add source to instruction

for debug

lib/register/instruction.rb

@@ -9,6 +9,11 @@ module Register
   # constants can/must be loaded into registers before use
   class Instruction
 
+    def initialize source
+        @source = source
+    end
+    attr_reader :block , :source
+
     # returns an array of registers (RegisterReferences) that this instruction uses.
     # ie for r1 = r2 + r3
     # which in assembler is add r1 , r2 , r3

lib/register/instructions/branch.rb

@@ -3,10 +3,17 @@ module Register
 
   # a branch must branch to a block.
   class Branch < Instruction
-    def initialize to
+    def initialize source , to
+      super(source)
       raise "No block" unless to
       @block = to
     end
     attr_reader :block 
+
+    def to_s
+      "Branch(to: #{block.name})"
     end
+
+  end
+
 end

lib/register/passes/main_implementation.rb

@@ -8,7 +8,7 @@ module Register
     def run block
       block.codes.dup.each do |code|
         next unless code.is_a? Virtual::VirtualMain
-        branch = Register::Branch.new( code.method.source.blocks.first )
+        branch = Register::Branch.new( code , code.method.source.blocks.first )
         block.replace(code , branch )
       end
     end

lib/virtual/instructions/virtual_main.rb

@@ -15,5 +15,9 @@ module Virtual
     def word_length
       4
     end
+
+    def to_s
+      "#{self.class.name}( method: #{method.name})"
+    end
   end
 end

lib/virtual/machine.rb

@@ -35,6 +35,8 @@ module Virtual
   class Machine
 
     FIRST_PASS = "Virtual::SendImplementation"
+    LAST_PASS = "Virtual::SetOptimisation"
+    
     def initialize
       @parser  = Parser::Salama.new
       @passes = [  FIRST_PASS ]