From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 6E6283858431; Mon, 15 Nov 2021 10:34:47 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6E6283858431 From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/103237] [10/11/12 Regression] wrong code with -ftree-vectorize at -O1 on x86_64-linux-gnu starting with r7-1219-gb28ead45fe630b9e Date: Mon, 15 Nov 2021 10:34:47 +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: 12.0 X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: rguenth at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: rguenth at gcc dot gnu.org X-Bugzilla-Target-Milestone: 9.5 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-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 15 Nov 2021 10:34:47 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103237 --- Comment #7 from Richard Biener --- So what we get is a double reduction with two loop-closed PHIs on the inner loop where one is not classified as double-reduction (because we work from = the outer loop PHI to do that only). I think this case is simply not well supported and the easiest is to disall= ow it when analyzing the inner loop (because then we run into that duplicate LC PHI). Testing a patch to do that.=