[RFC] Add FMA support to sparc backend

[Eric Botcazou]

> There have never been TFmode float operations implemented in hardware
> ever for sparc, and I doubt we'll see it in the future.
>
> And this applies also to the FMA instructions.

Do the specs totally disregard quad floats for FMA or...?

> And especially since the presence of the FMA patterns is meant to be a
> performance enhancement, I don't see much value to considering TFmode
> cases.
>
> Did you have something specific in mind?

No, this was purely for my own education. :-)  Maybe a comment explaining the 
situation/(non-)implementation choice wrt TFmode would be in order.

-- 
Eric Botcazou