[PATCH 0/3] ARM with only 32-bit floats do not have fast 64-bit FMA

[Keith Packard]

Brian Inglis <Brian.Inglis@SystematicSw.ab.ca> writes:

> Can't the "super-smart" compiler use that information to work around your
> careful approach by conditionally skipping the FMA and conditionally return just
> z, or even unconditionally return z, as C makes no guarantees?
> And couldn't the "super-smart" instruction scheduler do similar at the hardware
> level?

I don't think that would be in conformance with the C specification
which says that arithmetic follows IEC 60559 that defines the various
exceptions and results. Now, if you enable -ffast-math, all bets are off...

-- 
-keith
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