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Take advantage of undefined behavior if the source program tries to GEP 

beyond the end of an alloca to make FastDSE faster and more aggressive.

llvm-svn: 39945
This commit is contained in:
Owen Anderson 2007-07-16 23:34:39 +00:00
parent 81f1a6c4cb
commit 09f86993bd
1 changed files with 4 additions and 11 deletions
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15
llvm/lib/Transforms/Scalar/FastDSE.cpp
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@ -61,17 +61,10 @@ namespace {
// See through pointer-to-pointer bitcasts
while (isa<BitCastInst>(v) || isa<GetElementPtrInst>(v))
if (BitCastInst* C = dyn_cast<BitCastInst>(v)) {
if (isa<PointerType>(C->getSrcTy()))
v = C->getOperand(0);
else
break;
} else if (GetElementPtrInst* G = dyn_cast<GetElementPtrInst>(v)) {
if (G->hasAllZeroIndices())
v = G->getOperand(0);
else
break;
}
if (BitCastInst* C = dyn_cast<BitCastInst>(v))
v = C->getOperand(0);
else if (GetElementPtrInst* G = dyn_cast<GetElementPtrInst>(v))
v = G->getOperand(0);
}
// getAnalysisUsage - We require post dominance frontiers (aka Control