public inbox for gcc@gcc.gnu.org
 help / color / mirror / Atom feed
From: Paul Koning <pkoning@equallogic.com>
To: pinskia@physics.uc.edu
Cc: mrs@apple.com, dave.korn@artimi.com, gcc@sources.redhat.com,
	sjackman@gmail.com
Subject: Re: memcpy to an unaligned address
Date: Tue, 02 Aug 2005 20:46:00 -0000	[thread overview]
Message-ID: <17135.56182.648000.413121@gargle.gargle.HOWL> (raw)
In-Reply-To: <200508022037.j72Kbr4T012558@earth.phy.uc.edu>

>>>>> "Andrew" == Andrew Pinski <pinskia@physics.uc.edu> writes:

 >> Yes, this is a compiler bug in the expansion of memcpy, please
 >> file a bug report.  The solution is for the compiler to notice the
 >> memory alignment of the destination and `do-the-right-thing' when
 >> it isn't aligned.

 Andrew> No it is not, once you take the address (which should be
 Andrew> rejected), it is of type "unsigned int *" and not unaligned
 Andrew> variable, passing it to memcpy assumes the type alignment is
 Andrew> the natural alignment.

That seems like a misfeature.

It sounds like the workaround is to avoid memcpy, and just use
variable assignment.  Alternatively, cast the pointers to char*, which
should force memcpy to do the right thing.  Ugh.

       paul

  parent reply	other threads:[~2005-08-02 20:46 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-02 17:32 Shaun Jackman
2005-08-02 17:43 ` Dave Korn
2005-08-02 19:13   ` Shaun Jackman
2005-08-02 19:19     ` Paul Koning
2005-08-02 19:26       ` Shaun Jackman
2005-08-02 19:40         ` Dave Korn
2005-08-02 19:48           ` Paul Koning
2005-08-02 20:15           ` Shaun Jackman
2005-08-02 20:29             ` Mike Stump
2005-08-02 20:38               ` Andrew Pinski
2005-08-02 20:45                 ` Ian Lance Taylor
2005-08-02 21:30                   ` Mike Stump
2005-08-02 21:34                     ` Joe Buck
2005-08-03 18:00                   ` Richard Henderson
2005-08-03 18:15                     ` Shaun Jackman
2005-08-03 18:19                       ` Dave Korn
2005-08-03 21:26                       ` Richard Henderson
2005-08-04  4:42                     ` Ian Lance Taylor
2005-08-04 12:40                     ` Paul Koning
2005-08-02 20:46                 ` Paul Koning [this message]
2005-08-02 22:17                   ` Shaun Jackman
2005-08-03 17:16                     ` Paul Koning
2005-08-02 22:26                   ` Shaun Jackman
2005-08-02 22:29                     ` Shaun Jackman
2005-08-02 21:05                 ` Mike Stump
2005-08-02 21:11                   ` Joe Buck
2005-08-02 22:15                     ` Shaun Jackman
2005-08-02 22:12                       ` Joe Buck
2005-08-02 20:29             ` Paul Koning
2005-08-02 17:48 ` Falk Hueffner
2005-08-02 18:03 ` Mike Stump
     [not found] <345be691050804025955c0b4ab@mail.gmail.com>
2005-08-04 15:06 ` Shaun Jackman
2005-08-04 15:09   ` Christian Joensson
2005-08-05  8:41   ` Carl Whitwell
2005-08-05 16:09     ` Shaun Jackman

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=17135.56182.648000.413121@gargle.gargle.HOWL \
    --to=pkoning@equallogic.com \
    --cc=dave.korn@artimi.com \
    --cc=gcc@sources.redhat.com \
    --cc=mrs@apple.com \
    --cc=pinskia@physics.uc.edu \
    --cc=sjackman@gmail.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).