From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5531 invoked by alias); 3 Nov 2010 18:47:31 -0000 Received: (qmail 5522 invoked by uid 22791); 3 Nov 2010 18:47:31 -0000 X-SWARE-Spam-Status: No, hits=-2.0 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from mel.act-europe.fr (HELO mel.act-europe.fr) (194.98.77.210) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 03 Nov 2010 18:47:26 +0000 Received: from localhost (localhost [127.0.0.1]) by filtered-smtp.eu.adacore.com (Postfix) with ESMTP id 844D1CB0232; Wed, 3 Nov 2010 19:47:24 +0100 (CET) Received: from mel.act-europe.fr ([127.0.0.1]) by localhost (smtp.eu.adacore.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dmrphm36t1w2; Wed, 3 Nov 2010 19:47:24 +0100 (CET) Received: from [192.168.1.2] (bon31-9-83-155-120-49.fbx.proxad.net [83.155.120.49]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mel.act-europe.fr (Postfix) with ESMTP id 42361CB01DE; Wed, 3 Nov 2010 19:47:24 +0100 (CET) From: Eric Botcazou To: Paolo Bonzini Subject: Re: new sign/zero extension elimination pass Date: Wed, 03 Nov 2010 18:49:00 -0000 User-Agent: KMail/1.9.9 Cc: Tom de Vries , gcc-patches@gcc.gnu.org, Bernd Schmidt References: <4CBC698B.3080204@codesourcery.com> <4CCDAD7E.9040005@codesourcery.com> In-Reply-To: MIME-Version: 1.0 Content-Disposition: inline Message-Id: <201011031945.54009.ebotcazou@adacore.com> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org X-SW-Source: 2010-11/txt/msg00334.txt.bz2 > No problem, I discovered it the hard way (and had to rewrite fwprop's > dataflow to work around it). The other ZEE pass uses UD/DU chains though. The now removed SEE pass used them as well. > I think you're right, as Joseph confirmed. There is one occurrence of > flag_wrapv in simplify-rtx.c and zero in combine.c, so this means that > indeed RTL treats PLUS/MINUS as wrapping. I remember seeing more but > my memory must be at fault. Since it's so limited, the one occurrence > that is there should be removed. They were introduced to fix PR rtl-optimization/23047. > If you can fix the performance issues that Eric has without a rewrite, > and if it's not quadratic, I would have no problem at all with RTL. Yes, I also think that the pass makes sense at the RTL level, as it does something that cannot be done (easily) elsewhere. On the other hand, it's unfortunate to have 2 different ZEE passes. -- Eric Botcazou