[all-commits] [llvm/llvm-project] 5f2fe4: [X86][TLI] SimplifyDemandedVectorEltsForTargetNode...

[Roman Lebedev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 5f2fe48d06c742872804da8b3d86596ed2bb9acb
      https://github.com/llvm/llvm-project/commit/5f2fe48d06c742872804da8b3d86596ed2bb9acb
  Author: Roman Lebedev <lebedev.ri at gmail.com>
  Date:   2021-09-19 (Sun, 19 Sep 2021)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/copy-low-subvec-elt-to-high-subvec-elt.ll
    M llvm/test/CodeGen/X86/horizontal-sum.ll
    M llvm/test/CodeGen/X86/sse41.ll

  Log Message:
  -----------
  [X86][TLI] SimplifyDemandedVectorEltsForTargetNode(): don't break apart broadcasts from which not just the 0'th elt is demanded

Apparently this has no test coverage before D108382,
but D108382 itself shows a few regressions that this fixes.

It doesn't seem worthwhile breaking apart broadcasts,
assuming we want the broadcasted value to be preset in several elements,
not just the 0'th one.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D108411