From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 114986 invoked by alias); 22 Jun 2016 18:49:28 -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 114976 invoked by uid 89); 22 Jun 2016 18:49:27 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.3 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=Hx-languages-length:870 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; Wed, 22 Jun 2016 18:49:26 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 46FB57F6A8; Wed, 22 Jun 2016 18:49:25 +0000 (UTC) Received: from localhost.localdomain (ovpn-116-33.rdu2.redhat.com [10.10.116.33]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u5MInMV1004875; Wed, 22 Jun 2016 14:49:23 -0400 Subject: Re: [PATCH] Add a new target hook to compute the frame layout To: Bernd Edlinger , "gcc-patches@gcc.gnu.org" References: <538a413b-ef74-4a9a-1665-f3b84a8d9035@redhat.com> Cc: Richard Biener , Jakub Jelinek , Richard Sandiford , Ramana Radhakrishnan From: Jeff Law Message-ID: <84142d4f-d247-cfd8-5f41-23633681358f@redhat.com> Date: Wed, 22 Jun 2016 18:49:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2016-06/txt/msg01638.txt.bz2 On 06/21/2016 11:12 PM, Bernd Edlinger wrote: > > What I wanted to say here, is that lra goes thru several iterations, > changes something in the register allocation that has an impact on the > frame layout, typically 4-5 times, and calls INITIAL_ELIMINATION_OFFSET > 3-4 times in a row, and in the results must be consistent in each > iteration to be usable. > > So I am open to suggestions, how would you explain this idea in the doc? I'm not sure :( The goal is still the same, you're trying to separate the O(n) from the O(1) operations. So you want the COMPUTE_FRAME_LAYOUT hook to be called once for things which don't vary and INITIAL_ELIMINATION_OFFSET multiple times for things that do vary. Thinking more about this, which port has has a particularly expensive INITIAL_ELIMINATION_OFFSET? Jeff