[all-commits] [llvm/llvm-project] e30d29: [X86][SSE] getFauxShuffleMask - peek through TRUNC...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: e30d29ebc12a29b2843d40e575809d642920b1a4
      https://github.com/llvm/llvm-project/commit/e30d29ebc12a29b2843d40e575809d642920b1a4
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2020-03-26 (Thu, 26 Mar 2020)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/buildvec-extract.ll
    M llvm/test/CodeGen/X86/buildvec-insertvec.ll
    M llvm/test/CodeGen/X86/extract-concat.ll

  Log Message:
  -----------
  [X86][SSE] getFauxShuffleMask - peek through TRUNCATE/AEXT/ZEXT for INSERT_VECTOR_ELT(EXTRACT_VECTOR_ELT())

As long we extract from a source vector with smaller elements and we zero-extend the element in the final shuffle mask then we can safely peek through truncations and any/zero-extensions to find the source extraction.