[PATCH] D107883: [DAGCombiner] Teach isKnownToBeAPowerOfTwo handle SPLAT_VECTOR.

Mon Aug 16 06:23:41 PDT 2021

jacquesguan added a comment.

In D107883#2943284 <https://reviews.llvm.org/D107883#2943284>, @frasercrmck wrote:

> Perhaps some extra tests for `mul`s by other powers of two?
>
> Are you able to get tests for the `(mulhu x, (1 << c)) -> x >> (bitwidth - c)` combine? In my experience `mulhu` can be tricky to source. Maybe D49248 <https://reviews.llvm.org/D49248> contains some hints.

`mulhu` cases with constant splat can not be generated from `combineShiftToMULH` now,  I create a new diff D108129 <https://reviews.llvm.org/D108129> to handle it.

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D107883/new/

https://reviews.llvm.org/D107883