On Thu, Sep 28, 2017 at 12:40:24AM +0000, Joseph Myers wrote:
> 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.
I have patches for this that I will submit shortly to replace the rs6000
specific patch.
I haven't yet found all of the places that need to be changed for more
traditional math functions like sqrtf128.
> 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).
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.vnet.ibm.com, phone: +1 (978) 899-4797
