From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 16679 invoked by alias); 3 Apr 2014 06:18:37 -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 16647 invoked by uid 48); 3 Apr 2014 06:18:33 -0000 From: "chbreitkopf at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/59967] [4.8/4.9 Regression] Performance regression from 4.7.x to 4.8.x (loop not unrolled) Date: Thu, 03 Apr 2014 06:18:00 -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: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: chbreitkopf at gmail dot com X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.8.3 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: 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: 2014-04/txt/msg00180.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59967 --- Comment #3 from Christoph Breitkopf --- It's this conditional in the inner loop. The expression becomes constant only if both loops are unrolled (i and j are the loop counters): if (1<