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simplify some code, remove escaped newline. 

llvm-svn: 60213
This commit is contained in:
Chris Lattner 2008-11-28 21:29:52 +00:00
parent dca2cd3562
commit f2a8ba4cf0
1 changed files with 28 additions and 22 deletions
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50
llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
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@ -87,37 +87,38 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
bool MadeChange = false; bool MadeChange = false;
// Do a top-down walk on the BB // Do a top-down walk on the BB
for (BasicBlock::iterator BBI = BB.begin(), BBE = BB.end(); for (BasicBlock::iterator BBI = BB.begin(), BBE = BB.end(); BBI != BBE; ) {
BBI != BBE; ++BBI) { Instruction *Inst = BBI++;
// If we find a store or a free... // If we find a store or a free...
if (!isa<StoreInst>(BBI) && !isa<FreeInst>(BBI)) if (!isa<StoreInst>(Inst) && !isa<FreeInst>(Inst))
continue; continue;
Value* pointer = 0; Value* pointer = 0;
if (StoreInst* S = dyn_cast<StoreInst>(BBI)) { if (StoreInst* S = dyn_cast<StoreInst>(Inst)) {
if (S->isVolatile()) if (S->isVolatile())
continue; continue;
pointer = S->getPointerOperand(); pointer = S->getPointerOperand();
} else { } else {
pointer = cast<FreeInst>(BBI)->getPointerOperand(); pointer = cast<FreeInst>(Inst)->getPointerOperand();
} }
pointer = pointer->stripPointerCasts(); pointer = pointer->stripPointerCasts();
StoreInst*& last = lastStore[pointer]; StoreInst *&last = lastStore[pointer];
bool deletedStore = false;
// ... to a pointer that has been stored to before... // ... to a pointer that has been stored to before...
if (last) { if (last) {
Instruction* dep = MD.getDependency(BBI); Instruction* dep = MD.getDependency(Inst);
bool deletedStore = false;
// ... and no other memory dependencies are between them.... // ... and no other memory dependencies are between them....
while (dep != MemoryDependenceAnalysis::None && while (dep != MemoryDependenceAnalysis::None &&
dep != MemoryDependenceAnalysis::NonLocal && dep != MemoryDependenceAnalysis::NonLocal &&
isa<StoreInst>(dep)) { isa<StoreInst>(dep)) {
if (dep != last || if (dep != last ||
TD.getTypeStoreSize(last->getOperand(0)->getType()) > TD.getTypeStoreSize(last->getOperand(0)->getType()) >
TD.getTypeStoreSize(BBI->getOperand(0)->getType())) { TD.getTypeStoreSize(Inst->getOperand(0)->getType())) {
dep = MD.getDependency(BBI, dep); dep = MD.getDependency(Inst, dep);
continue; continue;
} }
@ -128,21 +129,27 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
MadeChange = true; MadeChange = true;
break; break;
} }
// If we deleted a store, reinvestigate this instruction.
if (deletedStore) {
--BBI;
continue;
}
} }
// Handle frees whose dependencies are non-trivial. // Handle frees whose dependencies are non-trivial.
if (FreeInst* F = dyn_cast<FreeInst>(BBI)) { if (FreeInst* F = dyn_cast<FreeInst>(Inst)) {
if (!deletedStore) MadeChange |= handleFreeWithNonTrivialDependency(F, MD.getDependency(F));
MadeChange |= handleFreeWithNonTrivialDependency(F,MD.getDependency(F));
// No known stores after the free // No known stores after the free.
last = 0; last = 0;
} else { } else {
StoreInst* S = cast<StoreInst>(BBI); StoreInst* S = cast<StoreInst>(Inst);
// If we're storing the same value back to a pointer that we just // If we're storing the same value back to a pointer that we just
// loaded from, then the store can be removed; // loaded from, then the store can be removed;
if (LoadInst* L = dyn_cast<LoadInst>(S->getOperand(0))) { if (LoadInst* L = dyn_cast<LoadInst>(S->getOperand(0))) {
// FIXME: Don't do dep query if Parents don't match and other stuff!
Instruction* dep = MD.getDependency(S); Instruction* dep = MD.getDependency(S);
DominatorTree& DT = getAnalysis<DominatorTree>(); DominatorTree& DT = getAnalysis<DominatorTree>();
@ -152,9 +159,8 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
dep == MemoryDependenceAnalysis::NonLocal || dep == MemoryDependenceAnalysis::NonLocal ||
DT.dominates(dep, L))) { DT.dominates(dep, L))) {
// Avoid iterator invalidation.
BBI++;
DeleteDeadInstruction(S); DeleteDeadInstruction(S);
--BBI;
NumFastStores++; NumFastStores++;
MadeChange = true; MadeChange = true;
} else } else
@ -166,8 +172,8 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
} }
} }
// If this block ends in a return, unwind, unreachable, and eventually // If this block ends in a return, unwind, or unreachable, all allocas are
// tailcall, then all allocas are dead at its end. // dead at its end, which means stores to them are also dead.
if (BB.getTerminator()->getNumSuccessors() == 0) if (BB.getTerminator()->getNumSuccessors() == 0)
MadeChange |= handleEndBlock(BB); MadeChange |= handleEndBlock(BB);
@ -337,7 +343,7 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
unsigned pointerSize = ~0U; unsigned pointerSize = ~0U;
if (AllocaInst* A = dyn_cast<AllocaInst>(*I)) { if (AllocaInst* A = dyn_cast<AllocaInst>(*I)) {
if (ConstantInt* C = dyn_cast<ConstantInt>(A->getArraySize())) if (ConstantInt* C = dyn_cast<ConstantInt>(A->getArraySize()))
pointerSize = C->getZExtValue() * \ pointerSize = C->getZExtValue() *
TD.getABITypeSize(A->getAllocatedType()); TD.getABITypeSize(A->getAllocatedType());
} else { } else {
const PointerType* PT = cast<PointerType>( const PointerType* PT = cast<PointerType>(