anchor.diff:      is_not_used(Y, Is);
   is_not_used(Y, [{make_fun3,_,_,_,Dst,{list,Env}}|Is]) ->
       is_not_used_ss_dst(Y, Env, Dst, Is);
  -is_not_used(Y, [{recv_marker_bind,Mark,Ref}|Is]) ->
  -    Y =/= Mark andalso Y =/= Ref andalso is_not_used(Y, Is);
   is_not_used(Y, [{recv_marker_clear,Ref}|Is]) ->
       Y =/= Ref andalso is_not_used(Y, Is);
   is_not_used(Y, [{recv_marker_reserve,Dst}|Is]) ->
       Y =/= Dst andalso is_not_used(Y, Is);
  -is_not_used(Y, [{recv_marker_use,Ref}|Is]) ->
  -    Y =/= Ref andalso is_not_used(Y, Is);
   is_not_used(Y, [{swap,Reg1,Reg2}|Is]) ->
       Y =/= Reg1 andalso Y =/= Reg2 andalso is_not_used(Y, Is);
   is_not_used(Y, [{test,_,_,Ss}|Is]) ->
  
positive.code:     frame_size(Is, Safe);
  frame_size([{make_fun3,_,_,_,_,_}|Is], Safe) ->
      frame_size(Is, Safe);
  frame_size([{recv_marker_bind,_,_}|Is], Safe) ->
      frame_size(Is, Safe);
  frame_size([{recv_marker_clear,_}|Is], Safe) ->
      frame_size(Is, Safe);
  frame_size([{recv_marker_reserve,_}|Is], Safe) ->
      frame_size(Is, Safe);
  frame_size([{recv_marker_use,_}|Is], Safe) ->
      frame_size(Is, Safe);
  frame_size([{get_map_elements,{f,L},_,_}|Is], Safe) ->
      frame_size_branch(L, Is, Safe);
  
negative.code: remap([{deallocate,N}|Is], Map, Acc) ->
      I = {deallocate,Map({frame_size,N})},
      remap(Is, Map, [I|Acc]);
  remap([{recv_marker_clear,Ref}|Is], Map, Acc) ->
      I = {recv_marker_clear,Map(Ref)},
      remap(Is, Map, [I|Acc]);
  remap([{recv_marker_reserve,Mark}|Is], Map, Acc) ->
      I = {recv_marker_reserve,Map(Mark)},
      remap(Is, Map, [I|Acc]);
  remap([{swap,Reg1,Reg2}|Is], Map, Acc) ->
      I = {swap,Map(Reg1),Map(Reg2)},
  