# Handle common special cases before doing the effective method invocation
	# This methods handle the `==` and `!=` methods and the case of the null receiver.
	# Note: a { is open in the generated C, that enclose and protect the effective method invocation.
	# Client must not forget to close the } after them.
	#
	# The value returned is the result of the common special cases.
	# If not null, client must compile it with the result of their own effective method invocation.
	#
	# If `before_send` can shortcut the whole message sending, a dummy `if(0){`
	# is generated to cancel the effective method invocation that will follow
	# TODO: find a better approach
	private fun before_send(mmethod: MMethod, arguments: Array[RuntimeVariable]): nullable RuntimeVariable
	do
		var res: nullable RuntimeVariable = null
		var recv = arguments.first
		var consider_null = not self.compiler.modelbuilder.toolcontext.opt_no_check_null.value or mmethod.name == "==" or mmethod.name == "!="
		if maybe_null(recv) and consider_null then
			self.add("if ({recv} == NULL) \{")
			if mmethod.name == "==" or mmethod.name == "is_same_instance" then
				res = self.new_var(bool_type)
				var arg = arguments[1]
				if arg.mcasttype isa MNullableType then
					self.add("{res} = ({arg} == NULL);")
				else if arg.mcasttype isa MNullType then
					self.add("{res} = 1; /* is null */")
				else
					self.add("{res} = 0; /* {arg.inspect} cannot be null */")
				end
			else if mmethod.name == "!=" then
				res = self.new_var(bool_type)
				var arg = arguments[1]
				if arg.mcasttype isa MNullableType then
					self.add("{res} = ({arg} != NULL);")
				else if arg.mcasttype isa MNullType then
					self.add("{res} = 0; /* is null */")
				else
					self.add("{res} = 1; /* {arg.inspect} cannot be null */")
				end
			else
				self.add_abort("Receiver is null")
			end
			self.add("\} else \{")
		else
			self.add("\{")
		end
		if not self.compiler.modelbuilder.toolcontext.opt_no_shortcut_equate.value and (mmethod.name == "==" or mmethod.name == "!=" or mmethod.name == "is_same_instance") then
			# Recv is not null, thus if arg is, it is easy to conclude (and respect the invariants)
			var arg = arguments[1]
			if arg.mcasttype isa MNullType then
				if res == null then res = self.new_var(bool_type)
				if mmethod.name == "!=" then
					self.add("{res} = 1; /* arg is null and recv is not */")
				else # `==` and `is_same_instance`
					self.add("{res} = 0; /* arg is null but recv is not */")
				end
				self.add("\}") # closes the null case
				self.add("if (0) \{") # what follow is useless, CC will drop it
			end
		end
		return res
	end