@ static Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
   // we might be able to find the complete struct somewhere.
   
   // Find the value that is at that particular spot
-  Value *V = FindInsertedValue(From, Idxs.begin(), Idxs.end(), Context);
+  Value *V = FindInsertedValue(From, Idxs.begin(), Idxs.end());
 
   if (!V)
     return NULL;
@@ -1017,7 +1203,7 @@ static Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
 //
 // All inserted insertvalue instructions are inserted before InsertBefore
 static Value *BuildSubAggregate(Value *From, const unsigned *idx_begin,
-                                const unsigned *idx_end, LLVMContext &Context,
+                                const unsigned *idx_end,
                                 Instruction *InsertBefore) {
   assert(InsertBefore && "Must have someplace to insert!");
   const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
@@ -1027,8 +1213,7 @@ static Value *BuildSubAggregate(Value *From, const unsigned *idx_begin,
   SmallVector<unsigned, 10> Idxs(idx_begin, idx_end);
   unsigned IdxSkip = Idxs.size();
 
-  return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip,
-                           Context, InsertBefore);
+  return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore);
 }
 
 /// FindInsertedValue - Given an aggregrate and an sequence of indices, see if
@@ -1038,8 +1223,7 @@ static Value *BuildSubAggregate(Value *From, const unsigned *idx_begin,
 /// If InsertBefore is not null, this function will duplicate (modified)
 /// insertvalues when a part of a nested struct is extracted.
 Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
-                         const unsigned *idx_end, LLVMContext &Context,
-                         Instruction *InsertBefore) {
+                         const unsigned *idx_end, Instruction *InsertBefore) {
   // Nothing to index? Just return V then (this is useful at the end of our
   // recursion)
   if (idx_begin == idx_end)
@@ -1063,7 +1247,7 @@ Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
     if (isa<ConstantArray>(C) || isa<ConstantStruct>(C))
       // Recursively process this constant
       return FindInsertedValue(C->getOperand(*idx_begin), idx_begin + 1,
-                               idx_end, Context, InsertBefore);
+                               idx_end, InsertBefore);
   } else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) {
     // Loop the indices for the insertvalue instruction in parallel with the
     // requested indices
@@ -1082,8 +1266,7 @@ Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
           // %C = insertvalue {i32, i32 } %A, i32 11, 1
           // which allows the unused 0,0 element from the nested struct to be
           // removed.
-          return BuildSubAggregate(V, idx_begin, req_idx,
-                                   Context, InsertBefore);
+          return BuildSubAggregate(V, idx_begin, req_idx, InsertBefore);
         else
           // We can't handle this without inserting insertvalues
           return 0;
@@ -1094,13 +1277,13 @@ Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
       // looking for, then.
       if (*req_idx != *i)
         return FindInsertedValue(I->getAggregateOperand(), idx_begin, idx_end,
-                                 Context, InsertBefore);
+                                 InsertBefore);
     }
     // If we end up here, the indices of the insertvalue match with those
     // requested (though possibly only partially). Now we recursively look at
     // the inserted value, passing any remaining indices.
     return FindInsertedValue(I->getInsertedValueOperand(), req_idx, idx_end,
-                             Context, InsertBefore);
+                             InsertBefore);
   } else if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) {
     // If we're extracting a value from an aggregrate that was extracted from
     // something else, we can extract from that something else directly instead.
@@ -1124,7 +1307,7 @@ Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
            && "Number of indices added not correct?");
     
     return FindInsertedValue(I->getAggregateOperand(), Idxs.begin(), Idxs.end(),
-                             Context, InsertBefore);
+                             InsertBefore);
   }
   // Otherwise, we don't know (such as, extracting from a function return value
   // or load instruction)