From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 16813 invoked by alias); 7 Dec 2009 23:20:02 -0000 Received: (qmail 16736 invoked by uid 22791); 7 Dec 2009 23:20:01 -0000 X-SWARE-Spam-Status: No, hits=-2.5 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 07 Dec 2009 23:19:55 +0000 Received: from int-mx03.intmail.prod.int.phx2.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id nB7NJoBZ027265 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 7 Dec 2009 18:19:50 -0500 Received: from greed.delorie.com (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx03.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id nB7NJnfr015333 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 7 Dec 2009 18:19:50 -0500 Received: from greed.delorie.com (greed.delorie.com [127.0.0.1] (may be forged)) by greed.delorie.com (8.14.3/8.14.3) with ESMTP id nB7NJnHm025958; Mon, 7 Dec 2009 18:19:49 -0500 Received: (from dj@localhost) by greed.delorie.com (8.14.3/8.14.3/Submit) id nB7NJmV3025955; Mon, 7 Dec 2009 18:19:48 -0500 Date: Mon, 07 Dec 2009 23:20:00 -0000 Message-Id: <200912072319.nB7NJmV3025955@greed.delorie.com> From: DJ Delorie To: Doug Evans CC: gdb-patches@sourceware.org In-reply-to: (message from Doug Evans on Mon, 7 Dec 2009 14:35:52 -0800) Subject: Re: [RFC] Add support for Renesas RX architecture References: <20091203161906.7f7a6c06@redhat.com> <20091204173837.GD2891@adacore.com> <20091207133912.3e97099d@redhat.com> <20091207205641.GA30964@caradoc.them.org> <200912072120.nB7LKksp002963@greed.delorie.com> <20091207212849.GA455@caradoc.them.org> <200912072142.nB7LgL1a003385@greed.delorie.com> X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2009-12/txt/msg00110.txt.bz2 > Rather, it's that such support was always planned, it just needed > someone to add it. For the record, here's the limitations I've found... * The opcode descriptions are generated by exploding macros to get all the prefix/operand byte permutations (about 12,000 total). I.e. a single variable-length opcode is converted into dozens of fixed-length opcodes. Regenerating takes about an hour, and maintenance is a nightmare. * cgen doesn't handle the opcode-vs-decodable bits in m32c very well. The hash table has nothing left to work with (every bit is an operand in *some* opcode), so the disassembler takes a noticably long time starting up, especially given that the exploding macros create many opcodes to hash. * The disassembler always reads MAX(opsize) bytes, so the .text sections have to be padded with NOP bytes to prevent crashes.