From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 86633 invoked by alias); 30 Jul 2019 19:47:04 -0000 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 Received: (qmail 86593 invoked by uid 89); 30 Jul 2019 19:47:02 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-2.6 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 spammy=IEEE X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 30 Jul 2019 19:47:00 +0000 Received: from nat-ies.mentorg.com ([192.94.31.2] helo=svr-ies-mbx-01.mgc.mentorg.com) by relay1.mentorg.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-SHA384:256) id 1hsY5F-0002xw-Di from joseph_myers@mentor.com ; Tue, 30 Jul 2019 12:46:53 -0700 Received: from digraph.polyomino.org.uk (137.202.0.90) by svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) with Microsoft SMTP Server (TLS) id 15.0.1320.4; Tue, 30 Jul 2019 20:46:50 +0100 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.90_1) (envelope-from ) id 1hsY5B-00035M-GW; Tue, 30 Jul 2019 19:46:49 +0000 Date: Tue, 30 Jul 2019 19:47:00 -0000 From: Joseph Myers To: Segher Boessenkool CC: Martin Jambor , Tejas Joshi , Jan Hubicka , GCC Mailing List Subject: Re: Expansion of narrowing math built-ins into power instructions In-Reply-To: <20190729184002.GM31406@gate.crashing.org> Message-ID: References: <20190729184002.GM31406@gate.crashing.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-SW-Source: 2019-07/txt/msg00194.txt.bz2 On Mon, 29 Jul 2019, Segher Boessenkool wrote: > I think this is refering to the "fadds" and similar Power architecture > instructions, which take as inputs any single or double precision > numbers, and round the result to single precision? These instructions Yes. On Power9, it is *also* possible to do such narrowing operations from IEEE binary128 to binary32 or binary64 format, by first doing the operation on binary128 using one of the "round to odd" instruction variants, then doing a conversion to the narrower format. -- Joseph S. Myers joseph@codesourcery.com