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DSE: Remove an early exit optimization that depended on the ordering of a SmallPtrSet.

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Fixes PR9569 and will hopefully make selfhost on ASLR-enabled systems more deterministic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128482 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2011-03-29 20:28:57 +00:00
parent d0cfc99b30
commit ec3f227820
1 changed files with 0 additions and 13 deletions
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13
lib/Transforms/Scalar/DeadStoreElimination.cpp
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@ -640,28 +640,15 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
if (AA->doesNotAccessMemory(CS))
continue;
unsigned NumModRef = 0, NumOther = 0;
// If the call might load from any of our allocas, then any store above
// the call is live.
SmallVector<Value*, 8> LiveAllocas;
for (SmallPtrSet<Value*, 16>::iterator I = DeadStackObjects.begin(),
E = DeadStackObjects.end(); I != E; ++I) {
// If we detect that our AA is imprecise, it's not worth it to scan the
// rest of the DeadPointers set. Just assume that the AA will return
// ModRef for everything, and go ahead and bail out.
if (NumModRef >= 16 && NumOther == 0)
return MadeChange;
// See if the call site touches it.
AliasAnalysis::ModRefResult A =
AA->getModRefInfo(CS, *I, getPointerSize(*I, *AA));
if (A == AliasAnalysis::ModRef)
++NumModRef;
else
++NumOther;
if (A == AliasAnalysis::ModRef || A == AliasAnalysis::Ref)
LiveAllocas.push_back(*I);
}