PowerPC: Update __float128 and __ibm128 error messages.

[Michael Meissner]

On Tue, Oct 27, 2020 at 06:27:22PM -0500, Segher Boessenkool wrote:
> Hi!
> 
> On Thu, Oct 22, 2020 at 06:11:35PM -0400, Michael Meissner wrote:
> > This patch attempts to make the error messages for intermixing IEEE 128-bit
> > floating point with IBM 128-bit extended double types to be clearer if the long
> > double type uses the IEEE 128-bit format.
> 
> > We have gotten some requests to back port these changes to GCC 10.x.  At the
> > moment, I am not planning to do the back port, but I may need to in the future.
> 
> Ping the patches if/when that happens?

Certainly.

> > +/* { dg-do compile { target { powerpc*-*-linux* } } } */
> 
> Use *-*-linux* instead?  (In all relevant tests.)

Ok.

> Is there any reason these tests should only run on Linux?  If not, it
> should not restrict itself like this; and if so, you may want another
> selsector (something ieee128 perhaps), or at the very least add a
> comment why you do this.

Right now the float128 emulation is only built on Linux, because it needs the
support in GLIBC.  If/when other systems add support for float128 in there
C/C++ libraries, we can widen the tests.

> >  /* { dg-do compile { target { powerpc*-*-linux* } } } */
> > -/* { dg-require-effective-target powerpc_vsx_ok } */
> > -/* { dg-options "-O2 -mvsx" } */
> > +/* { dg-require-effective-target ppc_float128_sw } */
> 
> Removing powerpc_vsx_ok is wrong, you still use -mvsx.  That the only
> current soft float QP stuff requires VSX is irrelevant.
> 
> Please fix those everywhere.  Okay for trunk with that.  Thanks!

IIRC, these tests were added very early in the float128 cycle, before we had
the target supports for float128.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797