From: Shaun Jackman <sjackman@gmail.com>
To: Richard Henderson <rth@redhat.com>
Cc: Ian Lance Taylor <ian@airs.com>,
Andrew Pinski <pinskia@physics.uc.edu>,
Mike Stump <mrs@apple.com>, Dave Korn <dave.korn@artimi.com>,
Paul Koning <pkoning@equallogic.com>,
gcc@sources.redhat.com
Subject: Re: memcpy to an unaligned address
Date: Wed, 03 Aug 2005 18:15:00 -0000 [thread overview]
Message-ID: <7f45d93905080311152d530172@mail.gmail.com> (raw)
In-Reply-To: <20050803180011.GA16808@redhat.com>
On 8/3/05, Richard Henderson <rth@redhat.com> wrote:
> It is nevertheless correct. Examine all of the parts of the expression.
>
> In particular, "&s->b". What type does it have? In an ideal world, it
> would be "pointer to unaligned integer". But we have no such type in
> our type system, so it is "pointer to integer". This expression is ONLY
> THEN passed to memcpy. At which point we query the argument for its
> alignment, and get the non-intuitive result.
>
> If you instead pass "s" to memcpy, you should get the correct unaligned
> copy. If that isn't happening, that's a bug.
I'm not sure I understood the last line. s is a structure, and its
address is aligned. How would you pass it to memcpy, and why would it
generate an unaligned copy?
Cheers,
Shaun
next prev parent reply other threads:[~2005-08-03 18:15 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 [this message]
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
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
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