[all-commits] [llvm/llvm-project] 361111: [EarlyCSE] Retain poison flags, if program is UB i...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 361111906ba46494cbe888812ba7c0e500e2bb1e
      https://github.com/llvm/llvm-project/commit/361111906ba46494cbe888812ba7c0e500e2bb1e
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2021-12-11 (Sat, 11 Dec 2021)

  Changed paths:
    M llvm/lib/Transforms/Scalar/EarlyCSE.cpp
    M llvm/test/Transforms/EarlyCSE/flags.ll

  Log Message:
  -----------
  [EarlyCSE] Retain poison flags, if program is UB if poison.

Poison-generating flags can be retained during CSE on the earlier
instruction , *if* the earlier instruction being poison causes UB. For
now, always take AND for floating point instructions.

https://alive2.llvm.org/ce/z/4K3D7P

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D115247