From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15237 invoked by alias); 29 Oct 2014 00:07:48 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 15181 invoked by uid 55); 29 Oct 2014 00:07:43 -0000 From: "joseph at codesourcery dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/59448] Code generation doesn't respect C11 address-dependency Date: Wed, 29 Oct 2014 01:48:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: middle-end X-Bugzilla-Version: unknown X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: joseph at codesourcery dot com X-Bugzilla-Status: NEW X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-10/txt/msg02211.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59448 --- Comment #19 from joseph at codesourcery dot com --- On Tue, 28 Oct 2014, torvald at gcc dot gnu.org wrote: > Alternatively, we could try to be conservative and add an acquire barrier > before the function body if any parameter of the function has > carries_dependency; and, likewise, add an acquire barrier after every call to a > function which has carries_dependency. > > I don't have more input from the ISO C side, but I would guess that the > situation there is similar. As previously noted: * ISO C does not have carries_dependency (or attributes at all). * carries_dependency is about increasing optimization, not decreasing it. If it affects when barriers are added, it does so by allowing some barriers to be omitted that would otherwise be required.