How does the compiler benefit from C++'s new final keyword?

C++11 will allow to mark classes and virtual method to be final to prohibit deriving from them or overriding them.

class Driver {
  virtual void print() const;
};
class KeyboardDriver : public Driver {
  void print(int) const final;
};
class MouseDriver final : public Driver {
  void print(int) const;
};
class Data final {
  int values_;
};

This is very useful, because it tells the reader of the interface something about the intent of the use of this class/method. That the user gets diagnostics if he tries to override might be useful, too.

But is there an advantage from the compilers point of view? Can the compiler do anything different when he knows "this class will never be derived from" or "this virtual function will never be overridden"?

For final I mainly found only N2751 referring to it. Sifting through some of the discussions I found arguments coming from the C++/CLI side, but no clear hint why final may be useful for the compiler. I am thinking about this, because I also see some disadvantages of marking a class final: To unit-test protected member functions one can derive a class and insert test-code. Sometimes these classes are good candidates to be marked with final. This technique would be impossible in these cases.