Efficient dynamic dispatch without virtual function tables: the SmallEiffel compiler

[Craig Black]

BTW,  I am VERY interested in this stuff.  I am already kludging my C++ code 
to improve performance by reducing the number of virtual function calls 
performed.  (The most common functions get called non-virtually, and the 
rest are called virtually.)  If this feature was built into a compiler that 
would greatly simplify things.  I would allow me to use virtual functions 
more freely without worrying so much about the overhead involved.

Another idea:  a feature like this would probably require each function in 
the virtual hiearchy to be assigned a precedence.  The precedence would 
represent how often the function is expected to be called.  Functions with a 
higher precedence could be called optimized to be called directly, whereas 
lower precedence functions could be called via a vtable.  The precedence 
could be determined by profiling the code or by specifying a precedence 
explicitly.  Perhaps something like:

class A
{
public:
   void func() { ... }
}

class B : A
{
public:
   precedence(1) void func() { .. }
}

class C : A
{
   precedence(2) void func() { ... }
}

-Craig