[all-commits] [llvm/llvm-project] 10b0de: [X86] Ensure that bit reversals of byte vectors ar...

[Tobias Decking via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 10b0dee97dd7e5a122116f7ccb26a19b081db9fd
      https://github.com/llvm/llvm-project/commit/10b0dee97dd7e5a122116f7ccb26a19b081db9fd
  Author: Tobias Decking <Tobias.Decking at gmail.com>
  Date:   2025-07-18 (Fri, 18 Jul 2025)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/vector-bitreverse.ll

  Log Message:
  -----------
  [X86] Ensure that bit reversals of byte vectors are properly lowered on pure GFNI targets (#148304)

Fixes #148238.

When GFNI is present, custom bit reversal lowerings for scalar integers
become active. They work by swapping the bytes in the scalar value and
then reversing bits in a vector of bytes. However, the custom bit
reversal lowering for a vector of bytes is disabled if GFNI is present
in isolation, resulting messed up code.

---------

Co-authored-by: Simon Pilgrim <llvm-dev at redking.me.uk>



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