From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10308 invoked by alias); 3 Feb 2011 18:11:18 -0000 Received: (qmail 10298 invoked by uid 22791); 3 Feb 2011 18:11:17 -0000 X-SWARE-Spam-Status: No, hits=-2.6 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; Thu, 03 Feb 2011 18:11:11 +0000 From: "sebpop at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/46194] [4.5/4.6 Regression] gcc.dg/graphite/block-0.c FAILs with -ftree-parallelize-loops 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: sebpop at gmail dot com X-Bugzilla-Status: ASSIGNED X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: spop at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.5.3 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" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Date: Thu, 03 Feb 2011 18:11:00 -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: 2011-02/txt/msg00536.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D46194 --- Comment #7 from sebpop at gmail dot com 2011-= 02-03 18:11:09 UTC --- Here is the loop kernel from block-0.c for (i =3D 0; i < N; i++) for (j =3D 0; j < N; j++) a[j] =3D a[i] + 1; On Fri, Dec 31, 2010 at 06:01, jakub at gcc dot gnu.org wrote: > =C2=A0access_fn_A: {0, +, 1}_1 > =C2=A0access_fn_B: {0, +, 1}_2 > > =C2=A0(subscript > =C2=A0iterations_that_access_an_element_twice_in_A: [0 + 1 * x_1] > =C2=A0last_conflict: 1000 > =C2=A0iterations_that_access_an_element_twice_in_B: [0 + 1 * x_1] I think that this representation of affine functions is wrong: the access in B should read [0 + 0 * x_1 + 1 * x_2] and that would not lead to a wrong conclusion like the following... > =C2=A0last_conflict: 1000 > =C2=A0(Subscript distance: 0 > =C2=A0) > =C2=A0) > =C2=A0inner loop index: 0 > =C2=A0loop nest: (1 2 ) > =C2=A0distance_vector: =C2=A0 0 =C2=A0 0 > =C2=A0direction_vector: =C2=A0 =C2=A0 =3D =C2=A0 =C2=A0=3D > )