From: Jakub Jelinek <jakub@redhat.com>
To: Ulrich Drepper <drepper@redhat.com>
Cc: Glibc hackers <libc-hacker@sources.redhat.com>
Subject: [PATCH] Fix realloc prototype (BZ #4792)
Date: Mon, 16 Jul 2007 09:58:00 -0000 [thread overview]
Message-ID: <20070716100214.GP4603@sunsite.mff.cuni.cz> (raw)
Hi!
info gcc says on the malloc attribute:
`malloc'
The `malloc' attribute is used to tell the compiler that a function
may be treated as if any non-`NULL' pointer it returns cannot
alias any other pointer valid when the function returns. This
will often improve optimization. Standard functions with this
property include `malloc' and `calloc'. `realloc'-like functions
have this property as long as the old pointer is never referred to
(including comparing it to the new pointer) after the function
returns a non-`NULL' value.
and internally while GCC uses malloc attribute on malloc etc., it doesn't
use it for realloc.
http://gcc.gnu.org/ml/gcc-patches/2004-01/msg00189.html
2007-07-16 Jakub Jelinek <jakub@redhat.com>
[BZ #4792]
* stdlib/stdlib.h (realloc): Remove __attribute_malloc__.
* malloc/malloc.h (realloc): Likewise.
--- libc/stdlib/stdlib.h.jj 2007-07-03 12:37:00.000000000 +0200
+++ libc/stdlib/stdlib.h 2007-07-16 10:31:04.000000000 +0200
@@ -597,8 +597,11 @@ __END_NAMESPACE_STD
__BEGIN_NAMESPACE_STD
/* Re-allocate the previously allocated block
in PTR, making the new block SIZE bytes long. */
+/* __attribute_malloc__ is not used, because if realloc returns
+ the same pointer that was passed to it, aliasing needs to be allowed
+ between objects pointed by the old and new pointers. */
extern void *realloc (void *__ptr, size_t __size)
- __THROW __attribute_malloc__ __attribute_warn_unused_result__;
+ __THROW __attribute_warn_unused_result__;
/* Free a block allocated by `malloc', `realloc' or `calloc'. */
extern void free (void *__ptr) __THROW;
__END_NAMESPACE_STD
--- libc/malloc/malloc.h.jj 2005-03-08 01:44:45.000000000 +0100
+++ libc/malloc/malloc.h 2007-07-16 10:32:25.000000000 +0200
@@ -1,5 +1,6 @@
/* Prototypes and definition for malloc implementation.
- Copyright (C) 1996,97,99,2000,2002-2004,2005 Free Software Foundation, Inc.
+ Copyright (C) 1996, 1997, 1999, 2000, 2002-2004, 2005, 2007
+ Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -54,8 +55,11 @@ extern void *calloc __MALLOC_P ((size_t
/* Re-allocate the previously allocated block in __ptr, making the new
block SIZE bytes long. */
+/* __attribute_malloc__ is not used, because if realloc returns
+ the same pointer that was passed to it, aliasing needs to be allowed
+ between objects pointed by the old and new pointers. */
extern void *realloc __MALLOC_P ((void *__ptr, size_t __size))
- __attribute_malloc__ __attribute_warn_unused_result__;
+ __attribute_warn_unused_result__;
/* Free a block allocated by `malloc', `realloc' or `calloc'. */
extern void free __MALLOC_P ((void *__ptr));
Jakub
next reply other threads:[~2007-07-16 9:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-16 9:58 Jakub Jelinek [this message]
2007-07-16 10:30 ` Wolfram Gloger
2007-07-16 11:15 ` Jakub Jelinek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070716100214.GP4603@sunsite.mff.cuni.cz \
--to=jakub@redhat.com \
--cc=drepper@redhat.com \
--cc=libc-hacker@sources.redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).