From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7793 invoked by alias); 12 Mar 2014 14:33:59 -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 Received: (qmail 7766 invoked by uid 48); 12 Mar 2014 14:33:56 -0000 From: "dpb at corrigendum dot ru" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/60196] Incorrect compilation with -fwrapv and -ftree-vectorize Date: Wed, 12 Mar 2014 14:33:00 -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-Version: 4.8.2 X-Bugzilla-Keywords: X-Bugzilla-Severity: major X-Bugzilla-Who: dpb at corrigendum dot ru X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-03/txt/msg00980.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D60196 --- Comment #1 from =D0=A0=D0=BE=D0=BC=D0=B0=D0=BD =D0=94=D0=BE=D0=BD=D1=87= =D0=B5=D0=BD=D0=BA=D0=BE --- Here's another reproducer for what looks like the same problem: #include static const short a[8] =3D {1,1,1,1,1,1,1,1}; static const unsigned char b[8] =3D {0,0,0,0,0,0,0,0}; static int foo() { int sum =3D 0, i; for (i =3D 0; i < 8; ++i) sum +=3D a[i] * b[i]; return sum; } int main() { printf("%d\n", foo()); return 0; } The correct result is 0, but compiling with -O1 -ftree-vectorize yields 8. I looked at the disassembly, and it just sums the elements of a, b is not use= d at all. For this one, adding -fwrapv actually fixes it, but I don't think there are= any overflows here. >>From gcc-bugs-return-446112-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Wed Mar 12 14:38:15 2014 Return-Path: Delivered-To: listarch-gcc-bugs@gcc.gnu.org Received: (qmail 10925 invoked by alias); 12 Mar 2014 14:38:15 -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 Delivered-To: mailing list gcc-bugs@gcc.gnu.org Received: (qmail 10883 invoked by uid 48); 12 Mar 2014 14:38:11 -0000 From: "jakub at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/57189] [4.9 Regression] Vector register is spilled for vector extract pattern Date: Wed, 12 Mar 2014 14:38:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Version: 4.9.0 X-Bugzilla-Keywords: missed-optimization, ra X-Bugzilla-Severity: normal X-Bugzilla-Who: jakub at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.9.0 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: priority cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-03/txt/msg00981.txt.bz2 Content-length: 516 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57189 Jakub Jelinek changed: What |Removed |Added ---------------------------------------------------------------------------- Priority|P1 |P2 CC| |vmakarov at gcc dot gnu.org --- Comment #7 from Jakub Jelinek --- IMHO not worth P1 status. Would be nice if Vlad could have a look eventually though.