From: Jason Merrill <jason@redhat.com>
To: Nicola Pero <nicola@brainstorm.co.uk>
Cc: Andrew Haley <aph@redhat.com>, Robert Dewar <dewar@gnat.com>,
<nathan@codesourcery.com>, <shebs@apple.com>, <gcc@gcc.gnu.org>
Subject: Re: On alignment
Date: Tue, 22 Apr 2003 18:46:00 -0000 [thread overview]
Message-ID: <wvllly2fl5q.fsf@prospero.boston.redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0304221648080.31614-100000@nicola.brainstorm.co.uk> (Nicola Pero's message of "Tue, 22 Apr 2003 17:04:38 +0100 (BST)")
On Tue, 22 Apr 2003 17:04:38 +0100 (BST), Nicola Pero <nicola@brainstorm.co.uk> wrote:
> At runtime, the ObjC runtime library has information about the struct -
> the type of each member. At the moment, it loops on the struct members,
> and uses __alignof__ on each of them to get the alignment of that member
> inside the struct (then, can read/write the struct members). As far as I
> understand from this discussion, this doesn't work any longer.
If you actually take __alignof the member, this should work fine. If you
do __alignof the type, you will get the larger number.
On Tue, 22 Apr 2003 17:19:28 +0100, Andrew Haley <aph@redhat.com> wrote:
> It's rather scary. It means, for example, that
>
> template<class T> void copy (T *a, T *b)
> {
> if (__alignof__ (T) >= 8)
> copy_by_dwords (a, b);
> else
> copy_by_bytes (a, b);
> }
>
> won't do what is expected when applied to a member of a struct. I
> suppose we get away with this because the x86 never generates
> alignment traps in such cases.
Exactly. A STRICT_ALIGNMENT target wouldn't do this sort of thing.
Jason
next prev parent reply other threads:[~2003-04-22 18:24 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-22 14:43 Robert Dewar
2003-04-22 15:13 ` Andrew Haley
2003-04-22 16:22 ` Jason Merrill
2003-04-22 16:26 ` Nicola Pero
2003-04-22 17:19 ` Andrew Haley
2003-04-22 18:46 ` Jason Merrill [this message]
2003-04-22 17:17 ` Andrew Haley
-- strict thread matches above, loose matches on Subject: below --
2003-04-23 19:47 Robert Dewar
2003-04-23 19:34 Joern Rennecke
2003-04-22 17:19 Robert Dewar
2003-03-25 16:48 Kevin B. Hendricks
2003-03-25 18:39 ` Jason Merrill
2003-03-25 18:41 ` Jason Merrill
2003-03-25 19:14 ` Kevin B. Hendricks
2003-03-25 19:57 ` Jason Merrill
2003-04-22 11:36 ` Andrew Haley
2003-04-22 12:05 ` Nathan Sidwell
2003-04-22 12:37 ` Andrew Haley
2003-04-22 13:15 ` Andreas Schwab
2003-04-23 13:32 ` Jamie Lokier
2003-04-23 16:07 ` Jason Merrill
2003-04-23 17:41 ` Tom Tromey
2003-04-23 18:06 ` Jason Merrill
2003-04-23 18:42 ` Tom Tromey
2003-04-23 19:13 ` Jason Merrill
2003-04-23 19:43 ` Gabriel Dos Reis
2003-04-23 20:23 ` Tom Tromey
2003-04-23 21:45 ` Gabriel Dos Reis
2003-04-24 7:00 ` Jason Merrill
2003-04-24 11:45 ` Andrew Haley
2003-05-01 23:50 ` Tom Tromey
2003-05-02 13:08 ` Gabriel Dos Reis
2003-05-05 14:56 ` Jason Merrill
2003-05-08 9:58 ` Gabriel Dos Reis
2003-04-23 19:33 ` Gabriel Dos Reis
2003-04-24 1:32 ` Jamie Lokier
2003-03-25 21:27 ` Tom Tromey
2003-03-26 12:58 ` Andrew Haley
2003-03-26 22:26 ` Mark Mitchell
2003-03-25 18:57 ` Tom Tromey
2003-03-21 0:25 Jason Merrill
2003-03-21 11:49 ` Andrew Haley
2003-03-21 15:18 ` Andrew Haley
2003-03-21 19:31 ` Tom Tromey
2003-03-21 15:39 ` Michael Matz
2003-03-21 15:41 ` Andrew Haley
2003-03-22 0:25 ` Jason Merrill
2003-03-22 9:35 ` Tom Tromey
2003-03-22 10:31 ` Andrew Haley
2003-03-25 2:52 ` Jason Merrill
2003-03-25 10:16 ` Andrew Haley
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