i386 flags register clober in inline assembly

From: Momchil Velikov (velco@fadata.bg)
Date: Sat Nov 17 2001 - 09:06:22 EST


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 ?

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.

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/



This archive was generated by hypermail 2b29 : Fri Nov 23 2001 - 21:00:16 EST