From: Jan Engelhardt <jengelh@linux01.gwdg.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>,
Jeff Garzik <jeff@garzik.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: somebody dropped a (warning) bomb
Date: Fri, 9 Feb 2007 13:34:41 +0100 (MET) [thread overview]
Message-ID: <Pine.LNX.4.61.0702091330380.31955@yvahk01.tjqt.qr> (raw)
In-Reply-To: <Pine.LNX.4.64.0702081632200.8424@woody.linux-foundation.org>
On Feb 8 2007 16:42, Linus Torvalds wrote:
>
>Most C types don't, and some you can't even tell (do pointers generate
>"signed" or "unsigned" comparisons?
I'd say "neither", because both
signed void *ptr; and
unsigned void *xyz;
are impossible (and dull at that). That's why you explicitly will
have to cast one operand in a comparison to make it evident
what sort of comparison is intended, i.e.
if((unsigned long)ptr < PAGE_OFFSET)
Further, giving again answer to the question whether they generate signed or
unsigned comparisons: Have you ever seen a computer which addresses memory with
negative numbers? Since the answer is most likely no, signed comparisons would
not make sense for me.
> I'll argue that a compiler that
>generates signed comparisons for them is broken, but it tends to be
>something you can only see with a standards- conforming proghram if you
>can allocate memory across the sign boundary, which may or may not be
>true..)
Jan
--
ft: http://freshmeat.net/p/chaostables/
next prev parent reply other threads:[~2007-02-09 12:37 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-08 15:00 somebody dropped a (warning) bomb Jeff Garzik
2007-02-08 16:33 ` Linus Torvalds
2007-02-08 18:42 ` Jan Engelhardt
2007-02-08 19:53 ` Linus Torvalds
2007-02-08 21:10 ` Jan Engelhardt
2007-02-08 21:37 ` Linus Torvalds
2007-02-08 23:12 ` David Rientjes
2007-02-08 23:37 ` Linus Torvalds
2007-02-09 0:24 ` David Rientjes
2007-02-09 0:42 ` Linus Torvalds
2007-02-09 0:59 ` Linus Torvalds
2007-02-09 0:59 ` David Rientjes
2007-02-09 1:11 ` Linus Torvalds
2007-02-09 1:18 ` David Rientjes
2007-02-09 15:38 ` Linus Torvalds
2007-02-09 3:27 ` D. Hazelton
2007-02-09 19:54 ` Pete Zaitcev
2007-02-09 12:34 ` Jan Engelhardt [this message]
2007-02-09 13:16 ` linux-os (Dick Johnson)
2007-02-09 17:45 ` Jan Engelhardt
2007-02-09 20:29 ` linux-os (Dick Johnson)
2007-02-09 22:05 ` Jan Engelhardt
2007-02-09 22:58 ` Martin Mares
2007-02-12 18:50 ` linux-os (Dick Johnson)
2007-02-13 15:14 ` Dick Streefland
2007-02-08 21:13 ` J.A. Magallón
2007-02-08 21:42 ` Linus Torvalds
2007-02-08 22:03 ` Linus Torvalds
2007-02-08 22:19 ` Willy Tarreau
2007-02-09 0:03 ` J.A. Magallón
2007-02-09 0:22 ` Linus Torvalds
2007-02-09 12:38 ` Sergei Organov
2007-02-09 15:58 ` Linus Torvalds
2007-02-12 11:12 ` Sergei Organov
2007-02-12 16:26 ` Linus Torvalds
2007-02-13 18:06 ` Sergei Organov
2007-02-13 18:26 ` Pekka Enberg
2007-02-13 19:14 ` Sergei Organov
2007-02-13 19:43 ` Pekka Enberg
2007-02-13 20:29 ` Sergei Organov
2007-02-13 21:31 ` Jeff Garzik
2007-02-13 23:21 ` Linus Torvalds
2007-02-15 13:20 ` Sergei Organov
2007-02-15 15:57 ` Linus Torvalds
2007-02-15 18:53 ` Sergei Organov
2007-02-15 19:02 ` Linus Torvalds
2007-02-15 20:23 ` me, not " Oleg Verych
2007-02-16 4:26 ` Rene Herman
2007-02-19 11:58 ` Sergei Organov
2007-02-19 13:58 ` Sergei Organov
2007-02-15 22:32 ` Lennart Sorensen
2007-02-13 19:25 ` Linus Torvalds
2007-02-13 19:59 ` Sergei Organov
2007-02-13 20:24 ` Linus Torvalds
2007-02-15 15:15 ` Sergei Organov
2007-02-13 21:13 ` Rob Landley
2007-02-13 22:21 ` Olivier Galibert
2007-02-14 12:52 ` Sergei Organov
2007-02-15 20:06 ` Sergei Organov
2007-02-09 15:10 ` Sergei Organov
2007-02-08 16:35 ` Kumar Gala
[not found] <7Mj5f-3oz-21@gated-at.bofh.it>
[not found] ` <7MktH-5EW-35@gated-at.bofh.it>
[not found] ` <7Mmvy-vj-17@gated-at.bofh.it>
[not found] ` <7MnBC-2fk-13@gated-at.bofh.it>
[not found] ` <7MoQx-4p8-11@gated-at.bofh.it>
[not found] ` <7MpjE-50z-7@gated-at.bofh.it>
[not found] ` <7MpCS-5Fe-9@gated-at.bofh.it>
[not found] ` <7MDd7-17w-1@gated-at.bofh.it>
[not found] ` <7MGkB-62k-31@gated-at.bofh.it>
[not found] ` <7NHoe-2Mb-37@gated-at.bofh.it>
[not found] ` <7NMe9-1ZN-7@gated-at.bofh.it>
[not found] ` <7Oagl-6bO-1@gated-at.bofh.it>
[not found] ` <7ObvW-89N-23@gated-at.bofh.it>
[not found] ` <7Oc8t-NS-1@gated-at.bofh.it>
2007-02-15 20:08 ` Bodo Eggert
2007-02-16 11:21 ` Sergei Organov
2007-02-16 14:51 ` Bodo Eggert
2007-02-19 11:56 ` Sergei Organov
2007-02-16 12:46 ` Sergei Organov
2007-02-16 17:40 ` Bodo Eggert
2007-02-19 12:17 ` Sergei Organov
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