On Thu, Dec 27, 2012 at 10:10 AM, Florian Weimer <f...@deneb.enyo.de> wrote:
> * Uros Bizjak:
>
>> +#elif defined(__x86_64__)
>> +#define __cpuid(level, a, b, c, d) \
>> + __asm__ ("xchg{q}\t{%%}rbx, %q1\n\t" \
>> + "cpuid\n\t" \
>> + "xchg{q}\t{%%}rbx, %q1\n\t" \
>> + : "=a" (a), "=r" (b), "=c" (c), "=d" (d) \
>> + : "0" (level))
>> +
>> +#define __cpuid_count(level, count, a, b, c, d) \
>> + __asm__ ("xchg{q}\t{%%}rbx, %q1\n\t" \
>> + "cpuid\n\t" \
>> + "xchg{q}\t{%%}rbx, %q1\n\t" \
>> + : "=a" (a), "=r" (b), "=c" (c), "=d" (d) \
>> + : "0" (level), "2" (count))
>> +#endif
>
> Shouldn't the constraint for b be "=&r"?
Technically yes, but all input operands are matched to outputs, so in
practice it doesn't really matter.
Uros.
