[all-commits] [llvm/llvm-project] 6878be: [X86][SSE] Attempt to merge single-op hops for slo...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6878be5dc3ec7031d0deec3e321310115bd71103
      https://github.com/llvm/llvm-project/commit/6878be5dc3ec7031d0deec3e321310115bd71103
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2021-03-15 (Mon, 15 Mar 2021)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/horizontal-sum.ll

  Log Message:
  -----------
  [X86][SSE] Attempt to merge single-op hops for slow targets.

For slow-hop targets, see if any single-op hops are duplicating work already done on another (dual-op) hop, which can sometimes occur as isHorizontalBinOp tries to find potential duplicates (but can't merge them itself). If so, reuse the other hop and shuffle the result.