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i386 flags register clober in inline assembly
- From: Momchil Velikov <velco at fadata dot bg>
- To: linux-kernel at vger dot kernel dot org
- Cc: gcc at gcc dot gnu dot org
- Date: 17 Nov 2001 16:06:22 +0200
- Subject: 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 ?
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