[all-commits] [llvm/llvm-project] 585e65: [TLI] SimplifyDemandedVectorElts(): handle SCALAR_...

[Roman Lebedev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 585e65d3307f5f081b32b21421f2a0b84eccd1b5
      https://github.com/llvm/llvm-project/commit/585e65d3307f5f081b32b21421f2a0b84eccd1b5
  Author: Roman Lebedev <lebedev.ri at gmail.com>
  Date:   2021-06-14 (Mon, 14 Jun 2021)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    M llvm/test/CodeGen/X86/vector-fshl-256.ll
    M llvm/test/CodeGen/X86/vector-fshl-512.ll
    M llvm/test/CodeGen/X86/vector-fshl-rot-256.ll
    M llvm/test/CodeGen/X86/vector-fshl-rot-512.ll
    M llvm/test/CodeGen/X86/vector-fshr-256.ll
    M llvm/test/CodeGen/X86/vector-fshr-512.ll
    M llvm/test/CodeGen/X86/vector-fshr-rot-256.ll
    M llvm/test/CodeGen/X86/vector-fshr-rot-512.ll
    M llvm/test/CodeGen/X86/vector-rotate-256.ll

  Log Message:
  -----------
  [TLI] SimplifyDemandedVectorElts(): handle SCALAR_TO_VECTOR(EXTRACT_VECTOR_ELT(?, 0))

Iff we have `SCALAR_TO_VECTOR` (and we demand it's only defined 0'th element),
and said scalar was produced by `EXTRACT_VECTOR_ELT` from the 0'th element
of some vector, then we can just continue traversal into said source vector.

This comes up in X86 vector uniform shift lowering.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D104250