[PATCH] D66383: [InstCombine] Shift amount reassociation in bittest: trunc-of-lshr (PR42399)

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

In D66383#1649115 <https://reviews.llvm.org/D66383#1649115>, @spatel wrote:

> A few clean-ups noted inline.




> If I'm reading it correctly, this is more complicated than it could be only to support arbitrary vector constants. Do we have any evidence that says we need that support?
> 
> We've come this far on this series of patches without raising that question, so I'm not going to object to this particular patch now. But I think we should keep the code simpler unless we know there's a reason to handle the arbitrary vector constant pattern. It seems too rare to me to warrant this much effort.

Indeed, non-splat support is ugly here, and incomplete still.
I don't have any evidence, and furthermore i only need scalar support from this, so i will happily cripple it.


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