On Mar 25, 2015, at 3:02 PM, git...@crest.iu.edu wrote:
> +static inline int32_t opal_atomic_swap_32( volatile int32_t *addr,
> + int32_t newval)
> +{
> + int32_t oldval;
> +
> + __asm__ __volatile__("xchg %1, %0" :
This code *looks* buggy because it lacks the "SMPLOCK" prefix, but can be
safely omitted because "xchg" is always locked. A comment to this effect
should be added.
Also, this should probably be "xchgl" instead of "xchg".
> + "=r" (oldval), "=m" (*addr) :
Shouldn't the modifier on the second constraint above be "+" for the same
reasons as the rest of this commit? In that case I also think you can omit the
second constraint below altogether, though I'm less sure about that.
> + "0" (newval), "m" (*addr) :
> + "memory");
> + return oldval;
> +}
-Dave
