[PATCH] D47883: [InstSimplify] shl nuw C, %x -> C iff signbit is set on C.

Thu Jun 7 09:28:44 PDT 2018

lebedev.ri added a comment.

In https://reviews.llvm.org/D47883#1125194, @spatel wrote:

> LGTM.
>
> Watch out for seemingly unrelated failures though - any time we get smarter about optimizing using these flags, there's a chance that we will expose bugs in other parts of the optimizer.

Thank you for the review and a advice!

Posted `KnownBits` part as follow-up (https://reviews.llvm.org/D47891), but even that isn't sufficient to handle *all* the cases.

Repository:
  rL LLVM

https://reviews.llvm.org/D47883