From: Nathan Sidwell <nathan@codesourcery.com>
To: Mark Mitchell <mark@codesourcery.com>
Cc: Mike Stump <mikestump@comcast.net>, Michael Matz <matz@suse.de>,
Richard Guenther <richard.guenther@gmail.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [gimple] assignments to volatile
Date: Fri, 25 Jun 2010 09:20:00 -0000 [thread overview]
Message-ID: <4C244B2B.60206@codesourcery.com> (raw)
In-Reply-To: <4C236C7A.40303@codesourcery.com>
On 06/24/10 15:32, Mark Mitchell wrote:
> Mike Stump wrote:
>
>>> x = y = z;
>>>
>>> where "y" is volatile?
>
>> C++ requires a re-read of y, the patch was going to remove the
>> re-read, I objected because the patch then makes the compiler not
>> conform to the C++ standard.
>
> I think that you have to read rather a lot into the C++ standard to
> arrive at that conclusion. But, I suggest that you raise the issue on
> the C++ reflector and report back. I think that it would be very
> helpful to hear what other implementors think.
>
> But, this point may be moot; I don't know if the proposed patch changes
> the behavior here or not. Nathan, can you clarify that?
Yes, it changes the behaviour for C++ in the same way it changes it for C.
Specifically the assigned-to object is not reread.
For C and C++ to have different behaviour wrt volatile accesses is a mistake
(hence, as I mentioned, previous changes to G++ to make it have the same
behaviour as gcc).
nathan
--
Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery
next prev parent reply other threads:[~2010-06-25 6:22 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-21 12:44 Nathan Sidwell
2010-06-21 13:26 ` Richard Guenther
2010-06-21 13:55 ` Michael Matz
2010-06-21 14:07 ` Richard Guenther
2010-06-21 14:09 ` Nathan Sidwell
2010-06-21 14:17 ` Michael Matz
2010-06-21 14:19 ` Richard Guenther
2010-06-21 14:53 ` Michael Matz
2010-06-21 14:17 ` IainS
2010-06-21 14:24 ` Michael Matz
2010-06-21 14:50 ` Nathan Sidwell
2010-06-21 15:24 ` Michael Matz
2010-06-22 11:36 ` Dave Korn
2010-06-23 20:16 ` Mike Stump
2010-06-24 11:51 ` Michael Matz
2010-06-21 15:24 ` Nathan Sidwell
2010-06-21 15:46 ` Michael Matz
2010-06-22 15:37 ` Mark Mitchell
2010-06-22 15:37 ` Jakub Jelinek
2010-06-22 15:57 ` Paul Koning
2010-06-22 15:47 ` Michael Matz
2010-06-22 15:58 ` Mark Mitchell
2010-06-23 11:38 ` Nathan Sidwell
2010-06-23 14:05 ` Mark Mitchell
2010-06-23 14:06 ` Michael Matz
2010-06-23 16:00 ` Richard Guenther
2010-06-23 16:25 ` Paul Koning
2010-06-23 17:13 ` Mark Mitchell
2010-06-23 19:16 ` Mike Stump
2010-06-24 10:22 ` Mark Mitchell
2010-06-24 15:53 ` Mike Stump
2010-06-24 16:00 ` Mark Mitchell
2010-06-24 19:37 ` Mike Stump
2010-06-25 9:37 ` Nathan Sidwell
2010-06-25 19:06 ` Mike Stump
2010-06-25 21:33 ` Mark Mitchell
2010-06-26 9:35 ` Mike Stump
2010-06-26 10:18 ` Mark Mitchell
2010-06-26 12:18 ` Richard Guenther
2010-06-26 19:52 ` Michael Matz
2010-06-26 19:57 ` Mark Mitchell
2010-06-26 20:08 ` Michael Matz
2010-06-26 22:13 ` Mark Mitchell
2010-06-28 9:20 ` Nathan Sidwell
2010-06-28 9:27 ` Nathan Sidwell
2010-06-26 10:20 ` Richard Kenner
2010-06-28 9:52 ` Nathan Sidwell
2010-06-30 22:52 ` Mike Stump
2010-07-05 8:59 ` Nathan Sidwell
2010-07-09 5:27 ` Mike Stump
2010-07-09 7:22 ` Nathan Sidwell
2010-07-16 8:10 ` Nathan Sidwell
2010-07-16 15:20 ` Mark Mitchell
2010-07-19 8:41 ` Nathan Sidwell
2010-08-13 9:56 ` Nathan Sidwell
2010-08-18 15:32 ` Mark Mitchell
2010-08-18 16:18 ` Richard Guenther
2010-08-18 18:04 ` Mike Stump
2010-08-19 11:11 ` Nathan Sidwell
2010-08-20 4:22 ` Mark Mitchell
2010-08-20 16:59 ` Mike Stump
2010-08-20 18:00 ` H.J. Lu
2010-08-20 18:33 ` Nathan Sidwell
2010-06-25 9:20 ` Nathan Sidwell [this message]
2010-06-24 10:23 ` Nathan Sidwell
2010-06-24 17:05 ` Mike Stump
2010-06-24 17:29 ` Paul Koning
2010-06-25 9:26 ` Nathan Sidwell
2010-06-25 18:20 ` Mike Stump
2010-06-28 8:49 ` Nathan Sidwell
2010-07-01 1:02 ` Mike Stump
2010-07-05 9:02 ` Nathan Sidwell
2010-07-09 5:14 ` Mike Stump
2010-07-09 7:20 ` Nathan Sidwell
2010-06-22 15:56 ` Paul Koning
2010-06-22 12:08 ` Nathan Sidwell
2010-06-22 12:25 ` Richard Guenther
2010-06-22 13:12 ` Michael Matz
2010-06-22 13:54 ` Nathan Sidwell
2010-06-22 15:21 ` Michael Matz
2010-06-22 16:12 ` Joseph S. Myers
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