From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1Lw3j2-0006Ts-SS for garchives@archives.gentoo.org; Tue, 21 Apr 2009 00:20:37 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 5594AE04AF; Tue, 21 Apr 2009 00:20:35 +0000 (UTC) Received: from rv-out-0708.google.com (rv-out-0708.google.com [209.85.198.243]) by pigeon.gentoo.org (Postfix) with ESMTP id 1FB97E04AF for ; Tue, 21 Apr 2009 00:20:35 +0000 (UTC) Received: by rv-out-0708.google.com with SMTP id b17so1008584rvf.46 for ; Mon, 20 Apr 2009 17:20:34 -0700 (PDT) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Received: by 10.114.178.13 with SMTP id a13mr3618048waf.88.1240273234688; Mon, 20 Apr 2009 17:20:34 -0700 (PDT) Date: Tue, 21 Apr 2009 10:20:34 +1000 Message-ID: <955d685d0904201720h414b7a5v72782e548e9edb85@mail.gmail.com> Subject: [gentoo-user] gcc and -match=native From: Beau Henderson To: gentoo-user@lists.gentoo.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Archives-Salt: a102d465-8ad0-4782-846f-7ae40f401145 X-Archives-Hash: 48dbcd9ddfab029409a2eb1e6db6ebba G'day, I was playing around with a few non-essential packages the other day using -march=native -v on my core2 duo ( configured with CHOST="i686-pc-linux-gnu" ) and noticed that GCC set the -march=core2 rather than what is typically suggested on the 3rd party wiki ( which is to use prescott ). According to the GCC docs, the core2 option includes instructions for x86_64 but would this be ultimately ignored seeing as the CHOST is set to i686 or would these instructions bloat the resulting binaries or could they result in conflicts of some sort down the line ? on my Athlon64 it uses ( the 3rd party wiki recommended ) k8-sse3 but I did notice that the option -mtune=k8 ( no -sse3 ) is set. I'm a little confused as to how the native option selects the best fit. I know that -march=native is not "supported". I'm just rather interested in figuring out why these options are selected and if I'm better off with them in place. Note, that there have been no issues *noticed* with final results. -- Beau Dylan Henderson "No human being should be denied the fundamental right to educate themselves or indulge their curiosities. To deny any person the right to do so, for whatever reason, is nothing more than the safeguarding of ignorance to ensure that enlightenment does not become a threat. For nothing in this world is more dangerous than an open mind." -- Matthew Good