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Treat lifetime begin/end markers as allocations/frees respectively for the

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purposes for GVN/DSE.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85383 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson
2009-10-28 07:05:35 +00:00
parent 40cc524ede
commit b62f792e78
5 changed files with 94 additions and 3 deletions
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18
lib/Analysis/MemoryDependenceAnalysis.cpp
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@ -185,10 +185,9 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
if (invariantTag == Inst) {
invariantTag = 0;
continue;
// If we pass an invariant-end marker, then we've just entered an invariant
// region and can start ignoring dependencies.
} else if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(Inst)) {
// If we pass an invariant-end marker, then we've just entered an
// invariant region and can start ignoring dependencies.
if (II->getIntrinsicID() == Intrinsic::invariant_end) {
uint64_t invariantSize = ~0ULL;
if (ConstantInt* CI = dyn_cast<ConstantInt>(II->getOperand(2)))
@ -200,6 +199,19 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
invariantTag = II->getOperand(1);
continue;
}
// If we reach a lifetime begin or end marker, then the query ends here
// because the value is undefined.
} else if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
II->getIntrinsicID() == Intrinsic::lifetime_end) {
uint64_t invariantSize = ~0ULL;
if (ConstantInt* CI = dyn_cast<ConstantInt>(II->getOperand(1)))
invariantSize = CI->getZExtValue();
AliasAnalysis::AliasResult R =
AA->alias(II->getOperand(2), invariantSize, MemPtr, MemSize);
if (R == AliasAnalysis::MustAlias)
return MemDepResult::getDef(II);
}
}