[Bug fortran/34153] New: Unable to debug code compiled with gfortran on MacOSX 10.4.11

[Bug fortran/34153] New: Unable to debug code compiled with gfortran on MacOSX 10.4.11

[j dot wookey at bristol dot ac dot uk]

Hi,

I'm having a problem using gdb to debug code compiled with gfortran (v 4.3.0).
The code:

      program test
      i = 1
C     Breakpoint here
      end

when compiled with "gfortran -gstabs -o prog prog.f", debugged with "gdb prog"
demonstrates the error. 

The commands:

(gdb) break 3
(gdb) run

produces the output:

> Starting program: /private/tmp/prog 
> Reading symbols for shared libraries .++ done
> 
> Breakpoint 1, main (argc=1, argv=0xbfffe9b8) at ../../../gcc-4.3-20070810/libgfortran/fmain.c:12
> 12      ../../../gcc-4.3-20070810/libgfortran/fmain.c: No such file or directory.
>       in ../../../gcc-4.3-20070810/libgfortran/fmain.c

At this point commands to examine symbols fail:

(gdb) display i
No symbol "i" in current context.

The problem is the same on a PowerPC machine also.


-- 
           Summary: Unable to debug code compiled with gfortran on MacOSX
                    10.4.11
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: j dot wookey at bristol dot ac dot uk
  GCC host triplet: i386-apple-darwin


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34153

[Bug fortran/34153] Debugging: Cannot set breakpoint in comment lines or "END PROGRAM"

[burnus at gcc dot gnu dot org]

------- Comment #1 from burnus at gcc dot gnu dot org  2007-11-20 11:34 -------
The problem is that you end up in the wrong file. If you enter "break 3" you
are debugging the wrapping program not the Fortran "program test", which is the
reason that there is no "i" available.

Try: break file.f:line, e.g.
(gdb) b b.f:2

However, there is another problem: One cannot set the break point after the
assignment:

      program test    ! Breakpoint possible
      i = 1           ! Breakpoint possible
!     Breakpoint here ! No breakpoint possible
      end             ! No breakpoint possible

Setting a breakpoint in line 2, one can print the value "i" before the
assignment; however, doing a "step" one ends in the wrapping main() program and
can thus never read the value after the assignment.

Using g77 or ifort, one can set a break point in line 3 or 4 and gdb shows
then:

Breakpoint 1, test () at b.f:4
4             end


-- 

burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   GCC host triplet|i386-apple-darwin           |
            Summary|Unable to debug code        |Debugging: Cannot set
                   |compiled with gfortran on   |breakpoint in comment lines
                   |MacOSX 10.4.11              |or "END PROGRAM"


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34153

[Bug fortran/34153] Debugging: Cannot set breakpoint in comment lines or "END PROGRAM"

[fxcoudert at gcc dot gnu dot org]

------- Comment #2 from fxcoudert at gcc dot gnu dot org  2007-11-20 13:10 -------
(In reply to comment #1)
> The problem is that you end up in the wrong file. If you enter "break 3" you
> are debugging the wrapping program not the Fortran "program test", which is the
> reason that there is no "i" available.

This part of the bug was fixed by a recent commit of mine (and a gdb patch).
With development versions of gfortran and gdb, breaking by "b 2" will break at
line 2 of the Fortran main program.

> However, there is another problem: One cannot set the break point after the
> assignment:
> 
>       program test    ! Breakpoint possible
>       i = 1           ! Breakpoint possible
> !     Breakpoint here ! No breakpoint possible
>       end             ! No breakpoint possible

It's also possible in C with GCC mainline:

(gdb) l
1       int main(void)
2       {
3         int i;
4         i = 1;
5         /* That's all, folks!  */
6       }
(gdb) b 5
Breakpoint 1 at 0x400467: file z.c, line 5.
(gdb) r
Starting program: /home/fxcoudert/devel/debug2/irun/a.out

Breakpoint 1, main () at z.c:6
6       }


-- 

fxcoudert at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fxcoudert at gcc dot gnu dot
                   |                            |org
OtherBugsDependingO|                            |24546
              nThis|                            |
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |wrong-debug
   Last reconfirmed|0000-00-00 00:00:00         |2007-11-20 13:10:19
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34153

[Bug fortran/34153] Debugging: Cannot set breakpoint in comment lines or "END PROGRAM"

[burnus at gcc dot gnu dot org]

------- Comment #3 from burnus at gcc dot gnu dot org  2009-05-12 21:10 -------
I have a patch for this. Note, however, that the compiler - even with default
options - (too) aggressively optimizes your program, i.e. the assignment is
optimized away even with -O0 and thus for your program the value is alway some
random value. (This is also the the case for the analogous C program - if you
think it should be fixed, please fill a middle-end bug.)

If you do:
      subroutine test
      save  ! or actual argument or in common or ...
      i = 1
!     Breakpoint here      ! a break point here becomes a b. in the next line
      end subroutine test  ! <<< the breakpoint can be set to this line
with my patch, it properly prints the value "1" for "i" after the assignment.


-- 

burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |burnus at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2007-11-20 13:10:19         |2009-05-12 21:10:26
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34153

[Bug fortran/34153] Debugging: Cannot set breakpoint in comment lines or "END PROGRAM"

[burnus at gcc dot gnu dot org]

------- Comment #4 from burnus at gcc dot gnu dot org  2009-05-13 14:53 -------
Subject: Bug 34153

Author: burnus
Date: Wed May 13 14:52:54 2009
New Revision: 147477

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=147477
Log:
2009-05-13  Tobias Burnus  <burnus@net-b.de>

        PR fortran/34153
        * gfortran.h (gfc_exec_op): Add EXEC_END_PROCEDURE.
        * dump-parse-tree.c (show_code_node): Use EXEC_END_PROCEDURE.
        * trans.c (gfc_trans_code): Ditto.
        * resolve.c (resolve_code): Ditto.
        * st.c (gfc_free_statement): Ditto.


Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/dump-parse-tree.c
    trunk/gcc/fortran/gfortran.h
    trunk/gcc/fortran/parse.c
    trunk/gcc/fortran/resolve.c
    trunk/gcc/fortran/st.c
    trunk/gcc/fortran/trans.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34153

[Bug fortran/34153] Debugging: Cannot set breakpoint in comment lines or "END PROGRAM"

[burnus at gcc dot gnu dot org]

------- Comment #5 from burnus at gcc dot gnu dot org  2009-05-13 16:14 -------
FIXED on the trunk (4.5). Thanks for the bug report!


-- 

burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34153