[gomp] i386 cmpxchg8b and x86_64 cmpxchg16b support

[Jakub Jelinek]

On Tue, Oct 11, 2005 at 01:34:34AM +0200, Andi Kleen wrote:
> Jakub Jelinek <jakub@redhat.com> writes:
> > 
> > --- libgomp/testsuite/libgomp.dg/atomic-2.c.jj	2005-10-10 23:23:40.000000000 +0200
> > +++ libgomp/testsuite/libgomp.dg/atomic-2.c	2005-10-10 23:28:51.000000000 +0200
> > @@ -0,0 +1,35 @@
> > +/* { dg-do run } */
> > +/* { dg-options "-O2 -fopenmp" } */
> > +/* { dg-options "-O2 -fopenmp -march=nocona" { target i?86-*-* x86_64-*-* } } */

You missed one line below it:
/* { dg-options "-O2 -fopenmp" { target ilp32 } } */

> > +main (void)
> > +{
> > +#ifdef __x86_64__
> 
> This needs to be #if defined(__i386__) || defined(__x86_64__) 
> otherwise you will crash on most i386 boxes.

The above means, add -march=nocona only on {i?86,x86_64}-*-* if generating
64-bit code.  So #ifdef __x86_64__ is correct.

> > +# define bit_SSE3 (1 << 0)
> > +# define bit_CX16 (1 << 13)
> > +  unsigned int ax, bx, cx, dx;
> > +  __asm__ ("cpuid" : "=a" (ax), "=b" (bx), "=c" (cx), "=d" (dx)
> > +           : "0" (1) : "cc");
> > +  if ((cx & (bit_SSE3 | bit_CX16)) != (bit_SSE3 | bit_CX16))
> > +    return 0;
> > +#endif
> 
> Also as a nitpick CX16 is in theory legal without SSE3.

True, but I'm not adding -mcmpxchg16b switch (which doesn't exist),
but selecting -march=nocona.  So I'd better make sure all code gcc generates
for -march=nocona runs on the target processor.

	Jakub