2010/10/26 M.-A. Lemburg <mal@egenix.com>
Cesare Di Mauro wrote:
 > I can provide another patch that will not use EXTENDED_ARG (no VM changes),
> and uses *args and/or **kwargs function calls when there are more than 255
> arguments or keyword arguments.
> But I need some days.
> If needed, I'll post it at most on this week-end.

You mean a version that pushes the *args tuple and **kws dict
on the stack and then uses those for calling the function/method ?

I think that would be a lot more efficient than pushing/popping
hundreds of parameters on/off the stack.

 Marc-Andre Lemburg

I was referring to the solution (which I prefer) that I proposed answering to Greg, two days ago.

Unfortunately, the stack must be used whatever the solution we will use.

Pushing the "final" tuple and/or dictionary is a possible optimization, but we can use it only when we have a tuple or dict of constants; otherwise we need to use the stack.

Good case:  f(1, 2, 3, a = 1, b = 2)
We can push (1, 2, 3) tuple and {'a' : 1, 'b' : 2}, then calling f with CALL_FUNCTION_VAR_KW opcode passing narg = nkarg = 0.

Worst case: f(1, x, 3, a = x, b = 2)
We can't push the tuple and dict as a whole, because they need first to be built using the stack.

The good case is possible, and I have already done some work in wpython collecting constants on parameters push (even partial constant sequences), but some additional work must be done recognizing costants-only tuple / dict.

However, the worst case rest unresolved.