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diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp
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+++ b/lib/Transforms/Scalar/DeadStoreElimination.cpp
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+//===- DeadStoreElimination.cpp - Fast Dead Store Elimination -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a trivial dead store elimination that only considers
+// basic-block local redundant stores.
+//
+// FIXME: This should eventually be extended to be a post-dominator tree
+// traversal.  Doing so would be pretty trivial.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "dse"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Constants.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Pass.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/MemoryDependenceAnalysis.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
+
+STATISTIC(NumFastStores, "Number of stores deleted");
+STATISTIC(NumFastOther , "Number of other instrs removed");
+
+namespace {
+  struct VISIBILITY_HIDDEN DSE : public FunctionPass {
+    static char ID; // Pass identification, replacement for typeid
+    DSE() : FunctionPass(&ID) {}
+
+    virtual bool runOnFunction(Function &F) {
+      bool Changed = false;
+      for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+        Changed |= runOnBasicBlock(*I);
+      return Changed;
+    }
+    
+    bool runOnBasicBlock(BasicBlock &BB);
+    bool handleFreeWithNonTrivialDependency(FreeInst *F, MemDepResult Dep);
+    bool handleEndBlock(BasicBlock &BB);
+    bool RemoveUndeadPointers(Value* Ptr, uint64_t killPointerSize,
+                              BasicBlock::iterator& BBI,
+                              SmallPtrSet<Value*, 64>& deadPointers);
+    void DeleteDeadInstruction(Instruction *I,
+                               SmallPtrSet<Value*, 64> *deadPointers = 0);
+    
+
+    // getAnalysisUsage - We require post dominance frontiers (aka Control
+    // Dependence Graph)
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesCFG();
+      AU.addRequired<DominatorTree>();
+      AU.addRequired<TargetData>();
+      AU.addRequired<AliasAnalysis>();
+      AU.addRequired<MemoryDependenceAnalysis>();
+      AU.addPreserved<DominatorTree>();
+      AU.addPreserved<AliasAnalysis>();
+      AU.addPreserved<MemoryDependenceAnalysis>();
+    }
+  };
+}
+
+char DSE::ID = 0;
+static RegisterPass<DSE> X("dse", "Dead Store Elimination");
+
+FunctionPass *llvm::createDeadStoreEliminationPass() { return new DSE(); }
+
+bool DSE::runOnBasicBlock(BasicBlock &BB) {
+  MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
+  TargetData &TD = getAnalysis<TargetData>();  
+
+  bool MadeChange = false;
+  
+  // Do a top-down walk on the BB
+  for (BasicBlock::iterator BBI = BB.begin(), BBE = BB.end(); BBI != BBE; ) {
+    Instruction *Inst = BBI++;
+    
+    // If we find a store or a free, get it's memory dependence.
+    if (!isa<StoreInst>(Inst) && !isa<FreeInst>(Inst))
+      continue;
+    
+    // Don't molest volatile stores or do queries that will return "clobber".
+    if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
+      if (SI->isVolatile())
+        continue;
+
+    MemDepResult InstDep = MD.getDependency(Inst);
+    
+    // Ignore non-local stores.
+    // FIXME: cross-block DSE would be fun. :)
+    if (InstDep.isNonLocal()) continue;
+  
+    // Handle frees whose dependencies are non-trivial.
+    if (FreeInst *FI = dyn_cast<FreeInst>(Inst)) {
+      MadeChange |= handleFreeWithNonTrivialDependency(FI, InstDep);
+      continue;
+    }
+    
+    StoreInst *SI = cast<StoreInst>(Inst);
+    
+    // If not a definite must-alias dependency, ignore it.
+    if (!InstDep.isDef())
+      continue;
+    
+    // If this is a store-store dependence, then the previous store is dead so
+    // long as this store is at least as big as it.
+    if (StoreInst *DepStore = dyn_cast<StoreInst>(InstDep.getInst()))
+      if (TD.getTypeStoreSize(DepStore->getOperand(0)->getType()) <=
+          TD.getTypeStoreSize(SI->getOperand(0)->getType())) {
+        // Delete the store and now-dead instructions that feed it.
+        DeleteDeadInstruction(DepStore);
+        NumFastStores++;
+        MadeChange = true;
+        
+        if (BBI != BB.begin())
+          --BBI;
+        continue;
+      }
+    
+    // If we're storing the same value back to a pointer that we just
+    // loaded from, then the store can be removed.
+    if (LoadInst *DepLoad = dyn_cast<LoadInst>(InstDep.getInst())) {
+      if (SI->getPointerOperand() == DepLoad->getPointerOperand() &&
+          SI->getOperand(0) == DepLoad) {
+        DeleteDeadInstruction(SI);
+        if (BBI != BB.begin())
+          --BBI;
+        NumFastStores++;
+        MadeChange = true;
+        continue;
+      }
+    }
+  }
+  
+  // If this block ends in a return, unwind, or unreachable, all allocas are
+  // dead at its end, which means stores to them are also dead.
+  if (BB.getTerminator()->getNumSuccessors() == 0)
+    MadeChange |= handleEndBlock(BB);
+  
+  return MadeChange;
+}
+
+/// handleFreeWithNonTrivialDependency - Handle frees of entire structures whose
+/// dependency is a store to a field of that structure.
+bool DSE::handleFreeWithNonTrivialDependency(FreeInst *F, MemDepResult Dep) {
+  AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+  
+  StoreInst *Dependency = dyn_cast_or_null<StoreInst>(Dep.getInst());
+  if (!Dependency || Dependency->isVolatile())
+    return false;
+  
+  Value *DepPointer = Dependency->getPointerOperand()->getUnderlyingObject();
+
+  // Check for aliasing.
+  if (AA.alias(F->getPointerOperand(), 1, DepPointer, 1) !=
+         AliasAnalysis::MustAlias)
+    return false;
+  
+  // DCE instructions only used to calculate that store
+  DeleteDeadInstruction(Dependency);
+  NumFastStores++;
+  return true;
+}
+
+/// handleEndBlock - Remove dead stores to stack-allocated locations in the
+/// function end block.  Ex:
+/// %A = alloca i32
+/// ...
+/// store i32 1, i32* %A
+/// ret void
+bool DSE::handleEndBlock(BasicBlock &BB) {
+  TargetData &TD = getAnalysis<TargetData>();
+  AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+  
+  bool MadeChange = false;
+  
+  // Pointers alloca'd in this function are dead in the end block
+  SmallPtrSet<Value*, 64> deadPointers;
+  
+  // Find all of the alloca'd pointers in the entry block.
+  BasicBlock *Entry = BB.getParent()->begin();
+  for (BasicBlock::iterator I = Entry->begin(), E = Entry->end(); I != E; ++I)
+    if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
+      deadPointers.insert(AI);
+  
+  // Treat byval arguments the same, stores to them are dead at the end of the
+  // function.
+  for (Function::arg_iterator AI = BB.getParent()->arg_begin(),
+       AE = BB.getParent()->arg_end(); AI != AE; ++AI)
+    if (AI->hasByValAttr())
+      deadPointers.insert(AI);
+  
+  // Scan the basic block backwards
+  for (BasicBlock::iterator BBI = BB.end(); BBI != BB.begin(); ){
+    --BBI;
+    
+    // If we find a store whose pointer is dead.
+    if (StoreInst* S = dyn_cast<StoreInst>(BBI)) {
+      if (!S->isVolatile()) {
+        // See through pointer-to-pointer bitcasts
+        Value* pointerOperand = S->getPointerOperand()->getUnderlyingObject();
+
+        // Alloca'd pointers or byval arguments (which are functionally like
+        // alloca's) are valid candidates for removal.
+        if (deadPointers.count(pointerOperand)) {
+          // DCE instructions only used to calculate that store.
+          BBI++;
+          DeleteDeadInstruction(S, &deadPointers);
+          NumFastStores++;
+          MadeChange = true;
+        }
+      }
+      
+      continue;
+    }
+    
+    // We can also remove memcpy's to local variables at the end of a function.
+    if (MemCpyInst *M = dyn_cast<MemCpyInst>(BBI)) {
+      Value *dest = M->getDest()->getUnderlyingObject();
+
+      if (deadPointers.count(dest)) {
+        BBI++;
+        DeleteDeadInstruction(M, &deadPointers);
+        NumFastOther++;
+        MadeChange = true;
+        continue;
+      }
+      
+      // Because a memcpy is also a load, we can't skip it if we didn't remove
+      // it.
+    }
+    
+    Value* killPointer = 0;
+    uint64_t killPointerSize = ~0UL;
+    
+    // If we encounter a use of the pointer, it is no longer considered dead
+    if (LoadInst *L = dyn_cast<LoadInst>(BBI)) {
+      // However, if this load is unused and not volatile, we can go ahead and
+      // remove it, and not have to worry about it making our pointer undead!
+      if (L->use_empty() && !L->isVolatile()) {
+        BBI++;
+        DeleteDeadInstruction(L, &deadPointers);
+        NumFastOther++;
+        MadeChange = true;
+        continue;
+      }
+      
+      killPointer = L->getPointerOperand();
+    } else if (VAArgInst* V = dyn_cast<VAArgInst>(BBI)) {
+      killPointer = V->getOperand(0);
+    } else if (isa<MemCpyInst>(BBI) &&
+               isa<ConstantInt>(cast<MemCpyInst>(BBI)->getLength())) {
+      killPointer = cast<MemCpyInst>(BBI)->getSource();
+      killPointerSize = cast<ConstantInt>(
+                            cast<MemCpyInst>(BBI)->getLength())->getZExtValue();
+    } else if (AllocaInst* A = dyn_cast<AllocaInst>(BBI)) {
+      deadPointers.erase(A);
+      
+      // Dead alloca's can be DCE'd when we reach them
+      if (A->use_empty()) {
+        BBI++;
+        DeleteDeadInstruction(A, &deadPointers);
+        NumFastOther++;
+        MadeChange = true;
+      }
+      
+      continue;
+    } else if (CallSite::get(BBI).getInstruction() != 0) {
+      // If this call does not access memory, it can't
+      // be undeadifying any of our pointers.
+      CallSite CS = CallSite::get(BBI);
+      if (AA.doesNotAccessMemory(CS))
+        continue;
+      
+      unsigned modRef = 0;
+      unsigned other = 0;
+      
+      // Remove any pointers made undead by the call from the dead set
+      std::vector<Value*> dead;
+      for (SmallPtrSet<Value*, 64>::iterator I = deadPointers.begin(),
+           E = deadPointers.end(); I != E; ++I) {
+        // HACK: if we detect that our AA is imprecise, it's not
+        // worth it to scan the rest of the deadPointers set.  Just
+        // assume that the AA will return ModRef for everything, and
+        // go ahead and bail.
+        if (modRef >= 16 && other == 0) {
+          deadPointers.clear();
+          return MadeChange;
+        }
+
+        // Get size information for the alloca
+        unsigned pointerSize = ~0U;
+        if (AllocaInst* A = dyn_cast<AllocaInst>(*I)) {
+          if (ConstantInt* C = dyn_cast<ConstantInt>(A->getArraySize()))
+            pointerSize = C->getZExtValue() *
+                          TD.getTypeAllocSize(A->getAllocatedType());
+        } else {
+          const PointerType* PT = cast<PointerType>(
+                                                 cast<Argument>(*I)->getType());
+          pointerSize = TD.getTypeAllocSize(PT->getElementType());
+        }
+
+        // See if the call site touches it
+        AliasAnalysis::ModRefResult A = AA.getModRefInfo(CS, *I, pointerSize);
+        
+        if (A == AliasAnalysis::ModRef)
+          modRef++;
+        else
+          other++;
+        
+        if (A == AliasAnalysis::ModRef || A == AliasAnalysis::Ref)
+          dead.push_back(*I);
+      }
+
+      for (std::vector<Value*>::iterator I = dead.begin(), E = dead.end();
+           I != E; ++I)
+        deadPointers.erase(*I);
+      
+      continue;
+    } else if (isInstructionTriviallyDead(BBI)) {
+      // For any non-memory-affecting non-terminators, DCE them as we reach them
+      Instruction *Inst = BBI;
+      BBI++;
+      DeleteDeadInstruction(Inst, &deadPointers);
+      NumFastOther++;
+      MadeChange = true;
+      continue;
+    }
+    
+    if (!killPointer)
+      continue;
+
+    killPointer = killPointer->getUnderlyingObject();
+
+    // Deal with undead pointers
+    MadeChange |= RemoveUndeadPointers(killPointer, killPointerSize, BBI,
+                                       deadPointers);
+  }
+  
+  return MadeChange;
+}
+
+/// RemoveUndeadPointers - check for uses of a pointer that make it
+/// undead when scanning for dead stores to alloca's.
+bool DSE::RemoveUndeadPointers(Value* killPointer, uint64_t killPointerSize,
+                               BasicBlock::iterator &BBI,
+                               SmallPtrSet<Value*, 64>& deadPointers) {
+  TargetData &TD = getAnalysis<TargetData>();
+  AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+                                  
+  // If the kill pointer can be easily reduced to an alloca,
+  // don't bother doing extraneous AA queries.
+  if (deadPointers.count(killPointer)) {
+    deadPointers.erase(killPointer);
+    return false;
+  }
+  
+  // A global can't be in the dead pointer set.
+  if (isa<GlobalValue>(killPointer))
+    return false;
+  
+  bool MadeChange = false;
+  
+  SmallVector<Value*, 16> undead;
+    
+  for (SmallPtrSet<Value*, 64>::iterator I = deadPointers.begin(),
+      E = deadPointers.end(); I != E; ++I) {
+    // Get size information for the alloca.
+    unsigned pointerSize = ~0U;
+    if (AllocaInst* A = dyn_cast<AllocaInst>(*I)) {
+      if (ConstantInt* C = dyn_cast<ConstantInt>(A->getArraySize()))
+        pointerSize = C->getZExtValue() *
+                      TD.getTypeAllocSize(A->getAllocatedType());
+    } else {
+      const PointerType* PT = cast<PointerType>(cast<Argument>(*I)->getType());
+      pointerSize = TD.getTypeAllocSize(PT->getElementType());
+    }
+
+    // See if this pointer could alias it
+    AliasAnalysis::AliasResult A = AA.alias(*I, pointerSize,
+                                            killPointer, killPointerSize);
+
+    // If it must-alias and a store, we can delete it
+    if (isa<StoreInst>(BBI) && A == AliasAnalysis::MustAlias) {
+      StoreInst* S = cast<StoreInst>(BBI);
+
+      // Remove it!
+      BBI++;
+      DeleteDeadInstruction(S, &deadPointers);
+      NumFastStores++;
+      MadeChange = true;
+
+      continue;
+
+      // Otherwise, it is undead
+    } else if (A != AliasAnalysis::NoAlias)
+      undead.push_back(*I);
+  }
+
+  for (SmallVector<Value*, 16>::iterator I = undead.begin(), E = undead.end();
+       I != E; ++I)
+      deadPointers.erase(*I);
+  
+  return MadeChange;
+}
+
+/// DeleteDeadInstruction - Delete this instruction.  Before we do, go through
+/// and zero out all the operands of this instruction.  If any of them become
+/// dead, delete them and the computation tree that feeds them.
+///
+/// If ValueSet is non-null, remove any deleted instructions from it as well.
+///
+void DSE::DeleteDeadInstruction(Instruction *I,
+                                SmallPtrSet<Value*, 64> *ValueSet) {
+  SmallVector<Instruction*, 32> NowDeadInsts;
+  
+  NowDeadInsts.push_back(I);
+  --NumFastOther;
+
+  // Before we touch this instruction, remove it from memdep!
+  MemoryDependenceAnalysis &MDA = getAnalysis<MemoryDependenceAnalysis>();
+  while (!NowDeadInsts.empty()) {
+    Instruction *DeadInst = NowDeadInsts.back();
+    NowDeadInsts.pop_back();
+    
+    ++NumFastOther;
+    
+    // This instruction is dead, zap it, in stages.  Start by removing it from
+    // MemDep, which needs to know the operands and needs it to be in the
+    // function.
+    MDA.removeInstruction(DeadInst);
+    
+    for (unsigned op = 0, e = DeadInst->getNumOperands(); op != e; ++op) {
+      Value *Op = DeadInst->getOperand(op);
+      DeadInst->setOperand(op, 0);
+      
+      // If this operand just became dead, add it to the NowDeadInsts list.
+      if (!Op->use_empty()) continue;
+      
+      if (Instruction *OpI = dyn_cast<Instruction>(Op))
+        if (isInstructionTriviallyDead(OpI))
+          NowDeadInsts.push_back(OpI);
+    }
+    
+    DeadInst->eraseFromParent();
+    
+    if (ValueSet) ValueSet->erase(DeadInst);
+  }
+}