On Wed, 27 Sep 2017, Michael Meissner wrote:
> The glibc team has requested we define the standard macro (__FP_FAST_FMAF128)
> for PowerPC code when we have the IEEE 128-bit floating point hardware
> instructions enabled.
It's not a standard macro. TS 18661-3 has FP_FAST_FMAF128 as an optional
math.h macro (but glibc doesn't define it anywhere at present).
> This patch does this in the PowerPC backend. As I look at the whole issue, at
> some point we should do this more in the machine independent portion of the
> compiler. I have some initial patches to do this in the c-family files, but
> at
> the present time, the patches are not complete, and I need to think about it
> more.
I think a machine-independent definition (for _FloatN / _FloatNx types in
general) should go along with machine-independent fmafN / fmafNx built-in
functions; when the built-in function is machine-specific, it's natural
for the macro to be as well.
But in any case, the new macro should be documented in cpp.texi alongside
the existing __FP_FAST_FMA* macros (probably in the generic
__FP_FAST_FMAF@var{n} and __FP_FAST_FMAF@var{n}X form).
--
Joseph S. Myers
jos...@codesourcery.com
