From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 35695 invoked by alias); 13 Sep 2016 08:41:43 -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 35674 invoked by uid 89); 13 Sep 2016 08:41:41 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy= 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 ESMTP; Tue, 13 Sep 2016 08:41:40 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (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 954A143A3B; Tue, 13 Sep 2016 08:41:39 +0000 (UTC) Received: from tucnak.zalov.cz (ovpn-204-43.brq.redhat.com [10.40.204.43]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u8D8fbid020055 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 13 Sep 2016 04:41:38 -0400 Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.15.2/8.15.2) with ESMTP id u8D8fZ6P016472; Tue, 13 Sep 2016 10:41:36 +0200 Received: (from jakub@localhost) by tucnak.zalov.cz (8.15.2/8.15.2/Submit) id u8D8fXQ5016471; Tue, 13 Sep 2016 10:41:33 +0200 Date: Tue, 13 Sep 2016 08:58:00 -0000 From: Jakub Jelinek To: Tamar Christina Cc: GCC Patches , "rguenther@suse.de" , "law@redhat.com" , nd Subject: Re: [PATCH] Optimise the fpclassify builtin to perform integer operations when possible Message-ID: <20160913084133.GE7282@tucnak.redhat.com> Reply-To: Jakub Jelinek References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-IsSubscribed: yes X-SW-Source: 2016-09/txt/msg00702.txt.bz2 On Mon, Sep 12, 2016 at 04:19:32PM +0000, Tamar Christina wrote: > This patch adds an optimized route to the fpclassify builtin > for floating point numbers which are similar to IEEE-754 in format. > > The goal is to make it faster by: > 1. Trying to determine the most common case first > (e.g. the float is a Normal number) and then the > rest. The amount of code generated at -O2 are > about the same +/- 1 instruction, but the code > is much better. > 2. Using integer operation in the optimized path. Is it generally preferable to use integer operations for this instead of floating point operations? I mean various targets have quite high costs of moving data in between the general purpose and floating point register file, often it has to go through memory etc. Jakub