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Don't try to loop on iterators that are potentially invalidated inside the loop. Fixes PR11361!

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144454 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky
2011-11-12 03:09:12 +00:00
parent 7386612a16
commit d7ecff49d9
2 changed files with 60 additions and 0 deletions
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18
lib/Analysis/ScalarEvolution.cpp
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@ -4853,10 +4853,18 @@ ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
// Also evaluate the other PHI nodes. However, we don't get to stop if we
// cease to be able to evaluate one of them or if they stop evolving,
// because that doesn't necessarily prevent us from computing PN.
SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
for (DenseMap<Instruction *, Constant *>::const_iterator
I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){
PHINode *PHI = dyn_cast<PHINode>(I->first);
if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
PHIsToCompute.push_back(std::make_pair(PHI, I->second));
}
// We use two distinct loops because EvaluateExpression may invalidate any
// iterators into CurrentIterVals.
for (SmallVectorImpl<std::pair<PHINode *, Constant*> >::const_iterator
I = PHIsToCompute.begin(), E = PHIsToCompute.end(); I != E; ++I) {
PHINode *PHI = I->first;
Constant *&NextPHI = NextIterVals[PHI];
if (!NextPHI) { // Not already computed.
Value *BEValue = PHI->getIncomingValue(SecondIsBackedge);
@ -4928,10 +4936,20 @@ const SCEV *ScalarEvolution::ComputeExitCountExhaustively(const Loop *L,
// Update all the PHI nodes for the next iteration.
DenseMap<Instruction *, Constant *> NextIterVals;
// Create a list of which PHIs we need to compute. We want to do this before
// calling EvaluateExpression on them because that may invalidate iterators
// into CurrentIterVals.
SmallVector<PHINode *, 8> PHIsToCompute;
for (DenseMap<Instruction *, Constant *>::const_iterator
I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){
PHINode *PHI = dyn_cast<PHINode>(I->first);
if (!PHI || PHI->getParent() != Header) continue;
PHIsToCompute.push_back(PHI);
}
for (SmallVectorImpl<PHINode *>::const_iterator I = PHIsToCompute.begin(),
E = PHIsToCompute.end(); I != E; ++I) {
PHINode *PHI = *I;
Constant *&NextPHI = NextIterVals[PHI];
if (NextPHI) continue; // Already computed!