[all-commits] [llvm/llvm-project] 4431a2: [X86][SSE] Combine unary shuffle(HORIZOP, HORIZOP) ...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 4431a29c60e7c56fe17a1053f7ae55994af6fdba
      https://github.com/llvm/llvm-project/commit/4431a29c60e7c56fe17a1053f7ae55994af6fdba
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2020-04-05 (Sun, 05 Apr 2020)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/haddsub-shuf.ll
    M llvm/test/CodeGen/X86/haddsub-undef.ll
    M llvm/test/CodeGen/X86/phaddsub-undef.ll
    M llvm/test/CodeGen/X86/shuffle-vs-trunc-256.ll
    M llvm/test/CodeGen/X86/vec_saddo.ll
    M llvm/test/CodeGen/X86/vec_smulo.ll
    M llvm/test/CodeGen/X86/vec_ssubo.ll
    M llvm/test/CodeGen/X86/vec_uaddo.ll
    M llvm/test/CodeGen/X86/vec_umulo.ll
    M llvm/test/CodeGen/X86/vec_usubo.ll

  Log Message:
  -----------
  [X86][SSE] Combine unary shuffle(HORIZOP,HORIZOP) -> HORIZOP

We had previously limited the shuffle(HORIZOP,HORIZOP) combine to binary shuffles, but we can often merge unary shuffles just as well, folding in UNDEF/ZERO values into the 64-bit half lanes.

For the (P)HADD/HSUB cases this is limited to fast-horizontal cases but PACKSS/PACKUS combines under all cases.