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 1GgziW-00068i-9U for garchives@archives.gentoo.org; Mon, 06 Nov 2006 08:20:28 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.13.8/8.13.8) with SMTP id kA68I7fF005641; Mon, 6 Nov 2006 08:18:07 GMT Received: from ciao.gmane.org (main.gmane.org [80.91.229.2]) by robin.gentoo.org (8.13.8/8.13.8) with ESMTP id kA68I7DR011029 for ; Mon, 6 Nov 2006 08:18:07 GMT Received: from list by ciao.gmane.org with local (Exim 4.43) id 1Ggzg4-0000VD-4w for gentoo-amd64@lists.gentoo.org; Mon, 06 Nov 2006 09:17:56 +0100 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, 06 Nov 2006 09:17:56 +0100 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, 06 Nov 2006 09:17:56 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: gentoo-amd64@lists.gentoo.org From: Duncan <1i5t5.duncan@cox.net> Subject: [gentoo-amd64] Re: Unexpected side effect of GCC 4 Date: Mon, 6 Nov 2006 08:17:44 +0000 (UTC) Message-ID: References: <200611050845.42865.prh@gotadsl.co.uk> <200611051150.06468.prh@gotadsl.co.uk> <200611051210.25023.prh@gotadsl.co.uk> 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 0.118 (Gustaf Von Musterhausen) Sender: news X-Archives-Salt: ba039bb7-c20d-4370-81e0-b2b5625d862a X-Archives-Hash: c535ea8c07e1b88b22a5d1fad93eb0b8 Peter Humphrey posted 200611051210.25023.prh@gotadsl.co.uk, excerpted below, on Sun, 05 Nov 2006 12:10:24 +0000: [rewrapped] > $ emerge --info | grep FLAGS > CFLAGS="-march=k8 -Os -pipe -frename-registers -fweb -freorder-blocks > -freorder-blocks-and-partition -funit-at-a-time -fgcse-sm -fgcse-las > -fgcse-after-reload -fmerge-all-constants" > CXXFLAGS="-march=k8 -Os -pipe -frename-registers -fweb -freorder-blocks > -funit-at-a-time -fgcse-sm -fgcse-las -fgcse-after-reload > -fmerge-all-constants" > Unset: CTARGET, INSTALL_MASK, LDFLAGS, PORTAGE_RSYNC_EXTRA_OPTS > So I have a pointer away from glibc and linux-headers. CFLAGS on the new > system are as on the old but with -combine added.The old and new systems > have the same versions of kernel, linux-headers and glibc, but different > versions of gcc. Rsync is crippled on the old system but fine on the new > one. Well, I /did/ say gcc 4.1.1 seemed way (as in, vastly) better than 3.4.x, for me, so at least that's being borne out. As for CFLAGS, the only change I've made recently is adding -ftree-vectorize, experimentally, given the discussion here. I'm not sure it's the problem, particularly as where I /am/ experiencing issues the first thing I tried was compiling stuff without it, so if it's the problem, it's in some obscure dependency somewhere, but I certainly had no issues before trying it and now I do, so for anyone else thinking of trying it, I'd recommend staying well away from -ftree-vectorize for the time being. I'd really like to be able to say for sure it is the problem, and find it very frustrating not to be able to nail it down, but suffice it to say /something's/ causing me problems right now and that's one of my recent changes, so I'd recommend staying well away from it. I mentioned that I need to do an emerge -emptytree again, as it has been awhile. I'm still debating whether to try it with or without -ftree-vectorize. If that's the problem, it may well go away if everything is compiled with it. OTOH, it may not. That's an awful lot of compiling to do and still have a problem if -ftree-vectorize is causing it and it doesn't go away with everything compiled with it, but OTOH, if that's /not/ the problem, and I decide not to try it, I'll never know whether that was the problem or not. I'm about to decide to simply play it safe and pretend nobody here ever called -ftree-vectorize to my attention, at least until the flag has had a bit more time to mature (say gcc 4.2 or 4.3). Only just because I'm the type of person I am, that would bother me as I will have never nailed it for sure. In any case, my best guess right now are that the issues I am having are related to a nasty interplay between -ftree-vectorize and glibc-2.5. In looking around at Gentoo glibc bugs, I found at least one equally strange one, on x86. The bug required glibc 2.5, and it required that a certain package be compiled with a certain cflag. With that cflag on glibc 2.4, it worked fine, as it did without the cflag on 2.5, but put them together and things blew up. It wasn't -ftree-vectorize, and it was on x86, but I've a rather strong suspicion my case is similar, only on amd64 and with a different cflag, -ftree-vectorize most likely. I've just not figured out which particular package is doing it, and not being able to figure it out as I said is VERY annoying to me, WAY more so than the bit of inconvenience the actual bug is causing. (Yes, I know I said all that already, but it's still annoying and I'm still griping about it! =8^( -- 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