-g level (Debugging level)
-g1
It produces minimal information, enough for making back-traces in parts of the program that you don't plan to debug. This includes descriptions of functions and external variables but no information about local variables and no line numbers.
-g2
It is the default debugging level.
-g3
It includes extra information, such as all the macro definitions present in the program. Some debuggers support macro expansion when you use -g3.