From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Delivered-To: caml-list@yquem.inria.fr Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by yquem.inria.fr (Postfix) with ESMTP id 18F6ABC48 for ; Sat, 2 Apr 2005 22:50:45 +0200 (CEST) Received: from pauillac.inria.fr (pauillac.inria.fr [128.93.11.35]) by nez-perce.inria.fr (8.13.0/8.13.0) with ESMTP id j32KoiVk022881 for ; Sat, 2 Apr 2005 22:50:44 +0200 Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id WAA10374 for ; Sat, 2 Apr 2005 22:50:44 +0200 (MET DST) Received: from mail.davidb.org (adsl-64-172-240-129.dsl.sndg02.pacbell.net [64.172.240.129]) by nez-perce.inria.fr (8.13.0/8.13.0) with ESMTP id j32KogQU022878 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Sat, 2 Apr 2005 22:50:43 +0200 Received: from a64.davidb.org ([192.168.1.23]) by mail.davidb.org with esmtpa (Exim 4.43 #1 (Debian)) id 1DHpZp-0000UT-6b; Sat, 02 Apr 2005 12:50:41 -0800 To: "Stefan Monnier" , caml-list@inria.fr Subject: Re: [Caml-list] Re: 32- and 64-bit performance References: <200503300340.15874.jon@ffconsultancy.com> <871x9vzwk7.fsf-monnier+gmane.comp.lang.caml.inria@gnu.org> <200503311940.18701.jon@ffconsultancy.com> <87zmwh3p8m.fsf-monnier+gmane.comp.lang.caml.inria@gnu.org> Message-ID: Date: Sat, 02 Apr 2005 12:50:35 -0800 From: "David Brown" Content-Type: text/plain; format=flowed; delsp=yes; charset=iso-8859-1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In-Reply-To: <87zmwh3p8m.fsf-monnier+gmane.comp.lang.caml.inria@gnu.org> User-Agent: Opera M2/7.54 (Linux, build 955) X-Miltered: at nez-perce with ID 424F05A4.000 by Joe's j-chkmail (http://j-chkmail.ensmp.fr)! X-Miltered: at nez-perce with ID 424F05A2.000 by Joe's j-chkmail (http://j-chkmail.ensmp.fr)! X-Spam: no; 0.00; caml-list:01 umontreal:01 compiler:01 pointer:01 gcc:01 pointers:01 model:01 pointers:01 model:01 wrote:01 int:01 caml:02 implemented:02 library:03 apps:04 X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on yquem.inria.fr X-Spam-Status: No, score=1.8 required=5.0 tests=FORGED_RCVD_HELO,MSGID_RANDY autolearn=disabled version=3.0.2 X-Spam-Level: * On Sat, 02 Apr 2005 15:23:21 -0500, Stefan Monnier wrote: > Under Alpha they called it "taso". Mostly used for compatibility with > apps > that were assuming the size of ptrs is the same as the size of int: it > just > made the C library use only the bottom 4GB of the address space such that > the compiler could use only 32bit to store pointer values. The default mode in gcc for amd64 is almost this (-mcmodel=small). It assumes pointers live in the lower 2GB of address space, but 'sizeof (void *)' is still 8. I'm not sure why the small model doesn't use 32-bit pointers. The -mcmodel=medium model does 64-bit operations on pointers, but the code must still live in the lower 2GB of address space. The -mcmodel=large isn't yet implemented. Dave