[PATCH] D13076: [InstCombine] transform masking off of an FP sign bit into a fabs() intrinsic call (PR24886)

[Sanjay Patel via llvm-commits]

spatel added a comment.

In http://reviews.llvm.org/D13076#251834, @spatel wrote:

> In http://reviews.llvm.org/D13076#251181, @majnemer wrote:
>
> > If we will canonicalize away from bitmath, can we please teach `computeKnownBitsFromOperator` how to reason about `llvm.fabs`?  Otherwise, this might be a pessimization.
>
>
> Sure, that seems fair. I see we already have that kind of logic for a few other intrinsics, so fabs should slide right in there.


Except that computeKnownBits and friends make assumptions about only operating on integers and scalars. There's no quick fix AFAICT.
See also: https://llvm.org/bugs/show_bug.cgi?id=24942


http://reviews.llvm.org/D13076