[all-commits] [llvm/llvm-project] 792052: [X86][AVX] combineBitcastvxi1 - improve handling o...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7920527796eacd596d362ab5266e23189565892e
      https://github.com/llvm/llvm-project/commit/7920527796eacd596d362ab5266e23189565892e
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2021-03-24 (Wed, 24 Mar 2021)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/vector-reduce-and-bool.ll
    M llvm/test/CodeGen/X86/vector-reduce-or-bool.ll
    M llvm/test/CodeGen/X86/vector-reduce-xor-bool.ll

  Log Message:
  -----------
  [X86][AVX] combineBitcastvxi1 - improve handling of vectors truncated to vXi1

If we're truncating to vXi1 from a wider type, then prefer the original wider vector as is simplifies folding the separate truncations + extensions.

AVX1 this is only worth it for v8i1 cases, not v4i1 where we're always better off truncating down to v4i32 for movmsk.

Helps with some regressions encountered in D96609