[PATCH] D60518: [InstCombine] Handle ssubo always overflow

[Nikita Popov via Phabricator via llvm-commits]

nikic marked an inline comment as done.
nikic added inline comments.


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Comment at: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp:4016
     if (isa<UndefValue>(RHS))
       return SetResult(RHS, UndefValue::get(Builder.getInt1Ty()), false);
 
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Not related to this patch, but this fold looks buggy to me. X * undef should be {0, false}, as that's the only results that's possible for all values of X (including X=0). IIRC not even undef * undef can result in {undef, undef} for all bitwidths.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60518/new/

https://reviews.llvm.org/D60518