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Split the optimizations in CodeGenPrepare that don't manipulate the iterators

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into a separate function, so that it can be called from a loop using a worklist
rather than a loop traversing a whole basic block.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122943 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Cameron Zwarich 2011-01-06 02:37:26 +00:00
parent 19bb35db1f
commit c061101e03
1 changed files with 52 additions and 41 deletions
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93
lib/Transforms/Scalar/CodeGenPrepare.cpp
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@ -98,6 +98,7 @@ namespace {
bool CanMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
void EliminateMostlyEmptyBlock(BasicBlock *BB);
bool OptimizeBlock(BasicBlock &BB);
bool OptimizeInst(Instruction *I);
bool OptimizeMemoryInst(Instruction *I, Value *Addr, const Type *AccessTy,
DenseMap<Value*,Value*> &SunkAddrs);
bool OptimizeInlineAsmInst(Instruction *I, CallSite CS,
@ -959,6 +960,54 @@ bool CodeGenPrepare::OptimizeExtUses(Instruction *I) {
return MadeChange;
}
bool CodeGenPrepare::OptimizeInst(Instruction *I) {
bool MadeChange = false;
if (PHINode *P = dyn_cast<PHINode>(I)) {
// It is possible for very late stage optimizations (such as SimplifyCFG)
// to introduce PHI nodes too late to be cleaned up. If we detect such a
// trivial PHI, go ahead and zap it here.
if (Value *V = SimplifyInstruction(P)) {
P->replaceAllUsesWith(V);
P->eraseFromParent();
++NumPHIsElim;
}
} else if (CastInst *CI = dyn_cast<CastInst>(I)) {
// If the source of the cast is a constant, then this should have
// already been constant folded. The only reason NOT to constant fold
// it is if something (e.g. LSR) was careful to place the constant
// evaluation in a block other than then one that uses it (e.g. to hoist
// the address of globals out of a loop). If this is the case, we don't
// want to forward-subst the cast.
if (isa<Constant>(CI->getOperand(0)))
return false;
bool Change = false;
if (TLI) {
Change = OptimizeNoopCopyExpression(CI, *TLI);
MadeChange |= Change;
}
if (!Change && (isa<ZExtInst>(I) || isa<SExtInst>(I))) {
MadeChange |= MoveExtToFormExtLoad(I);
MadeChange |= OptimizeExtUses(I);
}
} else if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
MadeChange |= OptimizeCmpExpression(CI);
} else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
if (TLI)
MadeChange |= OptimizeMemoryInst(I, I->getOperand(0), LI->getType(),
SunkAddrs);
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
if (TLI)
MadeChange |= OptimizeMemoryInst(I, SI->getOperand(1),
SI->getOperand(0)->getType(),
SunkAddrs);
}
return MadeChange;
}
// In this pass we look for GEP and cast instructions that are used
// across basic blocks and rewrite them to improve basic-block-at-a-time
// selection.
@ -982,47 +1031,7 @@ bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB) {
for (BasicBlock::iterator BBI = BB.begin(), E = BB.end(); BBI != E; ) {
Instruction *I = BBI++;
if (PHINode *P = dyn_cast<PHINode>(I)) {
// It is possible for very late stage optimizations (such as SimplifyCFG)
// to introduce PHI nodes too late to be cleaned up. If we detect such a
// trivial PHI, go ahead and zap it here.
if (Value *V = SimplifyInstruction(P)) {
P->replaceAllUsesWith(V);
P->eraseFromParent();
++NumPHIsElim;
}
} else if (CastInst *CI = dyn_cast<CastInst>(I)) {
// If the source of the cast is a constant, then this should have
// already been constant folded. The only reason NOT to constant fold
// it is if something (e.g. LSR) was careful to place the constant
// evaluation in a block other than then one that uses it (e.g. to hoist
// the address of globals out of a loop). If this is the case, we don't
// want to forward-subst the cast.
if (isa<Constant>(CI->getOperand(0)))
continue;
bool Change = false;
if (TLI) {
Change = OptimizeNoopCopyExpression(CI, *TLI);
MadeChange |= Change;
}
if (!Change && (isa<ZExtInst>(I) || isa<SExtInst>(I))) {
MadeChange |= MoveExtToFormExtLoad(I);
MadeChange |= OptimizeExtUses(I);
}
} else if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
MadeChange |= OptimizeCmpExpression(CI);
} else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
if (TLI)
MadeChange |= OptimizeMemoryInst(I, I->getOperand(0), LI->getType(),
SunkAddrs);
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
if (TLI)
MadeChange |= OptimizeMemoryInst(I, SI->getOperand(1),
SI->getOperand(0)->getType(),
SunkAddrs);
} else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
if (GEPI->hasAllZeroIndices()) {
/// The GEP operand must be a pointer, so must its result -> BitCast
Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
@ -1050,6 +1059,8 @@ bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB) {
// enclosing iterator here.
MadeChange |= OptimizeCallInst(CI);
}
} else {
MadeChange |= OptimizeInst(I);
}
}