From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5229 invoked by alias); 1 Oct 2003 15:21:38 -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 5222 invoked from network); 1 Oct 2003 15:21:37 -0000 Received: from unknown (HELO artax.karlin.mff.cuni.cz) (195.113.31.125) by sources.redhat.com with SMTP; 1 Oct 2003 15:21:37 -0000 Received: by artax.karlin.mff.cuni.cz (Postfix, from userid 29129) id 56BE43FAC; Wed, 1 Oct 2003 17:21:37 +0200 (CEST) Date: Wed, 01 Oct 2003 15:21:00 -0000 From: Josef Zlomek To: Daniel Jacobowitz Cc: gdb@sources.redhat.com Subject: Re: Problem with location lists and variables on stack Message-ID: <20031001152137.GA14527@artax.karlin.mff.cuni.cz> References: <20031001144330.GA11707@artax.karlin.mff.cuni.cz> <20031001144937.GA4613@nevyn.them.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20031001144937.GA4613@nevyn.them.org> User-Agent: Mutt/1.5.4i X-SW-Source: 2003-10/txt/msg00029.txt.bz2 > > I writing a better pass (variable tracking) for GCC which finally emits > > location lists for variables. (If you are insterested it is at > > http://artax.karlin.mff.cuni.cz/~zlomj9am/download/vt-main.patch > > It still contains many debugging checks and (disabled) prints.) > > > > Let the local variables and (some) arguments be addressed using stack pointer, > > for example x86-64 architecture with variables addressed using %rsp. > > The address emitted for variables located on stack by my new patch is always > > DW_OP_fbreg + constant. > > > > When I was testing the emitted debug info with mainline GDB I found that > > GDB probably does not adjust addresses of variables when stack pointer changes > > (like because of "pushq" instruction) if using location lists. > > I think GDB should adjust the address of %rsp addressed variables according to > > change of %rsp (probably DWARF2 sais so for DW_OP_fbreg). I think it is a > > better solution than emitting new locations to location list for all variables > > located on stack after each "push" and "pop" which would cause too large debug > > info. > > > > When I looked to gdb/dwarf2loc.c I see there: > > /* FIXME: cagney/2003-03-26: This code should be using > > get_frame_base_address(), and then implement a dwarf2 specific > > this_base method. */ > > Probably this is related to my problem. > > The FIXME is a cleanliness problem. We do evaluate DW_AT_frame_base, > so it _ought_ to work. > > > I tested it on attached C file, assembler with debug info and x86-64 binary > > is attached too. > > Do you suppose you could produce an x86 (ia32) testcase? I don't have > x86-64 hardware available yet. The debug info looks right so I'd like > to get my fingers into the problem. I think it will be the same on i386 with -fomit-frame-pointer. I'll test it and send you files if needed. Josef