Your bug reports play an essential role in making gdb reliable.
Reporting a bug may help you by bringing a solution to your problem, or it may not. But in any case the principal function of a bug report is to help the entire community by making the next version of gdb work better. Bug reports are your contribution to the maintenance of gdb.
In order for a bug report to serve its purpose, you must include the information that enables us to fix the bug.
If you are not sure whether you have found a bug, here are some guidelines:
If the debugger gets a fatal signal, for any input whatever, that is a gdb bug. Reliable debuggers never crash.
If gdb produces an error message for valid input, that is a bug. (Note that if you're cross debugging, the problem may also be somewhere in the connection to the target.)
If gdb does not produce an error message for invalid input, that is a bug. However, you should note that your idea of "invalid input" might be our idea of "an extension" or "support for traditional practice".
If you are an experienced user of debugging tools, your suggestions for improvement of gdb are welcome in any case.