add function_return helper to risc_value

create a function_return from within builder

lib/mom/instruction/message_setup.rb

@@ -6,7 +6,7 @@ module Mom
   # MessageSetup does Setup before a call can be made, acquiring and filling the message
   # basically.Only after MessageSetup is the next_message safe to use.
   #
-  # The space keeps a linked list of Messages, from which we take and currenty also return.
+  # The Space keeps a linked list of Messages, from which we take and currenty also return.
   #
   # Message setup set the name to the called method's name, and also set the arg and local
   # types on the new message, currently for debugging but later for dynamic checking

lib/risc/register_value.rb

@@ -134,6 +134,14 @@ module Risc
       op
     end
 
+    # generate a Function return instruction
+    # using the register as the parameter where the return address is passed
+    def function_return
+      ret = Risc::FunctionReturn.new("return", self)
+      builder.add_code(ret) if builder
+      ret
+    end
+
     # just capture the values in an intermediary object (RValue)
     # The RValue then gets used in a RegToSlot ot SlotToReg, where
     # the values are unpacked to call Risc.reg_to_slot or Risc.slot_to_reg

test/risc/test_register_value.rb

@@ -41,6 +41,11 @@ module Risc
       assert_equal :next_message , message.index
       assert_equal @r0 , message.register
     end
+    def test_return
+      ret = @r0.function_return
+      assert_equal FunctionReturn , ret.class
+      assert_equal @r0 , ret.register
+    end
     def test_slot_to_reg
       instr = @r0 << @r1[:next_message]
       assert_equal SlotToReg , instr.class