anchor.diff:  
   -include("beam_ssa_opt.hrl").
   
  --import(lists, [all/2,append/1,duplicate/2,flatten/1,foldl/3,keyfind/3,
  -                member/2,reverse/1,reverse/2,splitwith/2,sort/1,
  -                takewhile/2,unzip/1]).
  +-import(lists, [all/2,append/1,duplicate/2,flatten/1,foldl/3,
  +                keyfind/3,last/1,member/2,reverse/1,reverse/2,
  +                splitwith/2,sort/1,takewhile/2,unzip/1]).
   
   -define(MAX_REPETITIONS, 16).
   
  
positive.code:     {reverse(Acc),Count}.
  
  %%%
  %%% Merge blocks.
  %%%
  
  
negative.code: %% are repeated as required.
  repeated_passes(Opts) ->
      Ps = [?PASS(ssa_opt_live),
            ?PASS(ssa_opt_ne),
            ?PASS(ssa_opt_bs_puts),
            ?PASS(ssa_opt_dead),
            ?PASS(ssa_opt_cse),
  