Where does GDB handle user command?

[Fei Ding]

Hi

I'm looking for the source code of handling user command, for example,
I want to know which function(or functions) will work after a user
input command "set architecture i386", I've traced a long time but may
miss something, any suggestion?

And I just want to know the process BEFORE GDB create an event
according to user input, not after creating an event.

Thanks a lot