From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 60444 invoked by alias); 9 Oct 2015 11:06:51 -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 60432 invoked by uid 89); 9 Oct 2015 11:06:51 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.5 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Fri, 09 Oct 2015 11:06:50 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id 68E6746; Fri, 9 Oct 2015 11:06:48 +0000 (UTC) Received: from localhost.localdomain (vpn1-6-86.ams2.redhat.com [10.36.6.86]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t99B6kFu010525; Fri, 9 Oct 2015 07:06:47 -0400 Subject: Re: [RFC][PATCH] Preferred rename register in regrename pass To: Robert Suchanek , "ebotcazou@adacore.com" , "gcc-patches@gcc.gnu.org" References: <55FC2B8D.6000106@redhat.com> From: Bernd Schmidt Message-ID: <56179FC6.3040503@redhat.com> Date: Fri, 09 Oct 2015 11:06:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2015-10/txt/msg00956.txt.bz2 Hi Robert, > gcc/ > * regrename.c (create_new_chain): Initialize terminated_dead, > renamed and tied_chain. > (find_best_rename_reg): Pick and check register from the tied chain. > (regrename_do_replace): Mark head as renamed. > (scan_rtx_reg): Tie chains in move insns. Set terminate_dead flag. > * regrename.h (struct du_head): Add tied_chain, renamed and > terminated_dead members. Thanks - this looks a lot better already. You didn't say how it was bootstrapped and tested; please include this information for future submissions. For a patch like this, some data on the improvement you got would also be appreciated. I'd still like to investigate the possibility of further simplification: > + { > + /* Find the input chain. */ > + for (i = c->id - 1; id_to_chain.iterate (i, &head); i--) > + if (head->last && head->last->insn == insn > + && head->terminated_dead) > + { > + gcc_assert (head->regno == REGNO (recog_data.operand[1])); > + c->tied_chain = head; > + head->tied_chain = c; > + > + if (dump_file) > + fprintf (dump_file, "Tying chain %s (%d) with %s (%d)\n", > + reg_names[c->regno], c->id, > + reg_names[head->regno], head->id); > + /* Once tied, we're done. */ > + break; > + } > + } > + } > + This looks like it's a little more complicated than necessary. Couldn't you add a static var "terminated_this_insn" which gets initialized to NULL and set when a reg dies, and then you check this here rather than having a loop? That would also eliminate the new "terminated_dead" field. Other than that I'm pretty happy with this. Bernd