From: Mike Stump <mrs@apple.com>
To: Ian Lance Taylor <ian@airs.com>
Cc: Andrew Pinski <pinskia@physics.uc.edu>,
dave.korn@artimi.com (Dave Korn),
pkoning@equallogic.com (Paul Koning),
gcc@sources.redhat.com, sjackman@gmail.com (Shaun Jackman)
Subject: Re: memcpy to an unaligned address
Date: Tue, 02 Aug 2005 21:30:00 -0000 [thread overview]
Message-ID: <4AE0FF52-B95D-40D7-B49E-831534AD3CC8@apple.com> (raw)
In-Reply-To: <m3mzo0jcfm.fsf@gossamer.airs.com>
On Aug 2, 2005, at 1:45 PM, Ian Lance Taylor wrote:
> That argument doesn't make sense to me. memcpy takes a void*
> argument, which has no presumed alignment.
The memcpy builtin uses the static type of the actual argument
(before conversion to void*), to gain hints about the alignments of
the data coming in. This is so that we can producing nice fast code
for 1-16 bytes objects. This is actually good. The real problem is
formation of the address of the member doesn't produce a pointer to
unaligned type, but rather a pointer to aligned type, this is the
part that is wrong. We'd have to add pointers to unaligned data to
our type system to fix it. That should be done, but is a hard/big
job, and no one has stepped forward to do it.
next prev parent reply other threads:[~2005-08-02 21:30 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 [this message]
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
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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