Fwd: breakpoints and symbol examination problems

["Brian Budge" <brian dot budge at gmail dot com>]

Hi all -

This problem reproduces on my other system (opteron), which is running 6.7.1.

How can I tell if this is lack of debug info from gcc or if this is a
gdb problem?

Thanks,
  Brian



 On Tue, Mar 11, 2008 at 2:32 PM, Brian Budge <brian.budge@gmail.com> wrote:
> So here is a minimal repro case on my system:
>
> foo.h
> ---------------------------------------------
> template<typename joe>
> struct Class1 {
>    joe a;
>
>    Class1(int b) : a(b) {}
> };
>
> template<typename joe>
> struct Class2 {
>    joe a;
>
>    Class2(const Class1<joe> &rhs) {
>        a = 0;
>        for(int i = 0; i < 10; ++i) {
>            a += rhs.a;
>        }
>    }
> };
>
> ----------------------------------------------------
> foo.cpp
> --------------------------------------------------
> #include <iostream>
> #include "foo.h"
>
> int main() {
>
>    Class1<float> c1(15);
>
>    Class2<float> c2(c1);
>
>    std::cout << "value is " << c2.a << std::endl;
>
>    return 0;
> }
> --------------------------------------------------------------
>
> I'm compiling foo.cpp with
> > g++ -g foo.cpp
>
> Here's my gdb session:
>
> GNU gdb 6.7.90.20080311-cvs
> Copyright Stuff (removed for brevity)
> This GDB was configured as "x86_64-unknown-linux-gnu"...
> (gdb) b 8
> Breakpoint 1 at 0x40093b: file foo.cpp, line 8.
> (gdb) run
> Starting program: /home/budge/projects/rt_suite/apps/RtBatch/a.out
>
> Breakpoint 1, main () at foo.cpp:8
> 8           Class2<float> c2(c1);
> (gdb) s
> Class2 (this=0x7fff23e32c20, rhs=@0x7fff23e32c30) at foo.h:13
> 13              a = 0;
> (gdb) n
> 14              for(int i = 0; i < 10; ++i) {
> (gdb)
> 15                  a += rhs.a;
> (gdb) p i
> No symbol "i" in current context.
>
>
> g++ reports version "Gentoo 4.1.1-r3".  I'm running on amd64.
>
> Hopefully that will help a little in figuring out what is happening.
>
> Thanks,
>  Brian
>
>
>
>
> On Tue, Mar 11, 2008 at 2:20 PM, Brian Budge <brian.budge@gmail.com> wrote:
> > Hi Michael, Daniel, all -
> >
> >  I built gdb from CVS gdb_6_8-branch, and indeed it fixed my breakpoint
> >  problem.  Unfortunately, I still can't examine local variables.  I get
> >  this interaction, for example:
> >
> >  207             vector< dopVertex<T> > tmpVerts;
> >  (gdb)
> >  208             vector< dopEdge > tmpEdges;
> >  (gdb) p tmpVerts
> >  No symbol "tmpVerts" in current context.
> >
> >  Needless to say, not being able to examine your local variable makes
> >  debugging fairly tricky ;)
> >
> >  So, one down, one to go... not too shabby.  Any more ideas?
> >
> >  Thanks,
> >   Brian
> >
> >
> >
> >  On Tue, Mar 11, 2008 at 8:24 AM, Brian Budge <brian.budge@gmail.com> wrote:
> >  > Actually, this is already with -O0... at least I think.  I'm not
> >  >  passing any optimization flags.  For debug symbols I'm passing -ggdb.
> >  >
> >  >  I'll try the CVS current top of tree a bit later today.
> >  >
> >  >  Thanks,
> >  >   Brian
> >  >
> >  >
> >  >
> >  >  On Mon, Mar 10, 2008 at 5:52 PM, Michael Snyder <msnyder@specifix.com> wrote:
> >  >  > On Mon, 2008-03-10 at 20:32 -0400, Daniel Jacobowitz wrote:
> >  >  >  > On Mon, Mar 10, 2008 at 05:05:17PM -0700, Brian Budge wrote:
> >  >  >  >
> >  >  >
> >  >  > > > Additionally, I can't seem to examine any "stack" variables once in
> >  >  >  > > these template functions.  I can see member variables, global
> >  >  >  > > variables, and function parameters.
> >  >  >  >
> >  >  >  > This may be fixed, or it may be a compiler bug.  GCC is not very good
> >  >  >  > about emitting local variable information in optimized code.
> >  >  >
> >  >  >  Can you compile with -O0?
> >  >  >
> >  >  >
> >  >  >
> >  >
> >
>