From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9036 invoked by alias); 3 May 2006 19:00:19 -0000 Received: (qmail 8604 invoked by alias); 3 May 2006 19:00:05 -0000 Date: Wed, 03 May 2006 19:00:00 -0000 Message-ID: <20060503190005.8599.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug tree-optimization/26944] [4.1/4.2 Regression] -ftree-ch generates worse code In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "pinskia at physics dot uc dot edu" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2006-05/txt/msg00302.txt.bz2 List-Id: ------- Comment #6 from pinskia at physics dot uc dot edu 2006-05-03 19:00 ------- Subject: Re: [4.1/4.2 Regression] -ftree-ch generates worse code > > > > ------- Comment #5 from dann at godzilla dot ics dot uci dot edu 2006-05-03 18:54 ------- > IMO Comment #4 does not look close enough at what is actually happening. > IMO tree-ch is the root cause here. > > Given the above CFG, critical edge splitting transforms this into: > Given the above CFG PRE will dutifully fill with code a lot of the empty basic > blocks: None of the above issues are the real issue. TREE CH is doing the correct thing simplifying the loop. PRE is doing the correct thing by getting rid of redundants. The main issue is really the RA not being so good. -- Pinski -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26944