[all-commits] [llvm/llvm-project] da4373: [SCEVExp] Keep NUW/NSW if both original inc and is...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: da437330beca0411912ca46f2d5ef1e46403acbd
      https://github.com/llvm/llvm-project/commit/da437330beca0411912ca46f2d5ef1e46403acbd
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2024-02-01 (Thu, 01 Feb 2024)

  Changed paths:
    M llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
    M llvm/test/Transforms/IndVarSimplify/iv-poison.ll

  Log Message:
  -----------
  [SCEVExp] Keep NUW/NSW if both original inc and isomporphic inc agree. (#79512)

We are replacing with a wider increment. If both OrigInc and
IsomorphicInc are NUW/NSW, then we can preserve them on the wider
increment; the narrower IsomorphicInc would wrap before the wider
OrigInc, so the replacement won't make IsomorphicInc's uses more
poisonous.

PR: https://github.com/llvm/llvm-project/pull/79512