anchor.diff:  	#{ K1 := 1, c := 6, K2 := 8, h := 3} -> 6
       end.
   
  +%% register corruption discovered in 18 due to
  +%% get_map_elements might destroys registers when fail-label is taken.
  +%% Only seen when patterns have two targets,
  +%% specifically: we copy one register, and then jump.
  +%%    {test,is_map,{f,5},[{x,1}]}.
  +%%
  +%%    {get_map_elements,{f,7},{x,1},{list,[{atom,a},{x,1},{atom,b},{x,2}]}}.
  +%%    %% if 'a' exists but not 'b' {x,1} is overwritten, jump {f,7}
  +%%
  +%%    {move,{integer,1},{x,0}}.
  +%%    {call_only,3,{f,10}}.
  +%%
  +%%  {label,7}.
  +%%    {get_map_elements,{f,8},{x,1},{list,[{atom,b},{x,2}]}}.
  +%%    %% {x,1} (src) is now corrupt
  +%%
  +%%    {move,{x,0},{x,1}}.
  +%%    {move,{integer,2},{x,0}}.
  +%%    {call_only,3,{f,10}}.
  +%%
  +%% Only happens in beam_block opt_move pass with two destinations.
  +
  +t_register_corruption(Config) when is_list(Config) ->
  +    M = #{a=> <<"value">>, c=>3},
  +    {3,wanted,<<"value">>} = register_corruption_bar(M,wanted),
  +    {3,wanted,<<"value">>} = register_corruption_foo(wanted,M),
  +    ok.
  +
  +register_corruption_foo(A,#{a := V1, b := V2}) ->
  +    register_corruption_dummy_call(1,V1,V2);
  +register_corruption_foo(A,#{b := V}) ->
  +    register_corruption_dummy_call(2,A,V);
  +register_corruption_foo(A,#{a := V}) ->
  +    register_corruption_dummy_call(3,A,V).
  +
  +register_corruption_bar(M,A) ->
  +    case M of
  +        #{a := V1, b := V2} ->
  +            register_corruption_dummy_call(1,V1,V2);
  +        #{b := V} ->
  +            register_corruption_dummy_call(2,A,V);
  +        #{a := V} ->
  +            register_corruption_dummy_call(3,A,V)
  +    end.
  +
  +
  +register_corruption_dummy_call(A,B,C) -> {A,B,C}.
   
   
   t_frequency_table(Config) when is_list(Config) ->
  
positive.code: 	%% errors in 17.0-rc1
  	t_update_values/1,
          t_expand_map_update/1,
          t_export/1
      ]).
  
  suite() -> [].
  
negative.code: 	t_build_and_match_nil,
  	t_build_and_match_structure,
  
  	%% errors in 17.0-rc1
  	t_update_values,
          t_expand_map_update,
          t_export,
  
  	%% errors in 18
          t_register_corruption
      ].
  
  groups() -> [].
  