[all-commits] [llvm/llvm-project] ec9107: [X86] combineX86ShufflesRecursively - attempt to f...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ec910751fe5c4a0e0fe4e232da0f8bed307bf4e8
      https://github.com/llvm/llvm-project/commit/ec910751fe5c4a0e0fe4e232da0f8bed307bf4e8
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2022-02-20 (Sun, 20 Feb 2022)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/avx512-hadd-hsub.ll
    M llvm/test/CodeGen/X86/copy-low-subvec-elt-to-high-subvec-elt.ll
    M llvm/test/CodeGen/X86/vector-shuffle-256-v16.ll
    M llvm/test/CodeGen/X86/vector-shuffle-256-v32.ll
    M llvm/test/CodeGen/X86/vector-shuffle-256-v8.ll
    M llvm/test/CodeGen/X86/vector-shuffle-512-v32.ll

  Log Message:
  -----------
  [X86] combineX86ShufflesRecursively - attempt to fold ISD::EXTRACT_SUBVECTOR into a shuffle chain

Peek through if we're extracting a non-zero'th subvector in an attempt to fold the extract into a lane-crossing shuffle

This also exposes a failure to fold extract_subvector(movddup(x),c) -> movddup(extract_subvector(x,c))