[PATCH] D53965: IR: Add fp operations to atomicrmw

Thu Nov 1 11:05:24 PDT 2018

arsenm added a comment.

In https://reviews.llvm.org/D53965#1284143, @jfb wrote:

> Is this to support wg21.link/p0020 ?

Yes

> Can you do fsub while you're there. It should be exactly the same thing.

AMDGPU has hardware for fadd, fmin and fmax so I was focusing on those first, but it's trivial to add fsub. fmin/fmax are problematic since it requires deciding NaN behaviors (so I fear we'll end up with 2 or 3 versions of each)

> AFAIK we don't care about FP flags at all here, correct? Even `strictfp` is irrelevant.

We can't algebraically combine this, so the flags shouldn't matter.

https://reviews.llvm.org/D53965