From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.gentoo.org ([140.105.134.102] helo=robin.gentoo.org) by nuthatch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1GURyu-0003AZ-Jv for garchives@archives.gentoo.org; Mon, 02 Oct 2006 17:53:33 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.13.8/8.13.6) with SMTP id k92HoL3I002299; Mon, 2 Oct 2006 17:50:21 GMT Received: from ciao.gmane.org (main.gmane.org [80.91.229.2]) by robin.gentoo.org (8.13.8/8.13.6) with ESMTP id k92HoKoH004429 for ; Mon, 2 Oct 2006 17:50:20 GMT Received: from list by ciao.gmane.org with local (Exim 4.43) id 1GURva-0003Yo-5d for gentoo-amd64@lists.gentoo.org; Mon, 02 Oct 2006 19:50:06 +0200 Received: from ip68-230-97-209.ph.ph.cox.net ([68.230.97.209]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 02 Oct 2006 19:50:06 +0200 Received: from 1i5t5.duncan by ip68-230-97-209.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 02 Oct 2006 19:50:06 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: gentoo-amd64@lists.gentoo.org From: "Duncan" <1i5t5.duncan@cox.net> Subject: [gentoo-amd64] Re: FW: GCC4 and -ftree-vectorize Date: Mon, 2 Oct 2006 17:49:59 +0000 (UTC) Message-ID: References: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-amd64@gentoo.org Reply-to: gentoo-amd64@lists.gentoo.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Complaints-To: usenet@sea.gmane.org X-Gmane-NNTP-Posting-Host: ip68-230-97-209.ph.ph.cox.net User-Agent: pan 0.115 (Mrs. Kerr Says Remember the Tip Jar) Sender: news X-Archives-Salt: d71de827-d331-45fa-adc4-8bb23ad587ad X-Archives-Hash: 4df5e30c31053a6fc961bbff7b2bb501 "Duncan" <1i5t5.duncan@cox.net> posted efqqvt$sqh$6@sea.gmane.org, excerpted below, on Mon, 02 Oct 2006 10:51:41 +0000: > I'll probably have a bit more to say about it after checking the > tinyurls, which at this point I don't even know where they go yet, let > alone their content. > > > > Duncan wrote: > >> Could you point me at some info on this one (-ftree-vectorize)? It >> came up on the amd64 list a week or so ago[] > > http://tinyurl.com/l75we OK, this one's the gcc bugtracker list of -ftree-vectorize bugs. Lots of reports, many of them reduced to skeleton programs with just the triggering code. Of note, /most/ of the issues involve x86/ppc and/or size increasing loop optimizations that aren't of interest to those whose strategy targets -Os in any case. For example, one of the triggers seems to be -funswitch-loops, enabled by default with -O3, another is -funroll-loops, neither of which (again) are of interest to those targeting size for cache efficiency among other reasons. > See http://tinyurl.com/rt3aa for some real-world examples. This one's the Gentoo bugtracker -ftree-vectorize related bug list. Again, most are x86/ppc and/or involve flags folks interested in -Os won't be worrying about. Looks like on amd64 it may be less trouble than -combine is, and Flameeyes said he has been using it for awhile, so it looks like it'll be standard in my cflags now, to be removed only where it seems to cause problems, which shouldn't be that often, hopefully. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- gentoo-amd64@gentoo.org mailing list