From mboxrd@z Thu Jan 1 00:00:00 1970 Path: main.gmane.org!not-for-mail From: "Stephen J. Turnbull" Newsgroups: gmane.emacs.devel Subject: Re: malloc and alignment Date: Tue, 17 Jun 2003 13:48:44 +0900 Organization: The XEmacs Project Sender: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Message-ID: <87adchwbpv.fsf@tleepslib.sk.tsukuba.ac.jp> References: <200306161438.h5GEcodM011551@rum.cs.yale.edu> NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: main.gmane.org 1055825510 6303 80.91.224.249 (17 Jun 2003 04:51:50 GMT) X-Complaints-To: usenet@main.gmane.org NNTP-Posting-Date: Tue, 17 Jun 2003 04:51:50 +0000 (UTC) Cc: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Tue Jun 17 06:51:48 2003 Return-path: Original-Received: from quimby.gnus.org ([80.91.224.244]) by main.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 19S8Rg-0001dW-00 for ; Tue, 17 Jun 2003 06:51:48 +0200 Original-Received: from monty-python.gnu.org ([199.232.76.173]) by quimby.gnus.org with esmtp (Exim 3.12 #1 (Debian)) id 19S8pQ-0004yf-00 for ; Tue, 17 Jun 2003 07:16:20 +0200 Original-Received: from localhost ([127.0.0.1] helo=monty-python.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.20) id 19S8SE-0005Ll-Ey for emacs-devel@quimby.gnus.org; Tue, 17 Jun 2003 00:52:22 -0400 Original-Received: from list by monty-python.gnu.org with tmda-scanned (Exim 4.20) id 19S8PN-0004U5-1C for emacs-devel@gnu.org; Tue, 17 Jun 2003 00:49:25 -0400 Original-Received: from mail by monty-python.gnu.org with spam-scanned (Exim 4.20) id 19S8P9-0004Dv-0R for emacs-devel@gnu.org; Tue, 17 Jun 2003 00:49:15 -0400 Original-Received: from tleepslib.sk.tsukuba.ac.jp ([130.158.98.109]) by monty-python.gnu.org with esmtp (Exim 4.20) id 19S8Os-0003j1-PO for emacs-devel@gnu.org; Tue, 17 Jun 2003 00:48:55 -0400 Original-Received: from steve by tleepslib.sk.tsukuba.ac.jp with local (Exim 3.36 #1 (Debian)) id 19S8Oi-00044R-00; Tue, 17 Jun 2003 13:48:44 +0900 Original-To: "Stefan Monnier" In-Reply-To: <200306161438.h5GEcodM011551@rum.cs.yale.edu> (Stefan Monnier's message of "Mon, 16 Jun 2003 10:38:50 -0400") User-Agent: Gnus/5.1002 (Gnus v5.10.2) XEmacs/21.5 (cassava, linux) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1b5 Precedence: list List-Id: Emacs development discussions. List-Help: List-Post: List-Subscribe: , List-Archive: List-Unsubscribe: , Errors-To: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Xref: main.gmane.org gmane.emacs.devel:15146 X-Report-Spam: http://spam.gmane.org/gmane.emacs.devel:15146 >>>>> "Stefan" == Stefan Monnier writes: Stefan> I'd like to try and get rid of the markbit on Lisp_Object Stefan> values. The idea is to scrape off a few more bits (I'd Stefan> like to bump maxint to 512MB instead of 128MB). And I'd Stefan> also like to represent floats in 8bytes rather than 12. Er, have you talked to Kyle Jones , Martin Buchholz , or Olivier Galibert ? It sounds like your goals are different, but XEmacs went through this process about 5 years ago (how time flies, make that 7!). XEmacs has 31-bit integers, but at the cost of conses being indirect objects. IIRC, those guys were the ones who designed and implemented the new system. Actually, if you are happy with character is-a int (up to now, you have been, but Ken'ichi recently made some noises about a true character type) you might be able to stuff the cons type in instead of characters. I'm not sure how you'd handle marking (maybe you could use the tagbits in the cdr, or the integer bit?) but that might be a way to go. That doesn't help with the floats, unfortunately (or does it? I guess you're not using platform floats directly?) Even though the goals are different, those guys would certainly have a lot to say about possible pitfalls, and maybe have some ideas about how to extend this to the situation where you want more tagbits than the "natural" alignment (of a pointer to Lisp_Object). -- Institute of Policy and Planning Sciences http://turnbull.sk.tsukuba.ac.jp University of Tsukuba Tennodai 1-1-1 Tsukuba 305-8573 JAPAN Ask not how you can "do" free software business; ask what your business can "do for" free software.