From e551732f18ba78ee0bda0a298c91fc271d1be20f Mon Sep 17 00:00:00 2001
From: Torsten Ruger <torsten@villataika.fi>
Date: Wed, 28 Dec 2016 20:37:54 +0200
Subject: [PATCH] tighter integration with factory methods for adding code

define methods to collapse the code Register.
in add_code Register.factory_method
most instructions done, except op and branch that are rare
---
 lib/register/builtin/compile_helper.rb        |  4 +--
 lib/register/builtin/integer.rb               | 28 +++++++++---------
 lib/register/builtin/kernel.rb                | 20 ++++++-------
 lib/register/builtin/object.rb                |  6 ++--
 lib/register/builtin/word.rb                  | 10 +++----
 lib/register/instructions/function_call.rb    | 10 +++----
 lib/typed/method_compiler.rb                  | 11 +++++--
 lib/typed/method_compiler/assignment.rb       |  4 +--
 lib/typed/method_compiler/basic_values.rb     | 12 ++++----
 lib/typed/method_compiler/call_site.rb        | 29 +++++++++----------
 lib/typed/method_compiler/field_access.rb     |  2 +-
 lib/typed/method_compiler/name_expression.rb  | 14 ++++-----
 lib/typed/method_compiler/return_statement.rb |  2 +-
 13 files changed, 79 insertions(+), 73 deletions(-)

diff --git a/lib/register/builtin/compile_helper.rb b/lib/register/builtin/compile_helper.rb
index ef35733b..bbd67680 100644
--- a/lib/register/builtin/compile_helper.rb
+++ b/lib/register/builtin/compile_helper.rb
@@ -17,8 +17,8 @@ module Register
       # Load the value
       def load_int_arg_at(compiler, source , at)
         int_arg = compiler.use_reg :Integer
-        compiler.add_code Register.slot_to_reg(source , :message , :arguments , int_arg )
-        compiler.add_code Register.slot_to_reg(source , int_arg , at + 1, int_arg ) #1 for type
+        compiler.add_slot_to_reg(source , :message , :arguments , int_arg )
+        compiler.add_slot_to_reg(source , int_arg , at + 1, int_arg ) #1 for type
         return int_arg
       end
 
diff --git a/lib/register/builtin/integer.rb b/lib/register/builtin/integer.rb
index 74a0363b..ed9b5c8e 100644
--- a/lib/register/builtin/integer.rb
+++ b/lib/register/builtin/integer.rb
@@ -25,47 +25,47 @@ module Register
           # int tmp = self >> 1
           compiler.add_code Register.op( s , ">>" , tmp , const)
           # int q = self >> 2
-          compiler.add_code Register.load_constant( s , 2 , const)
+          compiler.add_load_constant( s , 2 , const)
           compiler.add_code Register.op( s , ">>" , q , const)
           # q = q + tmp
           compiler.add_code Register.op( s , "+" , q , tmp )
           # tmp = q >> 4
-          compiler.add_code Register.load_constant( s , 4 , const)
-          compiler.add_code Register.transfer( s, q , tmp)
+          compiler.add_load_constant( s , 4 , const)
+          compiler.add_transfer( s, q , tmp)
           compiler.add_code Register.op( s , ">>" , tmp , const)
           # q = q + tmp
           compiler.add_code Register.op( s , "+" , q , tmp )
           # tmp = q >> 8
-          compiler.add_code Register.load_constant( s , 8 , const)
-          compiler.add_code Register.transfer( s, q , tmp)
+          compiler.add_load_constant( s , 8 , const)
+          compiler.add_transfer( s, q , tmp)
           compiler.add_code Register.op( s , ">>" , tmp , const)
           # q = q + tmp
           compiler.add_code Register.op( s , "+" , q , tmp )
           # tmp = q >> 16
-          compiler.add_code Register.load_constant( s , 16 , const)
-          compiler.add_code Register.transfer( s, q , tmp)
+          compiler.add_load_constant( s , 16 , const)
+          compiler.add_transfer( s, q , tmp)
           compiler.add_code Register.op( s , ">>" , tmp , const)
           # q = q + tmp
           compiler.add_code Register.op( s , "+" , q , tmp )
           # q = q >> 3
-          compiler.add_code Register.load_constant( s , 3 , const)
+          compiler.add_load_constant( s , 3 , const)
           compiler.add_code Register.op( s , ">>" , q , const)
           # tmp = q * 10
-          compiler.add_code Register.load_constant( s , 10 , const)
-          compiler.add_code Register.transfer( s, q , tmp)
+          compiler.add_load_constant( s , 10 , const)
+          compiler.add_transfer( s, q , tmp)
           compiler.add_code Register.op( s , "*" , tmp , const)
           # tmp = self - tmp
           compiler.add_code Register.op( s , "-" , me , tmp )
-          compiler.add_code Register.transfer( s , me , tmp)
+          compiler.add_transfer( s , me , tmp)
           # tmp = tmp + 6
-          compiler.add_code Register.load_constant( s , 6 , const)
+          compiler.add_load_constant( s , 6 , const)
           compiler.add_code Register.op( s , "+" , tmp , const )
           # tmp = tmp >> 4
-          compiler.add_code Register.load_constant( s , 4 , const)
+          compiler.add_load_constant( s , 4 , const)
           compiler.add_code Register.op( s , ">>" , tmp , const )
           # return q + tmp
           compiler.add_code Register.op( s , "+" , q , tmp )
-          compiler.add_code Register.reg_to_slot( s , q , :message , :return_value)
+          compiler.add_reg_to_slot( s , q , :message , :return_value)
           return compiler.method
         end
       end
diff --git a/lib/register/builtin/kernel.rb b/lib/register/builtin/kernel.rb
index 273d37d9..ac7c729b 100644
--- a/lib/register/builtin/kernel.rb
+++ b/lib/register/builtin/kernel.rb
@@ -13,14 +13,14 @@ module Register
 
           space = Parfait::Space.object_space
           space_reg = compiler.use_reg(:Space) #Set up the Space as self upon init
-          compiler.add_code Register.load_constant("__init__ load Space", space , space_reg)
+          compiler.add_load_constant("__init__ load Space", space , space_reg)
           message_ind = Register.resolve_to_index( :space , :first_message )
-          compiler.add_code Register.slot_to_reg( "__init__ load 1st message" , space_reg , message_ind , :message)
-          compiler.add_code Register.reg_to_slot( "__init__ store Space in message", space_reg , :message , :receiver)
+          compiler.add_slot_to_reg( "__init__ load 1st message" , space_reg , message_ind , :message)
+          compiler.add_reg_to_slot( "__init__ store Space in message", space_reg , :message , :receiver)
           exit_label = Register.label("_exit_label for __init__" , "#{compiler.type.object_class.name}.#{compiler.method.name}" )
           ret_tmp = compiler.use_reg(:Label)
-          compiler.add_code Register.load_constant("__init__ load return", exit_label , ret_tmp)
-          compiler.add_code Register.reg_to_slot("__init__ store return", ret_tmp , :message , :return_address)
+          compiler.add_load_constant("__init__ load return", exit_label , ret_tmp)
+          compiler.add_reg_to_slot("__init__ store return", ret_tmp , :message , :return_address)
           compiler.add_code Register.function_call( "__init__ issue call" ,  Register.machine.space.get_main )
           compiler.add_code exit_label
           emit_syscall( compiler , :exit )
@@ -38,7 +38,7 @@ module Register
           compiler.add_code Syscall.new("emit_syscall(#{name})", name )
           restore_message(compiler)
           return unless (@clazz and @method)
-          compiler.add_code Register.label( "#{@clazz.name}.#{@message.name}" , "return_syscall" )
+          compiler.add_label( "#{@clazz.name}.#{@message.name}" , "return_syscall" )
         end
 
         # save the current message, as the syscall destroys all context
@@ -47,7 +47,7 @@ module Register
         #
         def save_message(compiler)
           r8 = RegisterValue.new( :r8 , :Message)
-          compiler.add_code Register.transfer("save_message", Register.message_reg , r8 )
+          compiler.add_transfer("save_message", Register.message_reg , r8 )
         end
 
         def restore_message(compiler)
@@ -55,11 +55,11 @@ module Register
           return_tmp = Register.tmp_reg :Integer
           source = "_restore_message"
           # get the sys return out of the way
-          compiler.add_code Register.transfer(source, Register.message_reg , return_tmp )
+          compiler.add_transfer(source, Register.message_reg , return_tmp )
           # load the stored message into the base RegisterMachine
-          compiler.add_code Register.transfer(source, r8 , Register.message_reg )
+          compiler.add_transfer(source, r8 , Register.message_reg )
           # save the return value into the message
-          compiler.add_code Register.reg_to_slot( source , return_tmp , :message , :return_value )
+          compiler.add_reg_to_slot( source , return_tmp , :message , :return_value )
         end
       end
       extend ClassMethods
diff --git a/lib/register/builtin/object.rb b/lib/register/builtin/object.rb
index d8b1116e..a67132f0 100644
--- a/lib/register/builtin/object.rb
+++ b/lib/register/builtin/object.rb
@@ -14,9 +14,9 @@ module Register
           source = "get_internal_word"
           me , index = self_and_int_arg(compiler,source)
           # reduce me to me[index]
-          compiler.add_code  Register.slot_to_reg( source , me , index , me)
+          compiler.add_slot_to_reg( source , me , index , me)
           # and put it back into the return value
-          compiler.add_code Register.reg_to_slot( source , me , :message , :return_value)
+          compiler.add_reg_to_slot( source , me , :message , :return_value)
           return compiler.method
         end
 
@@ -29,7 +29,7 @@ module Register
           value = load_int_arg_at(compiler,source , 2)
 
           # do the set
-          compiler.add_code Register.reg_to_slot( source , value , me , index)
+          compiler.add_reg_to_slot( source , value , me , index)
           return compiler.method
         end
 
diff --git a/lib/register/builtin/word.rb b/lib/register/builtin/word.rb
index 7a7e90b8..536c2326 100644
--- a/lib/register/builtin/word.rb
+++ b/lib/register/builtin/word.rb
@@ -8,10 +8,10 @@ module Register
 
         def putstring context
           compiler = Typed::MethodCompiler.new.create_method(:Word , :putstring ).init_method
-          compiler.add_code Register.slot_to_reg( "putstring" , :message , :receiver , :new_message )
+          compiler.add_slot_to_reg( "putstring" , :message , :receiver , :new_message )
           index = Parfait::Word.get_length_index
           reg = RegisterValue.new(:r2 , :Integer)
-          compiler.add_code Register.slot_to_reg( "putstring" , :new_message , index , reg )
+          compiler.add_slot_to_reg( "putstring" , :new_message , index , reg )
           Kernel.emit_syscall( compiler , :putstring )
           compiler.method
         end
@@ -23,9 +23,9 @@ module Register
           source = "get_internal_byte"
           me , index = self_and_int_arg(compiler,source)
           # reduce me to me[index]
-          compiler.add_code Register.byte_to_reg( source , me , index , me)
+          compiler.add_byte_to_reg( source , me , index , me)
           # and put it back into the return value
-          compiler.add_code Register.reg_to_slot( source , me , :message , :return_value)
+          compiler.add_reg_to_slot( source , me , :message , :return_value)
           return compiler.method
         end
 
@@ -41,7 +41,7 @@ module Register
           me , index = self_and_int_arg(compiler,source)
           value = load_int_arg_at(compiler , source , 2 )
           # do the set
-          compiler.add_code Register.reg_to_byte( source , value , me , index)
+          compiler.add_reg_to_byte( source , value , me , index)
           return compiler.method
         end
 
diff --git a/lib/register/instructions/function_call.rb b/lib/register/instructions/function_call.rb
index 3c86a952..f9d6ea07 100644
--- a/lib/register/instructions/function_call.rb
+++ b/lib/register/instructions/function_call.rb
@@ -22,12 +22,12 @@ module Register
   def self.issue_call( compiler , callee )
     return_label = Register.label("_return_label #{callee.name}" , "#{compiler.type.object_class.name}.#{compiler.method.name}" )
     ret_tmp = compiler.use_reg(:Label)
-    compiler.add_code Register.load_constant("#{callee.name} load ret", return_label , ret_tmp)
-    compiler.add_code Register.reg_to_slot("#{callee.name} store ret", ret_tmp , :new_message , :return_address)
-    compiler.add_code Register.transfer("#{callee.name} move new message", Register.new_message_reg , Register.message_reg )
+    compiler.add_load_constant("#{callee.name} load ret", return_label , ret_tmp)
+    compiler.add_reg_to_slot("#{callee.name} store ret", ret_tmp , :new_message , :return_address)
+    compiler.add_transfer("#{callee.name} move new message", Register.new_message_reg , Register.message_reg )
     compiler.add_code Register.function_call( "#{callee.name} call" , callee )
     compiler.add_code return_label
-    compiler.add_code Register.transfer("#{callee.name} remove new message", Register.message_reg , Register.new_message_reg )
-    compiler.add_code Register.slot_to_reg("#{callee.name} restore message" , :new_message , :caller , :message )
+    compiler.add_transfer("#{callee.name} remove new message", Register.message_reg , Register.new_message_reg )
+    compiler.add_slot_to_reg("#{callee.name} restore message" , :new_message , :caller , :message )
   end
 end
diff --git a/lib/typed/method_compiler.rb b/lib/typed/method_compiler.rb
index 1c94486f..17eaea87 100644
--- a/lib/typed/method_compiler.rb
+++ b/lib/typed/method_compiler.rb
@@ -135,9 +135,9 @@ module Typed
       name = "#{method.for_type.name}.#{method.name}"
       @method.instructions = Register.label(source, name)
       @current = enter = method.instructions
-      add_code Register.label( source, "return #{name}")
+      add_label( source, "return #{name}")
       #load the return address into pc, affecting return. (other cpus have commands for this, but not arm)
-      add_code Register.function_return( source , Register.message_reg , Register.resolve_to_index(:message , :return_address) )
+      add_function_return( source , Register.message_reg , Register.resolve_to_index(:message , :return_address) )
       @current = enter
       self
     end
@@ -157,6 +157,13 @@ module Typed
       self
     end
 
+    [:label, :reg_to_slot , :slot_to_reg , :load_constant, :function_return ,
+      :transfer , :reg_to_slot , :byte_to_reg , :reg_to_byte].each do |method|
+      define_method("add_#{method}".to_sym) do |*args|
+        add_code Register.send( method , *args )
+      end
+    end
+
     # require a (temporary) register. code must give this back with release_reg
     def use_reg( type , value = nil )
       raise "Not type #{type.inspect}" unless type.is_a?(Symbol) or type.is_a?(Parfait::Type)
diff --git a/lib/typed/method_compiler/assignment.rb b/lib/typed/method_compiler/assignment.rb
index 3ffa5da2..eabc7a18 100644
--- a/lib/typed/method_compiler/assignment.rb
+++ b/lib/typed/method_compiler/assignment.rb
@@ -17,8 +17,8 @@ module Typed
          value_type = @method.locals_type( index )
       end
       raise "Type mismatch for #{type} access #{value.type}!=#{value_type}" unless value.type == value_type
-      add_code Register.slot_to_reg(statement , :message , type , named_list )
-      add_code Register.reg_to_slot(statement , value , named_list , index + 1 ) # one for type
+      add_slot_to_reg(statement , :message , type , named_list )
+      add_reg_to_slot(statement , value , named_list , index + 1 ) # one for type
     end
 
     # ensure the name given is not space and raise exception otherwise
diff --git a/lib/typed/method_compiler/basic_values.rb b/lib/typed/method_compiler/basic_values.rb
index b7551538..8b23ad3a 100644
--- a/lib/typed/method_compiler/basic_values.rb
+++ b/lib/typed/method_compiler/basic_values.rb
@@ -13,25 +13,25 @@ module Typed
     def on_IntegerExpression expression
       int = expression.value
       reg = use_reg :Integer , int
-      add_code Register.load_constant( expression, int , reg )
+      add_load_constant( expression, int , reg )
       return reg
     end
 
     def on_TrueExpression expression
       reg = use_reg :Boolean
-      add_code Register.load_constant( expression, true , reg )
+      add_load_constant( expression, true , reg )
       return reg
     end
 
     def on_FalseExpression expression
       reg = use_reg :Boolean
-      add_code Register.load_constant( expression, false , reg )
+      add_load_constant( expression, false , reg )
       return reg
     end
 
     def on_NilExpression expression
       reg = use_reg :NilClass
-      add_code Register.load_constant( expression, nil , reg )
+      add_load_constant( expression, nil , reg )
       return reg
     end
 
@@ -39,7 +39,7 @@ module Typed
       value = Parfait.new_word expression.value.to_sym
       reg = use_reg :Word
       Register.machine.constants << value
-      add_code Register.load_constant( expression, value , reg )
+      add_load_constant( expression, value , reg )
       return reg
     end
 
@@ -48,7 +48,7 @@ module Typed
       clazz = Parfait::Space.object_space.get_class_by_name! name
       raise "No such class #{name}" unless clazz
       reg = use_reg :MetaClass , clazz
-      add_code Register.load_constant( expression, clazz , reg )
+      add_load_constant( expression, clazz , reg )
       return reg
     end
 
diff --git a/lib/typed/method_compiler/call_site.rb b/lib/typed/method_compiler/call_site.rb
index 8c1dc7e7..6997dfb1 100644
--- a/lib/typed/method_compiler/call_site.rb
+++ b/lib/typed/method_compiler/call_site.rb
@@ -7,7 +7,7 @@ module Typed
       reset_regs
       #move the new message (that we need to populate to make a call) to std register
       new_message = Register.resolve_to_register(:new_message)
-      add_code Register.slot_to_reg(statement, :message , :next_message , new_message )
+      add_slot_to_reg(statement, :message , :next_message , new_message )
       me = get_me( statement )
       type = get_my_type(me)
 
@@ -15,7 +15,7 @@ module Typed
       raise "Method not implemented #{type.inspect}.#{statement.name}" unless method
 
       # move our receiver there
-      add_code Register.reg_to_slot( statement , me , :new_message , :receiver)
+      add_reg_to_slot( statement , me , :new_message , :receiver)
 
       set_message_details(method , statement , statement.arguments)
       set_arguments(method , statement.arguments)
@@ -25,7 +25,7 @@ module Typed
 
       # the effect of the method is that the NewMessage Return slot will be filled, return it
       # but move it into a register too
-      add_code Register.slot_to_reg(statement, :new_message , :return_value , ret )
+      add_slot_to_reg(statement, :new_message , :return_value , ret )
       ret
     end
 
@@ -36,7 +36,7 @@ module Typed
         me = process( statement.receiver  )
       else
         me = use_reg @method.for_type
-        add_code Register.slot_to_reg(statement, :message , :receiver , me )
+        add_slot_to_reg(statement, :message , :receiver , me )
       end
       me
     end
@@ -58,22 +58,22 @@ module Typed
     def set_message_details( method , name_s , arguments )
       name = name_s.name
       name_tmp = use_reg(:Word)
-      add_code Register.load_constant("#{name} load method name", name , name_tmp)
-      add_code Register.reg_to_slot( "#{name} store method name" , name_tmp , :new_message , :name)
+      add_load_constant("#{name} load method name", name , name_tmp)
+      add_reg_to_slot( "#{name} store method name" , name_tmp , :new_message , :name)
       # next arg and local types
       args_reg = use_reg(:Type , method.arguments )
       list_reg = use_reg(:NamedList , arguments )
-      add_code Register.load_constant("#{name} load methods", method , args_reg)
+      add_load_constant("#{name} load methods", method , args_reg)
       args_type_index = method.get_type().variable_index(:arguments)
       raise args_type_index.to_s unless args_type_index == 6
-      add_code Register.slot_to_reg( "#{name} get args type from method" , args_reg ,  args_type_index ,  args_reg  )
-      add_code Register.slot_to_reg( "#{name} get args from method" , :new_message , :arguments , list_reg )
-      add_code Register.reg_to_slot( "#{name} store args type in args" , args_reg , list_reg , 1  )
+      add_slot_to_reg( "#{name} get args type from method" , args_reg ,  args_type_index ,  args_reg  )
+      add_slot_to_reg( "#{name} get args from method" , :new_message , :arguments , list_reg )
+      add_reg_to_slot( "#{name} store args type in args" , args_reg , list_reg , 1  )
 
 #FIXME need to set type of locals too. sama sama
 #      len_tmp = use_reg(:Integer , arguments.to_a.length )
-#      add_code Register.load_constant(name_s, arguments.to_a.length , len_tmp)
-#      add_code Register.reg_to_slot( name_s , len_tmp , :new_message , :indexed_length)
+#      add_load_constant(name_s, arguments.to_a.length , len_tmp)
+#      add_reg_to_slot( name_s , len_tmp , :new_message , :indexed_length)
     end
 
     def set_arguments( method , arguments )
@@ -89,10 +89,9 @@ module Typed
         #FIXME definately needs some tests
         raise "TypeMismatch calling with #{val.type} , instead of #{arg_type.type_at(i + 2)}" if val.type != arg_type.type_at(i + 2)
         list_reg = use_reg(:NamedList , arguments )
-        add_code Register.slot_to_reg( "Set arg #{i}:#{arg}" , :new_message , :arguments , list_reg )
+        add_slot_to_reg( "Set arg #{i}:#{arg}" , :new_message , :arguments , list_reg )
         # which we load int the new_message at the argument's index
-        set = Register.reg_to_slot( arg , val , list_reg , i + 2 ) #one for type and one for ruby
-        add_code set
+        add_reg_to_slot( arg , val , list_reg , i + 2 ) #one for type and one for ruby
       end
     end
   end
diff --git a/lib/typed/method_compiler/field_access.rb b/lib/typed/method_compiler/field_access.rb
index 8aec8cbe..84569f20 100644
--- a/lib/typed/method_compiler/field_access.rb
+++ b/lib/typed/method_compiler/field_access.rb
@@ -15,7 +15,7 @@ module Typed
       raise "no such field:#{field_name} for class #{type.inspect}" unless index
       value = use_reg(type.type_at(index))
 
-      add_code Register.slot_to_reg(statement , receiver , index, value)
+      add_slot_to_reg(statement , receiver , index, value)
 
       value
     end
diff --git a/lib/typed/method_compiler/name_expression.rb b/lib/typed/method_compiler/name_expression.rb
index 2f9ad6f2..c3f452f7 100644
--- a/lib/typed/method_compiler/name_expression.rb
+++ b/lib/typed/method_compiler/name_expression.rb
@@ -15,8 +15,8 @@ module Typed
           named_list = use_reg :NamedList
           ret = use_reg @method.argument_type(index)
           #puts "For #{name} at #{index} got #{@method.arguments.inspect}"
-          add_code Register.slot_to_reg("#{statement} load args" , :message , :arguments, named_list )
-          add_code Register.slot_to_reg("#{statement} load #{name}" , named_list , index + 1, ret )
+          add_slot_to_reg("#{statement} load args" , :message , :arguments, named_list )
+          add_slot_to_reg("#{statement} load #{name}" , named_list , index + 1, ret )
           return ret
         end
         # or a local so it is in the named_list
@@ -30,28 +30,28 @@ module Typed
         index = @method.has_local( name )
         raise "must define variable '#{name}' before using it" unless index
         named_list = use_reg :NamedList
-        add_code Register.slot_to_reg("#{name} load locals" , :message , :locals , named_list )
+        add_slot_to_reg("#{name} load locals" , :message , :locals , named_list )
         ret = use_reg @method.locals_type( index )
-        add_code Register.slot_to_reg("#{name} load from locals" , named_list , index + 1, ret )
+        add_slot_to_reg("#{name} load from locals" , named_list , index + 1, ret )
         return ret
       end
 
       def handle_special_self(statement)
         ret = use_reg @type
-        add_code Register.slot_to_reg("#{statement} load self" , :message , :receiver , ret )
+        add_slot_to_reg("#{statement} load self" , :message , :receiver , ret )
         return ret
       end
 
       def handle_special_space(statement)
         space = Parfait::Space.object_space
         reg = use_reg :Space , space
-        add_code Register.load_constant( "#{statement} load space", space , reg )
+        add_load_constant( "#{statement} load space", space , reg )
         return reg
       end
 
       def handle_special_message(statement)
         reg = use_reg :Message
-        add_code Register.transfer( "#{statement} load message", Register.message_reg , reg )
+        add_transfer( "#{statement} load message", Register.message_reg , reg )
         return reg
       end
   end #module
diff --git a/lib/typed/method_compiler/return_statement.rb b/lib/typed/method_compiler/return_statement.rb
index d91b6120..18a8ae19 100644
--- a/lib/typed/method_compiler/return_statement.rb
+++ b/lib/typed/method_compiler/return_statement.rb
@@ -3,7 +3,7 @@ module Typed
 
     def on_ReturnStatement statement
       reg =  process(statement.return_value)
-      add_code Register.reg_to_slot( statement, reg , :message , :return_value)
+      add_reg_to_slot( statement, reg , :message , :return_value)
       nil # statements don't return
     end
   end