[Bug inline-asm/58234] In-line asm version of __FD_ZERO in /usr/include/bits/select.h

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58234

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
> Can you tell me how it is possible to specify the clobber side effects without
> requiring output constraints?

It is too hard if you have inputs in those registers too.  You could push/pop
on the stack those registers if you want instead

> Is it legal to specify output constraints without variables? 

No.

>the useless movl instead of a movq of the updated address pointer into __d1 on x86_64. 

That is due to use of int rather than long/long long but really one instruction
is not an issue really and the resulting of that instruction is not used at
all.