anchor.diff:      foldl(fun(R, A) -> save_reg(R, Save, A) end, Acc, Rs).
   
   save_reg({I,V,dirty}, Save, Acc) ->
  -    case gb_sets:is_member(V, Save) of
  +    case cerl_sets:is_element(V, Save) of
   	true -> [{set,[V],[{fr,I}],fmove}|checkerror(Acc)];
   	false -> Acc
       end;
  
positive.code:     Acc = flush_all(Rs, Is0, Acc0),
      {[],Acc};
  flush(Rs0, [{set,Ds,Ss,_Op}|_], Acc0) ->
      Save = gb_sets:from_list(Ss),
      Acc = save_regs(Rs0, Save, Acc0),
      Rs1 = foldl(fun(S, A) -> mark(S, A, clean) end, Rs0, Ss),
      Kill = gb_sets:from_list(Ds),
      Rs = kill_regs(Rs1, Kill),
      {Rs,Acc};
  flush(Rs0, Is, Acc0) ->
  
negative.code:     [kill_reg(R, Kill) || R <- Rs].
  
  kill_reg({_,V,_}=R, Kill) ->
      case cerl_sets:is_element(V, Kill) of
  	true -> free;
  	false -> R
      end;
  