[PATCH] D57359: [GlobalISel] Introduce a G_FSQRT generic instruction

Tue Jan 29 17:30:26 PST 2019

spatel added a comment.

In D57359#1376446 <https://reviews.llvm.org/D57359#1376446>, @aemerson wrote:

> Uhhh...from what I can tell it looks like llvm.sqrt's semantics have been changed to match the libm semantics, except for errno.
>
> @spatel can you confirm that the change from D39304 <https://reviews.llvm.org/D39304> indeed made llvm.sqrt(-x) == NaN?

That was just a cosmetic change to the docs. The real changes were made in:
D28797 <https://reviews.llvm.org/D28797>
D28928 <https://reviews.llvm.org/D28928>
D28929 <https://reviews.llvm.org/D28929>
D39204 <https://reviews.llvm.org/D39204>

So yes, llvm.sqrt() is supposed to have conformed to IEEE/libm sqrt for about 2 years now. If anyone sees misbehavior/missed optimizations, please let me know.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D57359/new/

https://reviews.llvm.org/D57359