From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 88774 invoked by alias); 3 Aug 2015 21:18:45 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 88762 invoked by uid 89); 3 Aug 2015 21:18:45 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 03 Aug 2015 21:18:43 +0000 Received: from nat-ies.mentorg.com ([192.94.31.2] helo=SVR-IES-FEM-01.mgc.mentorg.com) by relay1.mentorg.com with esmtp id 1ZMN83-0000un-NN from joseph_myers@mentor.com ; Mon, 03 Aug 2015 14:18:39 -0700 Received: from digraph.polyomino.org.uk (137.202.0.76) by SVR-IES-FEM-01.mgc.mentorg.com (137.202.0.104) with Microsoft SMTP Server id 14.3.224.2; Mon, 3 Aug 2015 22:18:37 +0100 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.82) (envelope-from ) id 1ZMN80-0005nH-P6; Mon, 03 Aug 2015 21:18:36 +0000 Date: Mon, 03 Aug 2015 21:18:00 -0000 From: Joseph Myers To: Michael Meissner CC: , Subject: Re: [PATCH], PowerPC IEEE 128-bit patch #4 In-Reply-To: <20150803190231.GA27569@ibm-tiger.the-meissners.org> Message-ID: References: <20150729200428.GA30347@ibm-tiger.the-meissners.org> <20150803190231.GA27569@ibm-tiger.the-meissners.org> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-SW-Source: 2015-08/txt/msg00126.txt.bz2 On Mon, 3 Aug 2015, Michael Meissner wrote: > The intention of theese changes (currently unwritten) is to change the existing > problematical names that use TF in their name to be something else, and provide > via a weak reference an alias for the old name. So if for example, we change > the default in GCC 7.0, code compiled by GCC 6.0 would work because it uses say > __gcc_ltoq to call convert a 64-bit integer to IBM extended double instead of > __floatditf. Older code that refers to __floatditf would still work fine. But as those names are in the implementation namespace and aren't user-visible, I don't see the point in such a change (other than as part of a complete new incompatible ABI which gets its own copies of libgcc, libstdc++, libc, libm and other affected libraries). Of course it *can* be done via symbol versioning to keep working with existing binaries / shared libraries using the existing symbols from libgcc, but the libgcc build system doesn't make that sort of target-specific symbol versioning particularly convenient. And as usual with symbol versioning, you'd break compatibility with existing static libraries / .o files. -- Joseph S. Myers joseph@codesourcery.com