From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22238 invoked by alias); 20 Jul 2011 19:02:44 -0000 Received: (qmail 22227 invoked by uid 22791); 20 Jul 2011 19:02:43 -0000 X-SWARE-Spam-Status: No, hits=-2.8 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 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; Wed, 20 Jul 2011 19:02:28 +0000 From: "wschmidt at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/49749] Reassociation rank algorithm does not include all non-NULL operands 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: wschmidt at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: wschmidt at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- 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 Date: Wed, 20 Jul 2011 19:02:00 -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 X-SW-Source: 2011-07/txt/msg01697.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49749 --- Comment #11 from William J. Schmidt 2011-07-20 19:01:30 UTC --- I forgot to mention some justification for the value of PHI_LOOP_BIAS, and I notice it has a misleading comment by it at the moment. The value is a constant that should be larger than the depth of the largest expected reassociation tree, but generally smaller than twice the rank of the basic block. The intent is to limit the effect to single-block loops for now. One of the questions I have is whether the bias should be allowed for more complex innermost loops. PHI_LOOP_BIAS is a crude method and something more refined is probably needed, but it serves to demonstrate the viability of the general approach.