[all-commits] [llvm/llvm-project] ffb288: [DAG] Fold shuffle(bop(shuffle(x, y), shuffle(z, w)), ...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ffb28871037105c899f63726953b6c4e7aa7b148
      https://github.com/llvm/llvm-project/commit/ffb28871037105c899f63726953b6c4e7aa7b148
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2021-03-19 (Fri, 19 Mar 2021)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/test/CodeGen/X86/haddsub-4.ll
    M llvm/test/CodeGen/X86/haddsub-shuf.ll
    M llvm/test/CodeGen/X86/known-signbits-vector.ll

  Log Message:
  -----------
  [DAG] Fold shuffle(bop(shuffle(x,y),shuffle(z,w)),undef) -> bop(shuffle'(x,y),shuffle'(z,w))

Followup to D96345, handle unary shuffles of binops (as well as binary shuffles) if we can merge the shuffle with inner operand shuffles.

Differential Revision: https://reviews.llvm.org/D98646