From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29868 invoked by alias); 31 Jan 2011 10:06:58 -0000 Received: (qmail 29814 invoked by uid 22791); 31 Jan 2011 10:06:56 -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, 31 Jan 2011 10:06:50 +0000 From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/44183] Vectorizer may generate invalid memory access 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: X-Bugzilla-Severity: normal X-Bugzilla-Who: rguenth at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- 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: Mon, 31 Jan 2011 10:28:00 -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: 2011-01/txt/msg03367.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44183 --- Comment #7 from Richard Guenther 2011-01-31 10:06:27 UTC --- (In reply to comment #6) > It depends on the specific values of (a) array end alignment and (b) the number > of bytes read. As long as the array end + number of bytes read can cross a page > boundary, you're potentially causing SEGV or other errors. I don't think this can happen. The access to the out-of-bounds area only happens if there are pieces inluded in the last (aligned) vector move. That vector move will be aligned so it can't cross page-boundary. As it contains at least one allocated element the access may not trap.