From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 25908 invoked by alias); 1 Nov 2011 13:51:13 -0000 Received: (qmail 25895 invoked by uid 22791); 1 Nov 2011 13:51:11 -0000 X-SWARE-Spam-Status: No, hits=-1.6 required=5.0 tests=AWL,BAYES_00,RCVD_NUMERIC_HELO,RP_MATCHES_RCVD,SPF_HELO_PASS X-Spam-Check-By: sourceware.org Received: from lo.gmane.org (HELO lo.gmane.org) (80.91.229.12) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 01 Nov 2011 13:50:51 +0000 Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1RLEjp-0006OG-BH for gcc@gcc.gnu.org; Tue, 01 Nov 2011 14:50:49 +0100 Received: from 193.128.72.68 ([193.128.72.68]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 01 Nov 2011 14:50:48 +0100 Received: from paulo by 193.128.72.68 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 01 Nov 2011 14:50:48 +0100 To: gcc@gcc.gnu.org From: "Paulo J. Matos" Subject: Re: approaches to carry-flag modelling in RTL Date: Tue, 01 Nov 2011 13:51:00 -0000 Message-ID: References: <4EAADF8F.2090002@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20110929 Thunderbird/7.0.1 In-Reply-To: X-IsSubscribed: yes Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2011-11/txt/msg00019.txt.bz2 On 01/11/11 02:43, Hans-Peter Nilsson wrote: > > Not obvious or maybe I was unclear as to what I alluded? > In the below insn-bodies, "sub" is the insn that sets cc0 as a > side-effect. > > Supposed canonical form : > > (parallel > [(set cc_reg) (compare ...)) > (set destreg) (sub ...))]) > and: > (parallel > [(set destreg) (sub ...)) > (clobber cc_reg)]) > > But IMHO it'd be easier (for most values of "easier") to combine > both patterns with that non-existing mechanism (and no, I don't > count match_parallel) if we instead canonicalized on the CC_REG > set being the same as the clobber position: > > (parallel > [(set destreg) (sub ...)) > (set cc_reg) (compare ...))]) > with: > (parallel > [(set destreg) (sub ...)) > (clobber cc_reg)]) > > brgds, H-P > That is very strange because if you look into RX or MN10300, they all have the set REG_CC as the last in the parallel. I wonder if it has anything to do with the fact that in these backends the set of the REG_CC only shows up after reload. -- PMatos