[PATCH] D81013: [InstCombine] move vector select ahead of select-shuffle

Thu Jun 4 14:23:45 PDT 2020

spatel added a comment.

In D81013#2074708 <https://reviews.llvm.org/D81013#2074708>, @lebedev.ri wrote:

> Ah, i guess i see it.
>  The problem is that `ShuffleVectorInst::isSingleSourceMask(ArrayRef<int> Mask)` is kinda broken:
>  it can't tell `isSingleSourceMaskImpl()` how many src elts there are,
>  so naturally it will immediately assert as long as it selects from non-first source..

Would this be fixed with "cast<ShuffleVectorInst>(TVal)->isSelect()" instead of the mask check? 
Let me know if I should revert or if we have a test case to work on.

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https://reviews.llvm.org/D81013