From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19259 invoked by alias); 6 Sep 2012 21:05:32 -0000 Received: (qmail 19241 invoked by uid 22791); 6 Sep 2012 21:05:31 -0000 X-SWARE-Spam-Status: No, hits=-4.3 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00,KHOP_THREADED 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, 06 Sep 2012 21:05:18 +0000 From: "pthaugen at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/54497] [4.8 Regression] Revision 190015 causes 22% degradation on 172.mgrid on PowerPC Date: Thu, 06 Sep 2012 21:05:00 -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-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: pthaugen at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.8.0 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" MIME-Version: 1.0 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: 2012-09/txt/msg00508.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54497 --- Comment #2 from Pat Haugen 2012-09-06 21:05:05 UTC --- (In reply to comment #1) > I suppose the loop is no longer predicted to execute enough times? I don't think that's the issue, I'm thinking it's somewhere in the data dependence analysis. Looking at the dump before .pcom (i.e. .dceloop3), both resid_ and resid_.constprop.0 list BB7, the inner loop block, as freq=10000. The .pcom dump has many differences in the data analysis portion between the two procedures, but the main difference is the analysis on resid_.constprop.0 ends with the following: Predictive commoning failed: no suitable chains