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[IndVars] Quick fix LHS/RHS bug 

The code relies on fact that LHS is the NarrowDef but never
really checks it. Adding the conservative restrictive check,
will follow-up with handling of case where RHS is a NarrowDef.
This commit is contained in:
Max Kazantsev 2020-12-04 11:57:39 +07:00
parent dec1bbb47c
commit 3df0daceb2
1 changed files with 3 additions and 0 deletions
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3
llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
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@ -1595,6 +1595,9 @@ bool WidenIV::widenWithVariantUse(WidenIV::NarrowIVDefUse DU) {
return false;
const SCEV *LHS = SE->getSCEV(OBO->getOperand(0));
const SCEV *RHS = SE->getSCEV(OBO->getOperand(1));
// TODO: Support case for NarrowDef = NarrowUse->getOperand(1).
if (NarrowUse->getOperand(0) != NarrowDef)
return false;
if (!SE->isKnownNegative(RHS))
return false;
bool ProvedSubNUW = SE->isKnownPredicateAt(