program compilation or interpretation optimizations in which a base-class pointer or reference points to a known subclass.
In programming languages in which object classes have an inheritance hierarchy or formal interfaces, it is common to work with pointers or references to base class or an interface, where the actual class can be anything inheriting or implementing the base class or interface - and its specific behavior will be executed.
This functionality often involves procedures such as looking up a class method's implementation memory address in a virtual table ("vtable") of the base class, whose memory location is common to all inheriting/implementing subclasses.
Also, at times, a base-class or interface reference or pointer is speculatively converted to the specific subclass or implementation class - a type conversion which may fail if the converter gets the information wrong or makes invalid assumptions.
When a compiler or interpreter works on a piece of code doing one of the above (or some other work) through a base class or an interface, but knows at compilation/interpretation time which class these procedure are applied to, it can skip them and let the execution proceed as if the specific class was being used directly: A type conversion with no checks, or a call to the specific class' known method without going through a virtual table.
which can in fact point to any subclass of the base class. A program uses the base class interface, and the specific implementation or concretization
A optimization in which a base-class pointer points to a known subclass, and the subclass' methods can be used directly rather than through a vtable lookup at run-time.
