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

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In https://reviews.llvm.org/D53965#1284240, @jfb wrote:

> >> 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.
>
> To clarify my concern: were LLVM to support fenv properly, this instruction can spuriously set FP flags if, say, the fadd executes in a loop and has spurious failure. The final store could hold a result which raised no FP exception, but intermediate results could have done so. But LLVM doesn't support fenv properly yet, so that's not an issue (I think!).


fenv support requires using the new constrained operation intrinsics, but the support there is incomplete (and still some confusion on how they should interact with the regular IR operations, which is used in the cmpxchg loop expansion)


https://reviews.llvm.org/D53965