on 2009-08-06, Mariusz Marszałkowski supposed :
> Czy w kompilatorach C++ ktoś zaimplementował jakieś optymalizacje do
> metod wirtualnych? Chodzi mi o jakąś technikę, dzięki której kompilator
> może wygenerować szybszy kod dla wywołań wirtualnych niż dla zwykłych
> wskaźników do funkcji.

Visual C++ od wersji 2005 przy użyciu Profile-Guided Optimization robi:

Virtual Call Speculation. Virtual calls can be expensive due to the
jumping through the vtable to invoke method. With PGO, the compiler can
speculate at the call site of a virtual call and inline the method of
the speculated object into the virtual call site; the data to make this
decision is gathered with the instrumented application. In the
optimized code, the guard around the inlined function is a check to
ensure that the type of the speculated object matches the derived
object.

G++ od wersji 3.0 ma:

If the library exports constructors to the user,
all the user callable virtual functions of the
class and its ancestors must be exported. Although
virtual functions are normally called
via the vtable (and therefore their names are
not needed, just the index in the vtable), by exposing
the constructor it might be possible to
determine the dynamic type of an expression at
compile time. Should the compiler do that, it
may elect to replace a virtual call with a direct
call, and hence require the name of the virtual
function.

pozdrawiam,
Jakub