Can't set bkpt at throw statement

Can't set bkpt at throw statement

[Allen Hopkins]

I have two essentially identical C++ classes with essentially identical
methods that both throw the same exception.  In gdb, I'm able to set a
breakpoint at the "throw" statement in one class, but not in the other.
Here are the break commands, first on the one that succeeds, then on
the one that fails:

     (gdb) break Ethel.cpp:12
     Breakpoint 1 at 0x80488b5: file Ethel.cpp, line 12.
     (gdb) break Fred.cpp:12
     Note: breakpoint -1 (disabled) also set at pc 0x0.
     Breakpoint 2 at 0x0: file Fred.cpp, line 12.

     (gdb) run
     Starting program: /tmp/allenh/metro_dev/examples/stuck/run.x
     Warning:
     Cannot insert breakpoint 2.
     Error accessing memory address 0x0: Input/output error.

Here is a shar of a simple demo of the problem.  You can also find these
files at http://www.eecs.berkeley.edu/~allenh/stuck.

Any advice may help save my sanity.  Thanks.

-Allen Hopkins

# This is a shell archive.  Save it in a file, remove anything before
# this line, and then unpack it by entering "sh file".  Note, it may
# create directories; files and directories will be owned by you and
# have default permissions.
#
# This archive contains:
#
#	DaBomb.h
#	demo
#	Ethel.cpp
#	Ethel.h
#	Fred.cpp
#	Fred.h
#	gdbrc
#	main.cpp
#	makefile
#
echo x - DaBomb.h
sed 's/^X//' >DaBomb.h << 'END-of-DaBomb.h'
X#ifndef DABOMB_H
X#define DABOMB_H
X
Xclass DaBomb {};
X
X#endif
END-of-DaBomb.h
echo x - demo
sed 's/^X//' >demo << 'END-of-demo'
X#!/bin/sh
X
Xmake
Xrun.x
Xgdb -x gdbrc run.x
X
END-of-demo
echo x - Ethel.cpp
sed 's/^X//' >Ethel.cpp << 'END-of-Ethel.cpp'
X#include "Ethel.h"
X#include "DaBomb.h"
X#include <iostream.h>
X
XEthel::Ethel(int i) {
X    trigger = i;
X};
X
Xvoid Ethel::myFunc(int i)
X{
X    if (i == trigger) {
X        throw DaBomb();
X    } else {
X        cout << "Ethel says " << i << endl;
X    }
X};
END-of-Ethel.cpp
echo x - Ethel.h
sed 's/^X//' >Ethel.h << 'END-of-Ethel.h'
X#ifndef ETHEL_H
X#define ETHEL_H
X
Xclass Ethel;
X
Xclass Ethel {
X    public:
X        int trigger;
X        Ethel(int i);
X        void myFunc(int i);
X};
X
X#endif
END-of-Ethel.h
echo x - Fred.cpp
sed 's/^X//' >Fred.cpp << 'END-of-Fred.cpp'
X#include "Fred.h"
X#include "DaBomb.h"
X#include <iostream.h>
X
XFred::Fred(int i) {
X    trigger = i;
X};
X
Xvoid Fred::myFunc(int i)
X{
X    if (i == trigger) {
X        throw DaBomb();
X    } else {
X        cout << "Fred says " << i << endl;
X    }
X};
END-of-Fred.cpp
echo x - Fred.h
sed 's/^X//' >Fred.h << 'END-of-Fred.h'
X#ifndef FRED_H
X#define FRED_H
X
Xclass Fred;
X
Xclass Fred {
X    public:
X        int trigger;
X        Fred(int i);
X        void myFunc(int i);
X};
X
X#endif
END-of-Fred.h
echo x - gdbrc
sed 's/^X//' >gdbrc << 'END-of-gdbrc'
Xbreak Fred.cpp:12
Xbreak Ethel.cpp:12
Xrun
END-of-gdbrc
echo x - main.cpp
sed 's/^X//' >main.cpp << 'END-of-main.cpp'
X#include "Fred.h"
X#include "Ethel.h"
X#include "DaBomb.h"
X#include <iostream.h>
X
Xint main(int argc, char* argv[])
X{
X    Fred*  fred  = new Fred(3);
X    Ethel* ethel = new Ethel(7);
X
X    for (int i = 0; i < 10; i++) {
X
X        try {
X            fred->myFunc(i);
X        } catch (DaBomb) {
X            cout << "FRED threw DaBomb." << endl;
X        }
X
X        try {
X            ethel->myFunc(i);
X        } catch (DaBomb) {
X            cout << "ETHEL threw DaBomb." << endl;
X        }
X    }
X}
END-of-main.cpp
echo x - makefile
sed 's/^X//' >makefile << 'END-of-makefile'
XOPTS = -ggdb -Wno-deprecated
X
Xall: Ethel.o Fred.o main.o
X	 g++ $(OPTS) -o run.x \
X		Ethel.o Fred.o main.o
X
XEthel.o: Ethel.cpp Ethel.h
X	g++ $(OPTS) -c Ethel.cpp
X
XFred.o: Fred.cpp Fred.h
X	g++ $(OPTS) -c Fred.cpp
X
Xmain.o: ./main.cpp
X	g++ $(OPTS) -c ./main.cpp
X
Xclean:
X	rm -f *.o run.x
END-of-makefile
exit

Re: Can't set bkpt at throw statement

[Ramana Radhakrishnan]

Hey Allen ,

> I have two essentially identical C++ classes with essentially identical
> methods that both throw the same exception.  In gdb, I'm able to set a
> breakpoint at the "throw" statement in one class, but not in the other.
> Here are the break commands, first on the one that succeeds, then on
> the one that fails:


What are the versions of g++, binutils and gdb that you are using. I 
tried your case on a 686 with g++ -3.3.4 debian , gdb - 6.1 and binutils 
2.14.90 and had no problems with inserting breakpoint #2 . If you could 
tell the versions of the tools, maybe someone can help you and also 
check if this is a problem with gdb.

regards
Ramana

Re: Can't set bkpt at throw statement

[Michael Chastain]

Your program works fine for me on:

  native i686-pc-linux-gnu
  red hat 8.0
  gcc 3.3.4
  binutils 2.15
  gdb 6.2

I also tested with gcc 3.4.1 and gcc 3.5.0 20040811 (experimental).
All worked fine.

However I see the bad breakpoint on Fred.cpp:12 with

  native i686-pc-linux-gnu
  red hat 8.0
  gcc 3.2-7-rh
  binutils 2.13.90.0.2-2-rh
  gdb 6.2

  (gdb) break Ethel.cpp:12
  Breakpoint 1 at 0x80488b5: file Ethel.cpp, line 12.
  (gdb) break Fred.cpp:12
  Note: breakpoint -1 (disabled) also set at pc 0x0.
  Breakpoint 2 at 0x0: file Fred.cpp, line 12.

Can you report:

  output of "gdb --version"
  output of "gcc -v"
    (or if the C++ compiler is not gcc, the equivalent)
  your os name and version number

I think you will have to install a newer gcc.
It's not hard, if you use the "--prefix" option to build gcc.

Michael C

Re: Can't set bkpt at throw statement

[Allen Hopkins]

Thanks.  I'll try updating gcc.  Here are the versions of gdb, gcc, o/s:

fortytwo[1001]$ gdb --version
GNU gdb 6.0
Copyright 2003 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 "i586-suse-linux".

fortytwo[1002]$ gcc -v
Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/3.2/specs
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man 
--infodir=/usr/share/info --enable-shared --enable-threads=posix 
--disable-checking --host=i386-redhat-linux --with-system-zlib 
--enable-__cxa_atexit
Thread model: posix
gcc version 3.2 20020903 (Red Hat Linux 8.0 3.2-7)

fortytwo[1004]$ uname -a
Linux fortytwo.eecs.berkeley.edu 2.4.20-28.8smp #1 SMP Thu Dec 18 
12:25:21 EST 2003 i686 i686 i386 GNU/Linux

-Allen

Michael Chastain wrote:

> Your program works fine for me on:
> 
>   native i686-pc-linux-gnu
>   red hat 8.0
>   gcc 3.3.4
>   binutils 2.15
>   gdb 6.2
> 
> I also tested with gcc 3.4.1 and gcc 3.5.0 20040811 (experimental).
> All worked fine.
> 
> However I see the bad breakpoint on Fred.cpp:12 with
> 
>   native i686-pc-linux-gnu
>   red hat 8.0
>   gcc 3.2-7-rh
>   binutils 2.13.90.0.2-2-rh
>   gdb 6.2
> 
>   (gdb) break Ethel.cpp:12
>   Breakpoint 1 at 0x80488b5: file Ethel.cpp, line 12.
>   (gdb) break Fred.cpp:12
>   Note: breakpoint -1 (disabled) also set at pc 0x0.
>   Breakpoint 2 at 0x0: file Fred.cpp, line 12.
> 
> Can you report:
> 
>   output of "gdb --version"
>   output of "gcc -v"
>     (or if the C++ compiler is not gcc, the equivalent)
>   your os name and version number
> 
> I think you will have to install a newer gcc.
> It's not hard, if you use the "--prefix" option to build gcc.
> 
> Michael C

Re: Can't set bkpt at throw statement

[Michael Chastain]

Ah, we both have red hat linux 8.

Upgrading gdb didn't help: gcc 3.2-7 + gdb 6.2, bug appears.
Upgrading gcc did help: gcc 3.3.4 + gdb 6.0, no bug.
Even gcc 3.3.4 + gdb 5.2.1-4, the gdb that shipped with rhl8, works.

Unfortunately there's still a lot of gcc 3.2 in the world.
It looks like people with gcc 3.2 using c++ would be wise to upgrade.

Michael C

Re: Can't set bkpt at throw statement

[Allen Hopkins]

I just tried it on a Sun Sparc maching running SunOS 5.8, gdb 6.0
and gcc 3.2.2.  No bug.

-Allen

Michael Chastain wrote:

> Ah, we both have red hat linux 8.
> 
> Upgrading gdb didn't help: gcc 3.2-7 + gdb 6.2, bug appears.
> Upgrading gcc did help: gcc 3.3.4 + gdb 6.0, no bug.
> Even gcc 3.3.4 + gdb 5.2.1-4, the gdb that shipped with rhl8, works.
> 
> Unfortunately there's still a lot of gcc 3.2 in the world.
> It looks like people with gcc 3.2 using c++ would be wise to upgrade.
> 
> Michael C