From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4917 invoked by alias); 13 Dec 2003 19:02:19 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 4909 invoked from network); 13 Dec 2003 19:02:15 -0000 Received: from unknown (HELO localhost.redhat.com) (65.49.0.121) by sources.redhat.com with SMTP; 13 Dec 2003 19:02:15 -0000 Received: from gnu.org (localhost [127.0.0.1]) by localhost.redhat.com (Postfix) with ESMTP id BA38B2B8F; Sat, 13 Dec 2003 14:02:10 -0500 (EST) Message-ID: <3FDB6232.5040102@gnu.org> Date: Sat, 13 Dec 2003 19:02:00 -0000 From: Andrew Cagney User-Agent: Mozilla/5.0 (X11; U; NetBSD macppc; en-US; rv:1.0.2) Gecko/20030820 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Mark Kettenis Cc: gdb-patches@sources.redhat.com Subject: Re: [PATCH] Remove zero PC check from blockframe.c:inside_main_func() References: <200312131509.hBDF9TLA035995@elgar.kettenis.dyndns.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2003-12/txt/msg00358.txt.bz2 > It really makes no sense to check for a zero PC here. This function > is only colled from frame.c:get_prev_frame(), and there we already > deal with PC being zero. > > The whole concept of using a zero PC as a marker for the end of the > frame chain is somewhat flawed. It prevents us from providing a > meaningful backtrace when the program has called a null function > pointer; see backtrace/1476. At the very least we will have to treat > a zero PC in the innermost differently. Classifying the a zero PC as > being inside the "main" function doesn't help. Therefore this patch > removes the first obstackle in fixing that PR. > > Objections. Otherwise I'll commit this within a few days. FYI, this was made active with: * blockframe.c: Include "gdbcmd.h" and "command.h". (backtrace_below_main): New variable. (file_frame_chain_valid, func_frame_chain_valid) (nonnull_frame_chain_valid, generic_file_frame_chain_valid) (generic_func_frame_chain_valid): Remove functions. (frame_chain_valid, do_flush_frames_sfunc): New functions. (_initialize_blockframe): New function. * Makefile.in (blockframe.o): Update dependencies. * frame.c (frame_saved_regs_id_unwind, get_prev_frame): Remove FIXME comment. Call frame_chain_valid (). * frame.h: Remove old prototypes. Add prototype for frame_chain_valid and update comments to match. * gdbarch.sh: Change FRAME_CHAIN_VALID into a predicated function. Remove old comment. * gdbarch.h: Regenerated. * gdbarch.c: Regenerated. rather than the new frame code. I looked at the new frame code and apart from the wild-card logic, there weren't any obvious PC==0 tests. Andrew