[all-commits] [llvm/llvm-project] 8a2bc9: [X86][AVX] getTargetShuffleMask - don't decode VBR...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/release/11.x
  Home:   https://github.com/llvm/llvm-project
  Commit: 8a2bc9431193026454745d538cf7e5a5a6b6d5be
      https://github.com/llvm/llvm-project/commit/8a2bc9431193026454745d538cf7e5a5a6b6d5be
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2020-07-23 (Thu, 23 Jul 2020)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/vector-fshl-256.ll
    M llvm/test/CodeGen/X86/vector-fshl-512.ll
    M llvm/test/CodeGen/X86/vector-fshl-rot-512.ll
    M llvm/test/CodeGen/X86/vector-fshr-256.ll
    M llvm/test/CodeGen/X86/vector-fshr-512.ll
    M llvm/test/CodeGen/X86/vector-fshr-rot-512.ll
    M llvm/test/CodeGen/X86/vector-rotate-512.ll

  Log Message:
  -----------
  [X86][AVX] getTargetShuffleMask - don't decode VBROADCAST(EXTRACT_SUBVECTOR(X,0)) patterns.

getTargetShuffleMask is used by the various "SimplifyDemanded" folds so we can't assume that the bypassed extract_subvector can be safely simplified - getFauxShuffleMask performs a more general decode that allows us to more safely catch many of these cases so the impact is minimal.

(cherry picked from commit 5b5dc2442ac7a574a3b7d17c15ebeeb9eb3bec26)