diff --git a/lib/register/builtin/kernel.rb b/lib/register/builtin/kernel.rb
index 32866f40..ee5eea04 100644
--- a/lib/register/builtin/kernel.rb
+++ b/lib/register/builtin/kernel.rb
@@ -13,12 +13,12 @@ module Register
           function.source.blocks.last.codes.pop # no Method return
           #Set up the Space as self upon init
           space = Parfait::Space.object_space
-          function.source.add_code LoadConstant.new( space , Register.self_reg)
+          function.source.add_code LoadConstant.new(function, space , Register.self_reg)
           message_ind = Register.resolve_index( :space , :first_message )
           # Load the message to new message register (r3)
-          function.source.add_code Register.get_slot( :self , message_ind , :new_message)
+          function.source.add_code Register.get_slot( function , :self , message_ind , :new_message)
           # And store the space as the new self (so the call can move it back as self)
-          function.source.add_code Register.set_slot( :self , :new_message , :receiver)
+          function.source.add_code Register.set_slot( function, :self , :new_message , :receiver)
           # now we are set up to issue a call to the main
           function.source.add_code Virtual::MethodCall.new(Virtual.machine.space.get_main)
           emit_syscall( function , :exit )
@@ -40,29 +40,29 @@ module Register
 
         def emit_syscall function , name
           save_message( function )
-          function.source.add_code Syscall.new( name )
+          function.source.add_code Syscall.new(function, name )
           restore_message(function)
         end
 
         # save the current message, as the syscall destroys all context
         #
         # This relies on linux to save and restore all registers
-        # 
+        #
         def save_message(function)
-          function.source.add_code RegisterTransfer.new( Register.message_reg , :r8 )
+          function.source.add_code RegisterTransfer.new(function, Register.message_reg , :r8 )
         end
 
         def restore_message(function)
           return_tmp = Register.tmp_reg
           # get the sys return out of the way
-          function.source.add_code RegisterTransfer.new( Register.message_reg , return_tmp )
+          function.source.add_code RegisterTransfer.new(function, Register.message_reg , return_tmp )
           # load the stored message into the base RegisterMachine
-          function.source.add_code RegisterTransfer.new( :r8 , Register.message_reg )
+          function.source.add_code RegisterTransfer.new(function, :r8 , Register.message_reg )
           # save the return value into the message
-          function.source.add_code Register.set_slot( return_tmp , :message , :return_value )
+          function.source.add_code Register.set_slot( function, return_tmp , :message , :return_value )
           # and "unroll" self and frame
-          function.source.add_code Register.get_slot(:message , :receiver, :self )
-          function.source.add_code Register.get_slot(:message , :frame , :frame)
+          function.source.add_code Register.get_slot(function, :message , :receiver, :self )
+          function.source.add_code Register.get_slot(function, :message , :frame , :frame)
         end
       end
       extend ClassMethods
diff --git a/lib/register/instruction.rb b/lib/register/instruction.rb
index d599ef8c..85bd7541 100644
--- a/lib/register/instruction.rb
+++ b/lib/register/instruction.rb
@@ -12,7 +12,7 @@ module Register
     def initialize source
         @source = source
     end
-    attr_reader :block , :source
+    attr_reader :source
 
     # returns an array of registers (RegisterReferences) that this instruction uses.
     # ie for r1 = r2 + r3
diff --git a/lib/register/instructions/function_call.rb b/lib/register/instructions/function_call.rb
index ab2e4b4b..88c8a69f 100644
--- a/lib/register/instructions/function_call.rb
+++ b/lib/register/instructions/function_call.rb
@@ -4,7 +4,8 @@ module Register
   # assembly takes care of the rest (ie getting the address)
 
   class FunctionCall < Instruction
-    def initialize method
+    def initialize source , method
+      super(source)
       @method = method
     end
     attr_reader :method
diff --git a/lib/register/instructions/function_return.rb b/lib/register/instructions/function_return.rb
index 93393178..6e4247fc 100644
--- a/lib/register/instructions/function_return.rb
+++ b/lib/register/instructions/function_return.rb
@@ -4,7 +4,8 @@ module Register
   # register and index specify where the return address is stored
 
   class FunctionReturn < Instruction
-    def initialize register , index
+    def initialize source , register , index
+      super(source)
       @register = register
       @index = index
     end
diff --git a/lib/register/instructions/get_slot.rb b/lib/register/instructions/get_slot.rb
index 5e7b5cf9..1189388f 100644
--- a/lib/register/instructions/get_slot.rb
+++ b/lib/register/instructions/get_slot.rb
@@ -18,30 +18,31 @@ module Register
     # the instruction would do register = array[index]
     # The arguments are in the order that makes sense for the Instruciton name
     # So GetSlot means the slot (array and index) moves to the register (last argument)
-    def initialize array , index , register
-      @register = register
+    def initialize source , array , index , register
+      super(source)
       @array = array
       @index = index
+      @register = register
       raise "not integer #{index}" unless index.is_a? Numeric
       raise "Not register #{register}" unless Register::RegisterReference.look_like_reg(register)
       raise "Not register #{array}" unless Register::RegisterReference.look_like_reg(array)
     end
-    attr_accessor :register , :array , :index
+    attr_accessor :array , :index , :register
 
     def to_s
-      "GetSlot: #{register} -> #{array} [#{index}]"
+      "GetSlot: #{array} [#{index}] -> #{register}"
     end
 
   end
 
   # Produce a GetSlot instruction.
-  # From and to are registers or symbols that can be transformed to a register by resolve_to_register
+  # Array and to are registers or symbols that can be transformed to a register by resolve_to_register
   # index resolves with resolve_index.
-  def self.get_slot from , index , to
-    index = resolve_index( from , index)
-    from = resolve_to_register from
+  def self.get_slot source , array , index , to
+    index = resolve_index( array , index)
+    array = resolve_to_register array
     to = resolve_to_register to
-    GetSlot.new( from , index , to)
+    GetSlot.new( source , array , index , to)
   end
 
 end
diff --git a/lib/register/instructions/load_constant.rb b/lib/register/instructions/load_constant.rb
index 00f52b97..614125d2 100644
--- a/lib/register/instructions/load_constant.rb
+++ b/lib/register/instructions/load_constant.rb
@@ -5,7 +5,8 @@ module Register
   # second argument is the register the constant is loaded into
 
   class LoadConstant < Instruction
-    def initialize constant , register
+    def initialize source , constant , register
+      super(source)
       @register = register
       @constant = constant
     end
diff --git a/lib/register/instructions/register_transfer.rb b/lib/register/instructions/register_transfer.rb
index 91945fde..382f1a8f 100644
--- a/lib/register/instructions/register_transfer.rb
+++ b/lib/register/instructions/register_transfer.rb
@@ -16,7 +16,8 @@ module Register
     # second arguemnt to
     #
     # Note: this may be reversed from some assembler notations (also arm)
-    def initialize from , to
+    def initialize source , from , to
+      super(source)
       @from = wrap_register(from)
       @to = wrap_register(to)
     end
diff --git a/lib/register/instructions/save_return.rb b/lib/register/instructions/save_return.rb
index 910346b8..9eb41a1a 100644
--- a/lib/register/instructions/save_return.rb
+++ b/lib/register/instructions/save_return.rb
@@ -7,7 +7,8 @@ module Register
   # address. In arm that is a register, but intel may (?) push it, and who knows, what other machines do.
 
   class SaveReturn < Instruction
-    def initialize register , index
+    def initialize source , register , index
+      super(source)
       @register = register
       @index = index
     end
@@ -22,10 +23,10 @@ module Register
   # Produce a SaveReturn instruction.
   # From is a register or symbol that can be transformed to a register by resolve_to_register
   # index resolves with resolve_index.
-  def self.save_return from , index
+  def self.save_return code, from , index
     index = resolve_index( from , index)
     from = resolve_to_register from
-    SaveReturn.new( from , index )
+    SaveReturn.new( code , from , index )
   end
 
 end
diff --git a/lib/register/instructions/set_slot.rb b/lib/register/instructions/set_slot.rb
index 926fc562..d56577ce 100644
--- a/lib/register/instructions/set_slot.rb
+++ b/lib/register/instructions/set_slot.rb
@@ -17,7 +17,8 @@ module Register
     # If you had a c array and index offset
     # the instruction would do array[index] = register
     # So SetSlot means the register (first argument) moves to the slot (array and index)
-    def initialize register , array , index
+    def initialize source , register , array , index
+      super(source)
       @register = register
       @array = array
       @index = index
@@ -35,11 +36,11 @@ module Register
   # Produce a SetSlot instruction.
   # From and to are registers or symbols that can be transformed to a register by resolve_to_register
   # index resolves with resolve_index.
-  def self.set_slot from , to , index
-    index = resolve_index( to , index)
+  def self.set_slot source , from , to , index
     from = resolve_to_register from
+    index = resolve_index( to , index)
     to = resolve_to_register to
-    SetSlot.new( from , to , index)
+    SetSlot.new( source, from , to , index)
   end
 
 end
diff --git a/lib/register/instructions/syscall.rb b/lib/register/instructions/syscall.rb
index a96f83be..11c9d975 100644
--- a/lib/register/instructions/syscall.rb
+++ b/lib/register/instructions/syscall.rb
@@ -9,7 +9,8 @@ module Register
 
   class Syscall < Instruction
 
-    def initialize name
+    def initialize source ,name
+      super(source)
       @name = name
     end
     attr_reader :name
diff --git a/lib/register/passes/call_implementation.rb b/lib/register/passes/call_implementation.rb
index 1ad73646..b529b59e 100644
--- a/lib/register/passes/call_implementation.rb
+++ b/lib/register/passes/call_implementation.rb
@@ -13,11 +13,11 @@ module Register
         next unless code.is_a? Virtual::MethodCall
         new_codes = []
         # move the current new_message to message
-        new_codes << RegisterTransfer.new( Register.new_message_reg , Register.message_reg )
+        new_codes << RegisterTransfer.new(code, Register.new_message_reg , Register.message_reg )
         # "roll out" self into its register
-        new_codes << Register.get_slot( :message , :receiver, :self )
+        new_codes << Register.get_slot( code , :message , :receiver, :self )
         # do the register call
-        new_codes << FunctionCall.new( code.method )
+        new_codes << FunctionCall.new( code , code.method )
         block.replace(code , new_codes )
       end
     end
diff --git a/lib/register/passes/frame_implementation.rb b/lib/register/passes/frame_implementation.rb
index 44c59141..3382bdcc 100644
--- a/lib/register/passes/frame_implementation.rb
+++ b/lib/register/passes/frame_implementation.rb
@@ -13,7 +13,7 @@ module Register
       block.codes.dup.each do |code|
         next unless code.is_a?(Virtual::NewFrame)
         # load the frame from message by index, simple get_slot
-        new_codes = [ Register.get_slot( :message , :frame , Register.resolve_to_register(:frame))]
+        new_codes = [ Register.get_slot( code, :message , :frame , Register.resolve_to_register(:frame))]
         block.replace(code , new_codes )
       end
     end
diff --git a/lib/register/passes/message_implementation.rb b/lib/register/passes/message_implementation.rb
index 38a03e34..f5e5255d 100644
--- a/lib/register/passes/message_implementation.rb
+++ b/lib/register/passes/message_implementation.rb
@@ -23,7 +23,7 @@ module Register
       block.codes.dup.each do |code|
         next unless code.is_a?(Virtual::NewMessage)
         # load the new_message from message by index, simple get_slot
-        new_codes = [ Register.get_slot( :message , :next_message , Register.resolve_to_register(:new_message))]
+        new_codes = [ Register.get_slot(code, :message , :next_message , Register.resolve_to_register(:new_message))]
         block.replace(code , new_codes )
       end
     end
diff --git a/lib/register/passes/return_implementation.rb b/lib/register/passes/return_implementation.rb
index 2fba2cd4..ba306273 100644
--- a/lib/register/passes/return_implementation.rb
+++ b/lib/register/passes/return_implementation.rb
@@ -5,14 +5,14 @@ module Register
         next unless code.is_a? Virtual::MethodReturn
         new_codes = []
         # move the current message to new_message
-        new_codes << RegisterTransfer.new( Register.message_reg , Register.new_message_reg )
+        new_codes << RegisterTransfer.new(code, Register.message_reg , Register.new_message_reg )
         # and restore the message from saved value in new_message
-        new_codes << Register.get_slot(:new_message , :caller , :message )
+        new_codes << Register.get_slot(code,:new_message , :caller , :message )
         # "roll out" self and frame into their registers
-        new_codes << Register.get_slot( :message , :receiver , :self )
-        new_codes << Register.get_slot( :message , :frame , :frame )
+        new_codes << Register.get_slot(code, :message , :receiver , :self )
+        new_codes << Register.get_slot(code, :message , :frame , :frame )
         #load the return address into pc, affecting return. (other cpus have commands for this, but not arm)
-        new_codes << FunctionReturn.new( Register.message_reg , Register.resolve_index(:message , :return_address) )
+        new_codes << FunctionReturn.new( code , Register.message_reg , Register.resolve_index(:message , :return_address) )
         block.replace(code , new_codes )
       end
     end
diff --git a/lib/register/passes/set_implementation.rb b/lib/register/passes/set_implementation.rb
index 13da1ca9..bca5a573 100644
--- a/lib/register/passes/set_implementation.rb
+++ b/lib/register/passes/set_implementation.rb
@@ -11,11 +11,11 @@ module Register
         tmp = Register.tmp_reg
         # for constants we have to "move" the constants value
         if( code.from.is_a?(Parfait::Value) or code.from.is_a?(Symbol))
-          move1 = LoadConstant.new( code.from , tmp )
+          move1 = LoadConstant.new(code, code.from , tmp )
         else # while otherwise we "load"
-          move1 = Register.get_slot( code.from.object_name , get_index(code.from) , tmp )
+          move1 = Register.get_slot(code, code.from.object_name , get_index(code.from) , tmp )
         end
-        move2 = Register.set_slot( tmp , code.to.object_name , get_index(code.to) )
+        move2 = Register.set_slot( code , tmp , code.to.object_name , get_index(code.to) )
         block.replace(code , [move1,move2] )
       end
     end
diff --git a/lib/virtual/passes/enter_implementation.rb b/lib/virtual/passes/enter_implementation.rb
index d5529675..378cd006 100644
--- a/lib/virtual/passes/enter_implementation.rb
+++ b/lib/virtual/passes/enter_implementation.rb
@@ -6,7 +6,7 @@ module Virtual
         next unless code.is_a? Virtual::MethodEnter
         new_codes = []
         # save return register to the message at instance return_address
-        new_codes << Register.save_return(:message , :return_address)
+        new_codes << Register.save_return(code, :message , :return_address)
         # and create a new frame if needed
         unless code.method.locals.empty? and code.method.tmps.empty?
           new_codes << Virtual::NewFrame.new