[all-commits] [llvm/llvm-project] eafe7c: [PowerPC] Fix combineVectorShuffle regression afte...

[Fangrui Song via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: eafe7c14ea38946e8c1fb64d548effaee7614718
      https://github.com/llvm/llvm-project/commit/eafe7c14ea38946e8c1fb64d548effaee7614718
  Author: Fangrui Song <maskray at google.com>
  Date:   2020-07-13 (Mon, 13 Jul 2020)

  Changed paths:
    M llvm/lib/Target/PowerPC/PPCISelLowering.cpp
    M llvm/test/CodeGen/PowerPC/canonical-merge-shuffles.ll

  Log Message:
  -----------
  [PowerPC] Fix combineVectorShuffle regression after D77448

Commit 1fed131660b2 assumed that NewShuffle (shuffle vector
canonicalization result) will always be ShuffleVectorSDNode, which may
be false (it may be a BITCAST node):

```
...
t12: v4i32 = scalar_to_vector t2
t15: v16i8 = bitcast t12  # LHS
t17: v16i8 = vector_shuffle<u,u,u,u,u,u,u,u,0,1,2,3,u,u,u,u> t15, undef:v16i8  # SVN
```

Reviewed By: #powerpc, nemanjai

Differential Revision: https://reviews.llvm.org/D83617