codes the while, but the testing throws stack too deep because loop detection is missing

lib/ast/while_expression.rb

@@ -2,7 +2,24 @@ module Ast
   class WhileExpression < Expression
 #    attr_reader  :condition, :body
     def compile frame , method
-      Virtual::Reference.new
+      start = Virtual::Label.new("while_start")
+      method.add start
+      is = condition.compile(frame , method)
+      branch = Virtual::ImplicitBranch.new "while"
+      merge = Virtual::Label.new(branch.name)
+      branch.other = merge   #false jumps to end of while
+      method.add branch
+      last = is
+      body.each do |part|
+        last = part.compile(frame,method )
+        raise part.inspect if last.nil?
+      end
+      # unconditionally brnach to the start
+      method.add start
+      # here we add the end of while that the branch jumps to
+      #but don't link it in (not using add)
+      method.current =  merge
+      last
     end
     def old
       into = context.function

lib/virtual/instruction.rb

@@ -77,7 +77,8 @@ module Virtual
         before_label.next = label
       end
     end
-    attr_reader :other , :name
+    attr_reader :name
+    attr_accessor :other
     def attributes
       [:name , :next , :other]
     end

test/virtual/test_methods.rb

@@ -58,14 +58,28 @@ HERE
       check
   end
 
-  def ttest_function_return
+  def test_function_while
+    @string_input    = <<HERE
+def fibonaccit(n)
+  a = 0
+  while (n) do
+    some = 43
+    other = some * 4
+  end
+end
+HERE
+    @output = [Virtual::MethodDefinition.new(:ofthen,[Virtual::Argument.new(:n,Virtual::Mystery.new())],Virtual::SelfReference.new(nil),Virtual::Local.new(:maybenot,Virtual::IntegerConstant.new(667)),Virtual::MethodEnter.new(Virtual::ImplicitBranch.new(:if_merge_2,Virtual::FrameSet.new(:isit,Virtual::IntegerConstant.new(42),Virtual::Label.new(:if_merge_2,nil)),Virtual::FrameSet.new(:maybenot,Virtual::IntegerConstant.new(667),Virtual::Label.new(:if_merge_2,nil)))))]
+    check
+  end
+
+  def test_function_return
     @string_input    = <<HERE
 def retvar(n)
   i = 5
   return i 
 end
 HERE
-    @output = [Virtual::MethodDefinition.new(:foo,[Ast::NameExpression.new(:x)])]
+    @output = [Virtual::MethodDefinition.new(:retvar,[Virtual::Argument.new(:n,Virtual::Mystery.new())],Virtual::SelfReference.new(nil),Virtual::Reference.new(nil),Virtual::MethodEnter.new(Virtual::FrameSet.new(:i,Virtual::IntegerConstant.new(5),nil)))]
     check
   end
 
@@ -96,20 +110,6 @@ HERE
     check
   end
 
-  def ttest_function_while
-    @string_input    = <<HERE
-def fibonaccit(n)
-  a = 0
-  while (n) do
-    some = 43
-    other = some * 4
-  end
-end
-HERE
-    @output = [Virtual::MethodDefinition.new(:foo,[Ast::NameExpression.new(:x)])]
-    check
-  end
-
   def ttest_function_big_while
     @string_input    = <<HERE
 def fibonaccit(n)