public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "gcc2eran at tromer dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/22278] gcc -O2 discards cast to volatile
Date: Sat, 02 Jul 2005 22:07:00 -0000	[thread overview]
Message-ID: <20050702220748.22499.qmail@sourceware.org> (raw)
In-Reply-To: <20050702164323.22278.olivier.baudron@m4x.org>


------- Additional Comments From gcc2eran at tromer dot org  2005-07-02 22:07 -------
Prior versions of gcc did "respect" casts to pointer-to-volatile and did not
optimize away the access. I've seen a lot of code that relies on that, and which
would thus be broken by gcc 4.x (in a subtle and hard-to-debug way). One recent
example is an elusive bug in Fedora Core 4's X.org package which bit many users
(https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=161242).

I can't imagine a programmer casting into a pointer to volatile without really
meaning it, so if the behavior is not defined by the standard then both
compatibility and the principle of least astonishment seem to suggest reverting
to the old behavior.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gcc2eran at tromer dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22278


  parent reply	other threads:[~2005-07-02 22:07 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-07-02 16:43 [Bug c/22278] New: " olivier dot baudron at m4x dot org
2005-07-02 16:48 ` [Bug c/22278] " pinskia at gcc dot gnu dot org
2005-07-02 22:08   ` Gabriel Dos Reis
2005-07-02 16:59 ` olivier dot baudron at m4x dot org
2005-07-02 17:03 ` pinskia at gcc dot gnu dot org
2005-07-02 17:33 ` falk at debian dot org
2005-07-02 17:42 ` pinskia at gcc dot gnu dot org
2005-07-02 17:53 ` falk at debian dot org
2005-07-02 20:38 ` falk at debian dot org
2005-07-02 22:07 ` gcc2eran at tromer dot org [this message]
2005-07-02 22:08 ` gdr at integrable-solutions dot net
2005-07-02 22:10 ` gdr at integrable-solutions dot net
2005-07-02 22:10 ` gdr at integrable-solutions dot net
2005-07-02 22:11 ` gdr at integrable-solutions dot net
2005-07-02 22:12 ` gdr at integrable-solutions dot net
2005-07-02 22:19 ` falk at debian dot org
2005-07-02 22:20 ` gdr at integrable-solutions dot net
2005-07-02 22:20 ` pinskia at gcc dot gnu dot org
2005-07-02 22:39 ` gdr at integrable-solutions dot net
2005-07-02 22:49 ` pinskia at gcc dot gnu dot org
2005-07-02 23:30 ` gcc2eran at tromer dot org
2005-07-03  0:03   ` Gabriel Dos Reis
2005-07-02 23:45 ` falk at debian dot org
2005-07-02 23:54 ` gdr at integrable-solutions dot net
2005-07-03  0:03 ` gdr at integrable-solutions dot net
2005-07-03  1:19 ` gcc2eran at tromer dot org
2005-07-03  1:27 ` joseph at codesourcery dot com
2005-07-03  1:42 ` gdr at integrable-solutions dot net
2005-07-03  1:43 ` gdr at integrable-solutions dot net
2005-07-03  1:47 ` gcc2eran at tromer dot org
2005-07-03  1:54 ` hugh at mimosa dot com
2005-07-03  2:30 ` gcc2eran at tromer dot org
2005-07-03  2:54 ` gdr at integrable-solutions dot net
2005-07-03  4:14 ` gcc2eran at tromer dot org
2005-07-03  4:43   ` Gabriel Dos Reis
2005-07-03  4:43 ` gdr at integrable-solutions dot net
2005-07-03  5:11   ` Gabriel Dos Reis
2005-07-03  5:09 ` gcc2eran at tromer dot org
2005-07-03  5:11 ` gdr at integrable-solutions dot net
2005-07-03  5:18 ` gdr at integrable-solutions dot net
2005-07-03  5:40 ` hugh at mimosa dot com
2005-07-03  6:59 ` gcc2eran at tromer dot org
2005-07-03  7:09 ` schlie at comcast dot net
2005-07-03  7:27 ` gdr at integrable-solutions dot net
2005-07-03  7:54 ` schlie at comcast dot net
2005-07-05  2:17 ` james at juranfamily dot org
2005-07-15  6:41 ` neroden at gcc dot gnu dot org
2005-07-15  7:52   ` Gabriel Dos Reis
2005-07-15  8:10 ` gdr at integrable-solutions dot net
2005-07-16 16:35 ` hugh at mimosa dot com
2005-07-16 17:53 ` gdr at integrable-solutions dot net
2005-07-17  8:09 ` hugh at mimosa dot com
2005-07-17 16:59 ` rth at gcc dot gnu dot org
2005-07-19 20:28 ` [Bug tree-optimization/22278] " cvs-commit at gcc dot gnu dot org
2005-07-20  0:11 ` cvs-commit at gcc dot gnu dot org
2005-07-20  0:26 ` rth at gcc dot gnu dot org
2005-08-11 23:56 ` cvs-commit at gcc dot gnu dot org

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=20050702220748.22499.qmail@sourceware.org \
    --to=gcc-bugzilla@gcc.gnu.org \
    --cc=gcc-bugs@gcc.gnu.org \
    /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).