anchor.diff:      St0 = #live{lbl=D,res=gb_trees:empty()},
       case check_liveness_at(R, Lbl, St0) of
   	{killed,_} -> true;
  -	{exit_not_used,_} -> true;
  +	{exit_not_used,_} -> false;
   	{_,_} -> false
       end.
   
  
positive.code:     St = #live{lbl=D,res=gb_trees:empty()},
      case check_liveness(R, Is, St) of
  	{used,_} -> false;
  	{exit_not_used,_} -> false;
  	{_,_} -> true
      end.
  
  
negative.code:     St = #live{lbl=D,res=gb_trees:empty()},
      case check_liveness(R, Is, St) of
  	{killed,_} -> true;
  	{exit_not_used,_} -> false;
  	{_,_} -> false
      end.
  
  