riscv: fmax/fmin sNaN fix

[Joseph Myers]

On Tue, 20 Feb 2018, Szabolcs Nagy wrote:

> On 20/02/18 02:57, DJ Delorie wrote:
> > 
> > RISC-V's FPU follows the IEEE spec, not the POSIX spec.  This patch
>                            ^^^^^^^^^
> which one?
> (the next ieee revision will have different min/max operations)

The point (as per 
<https://sourceware.org/ml/libc-alpha/2018-01/msg01084.html>) is that fmax 
and fmin in TS 18661-1 bind to maxNum and minNum.  Those operations are to 
be removed in IEEE 754-2018 so the C functions will have semantics that no 
longer have a corresponding IEEE operation (much like e.g. nextafter / 
nexttoward, which correspond to the Nextafter operation recommended in 
IEEE 754-1985 but removed in IEEE 754-2008).  Instead, the new minimum, 
minimumNumber, maximum and maximumNumber operations are proposed to have 
new functions fminimum, fminimum_num, fmaximum, fmaximum_num (and likewise 
*mag* functions) - but so far there is no public draft of those proposed 
TS changes (which might in any case more likely be dealt with in the C2x 
process rather than through a new revision of the TS being produced).

-- 
Joseph S. Myers
joseph@codesourcery.com