[all-commits] [llvm/llvm-project] 2bb418: [Utils] recognizeBSwapOrBitReverseIdiom - support ...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2bb41851a10c1473bda9a87b4bfabf99527b3929
      https://github.com/llvm/llvm-project/commit/2bb41851a10c1473bda9a87b4bfabf99527b3929
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2021-05-04 (Tue, 04 May 2021)

  Changed paths:
    M llvm/lib/Transforms/Utils/Local.cpp
    M llvm/test/Transforms/CodeGenPrepare/X86/bitreverse-recognize.ll

  Log Message:
  -----------
  [Utils] recognizeBSwapOrBitReverseIdiom - support matching from funnel shift roots (PR40058)

We were missing bitreverse matches in cases where InstCombine had seen a byte-level rotation at the end of a bitreverse sequence (replacing or() with fshl()), hindering the exhaustive bitreverse matching in CodeGenPrepare later on.