[PATCH] D64285: [InstCombine] Fold select (icmp sgt x, -1), lshr (X, Y), ashr (X, Y) to ashr (X, Y))

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

In D64285#1580359 <https://reviews.llvm.org/D64285#1580359>, @nikic wrote:

> In D64285#1576787 <https://reviews.llvm.org/D64285#1576787>, @lebedev.ri wrote:
>
> > Ugly, yeah, but powerful instsimplify is nice ^^
>
>
> I feel pretty strongly that this is the not the right tradeoff to make here. Unless there's some specific evidence that we benefit from having this in instsimplify, reducing code duplication is imho much more valuable than making sure that one out of thousands of ad-hoc folds runs in a few more cases than it otherwise would...


Feel free to bring this up as RFC on llvm-dev.


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