From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 25378 invoked by alias); 26 Feb 2015 09:56:35 -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 25353 invoked by uid 48); 26 Feb 2015 09:56:31 -0000 From: "jakub at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/65215] [5 Regression] Bswap load miscompilation Date: Thu, 26 Feb 2015 11:07:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 5.0 X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: jakub at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: jakub at gcc dot gnu.org X-Bugzilla-Target-Milestone: 5.0 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: attachments.created 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: 2015-02/txt/msg02893.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65215 --- Comment #1 from Jakub Jelinek --- Created attachment 34879 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34879&action=edit gcc5-pr65215.patch Untested fix. There are still issues left, e.g. I can't understand the "bswap &&" part in if (bswap && align < GET_MODE_ALIGNMENT (TYPE_MODE (load_type)) && SLOW_UNALIGNED_ACCESS (TYPE_MODE (load_type), align)) return false; Don't you use the new MEM_REF even for the !bswap (aka nop) case? So, I don't see how it would be safe to generate that. And the testsuite coverage of this is definitely suboptimal, from endianity POV, bitfields etc.