When is OP_LOADKX used?

[Thomas Jericke <tjericke@...>]

Hi,
I have a small question. In my project I will do some modifications to 
the Lua 5.2 interpreter to implement some things more efficient for our 
purposes.
As most changes are in the lvm.c luaV_execute function I wanted to have 
a full coverage unit test of that function. Unfortunately I haven't 
managed to provoke a OP_LOADKX. Maybe someone has an idea, or even 
better sample lua code that will compile and run a OP_LOADKX operation?

Thanks

--
Thomas