[LLVMdev] Documentation of fmuladd intrinsic

[dag at cray.com]

Justin Holewinski <justin.holewinski at gmail.com> writes:

> Out of curiosity, what is the use-case for isFMAFasterThanMulAndAdd?
>  If a target declares that FMA is actually slower for a given type,
> why not just declare it as illegal for that type?  Wouldn't that
> accomplish the same thing without another target hook?  I feel like I'm
> missing something here.

It's not expressed in the code Hal posted but I suppose a target could
have a slow fma that the user nonetheless wants to use for precision
reasons.

                              -David