RFC: New C++ Attribute: final

[Daniel Berlin]

> Certainly not.  But if such a pointer to member was final and bound to
> a known function, GCC might be able to short-curcuit function calls
> through it, and even inline them.  But since, for a virtual function,
> it is not possible to know the exact function that is going to be
> called unless you happen to know the dynamic type of the object, you
> lose.  With final, you'd win.
>

Compilers besides GCC have started to get good at determining the 
dynamic types of objects and "devirtualizing calls".  Some also 
implement more trivial methods (see if it must-alias a certain 
component of the virtual table object, and thus, must be pointing to 
that call) as a backup.
It's somewhere down on my list to implement some form of analysis 
(RTA/CHA/whatever) to be able to a determine a small set of actual 
calls a given virtual call can make.
No clue when i'll get to it. Probably around the same time we start 
doing other IPA things.