[PATCH] D43759: [SCEV] Smarter logic in computeConstantDifference

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev added inline comments.


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Comment at: lib/Analysis/ScalarEvolution.cpp:9455
 
   Optional<APInt> LDiff = computeConstantDifference(LHS, FoundLHS);
   Optional<APInt> RDiff = computeConstantDifference(RHS, FoundRHS);
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sanjoy wrote:
> mkazantsev wrote:
> > Also incorrect, because types of LHS and FoundLHS doesn't have to match.
> Do you have a test case for this?  `ScalarEvolution::isImpliedCond` should be zero/sign extending LHS/FoundLHS to make both of them have the same type before calling `ScalarEvolution::isImpliedCondOperands`.  If there are other callsites that don't respect this invariant they should zero/sign extend as well.
Never mind, it seems that I saw this failing due to a bug in another patch I'm working on. False alarm, most likely.


https://reviews.llvm.org/D43759