From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12681 invoked by alias); 15 Jul 2004 18:15:17 -0000 Mailing-List: contact gdb-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sources.redhat.com Received: (qmail 12551 invoked from network); 15 Jul 2004 18:15:07 -0000 Received: from unknown (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org with SMTP; 15 Jul 2004 18:15:07 -0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.12.10/8.12.10) with ESMTP id i6FIF7e1007283 for ; Thu, 15 Jul 2004 14:15:07 -0400 Received: from pobox.corp.redhat.com (pobox.corp.redhat.com [172.16.52.156]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id i6FIF7000767; Thu, 15 Jul 2004 14:15:07 -0400 Received: from [172.16.50.19] (vpn50-19.rdu.redhat.com [172.16.50.19]) by pobox.corp.redhat.com (8.12.8/8.12.8) with ESMTP id i6FIF6oI022832; Thu, 15 Jul 2004 14:15:06 -0400 Subject: Re: dwarf2-frame.c question for maintainers From: "Martin M. Hunt" To: Andrew Cagney Cc: Mark Kettenis , gdb@sources.redhat.com In-Reply-To: <40F6C5C3.3040302@gnu.org> References: <1089749730.3026.18.camel@dragon> <40F56CCA.5080106@gnu.org> <1089827266.3010.2.camel@dragon> <40F58971.7000304@gnu.org> <1089912741.3028.14.camel@dragon> <40F6C5C3.3040302@gnu.org> Content-Type: text/plain Organization: Red Hat Inc. Message-Id: <1089915300.3028.19.camel@dragon> Mime-Version: 1.0 Date: Thu, 15 Jul 2004 18:35:00 -0000 Content-Transfer-Encoding: 7bit X-SW-Source: 2004-07/txt/msg00175.txt.bz2 On Thu, 2004-07-15 at 10:58, Andrew Cagney wrote: > > On Wed, 2004-07-14 at 12:28, Andrew Cagney wrote: > > > >>>>>> >>> How come extract_typed_address, in read_reg, doesn't sign extend? > >>> > >>>> > > >>>> > > >>>> > I should have explained that. It does. However extract_typed_address is > >>>> > incorrect because it makes the invalid assumption that sizeof(address) > >>>> > == sizeof(register). So that has to go and be replaced with something > >>>> > like > >>>> > extract_signed_integer (buf, register_size (current_gdbarch, regnum)); > >> > >>> > >>> You mean the builtin_type_void_data_ptr parameter to > >>> extract_typed_address? Ah. > >>> > >>> I see builtin_type_void_data_ptr dates back to 1.1 (Mark?). It could > >>> instead use the register's type? > > > > > > extract_typed_address calls extract_[un]signed_integer with size = > > TYPE_LENGTH of builtin_type_void_data_ptr. > > > > Here's exactly what I am seeing. Maybe you can tell me if read_reg is > > the problem. > > > > For example big-endian Mips, with o64 or (eabi and mlong32): > > (registers are 64 bits and pointers are 32 bits) > > > > read_reg calls frame_unwind_register (next_frame, regnum, buf) > > after that, buf has something like ffffffff801fffb8 > > > > Now if you do extract_typed_address(), it knows addresses are 4 bytes > > and returns 0xffffffff sign extended to 0xfffffffffffffff > > Right, as it stands, that call is just wrong. > > > If instead, you call extract_[un]signed_integer((buf, register_size > > (current_gdbarch, regnum)), it returns 0xffffffff801fffb8 > > > > The real problem here is the the size. AFAICT, sign-extension here is > > unimportant; I get the same test results calling > > extract_unsigned_integer in read_reg() for mips, because, as you can > > see, nothing needs extending, just the whole register needs read. > > However, I can't prove that is always the case because I am not familiar > > enough with the code. > > Consider o32. Both the ABI and ISA are 32-bits, but GDB's CORE_ADDR may > be 64-bits. Even if it doesn't appear to make a difference, the MIPS > needs to always sign extend addresses/registers - that's the dogma :-) Right. And so back to the original question. What is the best way to have read_reg detect if it should sign-extend? We agreed that passing a pointer to the CU was out, as was using a global. Do I need to add something to gdbarch? -- Martin M. Hunt Red Hat Inc.