Compiling a Program for Debugging

You must prepare your program for debugging with dbx by compiling it with the- g or -g0 option.

Compiling with the -g Option

The -g option instructs the compiler to generate debugging information during compilation.

For example, to compile using C++, type:

% CC -g example_source.cc

In C++, the -g option turns on debugging and turns off inlining of functions. The- g0 (zero) option turns on debugging and does not affect inlining of functions. You cannot debug inline functions with the -g0 option. The -g0 option can significantly decrease link time and dbx start-up time (depending on the use of inlined functions by the program).

To compile optimized code for use with dbx, compile the source code with both the -O (uppercase letter O) and the -g options.

Using a Separate Debug File

dbx lets you use options in the objcopy command on Linux platforms and the gobjcopy command on Solaris platforms to copy the debugging information from an executable to a separate debug file, strip that information from the executable, and create a link between these two files.

dbx searches for the separate debug file in the following order and reads the debugging information from the first file it finds:

• The directory that contains the executable file.

• A subdirectory named debug in the directory that contains the executable file.

• A subdirectory of the global debug file directory, which you can view or change if the dbx environment variable debug_file_directory is set to the path name of the directory. The default value of the environment variable is /usr/lib/debug.

For example, to create a separate debug file for executable a.out, you would do the following.

Creating a Separate Debug File

1. Create a separate debug file named a.out.debug containing the debugging information.

2. Strip the debugging information from a.out.

3. Establish the link between the two files. On Solaris platforms, use the gobjcopy command. On Linux platforms, use the objcopy command.

   On a Linux platform, you can use the command objcopy -help to find out whether or not the -add-gnu-debuglink option is supported on the platform. You can replace the -only-keep-debug option of the objcopy command with the command cp a.out a.out.debug to make a.out.debug a fully executable file.