[all-commits] [llvm/llvm-project] c43a78: [InstCombine] don't let 'exact' inhibit demanded b...

[Sanjay Patel via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c43a7874a3012ae0c6aa983a882a0b23284c2ec7
      https://github.com/llvm/llvm-project/commit/c43a7874a3012ae0c6aa983a882a0b23284c2ec7
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2023-01-04 (Wed, 04 Jan 2023)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
    M llvm/test/Transforms/InstCombine/udiv-simplify.ll

  Log Message:
  -----------
  [InstCombine] don't let 'exact' inhibit demanded bits folds for udiv

We shouldn't penalize instructions that have extra flags.

Drop the poison-generating flags if needed instead of bailing out.
This makes canonicalization/optimization more uniform.

There is a chance that dropping flags will cause some
other transform to not fire, but we added a preliminary
patch to avoid that with:
f0faea571403

See D140665 for more details.