RPCSX/llvm
1
0
Fork 0
mirror of https://github.com/RPCSX/llvm.git synced 2024-12-13 23:18:51 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Be more aggressive in removing dead stores, and in removing instructions trivially dead after DSE.

Browse Source 
This drastically improves the effect of FastDSE on kimwitu++.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@39819 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2007-07-13 18:26:26 +00:00
parent 72f1596403
commit 3e8d001799
1 changed files with 24 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
lib/Transforms/Scalar/FastDSE.cpp
View File

@ -56,6 +56,14 @@ namespace {
SetVector<Instruction*>& possiblyDead);
void DeleteDeadInstructionChains(Instruction *I,
SetVector<Instruction*> &DeadInsts);
void TranslatePointerBitCasts(Value*& v) {
assert(isa<PointerType>(v->getType()) && "Translating a non-pointer type?");
// See through pointer-to-pointer bitcasts
while (BitCastInst* C = dyn_cast<BitCastInst>(v))
if (isa<PointerType>(C->getSrcTy()))
v = C->getOperand(0);
}
// getAnalysisUsage - We require post dominance frontiers (aka Control
// Dependence Graph)
@ -93,6 +101,7 @@ bool FDSE::runOnBasicBlock(BasicBlock &BB) {
pointer = S->getPointerOperand();
else if (FreeInst* F = dyn_cast<FreeInst>(BBI))
pointer = F->getPointerOperand();
assert(pointer && "Not a free or a store?");
StoreInst*& last = lastStore[pointer];
@ -110,6 +119,8 @@ bool FDSE::runOnBasicBlock(BasicBlock &BB) {
// DCE instructions only used to calculate that store
if (Instruction* D = dyn_cast<Instruction>(last->getOperand(0)))
possiblyDead.insert(D);
if (Instruction* D = dyn_cast<Instruction>(last->getOperand(1)))
possiblyDead.insert(D);
last->eraseFromParent();
NumFastStores++;
@ -165,7 +176,7 @@ bool FDSE::handleFreeWithNonTrivialDependency(FreeInst* F, Instruction* dep,
Value* depPointer = dependency->getPointerOperand();
unsigned depPointerSize = TD.getTypeSize(dependency->getOperand(0)->getType());
// Check for aliasing
AliasAnalysis::AliasResult A = AA.alias(F->getPointerOperand(), ~0UL,
depPointer, depPointerSize);
@ -177,6 +188,8 @@ bool FDSE::handleFreeWithNonTrivialDependency(FreeInst* F, Instruction* dep,
// DCE instructions only used to calculate that store
if (Instruction* D = dyn_cast<Instruction>(dependency->getOperand(0)))
possiblyDead.insert(D);
if (Instruction* D = dyn_cast<Instruction>(dependency->getOperand(1)))
possiblyDead.insert(D);
dependency->eraseFromParent();
NumFastStores++;
@ -216,23 +229,24 @@ bool FDSE::handleEndBlock(BasicBlock& BB, SetVector<Instruction*>& possiblyDead)
// If we find a store whose pointer is dead...
if (StoreInst* S = dyn_cast<StoreInst>(BBI)) {
if (deadPointers.count(S->getPointerOperand())){
Value* pointerOperand = S->getPointerOperand();
// See through pointer-to-pointer bitcasts
TranslatePointerBitCasts(pointerOperand);
if (deadPointers.count(pointerOperand)){
// Remove it!
MD.removeInstruction(S);
// DCE instructions only used to calculate that store
if (Instruction* D = dyn_cast<Instruction>(S->getOperand(0)))
possiblyDead.insert(D);
if (Instruction* D = dyn_cast<Instruction>(S->getOperand(1)))
possiblyDead.insert(D);
BBI++;
S->eraseFromParent();
NumFastStores++;
MadeChange = true;
// If we can't trivially delete this store, consider it undead
} else {
killPointer = S->getPointerOperand();
killPointerSize = TD.getTypeSize(S->getOperand(0)->getType());
}
// If we encounter a use of the pointer, it is no longer considered dead
@ -261,7 +275,7 @@ bool FDSE::handleEndBlock(BasicBlock& BB, SetVector<Instruction*>& possiblyDead)
// See if the call site touches it
AliasAnalysis::ModRefResult A = AA.getModRefInfo(CallSite::get(BBI),
*I, pointerSize);
if (A != AliasAnalysis::NoModRef)
if (A == AliasAnalysis::ModRef || A == AliasAnalysis::Ref)
dead.push_back(*I);
}
@ -315,6 +329,8 @@ bool FDSE::RemoveUndeadPointers(Value* killPointer, unsigned killPointerSize,
// DCE instructions only used to calculate that store
if (Instruction* D = dyn_cast<Instruction>(S->getOperand(0)))
possiblyDead.insert(D);
if (Instruction* D = dyn_cast<Instruction>(S->getOperand(1)))
possiblyDead.insert(D);
BBI++;
S->eraseFromParent();