anchor.diff:             end,
       Used = beam_ssa:used(I),
       Acc = [{V,{use,N}} || V <- Used] ++ Acc1,
  -    live_interval_blk_1(Is, FirstNumber, Aliases, Acc);
  -live_interval_blk_1([], _FirstNumber, Aliases, Acc) ->
  -    {Acc,Aliases}.
  +    live_interval_blk_1(Is, FirstNumber, Acc);
  +live_interval_blk_1([], _FirstNumber, Acc) ->
  +    Acc.
   
   %% first_number([#b_set{}]) -> InstructionNumber.
   %%  Return the number for the first instruction for the block.
  
positive.code:           %% Calculate live intervals.
            ?PASS(number_instructions),
            ?PASS(live_intervals),
            ?PASS(remove_unsuitable_aliases),
            ?PASS(reserve_regs),
            ?PASS(merge_intervals),
  
            %% If needed for a .precg file, save the live intervals
            %% so they can be included in an annotation.
  
negative.code: 
      %% Construct the ranges for this block.
      Vars = make_block_ranges(UseDef, FirstNumber, Vars0),
      {Vars,LiveMap}.
  
  make_block_ranges([{V,[{def,Def}]}|Vs], First, Acc) ->
      make_block_ranges(Vs, First, [{V,{Def,Def}}|Acc]);
  