From owner-freebsd-questions@FreeBSD.ORG Tue Feb 10 14:38:12 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id F30F916A4CE for ; Tue, 10 Feb 2004 14:38:11 -0800 (PST) Received: from obsecurity.dyndns.org (adsl-64-169-106-71.dsl.lsan03.pacbell.net [64.169.106.71]) by mx1.FreeBSD.org (Postfix) with ESMTP id A228A43D2F for ; Tue, 10 Feb 2004 14:38:11 -0800 (PST) (envelope-from kris@obsecurity.org) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id 200F066EC9; Tue, 10 Feb 2004 14:38:11 -0800 (PST) Date: Tue, 10 Feb 2004 14:38:11 -0800 From: Kris Kennaway To: Roop Nanuwa Message-ID: <20040210223810.GA42056@xor.obsecurity.org> References: <40293BB6.5060005@hqst.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="9jxsPFA5p3P2qPhR" Content-Disposition: inline In-Reply-To: <40293BB6.5060005@hqst.com> User-Agent: Mutt/1.4.1i cc: questions@FreeBSD.org Subject: Re: How about them optimizations? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Feb 2004 22:38:12 -0000 --9jxsPFA5p3P2qPhR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Feb 10, 2004 at 12:14:46PM -0800, Roop Nanuwa wrote: > Part of my current /etc/make.conf on my 5.2-CURRENT box looks like: >=20 > CPUTYPE=3D athlon-xp > CFLAGS=3D -O2 -pipe -fomit-frame-pointer -mmmx -msse -m3dnow -mfpmath=3Ds= se > COPTFLAGS=3D -O -pipe >=20 > Now what I'm wondering is if those extras like mmmx msse actually do=20 > anything. The > only reason they're in there is because I saw them on a website about=20 > what people > use to optimize gentoo. I had nothing better to do so I recompiled the=20 > world with > them. I didn't really notice anything good or bad happening after that.= =20 > I did have > to mess around with a couple of makefiles to get around the=20 > strict-aliasing problem > that O2 introduces. Besides that, though, are there any advantages or=20 > disadvantages > to compiling with those optimizations and switches? >=20 > Does -mfpmath=3Dsse actually do anything relevent for the FreeBSD world? = I=20 > know > what the GCC manual says about it but I'd rather hear some real world inf= o. >=20 > An enquiring mind wants to know. That's superfluous, because gcc already uses all available opcodes when you tell it to optimize for your CPU type with CPUTYPE=3Dathlon-xp. Using -O2 is recommended against, though - see the sample make.conf file. Kris --9jxsPFA5p3P2qPhR Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFAKV1SWry0BWjoQKURAq3vAJ4+QNVcX8shBTojIK6bKYozInvl9wCdFcMx ov0d+TCu+1p1xBtCaaWTLKo= =4EWQ -----END PGP SIGNATURE----- --9jxsPFA5p3P2qPhR--