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Simplify code and do not invalidate iterators.

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This fixes a crash compiling TimberWolfMC that was exposed due to recent
optimizer changes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18831 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-12-12 18:23:20 +00:00
parent 3ea78c4276
commit fb851ab281
1 changed files with 9 additions and 46 deletions
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55
lib/Transforms/Scalar/GCSE.cpp
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@ -100,10 +100,12 @@ bool GCSE::runOnFunction(Function &F) {
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
Instruction *Inst = I++;
// If this instruction computes a value, try to fold together common
// instructions that compute it.
//
if (Inst->getType() != Type::VoidTy) {
if (Constant *C = ConstantFoldInstruction(Inst)) {
ReplaceInstructionWith(Inst, C);
} else if (Inst->getType() != Type::VoidTy) {
// If this instruction computes a value, try to fold together common
// instructions that compute it.
//
VN.getEqualNumberNodes(Inst, EqualValues);
// If this instruction computes a value that is already computed
@ -183,54 +185,15 @@ void GCSE::ReplaceInstructionWith(Instruction *I, Value *V) {
// Update value numbering
getAnalysis<ValueNumbering>().deleteValue(I);
// If we are not replacing the instruction with a constant, we cannot do
// anything special.
if (!isa<Constant>(V)) {
I->replaceAllUsesWith(V);
if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
// Removing an invoke instruction requires adding a branch to the normal
// destination and removing PHI node entries in the exception destination.
new BranchInst(II->getNormalDest(), II);
II->getUnwindDest()->removePredecessor(II->getParent());
}
// Erase the instruction from the program.
I->getParent()->getInstList().erase(I);
return;
}
Constant *C = cast<Constant>(V);
std::vector<User*> Users(I->use_begin(), I->use_end());
// Perform the replacement.
I->replaceAllUsesWith(C);
I->replaceAllUsesWith(V);
if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
// Removing an invoke instruction requires adding a branch to the normal
// destination and removing PHI node entries in the exception destination.
new BranchInst(II->getNormalDest(), II);
II->getUnwindDest()->removePredecessor(II->getParent());
}
// Erase the instruction from the program.
I->getParent()->getInstList().erase(I);
// Check each user to see if we can constant fold it.
while (!Users.empty()) {
Instruction *U = cast<Instruction>(Users.back());
Users.pop_back();
if (Constant *C = ConstantFoldInstruction(U)) {
ReplaceInstructionWith(U, C);
// If the instruction used I more than once, it could be on the user list
// multiple times. Make sure we don't reprocess it.
std::vector<User*>::iterator It = std::find(Users.begin(), Users.end(),U);
while (It != Users.end()) {
Users.erase(It);
It = std::find(Users.begin(), Users.end(), U);
}
}
}
}