[all-commits] [llvm/llvm-project] e19d1f: [X86] Fold XOR of two VGF2P8AFFINEQB instructions ...

[Walter via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e19d1f51a2c80b63cd8ca95bcc757b7077112808
      https://github.com/llvm/llvm-project/commit/e19d1f51a2c80b63cd8ca95bcc757b7077112808
  Author: Walter <90877047+WalterKruger at users.noreply.github.com>
  Date:   2026-06-14 (Sun, 14 Jun 2026)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/gfni-xor-fold-avx512.ll
    M llvm/test/CodeGen/X86/gfni-xor-fold.ll

  Log Message:
  -----------
  [X86] Fold XOR of two VGF2P8AFFINEQB instructions with same matrix (#199146)

Adds an optimization to fold a XOR between two `vgf2p8affineqb`
instructions that share the same matrix by XORing their sources
beforehand. This patch:

- Can eliminate one `vgf2p8affineqb` instruction.
- Doesn't occur if either affine is multi use, preventing an increase in code size.
- Includes test coverage for both positive and negative cases.

Fixes #196879



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