[all-commits] [llvm/llvm-project] 598ceb: [X86][AVX] Fold extract_subvector(splat, c) -> ext...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 598ceb25d4a42b6a814b2acc5e7ce5c73d6b8fb7
      https://github.com/llvm/llvm-project/commit/598ceb25d4a42b6a814b2acc5e7ce5c73d6b8fb7
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2021-02-07 (Sun, 07 Feb 2021)

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

  Log Message:
  -----------
  [X86][AVX] Fold extract_subvector(splat, c) -> extract_subvector(splat, 0)

We already do this for VBROADCASTs, extend this for any splat that SelectionDAG::isSplatValue recognises as well.