Adding __float128 (i.e TS 18661-3)

[Joseph Myers]

On Thu, 9 Jun 2016, Paul E. Murphy wrote:

> Macros added via math.h
> 
> 	From TS 18661-3:
> 	
> 	FP_FAST_FMA HUGE_VAL

I should take this opportunity to give a reminder:

A handful of GCC built-in functions should be added for float128 support, 
and are not currently present in the powerpc port.  You should add 
__builtin_infq __builtin_huge_valq __builtin_fabsq __builtin_copysignq as 
on x86 (or if you wish, use *f128 names instead of *q - *f128 may be 
better as in line with TS 18661-3 naming), plus __builtin_nan* 
__builtin_nans* which I noted in GCC bugs 71241 and 71242 are missing for 
x86 / ia64.

HUGE_VALF128 can then be defined as (__builtin_hugevalf128 ()).

-- 
Joseph S. Myers
joseph@codesourcery.com