# Optimize a `AIsaExpr`
	# `source` the source type of the expression
	# `target` the target type of the subtyping test
	private fun optimize(v: VirtualMachine, source: MType, target: MType)
	do
		# If the source class and target class are not classic classes (non-generics) then return
		if not source isa MClassType or not target isa MClassType or target isa MGenericType then
			return
		end

		if not target.mclass.abstract_loaded then return

		# If the value is positive, the target class has an invariant position in source's structures
		var value = source.mclass.get_position_methods(target.mclass)

		if value > 0 then
			# `value - 2` is the position of the target identifier in source vtable
			position = value - 2
			status = 1
		else
			# We use perfect hashing
			status = 2
		end
		id = target.mclass.vtable.id
	end