anchor.diff:      Src = mk_val(Src0),
       Dst = mk_val(Dst0),
       emit([Dst," = ",Src," - ",Int]);
  +enc_cg({set,{var,Src},{var,Dst}}) ->
  +    emit([Dst," = ",Src]);
   enc_cg({'try',Try,{P,Succ},Else,Dst}) ->
       emit([mk_val(Dst)," = try "]),
       enc_cg(Try),
  
positive.code:     Else = enc_pre_cg_1(Else0, StL, outside_seq),
      {'try',Try,{P,Succ},Else,Dst};
  enc_pre_cg_nonbuilding(Imm, _) -> Imm.
  
  
  %%%
  %%% Code generation for encoding.
  
negative.code:     {[PutBits],Al+N*U};
  enc_opt_al({put_bits,_,binary,[U]}=PutBits, Al) when U rem 8 =:= 0 ->
      {[PutBits],Al};
  enc_opt_al({set,_,_}=Imm, Al) ->
      {[Imm],Al};
  enc_opt_al({sub,_,_,_}=Imm, Al) ->
      {[Imm],Al};
  enc_opt_al({'try',_,_,_,_}=Imm, Al) ->
  