From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Philipp Stephani Newsgroups: gmane.emacs.bugs Subject: bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations? Date: Sat, 25 Jul 2020 22:03:03 +0200 Message-ID: References: <3A9CC2A3-8307-47B2-8D80-795C0AF020E1@acm.org> <0433A879-C98D-4B1A-B85C-A15DA9289099@acm.org> <1621669100.2102667.1593639091621@mail.yahoo.com> <33C2E2C8-16A6-47A9-B3A4-8A5F43648E04@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="19205"; mail-complaints-to="usenet@ciao.gmane.io" Cc: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= , Paul Eggert , Andrea Corallo , 42147@debbugs.gnu.org To: Stefan Monnier Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Sat Jul 25 22:04:09 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 1jzQOv-0004sR-Hs for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 25 Jul 2020 22:04:09 +0200 Original-Received: from localhost ([::1]:46552 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jzQOu-0003Ej-Jy for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 25 Jul 2020 16:04:08 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:46974) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jzQOo-0003ES-E1 for bug-gnu-emacs@gnu.org; Sat, 25 Jul 2020 16:04:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:39657) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jzQOo-0006ts-2L for bug-gnu-emacs@gnu.org; Sat, 25 Jul 2020 16:04:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1jzQOn-0002A4-Ui for bug-gnu-emacs@gnu.org; Sat, 25 Jul 2020 16:04:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Philipp Stephani Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sat, 25 Jul 2020 20:04:01 +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=B42147.15957074088265 (code B ref 42147); Sat, 25 Jul 2020 20:04:01 +0000 Original-Received: (at 42147) by debbugs.gnu.org; 25 Jul 2020 20:03:28 +0000 Original-Received: from localhost ([127.0.0.1]:51203 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jzQOF-00029F-Jv for submit@debbugs.gnu.org; Sat, 25 Jul 2020 16:03:27 -0400 Original-Received: from mail-oi1-f194.google.com ([209.85.167.194]:36725) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jzQO8-00028v-56 for 42147@debbugs.gnu.org; Sat, 25 Jul 2020 16:03:22 -0400 Original-Received: by mail-oi1-f194.google.com with SMTP id s144so1130710oie.3 for <42147@debbugs.gnu.org>; Sat, 25 Jul 2020 13:03:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=9jWMODdMVeipg9JBt6ZFVJwbKsp1WIhtQD/ZbOtf2NI=; b=LWRymqA+5Ugi7oeXlbkb2PTC0j9WWvSTZBiKB9YbLU3wyxZMAYdKhjoJdt/d5lT9I9 moq6fTquVGdar9oJ29V/G5SbzqtaHlaF9VlFqzv3JbXil1nNkgyNDTWSxmlQ9iGN8xM4 WSgkQapOhxD7NOrKhujayqbi5Ss3ACBYoR//R8JE6MEZdw3WugLXhL/TtInnX8aUoLTh psaFa8ZLBWFcpM8rfQMjZHE8LcOjihXJzf29W7Il7y+/gKgmoNlPCR1LICQQGN1CUxzz im2xoQ2qz6HItJCjIi7QVFD2vRL2/GaIg33jUKgdiyj0GMotKVYr7b0Z0FaIsMyI7ixZ Kpiw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9jWMODdMVeipg9JBt6ZFVJwbKsp1WIhtQD/ZbOtf2NI=; b=ZdgVHAN/kWwRsTKtzzVbvpvPolp42tToPtZrrxLFkIuLyp+jcMmf5bqn5gVflmnLjV HThM7Gg2C9DfvO/ZrXTmEEjrrVNWv/3eeJzvEXYqqZcScEDNVKze2jh57oki/CxjRs+V TtbTMuyfiRl0S644Ys8VUFLRq4UMMSoF7fN9YPfcOfHVZOoN/Fp/hn45JAsnhAnWQ4Vy rgncKfRffNs7E9VoAyvnEYMzmRF8pMsnjLqolPxaSDOyjZIBUvhgh7zG4qKvY1IwlQ07 brb8Gre7fTMOAAV2T+b4o3ts0OY4JAOHnLLWBsIHPoJfCms2ukyNv+qIq9j0dWFImada m3xQ== X-Gm-Message-State: AOAM532AceTeX1hXDTEVLmssfU2JQVwPPQAu9s3M0S+LIxHa8kts0rf+ Rd/NyScoOH/kFe/iX7w2Zn6DEDF3qt8M/H4mOj8= X-Google-Smtp-Source: ABdhPJwuXZsiLdOKccrD/daDOFWUqKM/fBp340nTbOf7ZUcWqNu8LfJcEoqU3a/tEfp5tfbKQfKBJtsvADEAL2Vyh8A= X-Received: by 2002:aca:54d3:: with SMTP id i202mr12930736oib.170.1595707394364; Sat, 25 Jul 2020 13:03:14 -0700 (PDT) In-Reply-To: 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:183548 Archived-At: Am Sa., 25. Juli 2020 um 20:10 Uhr schrieb Stefan Monnier : > > > and "side-effect free" is like GCC's "pure." That is, a side-effect > > free function can dereference pointers stored in Lisp_Objects, but a > > pure function can't. > > I think it's still not very satisfactory since it's written in terms of > low-level operations in the C code. Agreed, I'd rather think of this hypothesis as a first step towards a definition that we can put into the manual. > > I think the current intention of our "pure" goes something along the > lines of: the function will always return the "same" (the sense of `eql`) > value (or signal the same error) when called with `eql` arguments. > IOW "the function preserves `eql`ity". > That sounds like a very reasonable definition. Do you think it's equivalent to my hypothesis and/or to the current behavior of the byte optimizer? Is it a complete definition in the sense that it gives an unambiguous yes/no answer for every current and future function?