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Small cleanups, refactor some duplicated code into a single method. No

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functionality change.

llvm-svn: 92445
This commit is contained in:
Nick Lewycky 2010-01-03 04:39:07 +00:00
parent 647c629ee4
commit ebb78c871c
1 changed files with 35 additions and 44 deletions
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79
lib/Transforms/Scalar/DeadStoreElimination.cpp
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@ -52,9 +52,9 @@ namespace {
bool runOnBasicBlock(BasicBlock &BB);
bool handleFreeWithNonTrivialDependency(Instruction *F, MemDepResult Dep);
bool handleEndBlock(BasicBlock &BB);
bool RemoveUndeadPointers(Value* Ptr, uint64_t killPointerSize,
BasicBlock::iterator& BBI,
SmallPtrSet<Value*, 64>& deadPointers);
bool RemoveUndeadPointers(Value *Ptr, uint64_t killPointerSize,
BasicBlock::iterator &BBI,
SmallPtrSet<Value*, 64> &deadPointers);
void DeleteDeadInstruction(Instruction *I,
SmallPtrSet<Value*, 64> *deadPointers = 0);
@ -70,6 +70,8 @@ namespace {
AU.addPreserved<AliasAnalysis>();
AU.addPreserved<MemoryDependenceAnalysis>();
}
unsigned getPointerSize(Value *V) const;
};
}
@ -173,7 +175,7 @@ static bool isStoreAtLeastAsWideAs(Instruction *I1, Instruction *I2,
}
bool DSE::runOnBasicBlock(BasicBlock &BB) {
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
MemoryDependenceAnalysis &MD = getAnalysis<MemoryDependenceAnalysis>();
TD = getAnalysisIfAvailable<TargetData>();
bool MadeChange = false;
@ -355,7 +357,7 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
continue;
}
Value* killPointer = 0;
Value *killPointer = 0;
uint64_t killPointerSize = ~0UL;
// If we encounter a use of the pointer, it is no longer considered dead
@ -371,14 +373,14 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
}
killPointer = L->getPointerOperand();
} else if (VAArgInst* V = dyn_cast<VAArgInst>(BBI)) {
} else if (VAArgInst *V = dyn_cast<VAArgInst>(BBI)) {
killPointer = V->getOperand(0);
} else if (isa<MemTransferInst>(BBI) &&
isa<ConstantInt>(cast<MemTransferInst>(BBI)->getLength())) {
killPointer = cast<MemTransferInst>(BBI)->getSource();
killPointerSize = cast<ConstantInt>(
cast<MemTransferInst>(BBI)->getLength())->getZExtValue();
} else if (AllocaInst* A = dyn_cast<AllocaInst>(BBI)) {
} else if (AllocaInst *A = dyn_cast<AllocaInst>(BBI)) {
deadPointers.erase(A);
// Dead alloca's can be DCE'd when we reach them
@ -412,23 +414,10 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
deadPointers.clear();
return MadeChange;
}
// Get size information for the alloca
unsigned pointerSize = ~0U;
if (TD) {
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);
AliasAnalysis::ModRefResult A = AA.getModRefInfo(CS, *I,
getPointerSize(*I));
if (A == AliasAnalysis::ModRef)
modRef++;
@ -469,11 +458,11 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
/// 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,
bool DSE::RemoveUndeadPointers(Value *killPointer, uint64_t killPointerSize,
BasicBlock::iterator &BBI,
SmallPtrSet<Value*, 64>& deadPointers) {
SmallPtrSet<Value*, 64> &deadPointers) {
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)) {
@ -488,32 +477,19 @@ bool DSE::RemoveUndeadPointers(Value* killPointer, uint64_t killPointerSize,
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 (TD) {
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());
}
}
E = deadPointers.end(); I != E; ++I) {
// See if this pointer could alias it
AliasAnalysis::AliasResult A = AA.alias(*I, pointerSize,
AliasAnalysis::AliasResult A = AA.alias(*I, getPointerSize(*I),
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);
StoreInst *S = cast<StoreInst>(BBI);
// Remove it!
BBI++;
++BBI;
DeleteDeadInstruction(S, &deadPointers);
NumFastStores++;
MadeChange = true;
@ -575,3 +551,18 @@ void DSE::DeleteDeadInstruction(Instruction *I,
if (ValueSet) ValueSet->erase(DeadInst);
}
}
unsigned DSE::getPointerSize(Value *V) const {
if (TD) {
if (AllocaInst *A = dyn_cast<AllocaInst>(V)) {
// Get size information for the alloca
if (ConstantInt *C = dyn_cast<ConstantInt>(A->getArraySize()))
return C->getZExtValue() * TD->getTypeAllocSize(A->getAllocatedType());
} else {
assert(isa<Argument>(V) && "Expected AllocaInst or Argument!");
const PointerType *PT = cast<PointerType>(V->getType());
return TD->getTypeAllocSize(PT->getElementType());
}
}
return ~0U;
}