From owner-cvs-all@FreeBSD.ORG Thu Mar 6 02:11:12 2008 Return-Path: Delivered-To: cvs-all@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0798A1065674; Thu, 6 Mar 2008 02:11:12 +0000 (UTC) (envelope-from das@FreeBSD.ORG) Received: from zim.MIT.EDU (ZIM.MIT.EDU [18.95.3.101]) by mx1.freebsd.org (Postfix) with ESMTP id 8C5F68FC13; Thu, 6 Mar 2008 02:11:11 +0000 (UTC) (envelope-from das@FreeBSD.ORG) Received: from zim.MIT.EDU (localhost [127.0.0.1]) by zim.MIT.EDU (8.14.2/8.14.2) with ESMTP id m262CME6046918; Wed, 5 Mar 2008 21:12:22 -0500 (EST) (envelope-from das@FreeBSD.ORG) Received: (from das@localhost) by zim.MIT.EDU (8.14.2/8.14.2/Submit) id m262CMre046917; Wed, 5 Mar 2008 21:12:22 -0500 (EST) (envelope-from das@FreeBSD.ORG) Date: Wed, 5 Mar 2008 21:12:22 -0500 From: David Schultz To: Colin Percival , Peter Jeremy Message-ID: <20080306021222.GA46783@zim.MIT.EDU> Mail-Followup-To: Colin Percival , Peter Jeremy , Bruce Evans , src-committers@FreeBSD.ORG, cvs-src@FreeBSD.ORG, cvs-all@FreeBSD.ORG References: <200803051121.m25BLE03035426@repoman.freebsd.org> <20080305182531.GS68971@server.vk2pj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080305182531.GS68971@server.vk2pj.dyndns.org> Cc: cvs-src@FreeBSD.ORG, src-committers@FreeBSD.ORG, Bruce Evans , cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/i386/include _types.h X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 06 Mar 2008 02:11:12 -0000 On Wed, Mar 05, 2008, Colin Percival wrote: > Bruce Evans wrote: > > Modified files: > > sys/i386/include _types.h > > Log: > > Change float_t and double_t to long double on i386. > > Doesn't this have a rather severe performance impact on any code which > uses double_t? Yes, if the code is compiled with -msse2. Otherwise, doubles get fed to the i387 anyway. On Thu, Mar 06, 2008, Peter Jeremy wrote: > npx.h currently defines __INITIAL_NPXCW__ as 0x127f which makes the x87 > emulate double (53-bit) precision rather than its native 64-bit long > double. Doesn't this change also need a corresponding change to npx.h > to make the x87 run with 64-bit precision? Technically Bruce's change isn't wrong without changing the default precision, it's just rather pointless. (Why tell programs to store variables in a wider format if you're just going to evaluate them in a narrower format anyway?) So I guess I agree that if we're going to go down this path, we ought to just bite the bullet and change npx.h and contrib/gcc/config/i386/freebsd.h to use 64-bit precision by default on i386.