I usually prefer the expanded notation:
unsigned char ret;
__asm__ __volatile__ (
"lock; cmpxchgl %3,%4 \n\t"
" sete %0 \n\t"
: "=qm" (ret), "=a" (oldval), "=m" (*addr)
: "q"(newval), "m"(*addr), "1"(oldval)
: "memory", "cc");
return (int)ret;
}
as it shows more clearly the input and output registers. But your version does
exactly the same thing. I'll commit shortly.
Thanks,
george.
On Feb 10, 2010, at 10:55 , Ake Sandgren wrote:
> On Wed, 2010-02-10 at 08:42 -0700, Barrett, Brian W wrote:
>> Adding the memory and cc will certainly do no harm, and someone tried to
>> remove them as an optimization. I wouldn't change the input and output
>> lines - the differences are mainly syntactic sugar.
>
> Gcc actually didn't like the example i sent earlier.
> Another iteration gave this as a working (gcc/intel/pgi/pathscale works)
> code.
>
> static inline int opal_atomic_cmpset_32( volatile int32_t *addr,
> int32_t oldval, int32_t newval)
> {
> unsigned char ret;
> __asm__ __volatile__ (
> SMPLOCK "cmpxchgl %3,%2 \n\t"
> "sete %0 \n\t"
> : "=qm" (ret), "+a" (oldval), "+m" (*addr)
> : "q"(newval)
> : "memory", "cc");
>
> return (int)ret;
> }
>
> --
> Ake Sandgren, HPC2N, Umea University, S-90187 Umea, Sweden
> Internet: a...@hpc2n.umu.se Phone: +46 90 7866134 Fax: +46 90 7866126
> Mobile: +46 70 7716134 WWW: http://www.hpc2n.umu.se
>
> _______________________________________________
> users mailing list
> us...@open-mpi.org
> http://www.open-mpi.org/mailman/listinfo.cgi/users
