%% ``The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved via the world wide web at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% The Initial Developer of the Original Code is Ericsson Utvecklings AB.
%% Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
%% AB. All Rights Reserved.''
%%
%% $Id: beam_clean.erl,v 1.1 2008/12/17 09:53:41 mikpe Exp $
%%
%% Purpose : Clean up, such as removing unused labels and unused functions.
-module(beam_clean).
-export([module/2]).
-import(lists, [member/2,map/2,foldl/3,mapfoldl/3,reverse/1]).
module({Mod,Exp,Attr,Fs0,_}, _Opt) ->
Order = [Lbl || {function,_,_,Lbl,_} <- Fs0],
All = foldl(fun({function,_,_,Lbl,_}=Func,D) -> dict:store(Lbl, Func, D) end,
dict:new(), Fs0),
{WorkList,Used0} = exp_to_labels(Fs0, Exp),
Used = find_all_used(WorkList, All, Used0),
Fs1 = remove_unused(Order, Used, All),
{Fs,Lc} = clean_labels(Fs1),
{ok,{Mod,Exp,Attr,Fs,Lc}}.
%% Convert the export list ({Name,Arity} pairs) to a list of entry labels.
exp_to_labels(Fs, Exp) -> exp_to_labels(Fs, Exp, [], sets:new()).
exp_to_labels([{function,Name,Arity,Lbl,_}|Fs], Exp, Acc, Used) ->
case member({Name,Arity}, Exp) of
true -> exp_to_labels(Fs, Exp, [Lbl|Acc], sets:add_element(Lbl, Used));
false -> exp_to_labels(Fs, Exp, Acc, Used)
end;
exp_to_labels([], _, Acc, Used) -> {Acc,Used}.
%% Remove the unused functions.
remove_unused([F|Fs], Used, All) ->
case sets:is_element(F, Used) of
false -> remove_unused(Fs, Used, All);
true -> [dict:fetch(F, All)|remove_unused(Fs, Used, All)]
end;
remove_unused([], _, _) -> [].
%% Find all used functions.
find_all_used([F|Fs0], All, Used0) ->
{function,_,_,_,Code} = dict:fetch(F, All),
{Fs,Used} = update_work_list(Code, {Fs0,Used0}),
find_all_used(Fs, All, Used);
find_all_used([], _All, Used) -> Used.
update_work_list([{call,_,{f,L}}|Is], Sets) ->
update_work_list(Is, add_to_work_list(L, Sets));
update_work_list([{call_last,_,{f,L},_}|Is], Sets) ->
update_work_list(Is, add_to_work_list(L, Sets));
update_work_list([{call_only,_,{f,L}}|Is], Sets) ->
update_work_list(Is, add_to_work_list(L, Sets));
update_work_list([{make_fun,{f,L},_,_}|Is], Sets) ->
update_work_list(Is, add_to_work_list(L, Sets));
update_work_list([{make_fun2,{f,L},_,_,_}|Is], Sets) ->
update_work_list(Is, add_to_work_list(L, Sets));
update_work_list([_|Is], Sets) ->
update_work_list(Is, Sets);
update_work_list([], Sets) -> Sets.
add_to_work_list(F, {Fs,Used}=Sets) ->
case sets:is_element(F, Used) of
true -> Sets;
false -> {[F|Fs],sets:add_element(F, Used)}
end.
%%%
%%% Coalesce adjacent labels. Renumber all labels to eliminate gaps.
%%% This cleanup will slightly reduce file size and slightly speed up loading.
%%%
%%% We also expand internal_is_record/3 to a sequence of instructions. It is done
%%% here merely because this module will always be called even if optimization
%%% is turned off. We don't want to do the expansion in beam_asm because we
%%% want to see the expanded code in a .S file.
%%%
-record(st, {lmap, %Translation tables for labels.
entry, %Number of entry label.
lc %Label counter
}).
clean_labels(Fs0) ->
St0 = #st{lmap=dict:new(),lc=1},
{Fs1,#st{lmap=Lmap,lc=Lc}} = mapfoldl(fun function_renumber/2, St0, Fs0),
{map(fun(F) -> function_replace(F, Lmap) end, Fs1),Lc}.
function_renumber({function,Name,Arity,_Entry,Asm0}, St0) ->
{Asm,St} = renumber_labels(Asm0, [], St0),
{{function,Name,Arity,St#st.entry,Asm},St}.
renumber_labels([{bif,internal_is_record,{f,_},
[Term,Tag,{integer,Arity}],Dst}|Is], Acc, St) ->
ContLabel = 900000000+2*St#st.lc,
FailLabel = ContLabel+1,
Fail = {f,FailLabel},
Tmp = Dst,
renumber_labels([{test,is_tuple,Fail,[Term]},
{test,test_arity,Fail,[Term,Arity]},
{get_tuple_element,Term,0,Tmp},
{test,is_eq_exact,Fail,[Tmp,Tag]},
{move,{atom,true},Dst},
{jump,{f,ContLabel}},
{label,FailLabel},
{move,{atom,false},Dst},
{label,ContLabel}|Is], Acc, St);
renumber_labels([{test,internal_is_record,{f,_}=Fail,
[Term,Tag,{integer,Arity}]}|Is], Acc, St) ->
Tmp = {x,1023},
case Term of
{Reg,_} when Reg == x; Reg == y ->
renumber_labels([{test,is_tuple,Fail,[Term]},
{test,test_arity,Fail,[Term,Arity]},
{get_tuple_element,Term,0,Tmp},
{test,is_eq_exact,Fail,[Tmp,Tag]}|Is], Acc, St);
_ ->
renumber_labels([{jump,Fail}|Is], Acc, St)
end;
renumber_labels([{label,Old}|Is], [{label,New}|_]=Acc, #st{lmap=D0}=St) ->
D = dict:store(Old, New, D0),
renumber_labels(Is, Acc, St#st{lmap=D});
renumber_labels([{label,Old}|Is], Acc, St0) ->
New = St0#st.lc,
D = dict:store(Old, New, St0#st.lmap),
renumber_labels(Is, [{label,New}|Acc], St0#st{lmap=D,lc=New+1});
renumber_labels([{func_info,_,_,_}=Fi|Is], Acc, St0) ->
renumber_labels(Is, [Fi|Acc], St0#st{entry=St0#st.lc});
renumber_labels([I|Is], Acc, St0) ->
renumber_labels(Is, [I|Acc], St0);
renumber_labels([], Acc, St0) -> {Acc,St0}.
function_replace({function,Name,Arity,Entry,Asm0}, Dict) ->
Asm = case catch replace(Asm0, [], Dict) of
{'EXIT',_}=Reason ->
exit(Reason);
{error,{undefined_label,Lbl}=Reason} ->
io:format("Function ~s/~w refers to undefined label ~w\n",
[Name,Arity,Lbl]),
exit(Reason);
Asm1 when list(Asm1) -> Asm1
end,
{function,Name,Arity,Entry,Asm}.
replace([{test,Test,{f,Lbl},Ops}|Is], Acc, D) ->
replace(Is, [{test,Test,{f,label(Lbl, D)},Ops}|Acc], D);
replace([{select_val,R,{f,Fail0},{list,Vls0}}|Is], Acc, D) ->
Vls1 = map(fun ({f,L}) -> {f,label(L, D)};
(Other) -> Other end, Vls0),
Fail = label(Fail0, D),
case redundant_values(Vls1, Fail, []) of
[] ->
%% Oops, no choices left. The loader will not accept that.
%% Convert to a plain jump.
replace(Is, [{jump,{f,Fail}}|Acc], D);
Vls ->
replace(Is, [{select_val,R,{f,Fail},{list,Vls}}|Acc], D)
end;
replace([{select_tuple_arity,R,{f,Fail},{list,Vls0}}|Is], Acc, D) ->
Vls = map(fun ({f,L}) -> {f,label(L, D)};
(Other) -> Other end, Vls0),
replace(Is, [{select_tuple_arity,R,{f,label(Fail, D)},{list,Vls}}|Acc], D);
replace([{'try',R,{f,Lbl}}|Is], Acc, D) ->
replace(Is, [{'try',R,{f,label(Lbl, D)}}|Acc], D);
replace([{'catch',R,{f,Lbl}}|Is], Acc, D) ->
replace(Is, [{'catch',R,{f,label(Lbl, D)}}|Acc], D);
replace([{jump,{f,Lbl}}|Is], Acc, D) ->
replace(Is, [{jump,{f,label(Lbl, D)}}|Acc], D);
replace([{loop_rec,{f,Lbl},R}|Is], Acc, D) ->
replace(Is, [{loop_rec,{f,label(Lbl, D)},R}|Acc], D);
replace([{loop_rec_end,{f,Lbl}}|Is], Acc, D) ->
replace(Is, [{loop_rec_end,{f,label(Lbl, D)}}|Acc], D);
replace([{wait,{f,Lbl}}|Is], Acc, D) ->
replace(Is, [{wait,{f,label(Lbl, D)}}|Acc], D);
replace([{wait_timeout,{f,Lbl},To}|Is], Acc, D) ->
replace(Is, [{wait_timeout,{f,label(Lbl, D)},To}|Acc], D);
replace([{bif,Name,{f,Lbl},As,R}|Is], Acc, D) when Lbl =/= 0 ->
replace(Is, [{bif,Name,{f,label(Lbl, D)},As,R}|Acc], D);
replace([{call,Ar,{f,Lbl}}|Is], Acc, D) ->
replace(Is, [{call,Ar,{f,label(Lbl,D)}}|Acc], D);
replace([{call_last,Ar,{f,Lbl},N}|Is], Acc, D) ->
replace(Is, [{call_last,Ar,{f,label(Lbl,D)},N}|Acc], D);
replace([{call_only,Ar,{f,Lbl}}|Is], Acc, D) ->
replace(Is, [{call_only,Ar,{f,label(Lbl, D)}}|Acc], D);
replace([{make_fun,{f,Lbl},U1,U2}|Is], Acc, D) ->
replace(Is, [{make_fun,{f,label(Lbl, D)},U1,U2}|Acc], D);
replace([{make_fun2,{f,Lbl},U1,U2,U3}|Is], Acc, D) ->
replace(Is, [{make_fun2,{f,label(Lbl, D)},U1,U2,U3}|Acc], D);
replace([{bs_init2,{f,Lbl},Sz,Words,R,F,Dst}|Is], Acc, D) when Lbl =/= 0 ->
replace(Is, [{bs_init2,{f,label(Lbl, D)},Sz,Words,R,F,Dst}|Acc], D);
replace([{bs_put_integer,{f,Lbl},Bits,Unit,Fl,Val}|Is], Acc, D) when Lbl =/= 0 ->
replace(Is, [{bs_put_integer,{f,label(Lbl, D)},Bits,Unit,Fl,Val}|Acc], D);
replace([{bs_put_binary,{f,Lbl},Bits,Unit,Fl,Val}|Is], Acc, D) when Lbl =/= 0 ->
replace(Is, [{bs_put_binary,{f,label(Lbl, D)},Bits,Unit,Fl,Val}|Acc], D);
replace([{bs_put_float,{f,Lbl},Bits,Unit,Fl,Val}|Is], Acc, D) when Lbl =/= 0 ->
replace(Is, [{bs_put_float,{f,label(Lbl, D)},Bits,Unit,Fl,Val}|Acc], D);
replace([{bs_final,{f,Lbl},R}|Is], Acc, D) when Lbl =/= 0 ->
replace(Is, [{bs_final,{f,label(Lbl, D)},R}|Acc], D);
replace([{bs_add,{f,Lbl},Src,Dst}|Is], Acc, D) when Lbl =/= 0 ->
replace(Is, [{bs_add,{f,label(Lbl, D)},Src,Dst}|Acc], D);
replace([{bs_bits_to_bytes,{f,Lbl},Bits,Dst}|Is], Acc, D) when Lbl =/= 0 ->
replace(Is, [{bs_bits_to_bytes,{f,label(Lbl, D)},Bits,Dst}|Acc], D);
replace([I|Is], Acc, D) ->
replace(Is, [I|Acc], D);
replace([], Acc, _) -> Acc.
label(Old, D) ->
case dict:find(Old, D) of
{ok,Val} -> Val;
error -> throw({error,{undefined_label,Old}})
end.
redundant_values([_,{f,Fail}|Vls], Fail, Acc) ->
redundant_values(Vls, Fail, Acc);
redundant_values([Val,Lbl|Vls], Fail, Acc) ->
redundant_values(Vls, Fail, [Lbl,Val|Acc]);
redundant_values([], _, Acc) -> reverse(Acc).
