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Avoid undefined behavior in negation in LSR. Patch by Ahmed Charles. 

Someone more familiar with LSR should double-check that the extra cast is actually doing the right thing in the overflow cases; I'm not completely confident that's that case. 

llvm-svn: 141916
This commit is contained in:
Eli Friedman 2011-10-13 23:48:33 +00:00
parent df4f7ca331
commit b46345d7c1
1 changed files with 2 additions and 2 deletions
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4
llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -1205,7 +1205,7 @@ static bool isLegalUse(const TargetLowering::AddrMode &AM,
// If we have low-level target information, ask the target if it can fold an
// integer immediate on an icmp.
if (AM.BaseOffs != 0) {
if (TLI) return TLI->isLegalICmpImmediate(-AM.BaseOffs);
if (TLI) return TLI->isLegalICmpImmediate(-(uint64_t)AM.BaseOffs);
return false;
}
@ -3593,7 +3593,7 @@ Value *LSRInstance::Expand(const LSRFixup &LF,
// The other interesting way of "folding" with an ICmpZero is to use a
// negated immediate.
if (!ICmpScaledV)
ICmpScaledV = ConstantInt::get(IntTy, -Offset);
ICmpScaledV = ConstantInt::get(IntTy, -(uint64_t)Offset);
else {
Ops.push_back(SE.getUnknown(ICmpScaledV));
ICmpScaledV = ConstantInt::get(IntTy, Offset);