On Sun, Oct 25, 2020 at 11:55:39AM +1030, Alan Modra wrote:
> On Sat, Oct 24, 2020 at 12:31:43PM -0500, Segher Boessenkool wrote:
> > On Sat, Oct 24, 2020 at 02:59:34PM +1030, Alan Modra wrote:
> > > Those instructions aren't generated, we don't see them anywhere on a
> > > power10 all-lang bootstrap except in one testcase designed to exercise
> > > them.
> > 
> > But that is completely not relevant :-)
> > 
> > If you use a macro that doesn't exist, the compiler simply does not
> > build!
> 
> My empirical evidence to the contrary says your theoretical arguments
> are invalid.  :-)
> 
> $ gcc/xgcc -Bgcc/ -S 
> ~/src/gcc/gcc/testsuite/gcc.target/powerpc/vsx_mask-count-runnable.c -O2 
> -mcpu=power10
> $ grep VSX_MM vsx_mask-count-runnable.s
>       vcntmb<VSX_MM_SUFFIX> 9,0,1
>       vcntmb<VSX_MM_SUFFIX> 9,0,1
>       vcntmb<VSX_MM_SUFFIX> 9,0,1
>       vcntmb<VSX_MM_SUFFIX> 9,0,1

Oh, wow.  How unexpected (to me, anyway).  I'll open a PR.


Segher

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