From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 6886 invoked by alias); 18 Jan 2004 07:01:11 -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 6824 invoked from network); 18 Jan 2004 07:01:00 -0000 Received: from unknown (HELO mx1.redhat.com) (66.187.233.31) by sources.redhat.com with SMTP; 18 Jan 2004 07:01:00 -0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.11.6/8.11.6) with ESMTP id i0I70vl05634; Sun, 18 Jan 2004 02:00:57 -0500 Received: from speedy.slc.redhat.com (vpn50-8.rdu.redhat.com [172.16.50.8]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id i0I70ta05424; Sun, 18 Jan 2004 02:00:55 -0500 Received: from redhat.com (law@localhost) by speedy.slc.redhat.com (8.12.10/8.12.8/Submit) with ESMTP id i0I6x9nS000882; Sat, 17 Jan 2004 23:59:10 -0700 Message-Id: <200401180659.i0I6x9nS000882@speedy.slc.redhat.com> X-Authentication-Warning: speedy.slc.redhat.com: law owned process doing -bs To: Jan Hubicka cc: Diego Novillo , "Kaveh R. Ghazi" , jsm@polyomino.org.uk, "gcc@gcc.gnu.org" , gp@suse.de Reply-To: law@redhat.com Subject: Re: [RFC] Contributing tree-ssa to mainline In-Reply-To: Your message of "Sat, 17 Jan 2004 14:53:44 +0100." <20040117135344.GH26819@atrey.karlin.mff.cuni.cz> From: law@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 18 Jan 2004 07:01:00 -0000 X-SW-Source: 2004-01/txt/msg01151.txt.bz2 In message <20040117135344.GH26819@atrey.karlin.mff.cuni.cz>, Jan Hubicka write s: >There are other easy targets - NULL pointer ellimination for instance >that I was discussing with Jeff. We could probably already turn off the RTL NULL pointer check elimination code. While I am aware of one case where the tree version misses something the RTL version catches, that case is extremely rare. Last I looked, it triggered once per stage in a GCC bootstrap. In contrast I've heard and seen firsthand the tree-ssa NULL pointer check elimination code eliminating NULL pointer checks that the RTL version misses. Jump threading/bypassing. Right now we've got about 175 cases where the RTL jump threader catches something that we should have detected at the tree-ssa level (contrast this to > 3000 a few months ago). I've got patches in my local tree which bring that number down to around 40. And (of course) I'm also seeing the tree-ssa code detect and thread a number of jumps that the RTL threader is missing. I haven't yet evaluated where we stand on making the RTL jump bypassing code useless -- I know we're detecting some of that stuff in the tree-ssa jump threader, but I really haven't evaluated it yet. We're also reasonably close to being able to simplify CSE in a major way -- specifically we're close to having the ability to turn off the path following code in CSE1. Jeff