anchor.diff:  backward([{test,bs_start_match2,{f,To0},Live,[Src|_]=Info,Dst}|Is], D, Acc) ->
       To = shortcut_bs_start_match(To0, Src, D),
       I = {test,bs_start_match2,{f,To},Live,Info,Dst},
  -    backward(Is, D, [I|Acc]);
  -backward([{test,is_eq_exact,{f,To0},[Reg,{atom,Val}]=Ops}|Is], D, Acc) ->
  -    To1 = shortcut_bs_test(To0, Is, D),
  -    To = shortcut_fail_label(To1, Reg, Val, D),
  -    I = combine_eqs(To, Ops, D, Acc),
       backward(Is, D, [I|Acc]);
   backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) ->
       To1 = shortcut_bs_test(To0, Is, D),
  
positive.code: equal_ops([], []) -> true;
  equal_ops(_, _) -> false.
      
  shortcut_select_list([{_,Val}=Lit,{f,To0}|T], Reg, D, Acc) ->
      To = shortcut_select_label(To0, Reg, Val, D),
      shortcut_select_list(T, Reg, D, [{f,To},Lit|Acc]);
  shortcut_select_list([], _, _, Acc) -> reverse(Acc).
  
  
negative.code: 	_ -> To0
      end.
  
  shortcut_select_label(To, Reg, Lit, D) ->
      shortcut_rel_op(To, is_ne_exact, [Reg,Lit], D).
  
  shortcut_boolean_label(To0, Reg, {atom,Bool0}=Lit, D) when is_boolean(Bool0) ->
      case beam_utils:code_at(To0, D) of
  	[{line,_},{bif,'not',_,[Reg],Reg},{jump,{f,To}}|_] ->
  	    Bool = {atom,not Bool0},
  	    {shortcut_select_label(To, Reg, Bool, D),Bool};
  	_ ->
  	    {To0,Lit}
      end;
  shortcut_boolean_label(To, _, Bool, _) -> {To,Bool}.
  
  replace_comp_op(To, Reg, Op, Ops, D) ->
      False = comp_op_find_shortcut(To, Reg, {atom,false}, D),
      True = comp_op_find_shortcut(To, Reg, {atom,true}, D),
      [bif_to_test(Op, Ops, False),{jump,{f,True}}].
  
  comp_op_find_shortcut(To0, Reg, Val, D) ->
  