From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Neil Jerram Newsgroups: gmane.lisp.guile.devel Subject: Re: guile 1.8 and x86_64 Date: Tue, 09 May 2006 07:49:01 +0100 Message-ID: <87y7xbn15u.fsf@ossau.uklinux.net> References: <3E76C952D0DE7C18F2E3A89F@cadabra-sw.stanford.edu> <87acatj19q.fsf@laas.fr> <87hd5111mz.fsf@ossau.uklinux.net> <8656DB86D246C1D9ACD84549@tribes2.stanford.edu> <87zmirvoew.fsf@ossau.uklinux.net> <20060505140534.GA13293@bordell.redhat.usu> <20060506111221.GA16844@bordell.redhat.usu> <87slnljzgj.fsf@minimini.mvo.home> <1147084130.23680.94.camel@localhost.localdomain> <87k68wjib9.fsf@minimini.mvo.home> NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1147157375 2600 80.91.229.2 (9 May 2006 06:49:35 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Tue, 9 May 2006 06:49:35 +0000 (UTC) Cc: guile-devel@gnu.org Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Tue May 09 08:49:30 2006 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by ciao.gmane.org with esmtp (Exim 4.43) id 1FdM26-0003UU-Ms for guile-devel@m.gmane.org; Tue, 09 May 2006 08:49:22 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1FdM26-0000Ok-6d for guile-devel@m.gmane.org; Tue, 09 May 2006 02:49:22 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1FdM23-0000OX-Oj for guile-devel@gnu.org; Tue, 09 May 2006 02:49:19 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1FdM21-0000OJ-SM for guile-devel@gnu.org; Tue, 09 May 2006 02:49:19 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1FdM21-0000OG-OY for guile-devel@gnu.org; Tue, 09 May 2006 02:49:17 -0400 Original-Received: from [80.84.72.33] (helo=mail3.uklinux.net) by monty-python.gnu.org with esmtp (Exim 4.52) id 1FdM31-0002wP-VD for guile-devel@gnu.org; Tue, 09 May 2006 02:50:20 -0400 Original-Received: from laruns (host86-129-134-171.range86-129.btcentralplus.com [86.129.134.171]) by mail3.uklinux.net (Postfix) with ESMTP id 37A70409FB0; Tue, 9 May 2006 06:49:16 +0000 (UTC) Original-Received: from laruns (laruns [127.0.0.1]) by laruns (Postfix) with ESMTP id 2CC026F70A; Tue, 9 May 2006 07:49:02 +0100 (BST) Original-To: Marius Vollmer In-Reply-To: <87k68wjib9.fsf@minimini.mvo.home> (Marius Vollmer's message of "09 May 2006 00:52:10 +0300") User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:5916 Archived-At: Marius Vollmer writes: > Here is what is going on: the CELL_P predicate is used during the > conservative scanning of the GC to decide whether a random word can > possibly be a non-immediate SCM value. Non-immediate values are the > ones that point into the heap. The type tag for such a non-immediate > value is "lower three bits zero". On 32-bit architectures, a cell is > 8 bytes, which means that a non-immediate value is always aligned to a > cell. On 64-bit machines, a cell is 16 bytes, and that means that a > word with "lower three bits zero" can still be invalid because it > points into the middle of a cell. > > (We have similar check already for double-cells, which are 16 bytes on > 32-bit machines.) That's great, but I believe there's one detail still to be explained: why is it a problem with GCC 4 but not with GCC 3? Neil _______________________________________________ Guile-devel mailing list Guile-devel@gnu.org http://lists.gnu.org/mailman/listinfo/guile-devel