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: Wed, 1 Jul 2020 14:44:28 +0200 Message-ID: <3A9CC2A3-8307-47B2-8D80-795C0AF020E1@acm.org> References: <1583748933.1069307.1593556032592@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="31850"; 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 Wed Jul 01 14:46:20 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 1jqc84-0008C6-9B for geb-bug-gnu-emacs@m.gmane-mx.org; Wed, 01 Jul 2020 14:46:20 +0200 Original-Received: from localhost ([::1]:46414 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jqc82-0006SU-80 for geb-bug-gnu-emacs@m.gmane-mx.org; Wed, 01 Jul 2020 08:46:18 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:40074) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jqc6o-0005Rk-Bf for bug-gnu-emacs@gnu.org; Wed, 01 Jul 2020 08:45:03 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:40960) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jqc6n-0002gl-MK for bug-gnu-emacs@gnu.org; Wed, 01 Jul 2020 08:45:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1jqc6n-0000QU-HQ for bug-gnu-emacs@gnu.org; Wed, 01 Jul 2020 08:45:01 -0400 X-Loop: help-debbugs@gnu.org In-Reply-To: <1583748933.1069307.1593556032592@mail.yahoo.com> Resent-From: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Wed, 01 Jul 2020 12:45:01 +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=B42147.15936074901609 (code B ref 42147); Wed, 01 Jul 2020 12:45:01 +0000 Original-Received: (at 42147) by debbugs.gnu.org; 1 Jul 2020 12:44:50 +0000 Original-Received: from localhost ([127.0.0.1]:52506 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jqc6b-0000Pt-Qc for submit@debbugs.gnu.org; Wed, 01 Jul 2020 08:44:50 -0400 Original-Received: from mail209c50.megamailservers.eu ([91.136.10.219]:54322 helo=mail194c50.megamailservers.eu) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jqc6X-0000Ph-Es for 42147@debbugs.gnu.org; Wed, 01 Jul 2020 08:44:48 -0400 X-Authenticated-User: mattiase@bredband.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=megamailservers.eu; s=maildub; t=1593607475; bh=g3eC8TrzfloImmKX4R1FU8IwswtSHgJz/wSfgfMHDeg=; h=From:Subject:Date:Cc:To:From; b=YeC8Ihn0VwsawhAfZfurL54+jTCVz7boOBEVqyhUQVz2yLZbwj38CHbTwBrf2toGp OavsX2zyX3H0+WGdenr3v9+248xNFEldsoNbc/mJCU83a35iFrznnEH3hW3MRpmEvX j1AyJfHeiNDQTPEsReJtmIFL1Os6eghpuNrTGWzo= 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 mail194c50.megamailservers.eu (8.14.9/8.13.1) with ESMTP id 061CiTFP014200; Wed, 1 Jul 2020 12:44:32 +0000 X-Mailer: Apple Mail (2.3445.104.14) X-CTCH-RefID: str=0001.0A782F26.5EFC8533.0013, 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=KsozJleN c=1 sm=1 tr=0 a=SF+I6pRkHZhrawxbOkkvaA==:117 a=SF+I6pRkHZhrawxbOkkvaA==:17 a=kj9zAlcOel0A:10 a=M51BFTxLslgA:10 a=o4PFunNoQrfdS7EHdFgA:9 a=RPD5saMwKC-daLFD:21 a=0PV5PGcP_wwm1AIM:21 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:182603 Archived-At: Actually, pure functions are side-effect-free but not necessarily = error-free. But in essence, you are right. The following functions look like they could be marked pure. Given that = they currently aren't, there may be a good reason for their omission -- = do correct me! integerp natnump floatp characterp numberp arrayp vectorp bool-vector-p char-or-string-p integer-or-marker-p keywordp number-or-marker-p sequencep length safe-length ... and some more (symbolp, stringp etc) that are already explicitly = optimised. Regarding fixnump, we could add an optimiser since this predicate can be = constant-folded for certain arguments, but it's unclear whether it's = worth the trouble since this predicate (and bignump) are less commonly = used today. Most uses of fixnump (in Emacs) are in Calc, and those are = probably relics that should be replaced. More useful would be the ability to constant-fold ash, expt, %, mod and = abs for a subset of each respective domain. I can write a patch. We could also decide that it's not a problem if an operation returns = either a fixnum or bignum depending on the platform, on the grounds that (1) the distinction is not directly carried over through numeric = constants (bignums and fixnums look the same in .elc files) (2) any attempt to discriminate between fixnums and bignums is = non-portable anyway (and we can punt the discrimination to runtime) and thus constant-fold all integer operations (+, -, * etc), not just = those resulting in a portable fixnum.