From owner-freebsd-current Wed Feb 26 16: 4:17 2003 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D36B237B401 for ; Wed, 26 Feb 2003 16:04:15 -0800 (PST) Received: from mail.liwing.de (mail.liwing.de [213.70.188.162]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7FC8443F75 for ; Wed, 26 Feb 2003 16:04:14 -0800 (PST) (envelope-from rehsack@liwing.de) Received: (qmail 59689 invoked from network); 27 Feb 2003 00:04:12 -0000 Received: from stingray.liwing.de (HELO liwing.de) ([213.70.188.164]) (envelope-sender ) by mail.liwing.de (qmail-ldap-1.03) with SMTP for ; 27 Feb 2003 00:04:12 -0000 Message-ID: <3E5D55FB.3010605@liwing.de> Date: Thu, 27 Feb 2003 01:04:11 +0100 From: Jens Rehsack Organization: LiWing IT-Services User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.0.2) Gecko/20021120 Netscape/7.01 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Andre Guibert de Bruet Cc: Nuno Teixeira , current@FreeBSD.ORG Subject: Re: -O2 considered harmful References: <20030226113815.W5357@znfgre.tberna.bet> <20030226200635.GA1368@torment.storming.org> <20030226215547.GA5510@gw.tex.bogus> <20030226184315.F91528@alpha.siliconlandmark.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Andre Guibert de Bruet wrote: > On Wed, 26 Feb 2003, Nuno Teixeira wrote: > > >>Does -march=k6-2 implies -m3dnow? Or -march=pentiumpro implies -mmmx? >> >>I always thought that when I use -march it will enable other >>porcessor specific optimizations like mmx and 3dnow (if available). > > > IIRC, 166 and 180 Mhz PPros don't support MMX. Neither do PPro's 200: CPU: Pentium Pro (199.43-MHz 686-class CPU) Origin = "GenuineIntel" Id = 0x619 Stepping = 9 Features=0xf9ff > I'm seeing differences in compiled code between simple -march=athlon-xp > and -march=athlon-xp -mmmx -m3dnow -msse. The documentation says the same: those options have to be enabled to use extended instruction sets. -march/-mcpu just optmizes boundaries of jump labels, variables, etc... - and sometimes the kind of instructions to use, eg. 'loop label' or 'dec bcx, jne label', but that's all, AFAIK. So long, Jens -- L i W W W i Jens Rehsack L W W W L i W W W W i nnn gggg LiWing IT-Services L i W W W W i n n g g LLLL i W W i n n g g Friesenstraße 2 gggg 06112 Halle g g g Tel.: +49 - 3 45 - 5 17 05 91 ggg e-Mail: Fax: +49 - 3 45 - 5 17 05 92 http://www.liwing.de/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message