[all-commits] [llvm/llvm-project] e95d04: [X86][AVX] lowerV4X128Shuffle - attempt to widen t...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: e95d04f4f19db87ee8228fcfa8230845e89a9bb6
      https://github.com/llvm/llvm-project/commit/e95d04f4f19db87ee8228fcfa8230845e89a9bb6
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2020-03-30 (Mon, 30 Mar 2020)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/vector-shuffle-512-v8.ll

  Log Message:
  -----------
  [X86][AVX] lowerV4X128Shuffle - attempt to widen to 2x256 to simplify shuffles

If we are lowering to X86ISD::SHUF128 we are going to lose track of individual 128-bit lanes that are UNDEF, so if we can widen these to guarantee that they are sequential with their neighbour we should. This helps with later shuffle combines.