On Thu, Nov 12, 2020 at 09:15:11AM -0700, Jeff Law wrote:
> > void foo (void)
> > {
> > register float __attribute__ ((mode(SD))) r31 __asm__ ("r31");
> > register float __attribute__ ((mode(SD))) fr1 __asm__ ("fr1");
> >
> > __asm__ ("#" : "=d" (fr1));
> > r31 = fr1;
> > __asm__ ("#" : : "r" (r31));
> > }
>
> Looking at this again after many months away, I wonder the real problem
> is the reloads we have to generate for copies to/from he fr1 local
> variable, which is bound to hard reg fr1 rather than the asm statements
> themselves. It's not clear to me from the BZ and I don't have a PPC
> cross handy to look directly.
We should never do a reload of a (local) register variable.
Unfortunately we cannot currently tell during reload that something is
one!
See also PR97708, and many more, going many years back.
Segher
