From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Haggerty Subject: Re: Pack files, standards compliance, and efficiency Date: Fri, 05 Jun 2015 22:03:27 +0200 Message-ID: <5572008F.6030203@alum.mit.edu> References: <20150605014120.GE305479@vauxhall.crustytoothpaste.net> <20150605094545.GB11855@peff.net> <5571BEA0.2080305@alum.mit.edu> <20150605194200.GB356121@vauxhall.crustytoothpaste.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit To: "brian m. carlson" , Jeff King , git@vger.kernel.org, Stefan Beller , Duy Nguyen X-From: git-owner@vger.kernel.org Fri Jun 05 22:03:54 2015 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Z0xqE-0004bw-1j for gcvg-git-2@plane.gmane.org; Fri, 05 Jun 2015 22:03:46 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751812AbbFEUDm (ORCPT ); Fri, 5 Jun 2015 16:03:42 -0400 Received: from alum-mailsec-scanner-2.mit.edu ([18.7.68.13]:56145 "EHLO alum-mailsec-scanner-2.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751443AbbFEUDl (ORCPT ); Fri, 5 Jun 2015 16:03:41 -0400 X-AuditID: 1207440d-f79026d000000bad-9b-557200910619 Received: from outgoing-alum.mit.edu (OUTGOING-ALUM.MIT.EDU [18.7.68.33]) by alum-mailsec-scanner-2.mit.edu (Symantec Messaging Gateway) with SMTP id 8C.86.02989.19002755; Fri, 5 Jun 2015 16:03:29 -0400 (EDT) Received: from [192.168.69.130] (p4FC9741B.dip0.t-ipconnect.de [79.201.116.27]) (authenticated bits=0) (User authenticated as mhagger@ALUM.MIT.EDU) by outgoing-alum.mit.edu (8.13.8/8.12.4) with ESMTP id t55K3RRS024664 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT); Fri, 5 Jun 2015 16:03:28 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.7.0 In-Reply-To: <20150605194200.GB356121@vauxhall.crustytoothpaste.net> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrGKsWRmVeSWpSXmKPExsUixO6iqDuRoSjUYP0kA4uuK91MFt1T3jJa /GjpYbZom/mDyWLz5nYWB1aP5Tf/MnnsnHWX3WPBplKPZ717GD0+b5ILYI3itklKLCkLzkzP 07dL4M74eW4fc8FftooV/5cxNzAeYe1i5OSQEDCR+PZmISOELSZx4d56ti5GLg4hgcuMEidm z2eEcM4xSXT9XsMOUsUroC2x5Nl1JhCbRUBVYu+aS8wgNpuArsSinmagOAeHqECQxOuXuRDl ghInZz5hAZkjIrCbUWJV21mwzcICthJfZp9mh1iwl1Hi4N9OsASngIvExmsXwYYyC+hJ7Lj+ ixXClpfY/nYO8wRG/llIBs9CUjYLSdkCRuZVjHKJOaW5urmJmTnFqcm6xcmJeXmpRbpGermZ JXqpKaWbGCHhzLuD8f86mUOMAhyMSjy8DYaFoUKsiWXFlbmHGCU5mJREeXn/A4X4kvJTKjMS izPii0pzUosPMUpwMCuJ8O75DZTjTUmsrEotyodJSXOwKInzqi1R9xMSSE8sSc1OTS1ILYLJ ynBwKEnwfvwH1ChYlJqeWpGWmVOCkGbi4AQZziUlUpyal5JalFhakhEPisr4YmBcgqR4gPZ+ B2nnLS5IzAWKQrSeYtTluDPl/yImIZa8/LxUKaALQA4XACnKKM2DWwFLXq8YxYE+FuaNBqni ASY+uEmvgJYwAS25zloAsqQkESEl1cDo9dekbmeKU2Dl5bmH53LKWCx2DzoY+uXgnkQt5XCP BSoTFd3FhTnv6V38dkSd5c26+3Kq6aY++0Izqg3n7pyd26Zu0v4s9q+D9Pr5zz6t Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On 06/05/2015 09:42 PM, brian m. carlson wrote: > On Fri, Jun 05, 2015 at 05:22:08PM +0200, Michael Haggerty wrote: >> I don't know that there would necessarily be problems, but I >> would worry about code involving structure assignment. For >> example, suppose the following snippet: >> >> void f(struct object_id *oid) { struct object_id oid_copy = >> *oid; /* ... */ } >> >> The compiler is allowed to implement the copy using instructions >> that rely on proper alignment. Such code would fail if oid is not >> properly aligned. > > We use oidcpy which doesn't use object assignment. I brought that > up previously, and Junio was opposed to doing *dest = *src. So I > don't think this ends up being an issue. Sorry for overlooking (or forgetting :-( ) that discussion. Indeed, that would allay my worry. Michael -- Michael Haggerty mhagger@alum.mit.edu