From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Daniel Colascione Newsgroups: gmane.emacs.devel Subject: Re: [Emacs-diffs] emacs-25 3eb93c0: Rely on conservative stack scanning to find "emacs_value"s Date: Fri, 1 Apr 2016 11:34:16 -0700 Message-ID: <56FEBF28.40900@dancol.org> References: <20151130193446.22218.14685@vcs.savannah.gnu.org> <56892947.80308@dancol.org> <56894233.8010106@cs.ucla.edu> <56FB2D4E.5000609@cs.ucla.edu> <56FC4290.3020801@dancol.org> <56FD796B.4000703@dancol.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="3pqlvFJeObQJHRM4QMJ7JkAejMV8NTV0x" X-Trace: ger.gmane.org 1459535672 7147 80.91.229.3 (1 Apr 2016 18:34:32 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 1 Apr 2016 18:34:32 +0000 (UTC) Cc: Philipp Stephani , Paul Eggert , emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Apr 01 20:34:31 2016 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1am3tu-0005Qo-GT for ged-emacs-devel@m.gmane.org; Fri, 01 Apr 2016 20:34:30 +0200 Original-Received: from localhost ([::1]:45853 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1am3tt-0004VF-Nr for ged-emacs-devel@m.gmane.org; Fri, 01 Apr 2016 14:34:29 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:42115) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1am3tq-0004V0-Ot for emacs-devel@gnu.org; Fri, 01 Apr 2016 14:34:27 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1am3tp-0006bG-Uu for emacs-devel@gnu.org; Fri, 01 Apr 2016 14:34:26 -0400 Original-Received: from dancol.org ([2600:3c01::f03c:91ff:fedf:adf3]:48400) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1am3tp-0006bB-KZ for emacs-devel@gnu.org; Fri, 01 Apr 2016 14:34:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=dancol.org; s=x; h=Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:Cc:References:To:Subject; bh=3MJJzJ+xDZNkSeJGko5GUDTVy4/wReiGoTgGmkrXc+8=; b=Mk2I9mWShA6MZNsiFVOxxrWwDOdQjV8lYvjOH9oQqdgBQaKBB2pgMLQhdt3J6Z6brKKqu8jrGiT+YolzmVZCLb5NuU5623Z4vwDDGIwNrHGnPTsfETerb8YidJ8seKqzI/xTBrIgiLRWNgbHwThE58NmnqIEHNFaAzlPXsoPHViDuMOWQ+jNRJXqni96cedUj0AIfOhM3rXXiszmJfyjgo+1r0pOqrUNXNTzvocPAspUAONg+TBoVqekGhSG1diETTuqFInz38KRRq8yEUj7iqy1rI7v2KLLTrxzET2F2nB2clxFFrX1e7y1nNikjHgdd4956dnI5RnO5T6fqKx/vg==; Original-Received: from [2620:10d:c090:180::2b] (helo=[IPv6:2620:10d:c081:1103:2ab2:bdff:fe1c:db58]) by dancol.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84) (envelope-from ) id 1am3tm-0000PY-Qx; Fri, 01 Apr 2016 11:34:22 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 In-Reply-To: X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2600:3c01::f03c:91ff:fedf:adf3 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:202571 Archived-At: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --3pqlvFJeObQJHRM4QMJ7JkAejMV8NTV0x Content-Type: multipart/mixed; boundary="MGLAnjIxLjr9wm62Weo43IcVQq1r5c7HV" From: Daniel Colascione To: Stefan Monnier Cc: Philipp Stephani , Paul Eggert , emacs-devel@gnu.org Message-ID: <56FEBF28.40900@dancol.org> Subject: Re: [Emacs-diffs] emacs-25 3eb93c0: Rely on conservative stack scanning to find "emacs_value"s References: <20151130193446.22218.14685@vcs.savannah.gnu.org> <56892947.80308@dancol.org> <56894233.8010106@cs.ucla.edu> <56FB2D4E.5000609@cs.ucla.edu> <56FC4290.3020801@dancol.org> <56FD796B.4000703@dancol.org> In-Reply-To: --MGLAnjIxLjr9wm62Weo43IcVQq1r5c7HV Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 03/31/2016 02:29 PM, Stefan Monnier wrote: >> That's cheap: you can do it with linear allocation out of an array. >> Why would that be expensive? >=20 > That's very expensive compared to doing nothing. >=20 > It means that you have to allocate a new array,=20 Once. > loop through the old one > calling your "cheap allocation" function on each element, instead of > just passing the array pointer untouched. It's a pointer comparison of something that will be in L1 cache anyway. Of course it's slower than doing nothing. But you have not demonstrated that it is meaningfully slower, meanwhile, you're ignoring the compatibility benefits and consigning everyone to stack scanning forever.= --MGLAnjIxLjr9wm62Weo43IcVQq1r5c7HV-- --3pqlvFJeObQJHRM4QMJ7JkAejMV8NTV0x Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJW/r8pAAoJEN4WImmbpWBl5yIQAKUY/9QIMJ9J2fkNx6sZcObk lvf564H7MJb57ZEFkJdzGcJb4hvPt7IIkKUuZRQsKhKHEX0yortkelyPDmkL2gxg FeEtm1n34WKB5rEvZdDHv3kKTc24qZYOO1hEktDR6epxWd/9XeBiyoosy2ZUNATN WO/+hRS8NOU7+HmdnmukI0NF63uqXr2aQm9V52zTsAbIgPg/mLoEFpiL4r+wsnYj APYyREop5CEJxJ7qxWxO0e1L0pHX8jCzNyJt+n8gjK+AJ5UMXFrWczKm3hbRROUb xSuiEJJSQ9kPQTaxHl+AIRvzh3gxSpQACEzD/pJ5373KcrCfbhr9AKiSLe9RvImZ DTI8En9uA+k3uWYWS55owpjyB8FKres5HiQhMo7X3f/4tRvp9LmjEzRSiEs+n/Gp T4s3nSDcZlmGHZSu1UylqY0HvJWECF4p7ugpmfaeEKKzK8TTRs2QUm9Cx15mzukw LPybJR5QvtjJ4FG+CyaPHXU3gAnTX4YwzI4WQ8DPzPizTKvbGm0o8GJpzHfmQ5J1 5b+3qGGDPj7AxGUzG6T3pCNBbl4bBvCL/2kK7OyMT2rTaCNMAJsbxBfG+WzsLVb7 Apfvu9AmrQwLl+Mm8Tfhc7pQRzPRC6WogjIM4TppjZ4iBCiBiBQLr5V8ABAxIlAf M4vk9IjRL8FMOjkQAcqA =R5Qr -----END PGP SIGNATURE----- --3pqlvFJeObQJHRM4QMJ7JkAejMV8NTV0x--