For the varargs functions that used the Type field to validate their parameters, now a hidden additional argument is passed which contains a byte array with the type info for the current call's arguments. Since this is static per call location it can be better prepared once when the code is being compiled instead of being put in a runtime created array for each invocation. Everything else uses the per-function instance of the same data.
The only thing that still needed the type field with a VMValue is the defaults array, so this uses a different struct type now to store its data.
Currently used for loading parameters into registers.
For checking parameters of native functions some more work is needed to get the info to the function. Currently it doesn't receive the function descriptor.
The amount of support code for this minor optimization was quite large and this stood in the way of streamlining the VM's calling convention, so it was preferable to remove it before moving on.
The instruction one free instruction byte so it's now using that to extend its argument's register range to 65535.
For param this is needed because it passes strings by reference and creating an implicit temporary copy for string constants does not work here.
It used the expression's value type, but needs to use the variable's, which can be different when the assignment is synthesized from a builtin function.
- keep string registers which are being used as function parameters allocated until after the function call returns. This is for allowing to pass strings by reference which would avoid some costly constructor/destructor loops in the call instruction.
