From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 41888 invoked by alias); 9 Oct 2015 10:35:51 -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 41874 invoked by uid 89); 9 Oct 2015 10:35:50 -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 10:35:49 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 807CA8A344; Fri, 9 Oct 2015 10:35:47 +0000 (UTC) Received: from localhost.localdomain (vpn1-6-86.ams2.redhat.com [10.36.6.86]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t99AZkH7009303; Fri, 9 Oct 2015 06:35:47 -0400 Subject: Re: [PATCH] bb-reorder: Improve the simple algorithm for -Os (PR67864) To: Segher Boessenkool , gcc-patches@gcc.gnu.org References: From: Bernd Schmidt Message-ID: <56179882.6050501@redhat.com> Date: Fri, 09 Oct 2015 10:35:00 -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/msg00953.txt.bz2 On 10/08/2015 06:57 PM, Segher Boessenkool wrote: > As the PR points out, the "simple" reorder algorithm makes bigger code > than the STC algorithm did, for -Os, for x86. I now tested it for many > different targets and it turns out to be worse everywhere. That's somewhat disappointing. Wasn't it supposed to improve over it? What went wrong? > Is this okay for trunk? > > 2015-10-08 Segher Boessenkool > > PR rtl-optimization/67864 > * gcc/bb-reorder (reorder_basic_blocks_simple): Prefer existing > fallthrough edges for conditional jumps. Don't sort candidate > edges if not optimizing for speed. Ok. Although it would be nice to understand exactly what causes code growth and possibly get a real cost estimate rather than such a heuristic. Bernd