HP Fortran Programmer's Guide (B3908-90031; September 2011)

Debugging
Using the HP WDB debugger
Chapter 4 121
Using the HP WDB debugger
The HP WDB debugger is the primary tool for debugging HP Fortran programs. The debugger provides
such basic debugging functions as program control, process control, program and data monitoring, and
expression evaluation. The debugger has both a graphical interface and a line-mode interface.
The debugger software includes different managers that enable it to handle different source languages, target
machines, object file formats, and user formats. The Fortran language manager allows you to use Fortran
syntax when entering expressions on the debugger command line.
Before beginning a debugging session, you must compile the program with the -g compile-line option. If
you compile and link separately, you must use the -g option on both command lines. The option causes the
compiler to generate additional information needed by the debugger and to insert it into the output code.
After compiling your program with the -g option, invoke the debugger with the wdb command, supplying
the name of the executable as an argument. For example, the following command compiles prog.f90 for
debugging:
$ f90 -g prog.f90 -o db_prog
Here is the command to start debugging the executable program:
$ wdb db_prog
You can use the debugger to debug code that has been optimized at levels 0, 1, and 2. To debug optimized
code, compile the program with both the -g and +Oopt-level options, where opt-level is 0, 1, or 2.
The following command line prog.f90 at optimization level 2 and prepares for debugging:
$ f90 +O2 -g prog.f90 -o db_prog
Compiling with the -g option increases the size of both the object file and the executable file. After you
have debugged your program and are ready to build the production version, you may want to recompile
without the -g option.
For complete information about HP WDB debugger, refer to http://www.hp.com/go/wdb. Printed and
online documentation are available at this site.