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From: Nathan Sidwell <nathan@codesourcery.com>
To: Mike Stump <mikestump@comcast.net>
Cc: Mark Mitchell <mark@codesourcery.com>,
	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: Mon, 28 Jun 2010 08:49:00 -0000	[thread overview]
Message-ID: <4C2840FB.3010409@codesourcery.com> (raw)
In-Reply-To: <7F30721E-1B2E-41B7-B7BF-F66C936690D9@comcast.net>

On 06/25/10 17:41, Mike Stump wrote:
> On Jun 24, 2010, at 11:35 PM, Nathan Sidwell wrote:
>> On 06/24/10 16:42, Mike Stump wrote:
>>
>>> Sorry for not expounding.  I thought it would be obvious I was talking about well formed code...  First case would be something like:
>>>
>>> volatile int i, j, k;
>>> volatile int vi;
>>> void foo(volatile int&   j) {
>>>    foo(i = k);
>>> }
>>>
>>> here, we need to bind j to the address of i.  The second case is something like:
>>
>> Correct.  The patch does not change this behaviour -- the C++ front end already has to explicitly break out the lvalue from the assignment to conform to the semantics of TREEs.  The current G++ behaviour is not to re-read the assigned-to value.
>
> g++ seems not to share your position:
>
> 	movl	_i, %eax
> 	movl	%eax, (%esp)
>
> volatile int i, j, k;
> volatile int vi;
> void foo(int j) {
>    foo(i = k);
> }
>
> GNU C++ (GCC) version 4.6.0 20100620 (experimental) [trunk revision 161045] (x86_64-apple-darwin10)
> 	compiled by GNU C version 4.2.1 (Apple Inc. build 5659), GMP version 5.0.1
>
> ?  Certainly I must misunderstand something, can you spot it?

You have changed the testcase to be passing by value from passing by reference. 
  Why do you think those would be equivalent?

nathan
-- 
Nathan Sidwell    ::   http://www.codesourcery.com   ::         CodeSourcery

  reply	other threads:[~2010-06-28  6:28 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
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 [this message]
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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