gdb: Compilation
4.1 Compiling for Debugging
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In order to debug a program effectively, you need to generate debugging
information when you compile it. This debugging information is stored
in the object file; it describes the data type of each variable or
function and the correspondence between source line numbers and
addresses in the executable code.
To request debugging information, specify the '-g' option when you
run the compiler.
Programs that are to be shipped to your customers are compiled with
optimizations, using the '-O' compiler option. However, some compilers
are unable to handle the '-g' and '-O' options together. Using those
compilers, you cannot generate optimized executables containing
debugging information.
GCC, the GNU C/C++ compiler, supports '-g' with or without '-O',
making it possible to debug optimized code. We recommend that you
_always_ use '-g' whenever you compile a program. You may think your
program is correct, but there is no sense in pushing your luck. For
more information, see 
Optimized Code.
Older versions of the GNU C compiler permitted a variant option '-gg'
for debugging information. GDB no longer supports this format; if your
GNU C compiler has this option, do not use it.
GDB knows about preprocessor macros and can show you their expansion
(Macros). Most compilers do not include information about
preprocessor macros in the debugging information if you specify the '-g'
flag alone. Version 3.1 and later of GCC, the GNU C compiler, provides
macro information if you are using the DWARF debugging format, and
specify the option '-g3'.
Options for Debugging Your Program or GCC (gcc)Debugging
Options, for more information on GCC options affecting debug
information.
You will have the best debugging experience if you use the latest
version of the DWARF debugging format that your compiler supports.
DWARF is currently the most expressive and best supported debugging
format in GDB.
Info Catalog
gdb: Running
gdb: Starting