[Patch] Altivec ABI as default for powerpc64 linux

[Aldy Hernandez]

> > For starters, try this with powerpc-linux-gnu and -mabi=altivec (but
> > no -maltivec), and fix it :).
> > 
> >         typedef int vec __attribute__((mode(V4SI)));
> >         vec poo, bar;
> >         extern void funk(vec);
> >         f(){
> >                 funk(poo);
> >         }
> 
> How can this work?  "funk" expects its parameter in v1, but without
> -maltivec there are no instructions that can put it there.

Exactly.  It won't.  If they want one ABI, they need to fix all these
places.  I haven't looked in this particular case, but the test should
probably be TARGET_ALTIVEC_ABI *and* TARGET_ALTIVEC, otherwise stuff
should go in GPRs.