From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Newsgroups: gmane.emacs.bugs Subject: bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations? Date: Thu, 2 Jul 2020 14:46:47 +0200 Message-ID: <5F2B4684-34D1-4474-8909-9F435369FE54@acm.org> References: <3A9CC2A3-8307-47B2-8D80-795C0AF020E1@acm.org> <0433A879-C98D-4B1A-B85C-A15DA9289099@acm.org> <1621669100.2102667.1593639091621@mail.yahoo.com> <775819003.2516724.1593687594435@mail.yahoo.com> Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.14\)) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="39738"; mail-complaints-to="usenet@ciao.gmane.io" Cc: Paul Eggert , Stefan Monnier , 42147@debbugs.gnu.org To: Andrea Corallo Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Thu Jul 02 14:48:20 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jqydY-000AFd-6e for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 02 Jul 2020 14:48:20 +0200 Original-Received: from localhost ([::1]:33608 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jqydX-0002cI-4g for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 02 Jul 2020 08:48:19 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:51598) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jqydG-0002c4-Hd for bug-gnu-emacs@gnu.org; Thu, 02 Jul 2020 08:48:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:43014) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jqydG-0005Pp-8w for bug-gnu-emacs@gnu.org; Thu, 02 Jul 2020 08:48:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1jqydG-0006GJ-5L for bug-gnu-emacs@gnu.org; Thu, 02 Jul 2020 08:48:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Thu, 02 Jul 2020 12:48:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 42147 X-GNU-PR-Package: emacs Original-Received: via spool by 42147-submit@debbugs.gnu.org id=B42147.159369404624025 (code B ref 42147); Thu, 02 Jul 2020 12:48:02 +0000 Original-Received: (at 42147) by debbugs.gnu.org; 2 Jul 2020 12:47:26 +0000 Original-Received: from localhost ([127.0.0.1]:54560 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jqycR-0006FC-QD for submit@debbugs.gnu.org; Thu, 02 Jul 2020 08:47:26 -0400 Original-Received: from mail1452c50.megamailservers.eu ([91.136.14.52]:55408 helo=mail266c50.megamailservers.eu) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jqycO-0006Ef-98 for 42147@debbugs.gnu.org; Thu, 02 Jul 2020 08:47:10 -0400 X-Authenticated-User: mattiase@bredband.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=megamailservers.eu; s=maildub; t=1593694011; bh=wvF3+IcX2s1N6cyAt07+Mh/L7DhCyXXRyfpnQrOQJ/c=; h=Subject:From:In-Reply-To:Date:Cc:References:To:From; b=YMIUKBPk5cJS5CXfnqWzTAGvhJhypNk6bmPrZOQhoZiLe8A4izpzAN/mCBuiQnbMc xvH0vsL0Et8bfhc+znLOENHk6iNfnwc9+o/OxHYwYyf/uEY3J6gAWU224BSwdg7aPS mSNq1WZebNCI0rkXDEF9/kCJLE6NDb2mi9hfFo54= Feedback-ID: mattiase@acm.or Original-Received: from [192.168.0.4] (c188-150-171-71.bredband.comhem.se [188.150.171.71]) (authenticated bits=0) by mail266c50.megamailservers.eu (8.14.9/8.13.1) with ESMTP id 062CklAk001367; Thu, 2 Jul 2020 12:46:49 +0000 In-Reply-To: <775819003.2516724.1593687594435@mail.yahoo.com> X-Mailer: Apple Mail (2.3445.104.14) X-CTCH-RefID: str=0001.0A782F29.5EFDCF60.003A, ss=1, re=0.000, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0 X-CTCH-VOD: Unknown X-CTCH-Spam: Unknown X-CTCH-Score: 0.000 X-CTCH-Flags: 0 X-CTCH-ScoreCust: 0.000 X-CSC: 0 X-CHA: v=2.3 cv=A5MSwJeG c=1 sm=1 tr=0 a=SF+I6pRkHZhrawxbOkkvaA==:117 a=SF+I6pRkHZhrawxbOkkvaA==:17 a=kj9zAlcOel0A:10 a=M51BFTxLslgA:10 a=P_0GrDVPdYajMqkPTb8A:9 a=CjuIK1q_8ugA:10 X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:182630 Archived-At: 2 juli 2020 kl. 12.59 skrev Andrea Corallo : >> I still wonder if there is any reason to limit arithmetic constant >> folding to the portable fixnum range. Given that we don't evaluate >> fixnump or bignump at compile-time, what observable effects would >> constant-folding, say, (ash 1 32) have? Advice from deeper thinkers >> solicited! >=20 > I always thought the general idea is to respect the allocation side > effect we have creating a bignum. Not sure if the class of example = you > have in mind here fits this case. Number allocation isn't a semantically visible effect and we probably = don't want to change that. As far as I can tell, only fixnump and = bignump can discriminate fixnums from bignums. There may be functions = that only accept fixnums as arguments and thus fail with a different = error, but I don't think we constant-fold any of them, and they would be = easy to fix if we did. It may be preferable to defer generation of very big numbers to = run-time, to avoid evaluation of (ash 1 1000) at compile-time, but such = a limit should, if implemented, be independent of the fixnum limit (and = likely higher).