[PATCH] D51112: [ValueTracking] Teach computeNumSignBits to understand min/max clamp patterns with constant/splat values

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

In https://reviews.llvm.org/D51112#1209937, @craig.topper wrote:

> In https://reviews.llvm.org/D51112#1209885, @efriedma wrote:
>
> > > I'm still calling computeNumSignBits on the other input. I don't think SelectionDAG does that.
> >
> > Thinking about it a bit more, there's probably a good reason for that: if the number of sign bits for the variable input matters, either the SMIN or the SMAX is a no-op.
>
>
> That's true, but are we capable of making that optimization today.


Not sure off the top of my head?  But it's easy to implement.


https://reviews.llvm.org/D51112