From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27246 invoked by alias); 2 Apr 2013 15:29:56 -0000 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 Received: (qmail 27208 invoked by uid 89); 2 Apr 2013 15:29:50 -0000 X-Spam-SWARE-Status: No, score=-8.6 required=5.0 tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,KHOP_THREADED,RCVD_IN_DNSWL_HI,RCVD_IN_HOSTKARMA_W,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.1 Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.84/v0.84-167-ge50287c) with ESMTP; Tue, 02 Apr 2013 15:29:47 +0000 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r32FTiD5017640 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 2 Apr 2013 11:29:44 -0400 Received: from stumpy.slc.redhat.com (ovpn-113-84.phx2.redhat.com [10.3.113.84]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r32FTh9Z010471; Tue, 2 Apr 2013 11:29:43 -0400 Message-ID: <515AF967.4050107@redhat.com> Date: Tue, 02 Apr 2013 17:19:00 -0000 From: Jeff Law User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 MIME-Version: 1.0 To: Eric Botcazou CC: Marc Glisse , gcc-patches@gcc.gnu.org Subject: Re: [RTL] Canonicalize commutative operations more References: <1420303.Yr0JhII12W@polaris> <5990842.GuiiquCisS@polaris> In-Reply-To: <5990842.GuiiquCisS@polaris> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2013-04/txt/msg00112.txt.bz2 On 04/02/2013 04:54 AM, Eric Botcazou wrote: >> I wonder if those issues might in most cases be bugs in the back-ends >> (optimizations missed depending on the order), that the canonicalization >> would make more noticable (and thus easier to fix). > > There are certainly such issues in the back-ends (and even ??? comments about > it) so sensible canonicalization is desirable. Right. The choice between canonicalization and code bloat to support multiple RTL forms computing the same value is a never-ending problem. Where it's clearly made sense we have canonicalized, where it doesn't, we haven't. There's a huge no-mans land in the middle. Jeff