Re: [PATCH 2/3] Fix IEEE 128-bit min/max test.

[Segher Boessenkool <segher@kernel.crashing.org>]

On Thu, Jun 17, 2021 at 04:11:40PM -0400, Michael Meissner wrote:
> On Thu, Jun 17, 2021 at 01:11:58PM -0500, Segher Boessenkool wrote:
> > > --- a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
> > > +++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
> > > @@ -1,6 +1,5 @@
> > > -/* { dg-do compile { target lp64 } } */
> > 
> > Does that work?  Why was it there before?
> 
> The lp64 eliminates 32-bit, which does not support hardware IEEE 128-bit due to
> the lack of TImode.

I still do not understand this.  Why would support for QP float require
TImode?  "Need an integer mode of the same size" is not a convincing
argument, since double-double is a 16 byte mode as well.

> The test was written before the ppc_float128_hw test.  Now
> that we have ppc_float128_hw, we don't need an explicit lp64.

Ah good, some progress.  Well, it *is* an improvement, a better
abstraction, but on the other hand it only hides the actual problems
deeper :-/

> > >  /* { dg-require-effective-target powerpc_p9vector_ok } */
> > > -/* { dg-require-effective-target float128 } */
> > > +/* { dg-require-effective-target ppc_float128_hw } */
> > 
> > Why is it okay to no longer run this test where it ran before?
> 
> The ppc_float128_hw test is a more precise test than just float128 and power9.

You did not delete the p9 test though.


Segher