From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19052 invoked by alias); 5 Mar 2005 16:44:59 -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 18692 invoked from network); 5 Mar 2005 16:44:48 -0000 Received: from unknown (HELO nevyn.them.org) (66.93.172.17) by sourceware.org with SMTP; 5 Mar 2005 16:44:48 -0000 Received: from drow by nevyn.them.org with local (Exim 4.44 #1 (Debian)) id 1D7cOa-0002Dj-6Q; Sat, 05 Mar 2005 11:44:52 -0500 Date: Sat, 05 Mar 2005 16:44:00 -0000 From: Daniel Jacobowitz To: Mark Kettenis Cc: gdb-patches@sources.redhat.com Subject: Re: [RFA] New GDB target iq2000 Message-ID: <20050305164451.GA8398@nevyn.them.org> Mail-Followup-To: Mark Kettenis , gdb-patches@sources.redhat.com References: <20050222114141.GA18314@cygbert.vinschen.de> <20050303173443.GD18681@nevyn.them.org> <20050304094605.GU2839@cygbert.vinschen.de> <20050304141439.GA30249@nevyn.them.org> <20050304150129.GF2839@cygbert.vinschen.de> <20050304220104.GA14522@nevyn.them.org> <200503051128.j25BSruw007318@elgar.sibelius.xs4all.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200503051128.j25BSruw007318@elgar.sibelius.xs4all.nl> User-Agent: Mutt/1.5.6+20040907i X-SW-Source: 2005-03/txt/msg00062.txt.bz2 On Sat, Mar 05, 2005 at 12:28:53PM +0100, Mark Kettenis wrote: > Date: Fri, 4 Mar 2005 17:01:04 -0500 > From: Daniel Jacobowitz > > I left the other function alone. skip_prologue_using_sal is already a > bit bogus, for the reasons identified by Kevin as well as for at least > one other that I can see. find_last_line_symbol is even boguser. > Basically, any code that compares the LINE member of two arbitrary SALs > _must_ be wrong. They don't even need to be in the same source file. > > Another issue with skip_prologue_using_sal() is that it will happily > skip the entire function if the function body is basically empty. I > really think it should be deprecated, and shouldn't be used in any new > code. Hum... so it will. I rather think it should be fixed. I have a patch to fix the most common occurance of that, when the line notes look like: line1: line2: ret For a compiler which doesn't use the two line note convention, of course, it's bogus - but so is lots of the rest of GDB. Could you explain why you think it should be deprecated? Bear in mind that it's _new_ - it was derived from various similar things in tdep files, in an attempt to commonize. > There's two things that GDB uses the guessed prologue line information > for. One is to place an initial breakpoint, so that the arguments have > been saved. This problem will hopefully eventually go away, with > improved GCC -fvar-tracking - we should be able to print the arguments > from anywhere. Someone needs to spend a little love on the compiler > side of this. > > The important thing about placing the initial breakpoint, is that it > shouldn't be placed too far into the function. In particular it > should not end up after a branch instruction. Yes. I mentioned to Kevin off-list that I've been thinking about an ideal paradigm for implementing both this and prologue scanners. What we need is a common simulator architecture which can "describe" the effects of instructions - enough instructions to handle prologues, at least. A huge project for someday :-) -- Daniel Jacobowitz CodeSourcery, LLC