From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2389 invoked by alias); 11 Mar 2004 20:57:52 -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 2381 invoked from network); 11 Mar 2004 20:57:52 -0000 Received: from unknown (HELO nevyn.them.org) (66.93.172.17) by sources.redhat.com with SMTP; 11 Mar 2004 20:57:52 -0000 Received: from drow by nevyn.them.org with local (Exim 4.30 #1 (Debian)) id 1B1XFX-0007SF-Hu; Thu, 11 Mar 2004 15:57:51 -0500 Date: Fri, 19 Mar 2004 00:09:00 -0000 From: Daniel Jacobowitz To: Andrew Cagney Cc: gdb-patches@sources.redhat.com Subject: Re: [rfa/mips] Stop backtraces when we've lost the PC Message-ID: <20040311205751.GA28627@nevyn.them.org> Mail-Followup-To: Andrew Cagney , gdb-patches@sources.redhat.com References: <20040306231743.GA9379@nevyn.them.org> <404BC4B2.7000100@gnu.org> <20040308032324.GA1325@nevyn.them.org> <20040308154814.GA17012@nevyn.them.org> <4050D13F.1040306@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4050D13F.1040306@gnu.org> User-Agent: Mutt/1.5.1i X-SW-Source: 2004-03/txt/msg00275.txt.bz2 On Thu, Mar 11, 2004 at 03:51:11PM -0500, Andrew Cagney wrote: > >I hypothesize that if two consecutive frames, regardless of their type, > >claim to save the PC register at the same location, then unwinding is > >hosed. > > It would need to do a deep analysis of the location (think about a > register window architecture), hence I don't know that there's that much > cost benefit. Something simpler such as a list of functions known to > terminate the stack might be more useful. Er, no. frame_unwind_register tells us where, relative to the current machine state, the register is saved. If it returns lval_register and real_regnum == O7_REGNUM, then that means it leaves in read_register(O7_REGNUM) at this moment, not that it did at some point in the past. Isn't that the point of the recursive unwinder? -- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2389 invoked by alias); 11 Mar 2004 20:57:52 -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 2381 invoked from network); 11 Mar 2004 20:57:52 -0000 Received: from unknown (HELO nevyn.them.org) (66.93.172.17) by sources.redhat.com with SMTP; 11 Mar 2004 20:57:52 -0000 Received: from drow by nevyn.them.org with local (Exim 4.30 #1 (Debian)) id 1B1XFX-0007SF-Hu; Thu, 11 Mar 2004 15:57:51 -0500 Date: Thu, 11 Mar 2004 20:57:00 -0000 From: Daniel Jacobowitz To: Andrew Cagney Cc: gdb-patches@sources.redhat.com Subject: Re: [rfa/mips] Stop backtraces when we've lost the PC Message-ID: <20040311205751.GA28627@nevyn.them.org> Mail-Followup-To: Andrew Cagney , gdb-patches@sources.redhat.com References: <20040306231743.GA9379@nevyn.them.org> <404BC4B2.7000100@gnu.org> <20040308032324.GA1325@nevyn.them.org> <20040308154814.GA17012@nevyn.them.org> <4050D13F.1040306@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4050D13F.1040306@gnu.org> User-Agent: Mutt/1.5.1i X-SW-Source: 2004-03.o/txt/msg00275.txt Message-ID: <20040311205700.NvHUEzVhiTP5RVPAI5ZBpHBspIkYficDD6MdQgVDF1I@z> On Thu, Mar 11, 2004 at 03:51:11PM -0500, Andrew Cagney wrote: > >I hypothesize that if two consecutive frames, regardless of their type, > >claim to save the PC register at the same location, then unwinding is > >hosed. > > It would need to do a deep analysis of the location (think about a > register window architecture), hence I don't know that there's that much > cost benefit. Something simpler such as a list of functions known to > terminate the stack might be more useful. Er, no. frame_unwind_register tells us where, relative to the current machine state, the register is saved. If it returns lval_register and real_regnum == O7_REGNUM, then that means it leaves in read_register(O7_REGNUM) at this moment, not that it did at some point in the past. Isn't that the point of the recursive unwinder? -- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer