From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29280 invoked by alias); 21 Apr 2011 16:22:37 -0000 Received: (qmail 29271 invoked by uid 22791); 21 Apr 2011 16:22:36 -0000 X-SWARE-Spam-Status: No, hits=-2.8 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00,TW_DX 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; Thu, 21 Apr 2011 16:22:23 +0000 From: "xinliangli at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/48702] [4.6/4.7 Regression] optimization regression with gcc-4.6 on x86_64-unknown-linux-gnu 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: xinliangli at gmail dot com X-Bugzilla-Status: ASSIGNED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: rguenth at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.6.1 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 Date: Thu, 21 Apr 2011 16:22:00 -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 X-SW-Source: 2011-04/txt/msg02296.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48702 --- Comment #12 from davidxl 2011-04-21 16:22:03 UTC --- (In reply to comment #3) > I have a patch that makes it fail on trunk as well. IVOPTs generates > > for (p = &a; p != &a - 3; --p) > *(p + 3) = ... > > and alias analysis doesn't like this invalid pointer. I wonder why ivopt does not select the iv candidate whose base is &a+3.