From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19673 invoked by alias); 19 Jul 2011 17:52:45 -0000 Received: (qmail 19660 invoked by uid 22791); 19 Jul 2011 17:52:44 -0000 X-SWARE-Spam-Status: No, hits=-7.5 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,SPF_HELO_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; Tue, 19 Jul 2011 17:52:27 +0000 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p6JHqRmf007857 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 19 Jul 2011 13:52:27 -0400 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p6JHqRpt022853; Tue, 19 Jul 2011 13:52:27 -0400 Received: from barimba (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id p6JHqPFM008301; Tue, 19 Jul 2011 13:52:26 -0400 From: Tom Tromey To: Jan Kratochvil Cc: gdb-patches@sourceware.org Subject: Re: [patch 00/12] entryval: Fix x86_64 parameters, virtual tail call frames References: <20110718201344.GA30496@host1.jankratochvil.net> <20110719163728.GA10909@host1.jankratochvil.net> Date: Tue, 19 Jul 2011 18:17:00 -0000 In-Reply-To: <20110719163728.GA10909@host1.jankratochvil.net> (Jan Kratochvil's message of "Tue, 19 Jul 2011 18:37:28 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain 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: 2011-07/txt/msg00485.txt.bz2 >>>>> "Jan" == Jan Kratochvil writes: Jan> It may have been discussed - it is not in `(gdb)Rationale' - why Jan> isn't AX at least derived from DWARF? But I guess the answer is Jan> the part of DWARF expressions compatible with `(gdb)Rationale' --- Jan> the AX requirements - is negligibly small. I don't know, but we've collected a number of issues with AX as it now stands. These aren't merely theoretical, either, but problems with code actually generated by GCC. Those missing opcodes aren't missing out of laziness, but rather because for the most part they aren't efficiently implementable. (One exception is the typed DWARF extension -- but we could only handle integral types, which is probably not an interesting subset.) AX needs some big upgrades, or maybe an "AX 2.0" explicitly based on DWARF. I think the blocker here is that we (Red Hat) are on the cutting edge for compilers and debuginfo, but don't currently have many users using AX; but shops where the users are using AX are often (just guessing) a few compiler revisions behind -- so nobody has really felt the pain yet. A related problem closer to home is that watchpoints don't respect location lists. Whoops. I don't have a test case but I think one should be constructible. (I consider this related because it is another spot where DWARF expressiveness has not propagated throughout GDB.) Tom