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From: Momchil Velikov <velco@fadata.bg>
To: linux-kernel@vger.kernel.org
Cc: gcc@gcc.gnu.org
Subject: i386 flags register clober in inline assembly
Date: 17 Nov 2001 16:06:22 +0200	[thread overview]
Message-ID: <87y9l58pb5.fsf@fadata.bg> (raw)


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



             reply	other threads:[~2001-11-17 14:09 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-11-17 14:06 Momchil Velikov [this message]
2001-11-17 15:14 ` i386 flags register clober in inline assembly Jan Hubicka
2001-11-17 19:20 ` Linus Torvalds
2001-11-17 19:58   ` H. Peter Anvin
2001-11-17 20:24   ` Momchil Velikov
2001-11-17 20:30     ` Linus Torvalds
2001-11-17 20:40   ` Jan Hubicka
2001-11-17 20:42     ` Linus Torvalds
2001-11-18  1:09       ` Jan Hubicka
2001-11-18  2:48         ` Linus Torvalds
2001-11-20  8:33           ` Richard Henderson
2001-11-20 13:00             ` Jan Hubicka
2001-11-20 23:14               ` Richard Henderson
2001-11-20 17:12             ` Linus Torvalds
2001-11-17 21:00     ` H. Peter Anvin
2001-11-20 14:39   ` PATCH 2.4.15-pre6 idt compilation and proc_misc cleanup Martin Dalecki
2001-11-23 22:24     ` Roman Zippel

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