Re: GDB 5.2/5.3 breakpoint bug

[Daniel Jacobowitz <drow@mvista.com>]

On Tue, Jan 07, 2003 at 03:49:31PM -0800, Sunil Alankar wrote:
> Hi,
> 
> While debugging this in function, find_pc_sect_line (CORE_ADDR pc, struct
> sec *section, int notcurrent)
> I found there were two line items in a line table with the same value of PC.
> First one gets picked as the best match. But this had item->line == 0. The
> next line item with the same value for item->pc, but a valid item->line ( >
> 0) does not get picked as the best match.
> I put in the following check to correct this. My question is,
> Is it valid to have have more than one line item with same value faor PC and
> possibly 0 for line in one of them? What causes this?
> Would this be an appropriate fix? Or is the problem more deep rooted in
> creating the symbol table?

I'll look at this more precisely later (tomorrow, I hope...) but what
that means is that a function ends exactly where another one starts. 
Very interesting; we probably should ignore the ending marker in that
case, but I'm not sure you're doing it the best way.

> 
> --- ../original/gdb-5.3/gdb/symtab.c       Thu Aug 29 20:24:00 2002
> +++ gdb-5.3/gdb/symtab.c        Tue Jan  7 14:42:34 2003
> @@ -1950,6 +1950,21 @@
>             best_end = 0;
>         }
> 
> +      /* Handle the case where the prev->pc == best->pc due to more than
> one line
> +        items for a pc, but the best->line == 0. grab a better match if one
> exists
> +        that has a non zero line number  */
> +
> +      else if (prev && (!best || ((prev->pc == best->pc) && (best->line ==
> 0)
> +                                 && (prev->line != 0))))
> +       {
> +         best = prev;
> +         best_symtab = s;
> +
> +         /* Discard BEST_END if it's before the PC of the current BEST.  */
> +         if (best_end <= best->pc)
> +           best_end = 0;
> +       }
> +
>        /* If another line (denoted by ITEM) is in the linetable and its
>           PC is after BEST's PC, but before the current BEST_END, then
>          use ITEM's PC as the new best_end.  */
> 
> 
> -----Original Message-----
> From: gdb-owner@sources.redhat.com
> [mailto:gdb-owner@sources.redhat.com]On Behalf Of Sunil Alankar
> Sent: Sunday, January 05, 2003 3:11 PM
> To: Daniel Jacobowitz
> Cc: gdb@sources.redhat.com
> Subject: RE: GDB 5.2/5.3 breakpoint bug
> 
> 
> Correction to the link for the systemc library sources:
> 
> http://www.systemc.org/download.php/systemc/13/19/systemc-2.0.1.tgz
> 
> Thx
> 
> Sunil
> 
> -----Original Message-----
> From: gdb-owner@sources.redhat.com
> [mailto:gdb-owner@sources.redhat.com]On Behalf Of Sunil Alankar
> Sent: Sunday, January 05, 2003 3:07 PM
> To: Daniel Jacobowitz
> Cc: gdb@sources.redhat.com
> Subject: RE: GDB 5.2/5.3 breakpoint bug
> 
> 
> I guess the e-mail with the attachment of library and include files was not
> delivered. Here it is without attachments.
> The sources for the systemc library/include files are at
> http://www.systemc.org/download.php/systemc/1/4/systemc-1.0.2.tar.gz
> Sunil
> 
> -----Original Message-----
> From: Sunil Alankar [mailto:sunil.alankar@coware.com]
> Sent: Sunday, January 05, 2003 2:48 PM
> To: Daniel Jacobowitz
> Cc: gdb@sources.redhat.com
> Subject: RE: GDB 5.2/5.3 breakpoint bug
> 
> 
> Hi,
>   I have a detailed description of the problem here. Hope this would help. I
> appreciate your help.
> 
> Thank you
> 
> Sunil
> 
> 
> Problem:
> Unable to set class method breakpoints in solaris with gdb 5.3 while using
> systemc
> library in the program.
> 
> Platform:
> SunOS tesla 5.7 Generic_106541-23 sun4u sparc SUNW,Ultra-4
> 
> g++ version:
> Reading specs from
> /eng/devtools/SunOS_5.7/lib/gcc-lib/sparc-sun-solaris2.7/2.95.2/specs
> gcc version 2.95.2 19991024 (release)
> 
> gdb version:
> GNU gdb 5.3
> Copyright 2002 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "sparc-sun-solaris2.7".
> 
> 
> Test program:
> 
> This error occured while I am debugging a systemC (c++ library for system
> design) program.
> Here is a small example program that demonstrates the problem. ( I have
> attached the
> required library for solaris and include files with the e-mail)
> 
> //-------------------------------------------------------------
> #include <systemc.h>
> 
> SC_MODULE(top)
> {
>  public:
> 
>     sc_in_clk iclk;
> 
>     void func()
>         {
>             printf (".");
>         }
> 
>     SC_CTOR(top)
>         {
>             SC_METHOD(func);
>             sensitive_pos << iclk;
>             dont_initialize();
>         }
> };
> 
> int sc_main (int argc , char *argv[])
> {
>     sc_clock clk("clk", 20);
>     top *top1 = new top("Top1");
>     top1->iclk(clk);
>     sc_start(20000);
>     return 0;
> }
> 
> //-------------------------------------------------------------
> 
> Build the example with:
> % g++ -g -I./include -L./ -lm test1.cpp -lsystemc -o tx
> 
> %/home1/gdb-5.3/gdb/gdb tx
> GNU gdb 5.3
> Copyright 2002 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "sparc-sun-solaris2.7"...
> (gdb) b top::func
> the class top does not have any method named func
> Hint: try 'top::func<TAB> or 'top::func<ESC-?>
> (Note leading single quote.)
> (gdb)
> 
> 
> In some systemC programs, gdb attempts to set breakpoints at invalid
> addresses.
> 
> This works without a problem in gdb 5.1 with proper breakpoint being set.
> 
> 
> 
> I hope this test case can provide sufficient ground to get at the problem.
> 
> 
> 
> 
> -----Original Message-----
> From: Daniel Jacobowitz [mailto:drow@mvista.com]
> Sent: Friday, January 03, 2003 6:23 PM
> To: Sunil Alankar
> Cc: gdb@sources.redhat.com
> Subject: Re: GDB 5.2/5.3 breakpoint bug
> 
> 
> On Fri, Jan 03, 2003 at 06:15:26PM -0800, Sunil Alankar wrote:
> > Hi,
> >
> >  Attempting to set a class member function breakpoint (say break
> > myClass::funcOne) fails to set a proper break point in solaris 2.7.
> > This happens with GDB 5.2 and 5.3. Bug does not occur in GDB 5.1. Anybody
> > has any idea where to look?. I would appreciate any help.
> 
> What _does_ happen if it isn't a proper breakpoint?  Can you provide a
> transcript?
> 
> What version of what compiler are you using?
> 
> --
> Daniel Jacobowitz
> MontaVista Software                         Debian GNU/Linux Developer
> 
> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer