From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 25049 invoked by alias); 30 May 2013 07:13:01 -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 24581 invoked by uid 48); 30 May 2013 07:12:56 -0000 From: "jakub at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/57359] wrong code for union access at -O3 on x86_64-linux Date: Thu, 30 May 2013 07:13:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Version: 4.9.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: jakub at gcc dot gnu.org X-Bugzilla-Status: RESOLVED 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: cc 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: 2013-05/txt/msg02079.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57359 Jakub Jelinek changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jsm28 at gcc dot gnu.org --- Comment #6 from Jakub Jelinek --- I guess then the important question is what is supposed to be the effective type of the object inside the union (ISO C99, 6.5/6), if it isn't the union, but one of the types, then the testcase would be still invalid, because then one or the other of the stores would be through non-allowed type (6.5/7). If that wasn't invalid, it would be a loop-hole in TBAA disambiguation (because then two stores through pointers with non-conflicting alias set couldn't be just because of this considered non-aliasing.