From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Robert Pluim Newsgroups: gmane.emacs.devel Subject: Re: Floating-point constant folding in Emacs byte compiler Date: Mon, 26 Mar 2018 11:39:25 +0200 Message-ID: <87d0zr2n1u.fsf@gmail.com> References: <2ce39e5c-cd1b-65d6-b125-719caad67932@cs.ucla.edu> <83vadmgfbz.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1522057060 3315 195.159.176.226 (26 Mar 2018 09:37:40 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 26 Mar 2018 09:37:40 +0000 (UTC) Cc: eggert@cs.ucla.edu, Pip Cet , emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Mar 26 11:37:35 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1f0OZK-0000jz-Od for ged-emacs-devel@m.gmane.org; Mon, 26 Mar 2018 11:37:34 +0200 Original-Received: from localhost ([::1]:55515 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f0ObM-0005JV-Ee for ged-emacs-devel@m.gmane.org; Mon, 26 Mar 2018 05:39:40 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:54247) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f0ObF-0005J4-92 for emacs-devel@gnu.org; Mon, 26 Mar 2018 05:39:34 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f0ObC-0000CY-3W for emacs-devel@gnu.org; Mon, 26 Mar 2018 05:39:33 -0400 Original-Received: from mail-wm0-x242.google.com ([2a00:1450:400c:c09::242]:51596) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1f0ObB-0000Bu-TB; Mon, 26 Mar 2018 05:39:30 -0400 Original-Received: by mail-wm0-x242.google.com with SMTP id v21so14115998wmc.1; Mon, 26 Mar 2018 02:39:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:references:mail-followup-to:mail-copies-to :gmane-reply-to-list:date:in-reply-to:message-id:mime-version :content-transfer-encoding; bh=2XWA1LBGT0JmsR54AH0NFu7Q4wlZVx4YzJfcDmqJu+o=; b=iBOr8va8rAOLiiiIPtWzv7ufjzTl4WHnWUvBcIFDt5n6Ak7oATF670Ht8rHtDsfDn7 5RgeJbO8Qt8N8CT67zjW7WlYtmSWfJmsyAk0NvhrSbsqPN3RAcCOM2UBuMcuYDkzX79I zSYw5v0myny+242APQlaYuMZ/yGyo/kLloPrgKjYu4uDDxsJjNT+gRMZswm2As8H+w4A ADqlfJ99uX519ggKIfa1Zf6K18Ohjin4cnSsFFkMl7eUYEsBCp3jCgY3uNJgPy4e0kiU bjBTnFVqvRDQ0veE9f81M5jTV01090ux6ixsceHg6hZRbtGA2JW+Gm4RASF3zK5YMolZ BTTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:references:mail-followup-to :mail-copies-to:gmane-reply-to-list:date:in-reply-to:message-id :mime-version:content-transfer-encoding; bh=2XWA1LBGT0JmsR54AH0NFu7Q4wlZVx4YzJfcDmqJu+o=; b=py1vzvGQ5t6Gnc8FQ+3I7DtYx2Azee1rcIyPEygwVS6TPg4H8zs3n0wzjE/Tvs97o9 xoD7cg3KXtd0jaD5X01fg5XUh4V3gkwzsd6/LYZbtG0Mh36AluV4QyXa5B1WORTD4O1u wPoeO7TEVBz4XuCmq7vAUS9xEylTLM2hMjLtvTSlz4t4eSuWE3LJchTvPMkkmUBu1f7U BCFEkCjQ8tTG1zjUojzHE5rONR5rxvdecNaQ3YhPWlPoAjH01xD9AfmtkDsIcPkindSh 8BcIHUZlKHF10oggdK1gtGy1k7YQDP+WC4eBajsjWJdrePS2WvlDfNVYwZuUJTMiwJ4/ Llrg== X-Gm-Message-State: AElRT7FKJjah7zJ1RCGxL7TZyyLmqIrmQk1GCueG1d9SeLA3O+JqaQ+4 RJGMnaEiNcL019QDJzLgiCVfTsfy X-Google-Smtp-Source: AIpwx49ohdtqNShdrMJuxZmg4FrtOUnSHKwaM9cpqrlmQspnr6gHjYllS0lf/5jP29RN+aHYjs75VQ== X-Received: by 10.28.92.82 with SMTP id q79mr1844131wmb.130.1522057167641; Mon, 26 Mar 2018 02:39:27 -0700 (PDT) Original-Received: from rpluim ([149.5.228.1]) by smtp.gmail.com with ESMTPSA id j21sm19291812wrb.49.2018.03.26.02.39.25 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 26 Mar 2018 02:39:26 -0700 (PDT) Mail-Followup-To: emacs-devel@gnu.org Mail-Copies-To: never Gmane-Reply-To-List: yes In-Reply-To: <83vadmgfbz.fsf@gnu.org> (Eli Zaretskii's message of "Sat, 24 Mar 2018 09:25:36 +0300") X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2a00:1450:400c:c09::242 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:224030 Archived-At: Eli Zaretskii writes: >> From: Pip Cet >> Date: Fri, 23 Mar 2018 20:52:52 +0000 >> Cc: Emacs development discussions >>=20 >> Is this really specific to floating-point expressions, though? >>=20 >> (byte-compile (lambda (x) (* #x10000 #x10000 #x10000 #x10000))) >> #[(x) "=C3=80\207" [0] 1] >>=20 >> (at least on this somewhat oudated version of Emacs). Note the 0 in >> the constant vector, which hardcodes the <65-bit-ness of fixnums. >>=20 >> I imagine that on a 32-bit version of emacs, (byte-compile (lambda (x) >> (* #x10000 #x10000))) similarly produces a constant-zero function, > > The result depends on whether Emacs was build --with-wide-int. If it > was, the result is #[(x) "\300\207" [4294967296] 1], if it wasn't, I > get #[(x) "\300\207" [0] 1]. Hmm, would it be worthwhile to have Emacs signal overflow in such a situation (perhaps controlled by a configuration variable) so we could fix such issues? Robert