bring the blocks down to mom level

reusing message_setup, but adding yield specific instructions

lib/mom/instruction/block_yield.rb

@@ -0,0 +1,31 @@
+module Mom
+
+  # A BlockYield calls an argument block. All we need to know is the index
+  # of the argument, and the rest is almost as simple as a SimpleCall
+
+  class BlockYield < Instruction
+    attr :arg_index
+
+    def initialize(index)
+      @arg_index = index
+    end
+
+    def to_s
+      "BlockYield[#{arg_index}] "
+    end
+
+    def to_risc(compiler)
+      block = compiler.use_reg( :Block )
+      return_label = Risc.label(self, "continue_#{object_id}")
+      save_return =  SlotLoad.new([:message,:next_message,:return_address],[return_label],self)
+      moves = save_return.to_risc(compiler)
+      moves << Risc.slot_to_reg( self , Risc.message_reg ,:arguments , block)
+      moves << Risc.slot_to_reg( self , block ,arg_index , block)
+
+      moves << Risc.slot_to_reg(self, Risc.message_reg , :next_message , Risc.message_reg)
+      moves << Risc::DynamicJump.new(self, block )
+      moves << return_label
+    end
+  end
+
+end

lib/mom/instruction/instruction.rb

@@ -32,6 +32,7 @@ require_relative "check"
 require_relative "basic_values"
 require_relative "simple_call"
 require_relative "dynamic_call"
+require_relative "block_yield"
 require_relative "resolve_method"
 require_relative "truth_check"
 require_relative "not_same_check"

lib/mom/instruction/message_setup.rb

@@ -42,8 +42,13 @@ module Mom
           cache_entry << from
           callable_method << cache_entry[:cached_method]
         end
+      when Integer
+        builder.build do
+          arguments << message[:arguments]
+          callable_method << arguments[ from ]
+        end
       else
-        raise "unknown source #{method_source}"
+        raise "unknown source #{method_source.class}:#{method_source}"
       end
       build_message_data(builder)
       return builder.built