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From: Krzysztof Halasa <khc@pm.waw.pl>
To: "J.A. Magallón" <jamagallon@ono.com>
Cc: "Linux-Kernel\, " <linux-kernel@vger.kernel.org>
Subject: Re: Why is the kfree() argument const?
Date: Sat, 19 Jan 2008 00:44:46 +0100	[thread overview]
Message-ID: <m3ve5qk8b5.fsf@maximus.localdomain> (raw)
In-Reply-To: <20080118232911.22c9d8d5@werewolf> ("J. A. Magallón"'s message of "Fri\, 18 Jan 2008 23\:29\:11 +0100")

"J.A. Magallón" <jamagallon@ono.com> writes:

> That's what __attribute__ ((pure)) is for, but if none of the
> functions is pure, the compiler can not be sure about side effects
> and can not reorder things. Don't forget that functions can do
> anything apart from mangling with their arguments.

Though it seems it could legally transform:

void kfree(const int *x);

{
int v, *ptr = malloc(sizeof(int));
*ptr = 51;
v = *ptr;
kfree(ptr);
printf("%d", v);

into:

{
int v, *ptr = malloc(sizeof(int));
*ptr = 51;
kfree(ptr);
v = *ptr;
printf("%d", v);
}

if it knows that malloc generates unaliased pointers, which seems
reasonable in general.
-- 
Krzysztof Halasa

  reply	other threads:[~2008-01-18 23:44 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <MDEHLPKNGKAHNMBLJOLKIEGIJJAC.davids@webmaster.com>
2008-01-17 21:25 ` Why is the kfree() argument const? Linus Torvalds
2008-01-17 22:28   ` David Schwartz
2008-01-17 23:10     ` Linus Torvalds
2008-01-18  0:56       ` David Schwartz
2008-01-18  1:15         ` Linus Torvalds
2008-01-18  5:02           ` David Schwartz
2008-01-18 15:38             ` Chris Friesen
2008-01-18 16:10             ` Linus Torvalds
2008-01-18 20:55               ` David Schwartz
2008-01-18 17:37             ` Olivier Galibert
2008-01-18 18:06             ` DM
2008-01-18  7:51           ` Giacomo Catenazzi
2008-01-18  8:20             ` Giacomo Catenazzi
2008-01-18 13:53               ` Andy Lutomirski
2008-01-18 17:24                 ` Olivier Galibert
2008-01-18 22:29                   ` J.A. Magallón
2008-01-18 23:44                     ` Krzysztof Halasa [this message]
2008-01-18 13:54               ` Andy Lutomirski
2008-01-18 19:14                 ` Vadim Lobanov
2008-01-18 19:31                   ` Zan Lynx
2008-01-18 19:55                     ` Vadim Lobanov
2008-01-18  8:30             ` Vadim Lobanov
2008-01-18  9:48   ` Jakob Oestergaard
2008-01-18 11:47     ` Giacomo A. Catenazzi
2008-01-18 14:39       ` Jakob Oestergaard
2008-01-18 19:06       ` Vadim Lobanov
2008-01-18 13:31     ` Björn Steinbrink
2008-01-18 14:53       ` Jakob Oestergaard
     [not found] <fa.cHMztHfqJXv7vw5O0nQ8SdTrma0@ifi.uio.no>
     [not found] ` <fa.V9M+5l8C/um5KEiBtZOjbJDQmu4@ifi.uio.no>
2013-01-12 19:18   ` antoine.trux
2013-01-13  8:10     ` Chen Gang F T
2013-01-13 17:41       ` Guenter Roeck
2013-01-14  1:45         ` Chen Gang F T
2013-01-13 20:54       ` Cong Ding
2013-01-14  1:18         ` Chen Gang F T
2008-01-18 19:10 ecolbus
  -- strict thread matches above, loose matches on Subject: below --
2008-01-18 16:45 ecolbus
2008-01-18 18:20 ` Olivier Galibert
2008-01-18 12:45 ecolbus
2008-01-18 15:20 ` Giacomo A. Catenazzi
2008-01-16 16:32 Johannes Weiner
2008-01-16 16:48 ` Christoph Lameter
2008-01-16 17:34   ` Bernd Petrovitsch
2008-01-16 17:45   ` Pekka J Enberg
2008-01-16 18:39 ` Linus Torvalds
2008-01-16 22:19   ` Johannes Weiner
2008-01-16 22:20     ` Christoph Lameter
2008-01-16 22:37       ` Johannes Weiner
2008-01-16 23:13       ` Johannes Weiner
2008-01-16 23:18       ` Linus Torvalds
2008-01-16 23:16     ` Linus Torvalds
2008-01-16 22:33   ` Steven Rostedt

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