From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29009 invoked by alias); 6 Dec 2011 14:17:34 -0000 Received: (qmail 28995 invoked by uid 22791); 6 Dec 2011 14:17:32 -0000 X-SWARE-Spam-Status: No, hits=-2.9 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 06 Dec 2011 14:17:19 +0000 From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/51315] [4.6/4.7 regression] unaligned memory accesses generated with -ftree-sra Date: Tue, 06 Dec 2011 14:17:00 -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-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: rguenth at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: ebotcazou at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.6.3 X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 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 X-SW-Source: 2011-12/txt/msg00599.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51315 --- Comment #7 from Richard Guenther 2011-12-06 14:16:21 UTC --- Note that in the end it's always us transforming a->b.c to (effectively) T *tem = &a->b.c; *tem which expand unfortunately handles differently. So whenever we do that we have to either avoid doing that if expand would have a different idea about the results alignment (there is currently no way that computes just expands idea of an expressions alignment - one piece of a good solution would provide that, not only SRA has this "issue"), or, stick that information somewhere (on the TREE_TYPE of the MEM_REF tree, but then it will only be honoured if the target provides a movmisalign optab - the other piece of a good solution would be that expand _always_ honors such alignment information and goes the same way as when expanding component refs).