Re: [PATCH][fortran] Make cbrt, cexpi and sincos builtins available

["Richard Guenther" <richard dot guenther at gmail dot com>]

On 12/15/06, Jerry DeLisle <jvdelisle@verizon.net> wrote:
> Tobias Burnus wrote:
> > Let's    *ping*   for Richard.
> >
> > with the sincos infrastructure in the middle end (I think all patches
> > are now in the trunk), this speeds up the Polyhedron fatigue test a lot:
> > ~28.3s => ~18.3s  (35% faster).
> >
> > This can be seen at the page
> > http://www.suse.de/~gcctest/c++bench/polyhedron/polyhedron-summary.txt-fatigue-15.png
> > of http://www.suse.de/~gcctest/c++bench/polyhedron/
> > (The patch was applied for one day.)
> >
> > Tobias
> >
> > Richard Guenther schrieb:
> >> As $subject says.  The cbrt builtins can be used to expand x**1./3. to
> >> cbrt, the other two are on-top of the sincos patches.
> >>
> >> Bootstrap / regtest running.
> >>
> >> Ok if the sincos patch(es) go in?  How can we tell that the target
> >> supports sincos?  (I guess we would need a configure check for that?)
> >>
>
> It was not clear to me the consequences of the question about needing a
> configure check.  Has that been addressed?

No, it has not been addressed.  As far as I see we do not have infrastructure
in place to have tests on the target system in gcc/ because it wouldn't work
if we are cross-compiling.  We would need to do a two-stage compile in
the cross-compiling case as well - first build a cross compiler to be able
to compile/link target configure tests and then after those tests rebuild.

So the canonical way of introducing target dependencies in gcc/ is to
augment the gcc/config/ stuff with target macros/hooks dependent on
the target system.

For builtins, the __builtin_* variant is always available even if the target
does not provide a library implementation (see PR29719 for where this
causes a problem).
For the bare variant we only
have a destinction for TARGET_C99_FUNCTIONS - which doesn't help
in the case of sincos, as that is a (common) extension.  Also
TARGET_C99_FUNCTIONS is said to be too broad (see PR30181).

So before going down the route adding TARGET_HAS_SINCOS and
maybe lots of TARGET_HAS_C99_XYZ - are there better suggestions on
how to address the problems above?

Thanks,
Richard.