If you made changes to the function currently being executed, fix's impact depends on where the change is relative to the stopped in function:
If the change is in already executed code, the code is not re-executed. Execute the code by popping the current function off the stack and continuing from where the changed function is called. You need to know your code well enough to figure out whether the function has side effects that can't be undone (for example, opening a file).
If the change is in code yet to be executed, the new code is run.