[all-commits] [llvm/llvm-project] 1720ec: [InstCombine] restrict no-wrap propagation for i1/...

[Sanjay Patel via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1720ec6da040729f17dfc685f853b9c15658fbc6
      https://github.com/llvm/llvm-project/commit/1720ec6da040729f17dfc685f853b9c15658fbc6
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2023-01-18 (Wed, 18 Jan 2023)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
    M llvm/test/Transforms/InstCombine/sub.ll

  Log Message:
  -----------
  [InstCombine] restrict no-wrap propagation for i1/i2 to avoid miscompiles

This transform was added with 68c197f07eeae71b9b7,
and the post-commit review noted the potential
for miscompiles at narrow bitwidths.

I'm not sure how to expose the i1 nuw bug because we
already simplify that, but other cases show that
there are missing transforms to add in follow-up
patches.