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Indvars needs to explicitly notify ScalarEvolution when it is replacing

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a loop exit value, so that if a loop gets deleted, ScalarEvolution
isn't stick holding on to dangling SCEVAddRecExprs for that loop. This
fixes PR6339.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96626 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2010-02-18 23:26:33 +00:00
parent 1c40e188c5
commit aa11defd1c
3 changed files with 41 additions and 0 deletions
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29
lib/Analysis/ScalarEvolution.cpp
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@ -3485,6 +3485,35 @@ void ScalarEvolution::forgetLoop(const Loop *L) {
}
}
/// forgetValue - This method should be called by the client when it has
/// changed a value in a way that may effect its value, or which may
/// disconnect it from a def-use chain linking it to a loop.
void ScalarEvolution::forgetValue(Value *V) {
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return;
// Drop information about expressions based on loop-header PHIs.
SmallVector<Instruction *, 16> Worklist;
Worklist.push_back(I);
SmallPtrSet<Instruction *, 8> Visited;
while (!Worklist.empty()) {
I = Worklist.pop_back_val();
if (!Visited.insert(I)) continue;
std::map<SCEVCallbackVH, const SCEV *>::iterator It =
Scalars.find(static_cast<Value *>(I));
if (It != Scalars.end()) {
ValuesAtScopes.erase(It->second);
Scalars.erase(It);
if (PHINode *PN = dyn_cast<PHINode>(I))
ConstantEvolutionLoopExitValue.erase(PN);
}
PushDefUseChildren(I, Worklist);
}
}
/// ComputeBackedgeTakenCount - Compute the number of times the backedge
/// of the specified loop will execute.
ScalarEvolution::BackedgeTakenInfo