From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20761 invoked by alias); 18 Sep 2004 03:08:08 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 20743 invoked from network); 18 Sep 2004 03:08:07 -0000 Received: from unknown (HELO dberlin.org) (68.164.203.246) by sourceware.org with SMTP; 18 Sep 2004 03:08:07 -0000 Received: from [127.0.0.1] (HELO dberlin.org) by dberlin.org (CommuniGate Pro SMTP 4.2.1) with ESMTP-TLS id 7302842; Fri, 17 Sep 2004 23:08:07 -0400 Date: Sat, 18 Sep 2004 10:43:00 -0000 From: Daniel Berlin To: Jan Hubicka cc: gcc@gcc.gnu.org, rakdver@atrey.karlin.mff.cuni.cz, stevenb@suse.de Subject: Re: Critical edge splitting inconsistency In-Reply-To: <20040917214457.GE3425@atrey.karlin.mff.cuni.cz> Message-ID: References: <20040917214457.GE3425@atrey.karlin.mff.cuni.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-SW-Source: 2004-09/txt/msg01099.txt.bz2 On Fri, 17 Sep 2004, Jan Hubicka wrote: > Hi, > while looking into unrelated problem on tree-profiling branch I noticed > that we currently split critical edges before PRE and then cleanup_cfg > iff PRE appears to modify CFG. This means that sometimes we keep the > edges split after pre pass but sometimes we don't. This just looks > inconsistent as someone might jump into assumption that edges are always > split in the later pass (or into reversed one). > Would be possible to take care of this somehow? Perhaps the critical > edge spliteness can be made a property of CFG for the pass manager? Sure. But here's the interesting part: Right now, the pass manager is only verifying properties statically. This means that even if the gating function for the pass makes it so the pass doesn't execute, it still assumes it provides the property. So we can't tell if we actually need to redo something like critical edge splitting, in order to provide the necessary properties. It's kind of like a property that we can regenerate any time it's necessary. > > Honza >