From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3256 invoked by alias); 13 Apr 2002 18:32:46 -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 3228 invoked from network); 13 Apr 2002 18:32:41 -0000 Received: from unknown (HELO nevyn.them.org) (128.2.145.6) by sources.redhat.com with SMTP; 13 Apr 2002 18:32:41 -0000 Received: from drow by nevyn.them.org with local (Exim 3.35 #1 (Debian)) id 16wSKM-0003g1-00; Sat, 13 Apr 2002 14:32:46 -0400 Date: Sat, 13 Apr 2002 11:32:00 -0000 From: Daniel Jacobowitz To: Martin Baulig Cc: gdb@sources.redhat.com, Momchil Velikov Subject: Re: Lifetime of local variables Message-ID: <20020413143246.B13608@nevyn.them.org> Mail-Followup-To: Martin Baulig , gdb@sources.redhat.com, Momchil Velikov References: <86u1qghdp5.fsf@einstein.home-of-linux.org> <20020412194304.B11562@nevyn.them.org> <86bscnesxy.fsf@einstein.home-of-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86bscnesxy.fsf@einstein.home-of-linux.org> User-Agent: Mutt/1.3.23i X-SW-Source: 2002-04/txt/msg00234.txt.bz2 On Sat, Apr 13, 2002 at 01:31:05PM +0200, Martin Baulig wrote: > Daniel Jacobowitz writes: > > Also, I believe that this should be entirely subsumed by .debug_loc. > > The first variable's value may no longer be available, but it has not > > actually gone out of scope, has it? We should list it but claim that > > its value is unavailable. > > It has actually gone out of scope. I want to use this to debug machine > generated IL code and the JIT may want to create local variables > on-the-fly. For variables which have actually been defined by a human > programmer, listing them and claiming that their value is no longer > available is IMHO the right thing to do - but I'd like to tell the > debugger to make a machine-generated variable disappear when it's no > longer used, otherwise you'd get a large number of automatic variables > (having numbers, not names, which makes it even more confusing to the > user) and only a very few of them are actually used. What business does the JIT have actually creating local variables (rather than temporaries, which don't get names)? I don't understand. > Btw. are there any plans to implement .debug_loc anytime soon, I need > this for something else ? I believe it's in progress. On Sat, Apr 13, 2002 at 02:42:14PM +0200, Martin Baulig wrote: > Momchil Velikov writes: > > One can use DT_AT_artificial to distinguish machine generated > > temporaries and the .debug_loc ranges to decide whether to display the > > variable. > > What happens if you're outside any of the ranges listed in .debug_loc - > will the variable be listed or not or will this depend on DW_AT_artificial ? > > IMHO variables which have been created by a human should always be > listed, but machine generated ones (since there can be a large number > of them) should only be listed withing their lifetime ranges. We don't know yet, since DW_AT_artificial is currently only used for method arguments (and methods, but that patch is pending). Once we've got .debug_loc we can decide, but this seems reasonable to me. -- Daniel Jacobowitz Carnegie Mellon University MontaVista Software Debian GNU/Linux Developer