From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5069 invoked by alias); 19 Aug 2011 17:57:05 -0000 Received: (qmail 5061 invoked by uid 22791); 19 Aug 2011 17:57:04 -0000 X-SWARE-Spam-Status: No, hits=-1.2 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,TW_GD X-Spam-Check-By: sourceware.org Received: from mail-yi0-f41.google.com (HELO mail-yi0-f41.google.com) (209.85.218.41) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 19 Aug 2011 17:56:44 +0000 Received: by yib2 with SMTP id 2so2602157yib.0 for ; Fri, 19 Aug 2011 10:56:44 -0700 (PDT) MIME-Version: 1.0 Received: by 10.236.9.71 with SMTP id 47mr290734yhs.30.1313776604138; Fri, 19 Aug 2011 10:56:44 -0700 (PDT) Received: by 10.147.32.14 with HTTP; Fri, 19 Aug 2011 10:56:44 -0700 (PDT) In-Reply-To: <20110819162807.GA27393@host1.jankratochvil.net> References: <20110819162807.GA27393@host1.jankratochvil.net> Date: Fri, 19 Aug 2011 17:57:00 -0000 Message-ID: Subject: Re: How to skip function prologues with stabs debug infomation? From: Triple Yang To: Jan Kratochvil Cc: gdb@sourceware.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-IsSubscribed: yes Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2011-08/txt/msg00088.txt.bz2 Thank you. Of course GDB supports SATBS debug info. well, my question is mostly on HOW to support SATBS debug info (specifically, to skip prologue) when I have to write a new gdb backend, i.e. to port gdb to a new architecture whose function prologue instructions are not that orderly. I have checked several backend implementations such as or32 and i386, but their prologues are tidy and clean to make the analysis much easier. So we don't even need debug info to skip the prologue. It seems not that easy for a rescheduled prologue, because prologues generated with compiler optimization on make things complicated. It's well-known that people can take advantage of SAL info when to skip prologue with dwarf info. I wonder whether we can do the same thing with stabs. As for your examples, we sometimes need to skip prologue first before we can insert breakpoints. Skipping prologue is a lower-level function. Best regards. 2011/8/20 Jan Kratochvil : > On Fri, 19 Aug 2011 18:08:54 +0200, Triple Yang wrote: >> is there any chance that we use symbol and line (sal) to skip function >> prologues with stabs debug infomation? >> And if not, why? > > GDB does, why not? =A0The prologue skipping processes already decoded deb= ug > info, no matter if it is DWARF or STABS. > > gcc -Wall > Breakpoint 1 at 0x400478 > gcc -gstabs > Temporary breakpoint 1 at 0x40047c: file 24.c, line 3. > (gdb) p/x $pc > $1 =3D 0x40047c > gcc -gdwarf-3 > Temporary breakpoint 1 at 0x40047c: file 24.c, line 3. > > Sure STABS is discouraged. > > > Regards, > Jan > --=20 Yang Yong-Yong