Messages in this thread |  | | Date | Sat, 17 Nov 2001 16:14:36 +0100 | From | Jan Hubicka <> | Subject | Re: i386 flags register clober in inline assembly |
| |
> > There are several inline assembly routines in the i386 port, which > clobber the flags register, nevertheless fail to declare that. > E.g. atomic_inc > > __asm__ __volatile__( > LOCK "incl %0" > :"=m" (v->counter) > :"m" (v->counter)); > > should be > > __asm__ __volatile__( > LOCK "incl %0" > :"=m" (v->counter) > :"m" (v->counter) > : "cc"); > > since "incl" clobbers flags. > > Any ideas if these functions should be corrected ? They don't need to be. On i386, the flags are (partly for historical reasons) clobbered by default. > > Although gcc documentation says "cc" has no effect on some machines, > it seems this is not the case with i386, judging from the "(set (reg:CC 17) ..." > and "(clobber (reg:CC 17))" in i386.md. i386.md does add the clobber to each asm statement.
Honza > > Regards, > -velco > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |