[all-commits] [llvm/llvm-project] 55e4cd: [X86][AVX2] Recognise 256-bit truncation shuffles ...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 55e4cd8485dc6308211f85c60559a373ae96873e
      https://github.com/llvm/llvm-project/commit/55e4cd8485dc6308211f85c60559a373ae96873e
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2021-11-07 (Sun, 07 Nov 2021)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/masked_store_trunc.ll
    M llvm/test/CodeGen/X86/shuffle-vs-trunc-256.ll
    M llvm/test/CodeGen/X86/vector-interleaved-load-i16-stride-4.ll
    M llvm/test/CodeGen/X86/vector-trunc.ll

  Log Message:
  -----------
  [X86][AVX2] Recognise 256-bit truncation shuffles and mask 256-bit source

For v8i16 shuffle patterns that are lowered with AND+PACKUS, check to see if the sources are from a 256-bit vector and perform the masking using BLENDW at the 256-bit level.

With the test changes we can see more examples of duplicate XMM/YMM zero vectors (PR26018) :(