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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/51628] __attribute__((packed)) is unsafe in some cases
Date: Tue, 02 Apr 2013 08:30:00 -0000	[thread overview]
Message-ID: <bug-51628-4-dj4aS3J423@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-51628-4@http.gcc.gnu.org/bugzilla/>


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51628

--- Comment #16 from Richard Biener <rguenth at gcc dot gnu.org> 2013-04-02 08:30:16 UTC ---
(In reply to comment #14)
> > What Ada does looks just like a workaround for what should be done properly in
> > the expander.  So no, IMHO we shouldn't be changing all other FEs and the
> > middle-end (when it wants to generate them e.g. for memcpy) to do what Ada
> > does, but we should change the expander.
> 
> Of course I have the exactly opposite viewpoint, since I think that we should
> keep the invariants we have: integral modes are naturally aligned and
> TYPE_ALIGN >= MODE_ALIGN (TYPE_MODE).  Breaking them for a few pathological
> cases that the C compiler has shun for years doesn't seem the best course of
> action.

Well.  I'm fine with forcing BLKmode for unaligned accesses, but not sure
if that is less invasive.  You'd basically have to change modes whenever
more precise knowledge about alignment appears ...


  parent reply	other threads:[~2013-04-02  8:30 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-19 23:00 [Bug c/51628] New: " Keith.S.Thompson at gmail dot com
2011-12-19 23:17 ` [Bug c/51628] " Keith.S.Thompson at gmail dot com
2011-12-19 23:38 ` pinskia at gcc dot gnu.org
2011-12-20  0:43 ` Keith.S.Thompson at gmail dot com
2011-12-20 10:22 ` rguenth at gcc dot gnu.org
2011-12-20 10:54 ` ebotcazou at gcc dot gnu.org
2011-12-20 11:19 ` rguenther at suse dot de
2011-12-20 11:20 ` ebotcazou at gcc dot gnu.org
2011-12-20 11:34 ` rguenther at suse dot de
2011-12-20 11:57 ` ebotcazou at gcc dot gnu.org
2011-12-20 12:00 ` rguenther at suse dot de
2011-12-20 12:29 ` ebotcazou at gcc dot gnu.org
2011-12-20 13:11 ` jakub at gcc dot gnu.org
2011-12-20 13:29 ` rguenther at suse dot de
2011-12-20 17:45 ` ebotcazou at gcc dot gnu.org
2013-04-02  0:58 ` peter at axium dot co.nz
2013-04-02  8:30 ` rguenth at gcc dot gnu.org [this message]
2013-04-02  8:31 ` rguenth at gcc dot gnu.org
2013-04-02 20:21 ` peter at axium dot co.nz
2013-04-03  7:30 ` ebotcazou at gcc dot gnu.org
2013-04-03  7:55 ` rguenther at suse dot de
2013-04-03  8:51 ` ebotcazou at gcc dot gnu.org
2013-04-03  9:20 ` rguenther at suse dot de
2015-03-10 13:29 ` sven.koehler at gmail dot com
2015-03-10 13:40 ` sven.koehler at gmail dot com

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