From: Jason Merrill <jason@redhat.com>
To: Aldy Hernandez <aldyh@redhat.com>
Cc: Richard Guenther <richard.guenther@gmail.com>,
gcc-patches <gcc-patches@gcc.gnu.org>
Subject: Re: [C++0x] contiguous bitfields race implementation
Date: Thu, 01 Sep 2011 15:01:00 -0000 [thread overview]
Message-ID: <4E5F9E37.6010608@redhat.com> (raw)
In-Reply-To: <4E5F9C3E.1050405@redhat.com>
On 09/01/2011 10:52 AM, Aldy Hernandez wrote:
> To answer your question, I believe we can't touch past the last field
> (into the padding) if the subsequent record will be packed into the
> first's padding.
Right.
> struct A {
> int a : 17;
> };
> struct B : public A {
> char c;
> };
>
> So here, if <c> gets packed into the tail-padding of A, we can't touch
> the padding of A when storing into <a>.
But that doesn't apply to this testcase because A is a POD class, so we
don't mess with its tail padding.
> Is there a way of distinguishing this particular variant (possible
> tail-packing), or will we have to disallow storing into the record tail
> padding altogether? That would seriously suck.
Basically you can only touch the size of the CLASSTYPE_AS_BASE variant.
For many classes this will be the same as the size of the class itself.
Jason
next prev parent reply other threads:[~2011-09-01 15:01 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-09 17:12 Aldy Hernandez
2011-05-09 18:04 ` Jeff Law
2011-05-09 18:05 ` Aldy Hernandez
2011-05-09 19:19 ` Jeff Law
2011-05-09 20:11 ` Aldy Hernandez
2011-05-09 20:28 ` Jakub Jelinek
2011-05-10 11:42 ` Richard Guenther
2011-05-09 20:49 ` Jason Merrill
2011-05-13 22:35 ` Aldy Hernandez
2011-05-16 21:20 ` Aldy Hernandez
2011-05-19 7:17 ` Jason Merrill
2011-05-20 9:21 ` Aldy Hernandez
2011-05-26 18:05 ` Jason Merrill
2011-05-26 18:28 ` Aldy Hernandez
2011-05-26 19:07 ` Jason Merrill
2011-05-26 20:19 ` Aldy Hernandez
2011-05-27 20:41 ` Jason Merrill
2011-07-18 13:10 ` Aldy Hernandez
2011-07-22 19:16 ` Jason Merrill
2011-07-25 17:41 ` Aldy Hernandez
2011-07-26 5:28 ` Jason Merrill
2011-07-26 18:37 ` Aldy Hernandez
2011-07-26 17:54 ` Jason Merrill
2011-07-26 17:51 ` Aldy Hernandez
2011-07-26 18:05 ` Jason Merrill
2011-07-27 15:03 ` Richard Guenther
2011-07-27 15:12 ` Richard Guenther
2011-07-27 15:53 ` Richard Guenther
2011-07-28 13:00 ` Richard Guenther
2011-07-29 2:58 ` Jason Merrill
2011-07-29 12:02 ` Aldy Hernandez
2011-07-29 11:00 ` Richard Guenther
2011-08-01 13:51 ` Richard Guenther
2011-08-05 17:28 ` Aldy Hernandez
2011-08-09 10:52 ` Richard Guenther
2011-08-09 20:53 ` Aldy Hernandez
2011-08-10 13:34 ` Richard Guenther
2011-08-15 19:26 ` Aldy Hernandez
2011-08-27 0:05 ` Aldy Hernandez
2011-08-29 12:54 ` Richard Guenther
2011-08-30 16:07 ` Aldy Hernandez
2011-08-31 8:38 ` Richard Guenther
2011-08-31 13:56 ` Richard Guenther
2011-08-31 20:37 ` Aldy Hernandez
2011-09-01 6:58 ` Richard Guenther
2011-08-30 16:53 ` Aldy Hernandez
2011-08-31 8:55 ` Richard Guenther
2011-08-31 17:24 ` Aldy Hernandez
2011-08-30 21:33 ` Aldy Hernandez
2011-08-31 8:55 ` Richard Guenther
2011-08-31 20:37 ` Aldy Hernandez
2011-09-01 7:02 ` Richard Guenther
2011-09-01 7:05 ` Arnaud Charlet
2011-09-01 14:16 ` Aldy Hernandez
2011-09-02 8:48 ` Richard Guenther
2011-09-02 12:49 ` Aldy Hernandez
2011-09-02 13:05 ` Richard Guenther
2011-09-02 20:34 ` Jeff Law
2011-09-01 14:53 ` Aldy Hernandez
2011-09-01 15:01 ` Jason Merrill [this message]
2011-09-01 15:10 ` Aldy Hernandez
2011-09-01 15:20 ` Jason Merrill
2011-09-02 8:53 ` Richard Guenther
2011-09-02 14:10 ` Jason Merrill
2011-09-02 14:38 ` Richard Guenther
2011-09-07 18:12 ` Jason Merrill
2011-07-28 19:42 ` Aldy Hernandez
2011-07-27 18:22 ` Aldy Hernandez
2011-07-28 8:52 ` Richard Guenther
2011-07-29 12:05 ` Aldy Hernandez
2011-07-28 19:58 ` Richard Guenther
2011-07-27 17:29 ` Aldy Hernandez
2011-07-27 17:57 ` Andrew MacLeod
2011-07-27 22:27 ` Joseph S. Myers
2011-07-28 8:58 ` Richard Guenther
2011-07-28 22:26 ` Aldy Hernandez
2011-07-26 20:05 ` Aldy Hernandez
2011-07-27 18:24 ` H.J. Lu
2011-07-27 20:39 ` Aldy Hernandez
2011-07-27 20:54 ` Jakub Jelinek
2011-07-27 21:00 ` Aldy Hernandez
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