From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15647 invoked by alias); 22 Nov 2005 10:45:20 -0000 Received: (qmail 15640 invoked by uid 22791); 22 Nov 2005 10:45:20 -0000 X-Spam-Check-By: sourceware.org Received: from cam-admin0.cambridge.arm.com (HELO cam-admin0.cambridge.arm.com) (193.131.176.58) by sourceware.org (qpsmtpd/0.31) with ESMTP; Tue, 22 Nov 2005 10:45:18 +0000 Received: from pc960.cambridge.arm.com (pc960.cambridge.arm.com [10.1.205.4]) by cam-admin0.cambridge.arm.com (8.12.10/8.12.10) with ESMTP id jAMAilU3028207; Tue, 22 Nov 2005 10:44:47 GMT Received: from pc960.cambridge.arm.com (localhost.localdomain [127.0.0.1]) by pc960.cambridge.arm.com (8.12.8/8.12.8) with ESMTP id jAMAjCtZ027279; Tue, 22 Nov 2005 10:45:13 GMT Received: (from rearnsha@localhost) by pc960.cambridge.arm.com (8.12.8/8.12.8/Submit) id jAMAjC23027277; Tue, 22 Nov 2005 10:45:12 GMT Subject: Re: Why doesn't combine like volatiles? (volatile_ok again, sorry!) From: Richard Earnshaw To: Ian Lance Taylor Cc: Dave Korn , gcc@gcc.gnu.org In-Reply-To: References: Content-Type: text/plain Content-Transfer-Encoding: 7bit Message-Id: <1132656311.27134.1.camel@pc960.cambridge.arm.com> Mime-Version: 1.0 Date: Tue, 22 Nov 2005 10:45:00 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2005-11/txt/msg01033.txt.bz2 On Mon, 2005-11-21 at 21:46, Ian Lance Taylor wrote: > > In principle the combiner could make sure that the same number and > type of volatile memory references occur both before and after the > combination, and reject it if not. It would also have to ensure that the volatile memory operation wasn't moved across any other 'relevant' (for some suitable definition of relevant) memory operation (combine can cause limited re-ordering of load operations, for example). R.