[all-commits] [llvm/llvm-project] 3f087e: [X86][SSE] combineX86ShufflesRecursively - at Dept...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 3f087e38a2e7b87a5adaaac1c1b61e51220e7ff3
      https://github.com/llvm/llvm-project/commit/3f087e38a2e7b87a5adaaac1c1b61e51220e7ff3
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2019-11-03 (Sun, 03 Nov 2019)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/vector-shuffle-combining.ll

  Log Message:
  -----------
  [X86][SSE] combineX86ShufflesRecursively - at Depth==0, only resolve KnownZero if it removes an input.

This stops infinite loops where KnownUndef elements are converted to Zeroable, resulting in KnownZero elements which are then simplified (via SimplifyDemandedElts etc.) back to KnownUndef elements........

Prep fix for PR43024 which will allow rL368307 to be re-applied.