From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 6799 invoked by alias); 30 Jan 2012 13:58:19 -0000 Received: (qmail 6765 invoked by uid 22791); 30 Jan 2012 13:58:17 -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; Mon, 30 Jan 2012 13:58:05 +0000 From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/52028] [4.7 Regression] wrong code with -O2 -ftree-loop-distribution Date: Mon, 30 Jan 2012 14:13:00 -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: rguenth at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.7.0 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: 2012-01/txt/msg03519.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52028 --- Comment #4 from Richard Guenther 2012-01-30 13:57:30 UTC --- loop distribution splits the for (;;) { ... if (K != k) break; K += 16; } loop into three portions, the first writing to K[0..13], the next writing to K[14] and the last writing to K[15]. All of which is reasonable at a first glance. But then the first loop is discarded completely CDDCE2, so something is wrong.