The manual is worth a read. This is a software (as gcc) in which the "man" page or the information displayed with "--help" is not near the bunch of things there are described in the complete documentation.
(for those who don't know, the full manual can be read with `info gdb` - `man gdb` is only a short help)
People have been ignoring info for almost exactly as long as the FSF has been trying to supersede man with it.