From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23851 invoked by alias); 18 Sep 2017 14:08:32 -0000 Mailing-List: contact fortran-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: fortran-owner@gcc.gnu.org Received: (qmail 23643 invoked by uid 89); 18 Sep 2017 14:08:31 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.0 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD autolearn=no version=3.3.2 spammy=22am, 22AM, watch X-Spam-User: qpsmtpd, 3 recipients X-HELO: troutmask.apl.washington.edu Received: from troutmask.apl.washington.edu (HELO troutmask.apl.washington.edu) (128.95.76.21) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 18 Sep 2017 14:08:26 +0000 Received: from troutmask.apl.washington.edu (localhost [127.0.0.1]) by troutmask.apl.washington.edu (8.15.2/8.15.2) with ESMTPS id v8IE8OP6083340 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Mon, 18 Sep 2017 07:08:24 -0700 (PDT) (envelope-from sgk@troutmask.apl.washington.edu) Received: (from sgk@localhost) by troutmask.apl.washington.edu (8.15.2/8.15.2/Submit) id v8IE8NEt083339; Mon, 18 Sep 2017 07:08:23 -0700 (PDT) (envelope-from sgk) Date: Mon, 18 Sep 2017 14:08:00 -0000 From: Steve Kargl To: Janus Weil Cc: gfortran , gcc-patches Subject: Re: [Patch, Fortran] PR 82143: add a -fdefault-real-16 flag Message-ID: <20170918140823.GA83251@troutmask.apl.washington.edu> Reply-To: sgk@troutmask.apl.washington.edu References: <20170918045045.GA79226@troutmask.apl.washington.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.7.2 (2016-11-26) X-IsSubscribed: yes X-SW-Source: 2017-09/txt/msg00063.txt.bz2 On Mon, Sep 18, 2017 at 09:02:22AM +0200, Janus Weil wrote: > Hi Steve, > > >> attached is a (technically) simple patch that implements the compiler > >> flag "-fdefault-real-16" for gfortran. > > > > What about -fdefault-real-10? If you're going to add bloat to the > > compiler, then you might as well to it right. > > well, yeah. If my only aim was to add bloat to the compiler out of > plain boredom and nastiness, then I might as well add > -fdefault-real-37. But I don't think that would be very useful. Why? One gets 11-bits of additional precision (on most platforms) and a significant increase in the exponent range (+- ~1024 to +- ~16384). REAL(10) maps to hardware floating point, which is faster than software quad precision. -- Steve 20170425 https://www.youtube.com/watch?v=VWUpyCsUKR4 20161221 https://www.youtube.com/watch?v=IbCHE-hONow