From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 74B323858D20; Thu, 17 Feb 2022 07:35:51 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 74B323858D20 From: "crazylht at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/104579] vectorizer failed to reduce max & index search together Date: Thu, 17 Feb 2022 07:35:51 +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: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: crazylht at gmail dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: 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-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: Thu, 17 Feb 2022 07:35:51 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104579 --- Comment #2 from Hongtao.liu --- One possible way is sink maxInt =3D src[i] out of loop, when there's synchr= onised index search in the loop, just like below. int max (int *src, int n, int *position) { int maxInt; int maxIndex; int i; maxInt =3D src[0]; maxIndex =3D 0; for (i =3D 1; i < n; i++) { if (maxInt < src[i]) { maxIndex =3D i; } } maxInt =3D src[maxIndex]; *position =3D maxIndex; return (maxInt); }=