From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: macro FIXNUM_OVERFLOW_P in lisp.h is valid ? Date: Sat, 24 Oct 2009 15:00:03 +0200 Message-ID: <83my3heylo.fsf@gnu.org> References: <83y6n1gb14.fsf@gnu.org> <83vdi5f9gy.fsf@gnu.org> Reply-To: Eli Zaretskii NNTP-Posting-Host: lo.gmane.org X-Trace: ger.gmane.org 1256390591 23026 80.91.229.12 (24 Oct 2009 13:23:11 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 24 Oct 2009 13:23:11 +0000 (UTC) Cc: emacs-devel@gnu.org To: Toru TSUNEYOSHI Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Oct 24 15:23:04 2009 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1N1gaD-0002Eu-Pq for ged-emacs-devel@m.gmane.org; Sat, 24 Oct 2009 15:23:02 +0200 Original-Received: from localhost ([127.0.0.1]:59945 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1N1gaD-0002fT-6p for ged-emacs-devel@m.gmane.org; Sat, 24 Oct 2009 09:23:01 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1N1gEP-0002mQ-5x for emacs-devel@gnu.org; Sat, 24 Oct 2009 09:00:29 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1N1gEJ-0002kQ-C3 for emacs-devel@gnu.org; Sat, 24 Oct 2009 09:00:28 -0400 Original-Received: from [199.232.76.173] (port=50154 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1N1gEI-0002kA-3p for emacs-devel@gnu.org; Sat, 24 Oct 2009 09:00:22 -0400 Original-Received: from mtaout20.012.net.il ([80.179.55.166]:60063) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1N1gEH-0000wk-Iz for emacs-devel@gnu.org; Sat, 24 Oct 2009 09:00:21 -0400 Original-Received: from conversion-daemon.a-mtaout20.012.net.il by a-mtaout20.012.net.il (HyperSendmail v2007.08) id <0KS000000RBHTO00@a-mtaout20.012.net.il> for emacs-devel@gnu.org; Sat, 24 Oct 2009 15:00:03 +0200 (IST) Original-Received: from HOME-C4E4A596F7 ([87.70.77.20]) by a-mtaout20.012.net.il (HyperSendmail v2007.08) with ESMTPA id <0KS000043S43FA40@a-mtaout20.012.net.il>; Sat, 24 Oct 2009 15:00:03 +0200 (IST) In-reply-to: X-012-Sender: halo1@inter.net.il X-detected-operating-system: by monty-python.gnu.org: Solaris 10 (beta) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:116365 Archived-At: > Date: Sat, 24 Oct 2009 20:59:47 +0900 > Cc: emacs-devel@gnu.org > From: Toru TSUNEYOSHI > > BTW, how does Emacs on 64-bit platforms eval the following expressions? > > (string-to-number "1152921504606846975") ; 2^60 - 1 > => 1.1529215046068467e+018 ; on 32-bit platforms > > On 64-bit platforms, string-to-number should return the number as type > `EMACS_INT' (= `LONG'), I think. Yes, it should. > Although, the code of string-to-number (Fstring_to_number) deals with > the number as type `double' (of variable `v'). Yes, it does. And thus it loses least significant digits: (string-to-number "1152921504606846975") => 1152921504606846720 > #define make_fixnum_or_float(val) \ > (FIXNUM_OVERFLOW_P (val) \ > ? make_float (val) \ > : make_number ((EMACS_INT)(val))) > > In this code, FIXNUM_OVERFLOW_P (val) will returns 0. > Then Emacs processes `make_number ((EMACS_INT)(val)))'. > On that time, `val' is casted from type `double' to `EMACS_INT'. > At last, can string-to-number return all digits of the number > 1152921504606846975 properly? > > I guessed it can't. > That is the reason why I made my former patch. OK, but please make your patch compare against MOST_POSITIVE_FIXNUM, instead of using INT_MAX or LONG_MAX. Also, if you know that the value does not overflow an EMACS_INT, you can simply call make_number, instead of make_fixnum_or_float.