%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2007-2018. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
%% Purpose : Common utilities used by several optimization passes.
%%
-module(beam_utils).
-export([is_killed/3,is_killed_at/3,is_not_used/3,
empty_label_index/0,index_label/3,index_labels/1,replace_labels/4,
code_at/2,bif_to_test/3,is_pure_test/1,
split_even/1]).
-export_type([code_index/0,module_code/0,instruction/0]).
-import(lists, [map/2,member/2,sort/1,reverse/1]).
-define(is_const(Val), (Val =:= nil orelse
element(1, Val) =:= integer orelse
element(1, Val) =:= float orelse
element(1, Val) =:= atom orelse
element(1, Val) =:= literal)).
%% instruction() describes all instructions that are used during optimization
%% (from beam_a to beam_z).
-type instruction() :: atom() | tuple().
-type code_index() :: gb_trees:tree(beam_asm:label(), [instruction()]).
-type int_function() :: {'function',beam_asm:function_name(),arity(),
beam_asm:label(),[instruction()]}.
-type module_code() ::
{module(),[_],[_],[int_function()],pos_integer()}.
%% Internal types.
-type fail() :: beam_asm:fail() | 'fail'.
-type test() :: {'test',atom(),fail(),[beam_asm:src()]} |
{'test',atom(),fail(),integer(),list(),beam_asm:reg()}.
-type result_cache() :: gb_trees:tree(beam_asm:label(), 'killed' | 'used').
-record(live,
{lbl :: code_index(), %Label to code index.
res :: result_cache()}). %Result cache for each label.
%% is_killed(Register, [Instruction], State) -> true|false
%% Determine whether a register is killed by the instruction sequence.
%% If true is returned, it means that the register will not be
%% referenced in ANY way (not even indirectly by an allocate instruction);
%% i.e. it is OK to enter the instruction sequence with Register
%% containing garbage.
%%
%% The state (constructed by index_instructions/1) is used to allow us
%% to determine the kill state across branches.
-spec is_killed(beam_asm:reg(), [instruction()], code_index()) -> boolean().
is_killed(R, Is, D) ->
St = #live{lbl=D,res=gb_trees:empty()},
case check_liveness(R, Is, St) of
{killed,_} -> true;
{exit_not_used,_} -> false;
{_,_} -> false
end.
%% is_killed_at(Reg, Lbl, State) -> true|false
%% Determine whether Reg is killed at label Lbl.
-spec is_killed_at(beam_asm:reg(), beam_asm:label(), code_index()) -> boolean().
is_killed_at(R, Lbl, D) when is_integer(Lbl) ->
St0 = #live{lbl=D,res=gb_trees:empty()},
case check_liveness_at(R, Lbl, St0) of
{killed,_} -> true;
{exit_not_used,_} -> false;
{_,_} -> false
end.
%% is_not_used(Register, [Instruction], State) -> true|false
%% Determine whether a register is never used in the instruction sequence
%% (it could still be referenced by an allocate instruction, meaning that
%% it MUST be initialized, but that its value does not matter).
%% The state is used to allow us to determine the usage state
%% across branches.
-spec is_not_used(beam_asm:reg(), [instruction()], code_index()) -> boolean().
is_not_used(R, Is, D) ->
St = #live{lbl=D,res=gb_trees:empty()},
case check_liveness(R, Is, St) of
{used,_} -> false;
{exit_not_used,_} -> true;
{_,_} -> true
end.
%% index_labels(FunctionIs) -> State
%% Index the instruction sequence so that we can quickly
%% look up the instruction following a specific label.
-spec index_labels([instruction()]) -> code_index().
index_labels(Is) ->
index_labels_1(Is, []).
%% empty_label_index() -> State
%% Create an empty label index.
-spec empty_label_index() -> code_index().
empty_label_index() ->
gb_trees:empty().
%% index_label(Label, [Instruction], State) -> State
%% Add an index for a label.
-spec index_label(beam_asm:label(), [instruction()], code_index()) ->
code_index().
index_label(Lbl, Is0, Acc) ->
Is = drop_labels(Is0),
gb_trees:enter(Lbl, Is, Acc).
%% code_at(Label, State) -> [I].
%% Retrieve the code at the given label.
-spec code_at(beam_asm:label(), code_index()) -> [instruction()].
code_at(L, Ll) ->
gb_trees:get(L, Ll).
%% replace_labels(FunctionIs, Tail, ReplaceDb, Fallback) -> FunctionIs.
%% Replace all labels in instructions according to the ReplaceDb.
%% If label is not found the Fallback is called with the label to
%% produce a new one.
-spec replace_labels([instruction()],
[instruction()],
#{beam_asm:label() => beam_asm:label()},
fun((beam_asm:label()) -> term())) -> [instruction()].
replace_labels(Is, Acc, D, Fb) ->
replace_labels_1(Is, Acc, D, Fb).
%% bif_to_test(Bif, [Op], Fail) -> {test,Test,Fail,[Op]}
%% Convert a BIF to a test. Fail if not possible.
-spec bif_to_test(atom(), list(), fail()) -> test().
bif_to_test(is_atom, [_]=Ops, Fail) -> {test,is_atom,Fail,Ops};
bif_to_test(is_boolean, [_]=Ops, Fail) -> {test,is_boolean,Fail,Ops};
bif_to_test(is_binary, [_]=Ops, Fail) -> {test,is_binary,Fail,Ops};
bif_to_test(is_bitstring,[_]=Ops, Fail) -> {test,is_bitstr,Fail,Ops};
bif_to_test(is_float, [_]=Ops, Fail) -> {test,is_float,Fail,Ops};
bif_to_test(is_function, [_]=Ops, Fail) -> {test,is_function,Fail,Ops};
bif_to_test(is_function, [_,_]=Ops, Fail) -> {test,is_function2,Fail,Ops};
bif_to_test(is_integer, [_]=Ops, Fail) -> {test,is_integer,Fail,Ops};
bif_to_test(is_list, [_]=Ops, Fail) -> {test,is_list,Fail,Ops};
bif_to_test(is_map, [_]=Ops, Fail) -> {test,is_map,Fail,Ops};
bif_to_test(is_number, [_]=Ops, Fail) -> {test,is_number,Fail,Ops};
bif_to_test(is_pid, [_]=Ops, Fail) -> {test,is_pid,Fail,Ops};
bif_to_test(is_port, [_]=Ops, Fail) -> {test,is_port,Fail,Ops};
bif_to_test(is_reference, [_]=Ops, Fail) -> {test,is_reference,Fail,Ops};
bif_to_test(is_tuple, [_]=Ops, Fail) -> {test,is_tuple,Fail,Ops};
bif_to_test('=<', [A,B], Fail) -> {test,is_ge,Fail,[B,A]};
bif_to_test('>', [A,B], Fail) -> {test,is_lt,Fail,[B,A]};
bif_to_test('<', [_,_]=Ops, Fail) -> {test,is_lt,Fail,Ops};
bif_to_test('>=', [_,_]=Ops, Fail) -> {test,is_ge,Fail,Ops};
bif_to_test('==', [C,A], Fail) when ?is_const(C) ->
{test,is_eq,Fail,[A,C]};
bif_to_test('==', [_,_]=Ops, Fail) -> {test,is_eq,Fail,Ops};
bif_to_test('/=', [C,A], Fail) when ?is_const(C) ->
{test,is_ne,Fail,[A,C]};
bif_to_test('/=', [_,_]=Ops, Fail) -> {test,is_ne,Fail,Ops};
bif_to_test('=:=', [C,A], Fail) when ?is_const(C) ->
{test,is_eq_exact,Fail,[A,C]};
bif_to_test('=:=', [_,_]=Ops, Fail) -> {test,is_eq_exact,Fail,Ops};
bif_to_test('=/=', [C,A], Fail) when ?is_const(C) ->
{test,is_ne_exact,Fail,[A,C]};
bif_to_test('=/=', [_,_]=Ops, Fail) -> {test,is_ne_exact,Fail,Ops}.
%% is_pure_test({test,Op,Fail,Ops}) -> true|false.
%% Return 'true' if the test instruction does not modify any
%% registers and/or bit syntax matching state.
%%
-spec is_pure_test(test()) -> boolean().
is_pure_test({test,is_eq,_,[_,_]}) -> true;
is_pure_test({test,is_ne,_,[_,_]}) -> true;
is_pure_test({test,is_eq_exact,_,[_,_]}) -> true;
is_pure_test({test,is_ne_exact,_,[_,_]}) -> true;
is_pure_test({test,is_ge,_,[_,_]}) -> true;
is_pure_test({test,is_lt,_,[_,_]}) -> true;
is_pure_test({test,is_nonempty_list,_,[_]}) -> true;
is_pure_test({test,is_tagged_tuple,_,[_,_,_]}) -> true;
is_pure_test({test,test_arity,_,[_,_]}) -> true;
is_pure_test({test,has_map_fields,_,[_|_]}) -> true;
is_pure_test({test,is_bitstr,_,[_]}) -> true;
is_pure_test({test,is_function2,_,[_,_]}) -> true;
is_pure_test({test,Op,_,Ops}) ->
erl_internal:new_type_test(Op, length(Ops)).
%% split_even/1
%% [1,2,3,4,5,6] -> {[1,3,5],[2,4,6]}
-spec split_even(list()) -> {list(),list()}.
split_even(Rs) -> split_even(Rs, [], []).
%%%
%%% Local functions.
%%%
%% check_liveness(Reg, [Instruction], #live{}) ->
%% {killed | not_used | used, #live{}}
%% Find out whether Reg is used or killed in instruction sequence.
%%
%% killed - Reg is assigned or killed by an allocation instruction.
%% not_used - the value of Reg is not used, but Reg must not be garbage
%% exit_not_used - the value of Reg is not used, but must not be garbage
%% because the stack will be scanned because an
%% exit BIF will raise an exception
%% used - Reg is used
check_liveness({fr,_}, _, St) ->
%% Conservatively always consider the floating point register used.
{used,St};
check_liveness(R, [{block,Blk}|Is], St0) ->
case check_liveness_block(R, Blk, St0) of
{transparent,St1} ->
check_liveness(R, Is, St1);
{alloc_used,St1} ->
%% Used by an allocating instruction, but value not referenced.
%% Must check the rest of the instructions.
not_used(check_liveness(R, Is, St1));
{Other,_}=Res when is_atom(Other) ->
Res
end;
check_liveness(R, [{label,_}|Is], St) ->
check_liveness(R, Is, St);
check_liveness(R, [{test,_,{f,Fail},As}|Is], St0) ->
case member(R, As) of
true ->
{used,St0};
false ->
case check_liveness_at(R, Fail, St0) of
{killed,St1} ->
check_liveness(R, Is, St1);
{exit_not_used,St1} ->
not_used(check_liveness(R, Is, St1));
{not_used,St1} ->
not_used(check_liveness(R, Is, St1));
{used,_}=Used ->
Used
end
end;
check_liveness(R, [{test,Op,Fail,Live,Ss,Dst}|Is], St) ->
%% Check this instruction as a block to get a less conservative
%% result if the caller is is_not_used/3.
Block = [{set,[Dst],Ss,{alloc,Live,{bif,Op,Fail}}}],
check_liveness(R, [{block,Block}|Is], St);
check_liveness(R, [{select,_,R,_,_}|_], St) ->
{used,St};
check_liveness(R, [{select,_,_,Fail,Branches}|_], St) ->
check_liveness_everywhere(R, [Fail|Branches], St);
check_liveness(R, [{jump,{f,F}}|_], St) ->
check_liveness_at(R, F, St);
check_liveness(R, [{case_end,Used}|_], St) ->
check_liveness_exit(R, Used, St);
check_liveness(R, [{try_case_end,Used}|_], St) ->
check_liveness_exit(R, Used, St);
check_liveness(R, [{badmatch,Used}|_], St) ->
check_liveness_exit(R, Used, St);
check_liveness(R, [if_end|_], St) ->
check_liveness_exit(R, ignore, St);
check_liveness(R, [{func_info,_,_,Ar}|_], St) ->
case R of
{x,X} when X < Ar -> {used,St};
_ -> {killed,St}
end;
check_liveness(R, [{kill,R}|_], St) ->
{killed,St};
check_liveness(R, [{kill,_}|Is], St) ->
check_liveness(R, Is, St);
check_liveness(R, [{bs_init,_,_,none,Ss,Dst}|Is], St) ->
case member(R, Ss) of
true ->
{used,St};
false ->
if
R =:= Dst -> {killed,St};
true -> check_liveness(R, Is, St)
end
end;
check_liveness(R, [{bs_init,_,_,Live,Ss,Dst}|Is], St) ->
case R of
{x,X} ->
case member(R, Ss) of
true ->
{used,St};
false ->
if
X < Live ->
not_used(check_liveness(R, Is, St));
true ->
{killed,St}
end
end;
{y,_} ->
case member(R, Ss) of
true -> {used,St};
false ->
%% If the exception is taken, the stack may
%% be scanned. Therefore the register is not
%% guaranteed to be killed.
if
R =:= Dst -> {not_used,St};
true -> not_used(check_liveness(R, Is, St))
end
end
end;
check_liveness(R, [{deallocate,_}|Is], St) ->
case R of
{y,_} -> {killed,St};
_ -> check_liveness(R, Is, St)
end;
check_liveness({x,_}=R, [return|_], St) ->
case R of
{x,0} -> {used,St};
{x,_} -> {killed,St}
end;
check_liveness(R, [{call,Live,_}|Is], St) ->
case R of
{x,X} when X < Live -> {used,St};
{x,_} -> {killed,St};
{y,_} -> not_used(check_liveness(R, Is, St))
end;
check_liveness(R, [{call_ext,Live,_}=I|Is], St) ->
case R of
{x,X} when X < Live ->
{used,St};
{x,_} ->
{killed,St};
{y,_} ->
case beam_jump:is_exit_instruction(I) of
false ->
not_used(check_liveness(R, Is, St));
true ->
%% We must make sure we don't check beyond this
%% instruction or we will fall through into random
%% unrelated code and get stuck in a loop.
{exit_not_used,St}
end
end;
check_liveness(R, [{call_fun,Live}|Is], St) ->
case R of
{x,X} when X =< Live -> {used,St};
{x,_} -> {killed,St};
{y,_} -> not_used(check_liveness(R, Is, St))
end;
check_liveness(R, [{apply,Args}|Is], St) ->
case R of
{x,X} when X < Args+2 -> {used,St};
{x,_} -> {killed,St};
{y,_} -> not_used(check_liveness(R, Is, St))
end;
check_liveness(R, [{bif,Op,Fail,Ss,D}|Is], St) ->
Set = {set,[D],Ss,{bif,Op,Fail}},
check_liveness(R, [{block,[Set]}|Is], St);
check_liveness(R, [{gc_bif,Op,{f,Fail},Live,Ss,D}|Is], St) ->
Set = {set,[D],Ss,{alloc,Live,{gc_bif,Op,Fail}}},
check_liveness(R, [{block,[Set]}|Is], St);
check_liveness(R, [{bs_put,{f,0},_,Ss}|Is], St) ->
case member(R, Ss) of
true -> {used,St};
false -> check_liveness(R, Is, St)
end;
check_liveness(R, [{bs_restore2,S,_}|Is], St) ->
case R of
S -> {used,St};
_ -> check_liveness(R, Is, St)
end;
check_liveness(R, [{bs_save2,S,_}|Is], St) ->
case R of
S -> {used,St};
_ -> check_liveness(R, Is, St)
end;
check_liveness(R, [{move,S,D}|Is], St) ->
case R of
S -> {used,St};
D -> {killed,St};
_ -> check_liveness(R, Is, St)
end;
check_liveness(R, [{make_fun2,_,_,_,NumFree}|Is], St) ->
case R of
{x,X} when X < NumFree -> {used,St};
{x,_} -> {killed,St};
{y,_} -> not_used(check_liveness(R, Is, St))
end;
check_liveness(R, [{'catch'=Op,Y,Fail}|Is], St) ->
Set = {set,[Y],[],{try_catch,Op,Fail}},
check_liveness(R, [{block,[Set]}|Is], St);
check_liveness(R, [{'try'=Op,Y,Fail}|Is], St) ->
Set = {set,[Y],[],{try_catch,Op,Fail}},
check_liveness(R, [{block,[Set]}|Is], St);
check_liveness(R, [{try_end,Y}|Is], St) ->
case R of
Y ->
{killed,St};
{y,_} ->
%% y registers will be used if an exception occurs and
%% control transfers to the label given in the previous
%% try/2 instruction.
{used,St};
_ ->
check_liveness(R, Is, St)
end;
check_liveness(R, [{catch_end,Y}|Is], St) ->
case R of
Y -> {killed,St};
_ -> check_liveness(R, Is, St)
end;
check_liveness(R, [{get_tuple_element,S,_,D}|Is], St) ->
case R of
S -> {used,St};
D -> {killed,St};
_ -> check_liveness(R, Is, St)
end;
check_liveness(R, [{bs_context_to_binary,S}|Is], St) ->
case R of
S -> {used,St};
_ -> check_liveness(R, Is, St)
end;
check_liveness(R, [{loop_rec,{f,_},{x,0}}|_], St) ->
case R of
{x,_} ->
{killed,St};
_ ->
%% y register. Rarely happens. Be very conversative and
%% assume it's used.
{used,St}
end;
check_liveness(R, [{loop_rec_end,{f,Fail}}|_], St) ->
check_liveness_at(R, Fail, St);
check_liveness(R, [{line,_}|Is], St) ->
check_liveness(R, Is, St);
check_liveness(R, [{get_map_elements,{f,Fail},S,{list,L}}|Is], St0) ->
{Ss,Ds} = split_even(L),
case member(R, [S|Ss]) of
true ->
{used,St0};
false ->
case check_liveness_at(R, Fail, St0) of
{killed,St}=Killed ->
case member(R, Ds) of
true -> Killed;
false -> check_liveness(R, Is, St)
end;
Other ->
Other
end
end;
check_liveness(R, [{put_map,F,Op,S,D,Live,{list,Puts}}|Is], St) ->
Set = {set,[D],[S|Puts],{alloc,Live,{put_map,Op,F}}},
check_liveness(R, [{block,[Set]}||Is], St);
check_liveness(R, [{put_tuple,Ar,D}|Is], St) ->
Set = {set,[D],[],{put_tuple,Ar}},
check_liveness(R, [{block,[Set]}||Is], St);
check_liveness(R, [{put_list,S1,S2,D}|Is], St) ->
Set = {set,[D],[S1,S2],put_list},
check_liveness(R, [{block,[Set]}||Is], St);
check_liveness(R, [{test_heap,N,Live}|Is], St) ->
I = {block,[{set,[],[],{alloc,Live,{nozero,nostack,N,[]}}}]},
check_liveness(R, [I|Is], St);
check_liveness(R, [{allocate_zero,N,Live}|Is], St) ->
I = {block,[{set,[],[],{alloc,Live,{zero,N,0,[]}}}]},
check_liveness(R, [I|Is], St);
check_liveness(R, [{get_hd,S,D}|Is], St) ->
I = {block,[{set,[D],[S],get_hd}]},
check_liveness(R, [I|Is], St);
check_liveness(R, [{get_tl,S,D}|Is], St) ->
I = {block,[{set,[D],[S],get_tl}]},
check_liveness(R, [I|Is], St);
check_liveness(R, [remove_message|Is], St) ->
check_liveness(R, Is, St);
check_liveness({x,X}, [build_stacktrace|_], St) when X > 0 ->
{killed,St};
check_liveness(R, [{recv_mark,_}|Is], St) ->
check_liveness(R, Is, St);
check_liveness(R, [{recv_set,_}|Is], St) ->
check_liveness(R, Is, St);
check_liveness(R, [{'%',_}|Is], St) ->
check_liveness(R, Is, St);
check_liveness(_R, Is, St) when is_list(Is) ->
%% Not implemented. Conservatively assume that the register is used.
{used,St}.
check_liveness_everywhere(R, Lbls, St0) ->
check_liveness_everywhere_1(R, Lbls, killed, St0).
check_liveness_everywhere_1(R, [{f,Lbl}|T], Res0, St0) ->
{Res1,St} = check_liveness_at(R, Lbl, St0),
Res = case Res1 of
killed -> Res0;
_ -> Res1
end,
case Res of
used -> {used,St};
_ -> check_liveness_everywhere_1(R, T, Res, St)
end;
check_liveness_everywhere_1(R, [_|T], Res, St) ->
check_liveness_everywhere_1(R, T, Res, St);
check_liveness_everywhere_1(_, [], Res, St) ->
{Res,St}.
check_liveness_at(R, Lbl, #live{lbl=Ll,res=ResMemorized}=St0) ->
case gb_trees:lookup(Lbl, ResMemorized) of
{value,Res} ->
{Res,St0};
none ->
{Res,St} = case gb_trees:lookup(Lbl, Ll) of
{value,Is} -> check_liveness(R, Is, St0);
none -> {used,St0}
end,
{Res,St#live{res=gb_trees:insert(Lbl, Res, St#live.res)}}
end.
not_used({used,_}=Res) -> Res;
not_used({_,St}) -> {not_used,St}.
check_liveness_exit(R, R, St) -> {used,St};
check_liveness_exit({x,_}, _, St) -> {killed,St};
check_liveness_exit({y,_}, _, St) -> {exit_not_used,St}.
%% check_liveness_block(Reg, [Instruction], State) ->
%% {killed | not_used | used | alloc_used | transparent,State'}
%% Finds out how Reg is used in the instruction sequence inside a block.
%% Returns one of:
%% killed - Reg is assigned a new value or killed by an
%% allocation instruction
%% not_used - The value is not used, but the register is referenced
%% e.g. by an allocation instruction
%% transparent - Reg is neither used nor killed
%% alloc_used - Used only in an allocate instruction
%% used - Reg is explicitly used by an instruction
%%
%% Annotations are not allowed.
%%
%% (Unknown instructions will cause an exception.)
check_liveness_block({x,X}=R, [{set,Ds,Ss,{alloc,Live,Op}}|Is], St0) ->
if
X >= Live ->
{killed,St0};
true ->
case check_liveness_block_1(R, Ss, Ds, Op, Is, St0) of
{transparent,St} -> {alloc_used,St};
{_,_}=Res -> not_used(Res)
end
end;
check_liveness_block({y,_}=R, [{set,Ds,Ss,{alloc,_Live,Op}}|Is], St0) ->
case check_liveness_block_1(R, Ss, Ds, Op, Is, St0) of
{transparent,St} -> {alloc_used,St};
{_,_}=Res -> not_used(Res)
end;
check_liveness_block({y,_}=R, [{set,Ds,Ss,{try_catch,_,Op}}|Is], St0) ->
case Ds of
[R] ->
{killed,St0};
_ ->
case check_liveness_block_1(R, Ss, Ds, Op, Is, St0) of
{exit_not_used,St} ->
{used,St};
{transparent,St} ->
%% Conservatively assumed that it is used.
{used,St};
{_,_}=Res ->
Res
end
end;
check_liveness_block(R, [{set,Ds,Ss,Op}|Is], St) ->
check_liveness_block_1(R, Ss, Ds, Op, Is, St);
check_liveness_block(_, [], St) -> {transparent,St}.
check_liveness_block_1(R, Ss, Ds, Op, Is, St0) ->
case member(R, Ss) of
true ->
{used,St0};
false ->
case check_liveness_block_2(R, Op, Ss, St0) of
{killed,St} ->
case member(R, Ds) of
true -> {killed,St};
false -> check_liveness_block(R, Is, St)
end;
{exit_not_used,St} ->
case member(R, Ds) of
true -> {exit_not_used,St};
false -> check_liveness_block(R, Is, St)
end;
{not_used,St} ->
not_used(case member(R, Ds) of
true -> {killed,St};
false -> check_liveness_block(R, Is, St)
end);
{used,St} ->
{used,St}
end
end.
check_liveness_block_2(R, {gc_bif,Op,{f,Lbl}}, Ss, St) ->
check_liveness_block_3(R, Lbl, {Op,length(Ss)}, St);
check_liveness_block_2(R, {bif,Op,{f,Lbl}}, Ss, St) ->
Arity = length(Ss),
case erl_internal:comp_op(Op, Arity) orelse
erl_internal:new_type_test(Op, Arity) of
true ->
{killed,St};
false ->
check_liveness_block_3(R, Lbl, {Op,length(Ss)}, St)
end;
check_liveness_block_2(R, {put_map,_Op,{f,Lbl}}, _Ss, St) ->
check_liveness_block_3(R, Lbl, {unsafe,0}, St);
check_liveness_block_2(_, _, _, St) ->
{killed,St}.
check_liveness_block_3({x,_}, 0, _FA, St) ->
{killed,St};
check_liveness_block_3({y,_}, 0, {F,A}, St) ->
%% If the exception is thrown, the stack may be scanned,
%% thus implicitly using the y register.
case erl_bifs:is_safe(erlang, F, A) of
true -> {killed,St};
false -> {used,St}
end;
check_liveness_block_3(R, Lbl, _FA, St0) ->
check_liveness_at(R, Lbl, St0).
index_labels_1([{label,Lbl}|Is0], Acc) ->
Is = drop_labels(Is0),
index_labels_1(Is0, [{Lbl,Is}|Acc]);
index_labels_1([_|Is], Acc) ->
index_labels_1(Is, Acc);
index_labels_1([], Acc) -> gb_trees:from_orddict(sort(Acc)).
drop_labels([{label,_}|Is]) -> drop_labels(Is);
drop_labels(Is) -> Is.
replace_labels_1([{test,Test,{f,Lbl},Ops}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{test,Test,{f,label(Lbl, D, Fb)},Ops}|Acc], D, Fb);
replace_labels_1([{test,Test,{f,Lbl},Live,Ops,Dst}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{test,Test,{f,label(Lbl, D, Fb)},Live,Ops,Dst}|Acc], D, Fb);
replace_labels_1([{select,I,R,{f,Fail0},Vls0}|Is], Acc, D, Fb) ->
Vls = map(fun ({f,L}) -> {f,label(L, D, Fb)};
(Other) -> Other
end, Vls0),
Fail = label(Fail0, D, Fb),
replace_labels_1(Is, [{select,I,R,{f,Fail},Vls}|Acc], D, Fb);
replace_labels_1([{'try',R,{f,Lbl}}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{'try',R,{f,label(Lbl, D, Fb)}}|Acc], D, Fb);
replace_labels_1([{'catch',R,{f,Lbl}}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{'catch',R,{f,label(Lbl, D, Fb)}}|Acc], D, Fb);
replace_labels_1([{jump,{f,Lbl}}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{jump,{f,label(Lbl, D, Fb)}}|Acc], D, Fb);
replace_labels_1([{loop_rec,{f,Lbl},R}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{loop_rec,{f,label(Lbl, D, Fb)},R}|Acc], D, Fb);
replace_labels_1([{loop_rec_end,{f,Lbl}}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{loop_rec_end,{f,label(Lbl, D, Fb)}}|Acc], D, Fb);
replace_labels_1([{wait,{f,Lbl}}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{wait,{f,label(Lbl, D, Fb)}}|Acc], D, Fb);
replace_labels_1([{wait_timeout,{f,Lbl},To}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{wait_timeout,{f,label(Lbl, D, Fb)},To}|Acc], D, Fb);
replace_labels_1([{recv_mark=Op,{f,Lbl}}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{Op,{f,label(Lbl, D, Fb)}}|Acc], D, Fb);
replace_labels_1([{recv_set=Op,{f,Lbl}}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{Op,{f,label(Lbl, D, Fb)}}|Acc], D, Fb);
replace_labels_1([{bif,Name,{f,Lbl},As,R}|Is], Acc, D, Fb) when Lbl =/= 0 ->
replace_labels_1(Is, [{bif,Name,{f,label(Lbl, D, Fb)},As,R}|Acc], D, Fb);
replace_labels_1([{gc_bif,Name,{f,Lbl},Live,As,R}|Is], Acc, D, Fb) when Lbl =/= 0 ->
replace_labels_1(Is, [{gc_bif,Name,{f,label(Lbl, D, Fb)},Live,As,R}|Acc], D, Fb);
replace_labels_1([{call,Ar,{f,Lbl}}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{call,Ar,{f,label(Lbl, D, Fb)}}|Acc], D, Fb);
replace_labels_1([{make_fun2,{f,Lbl},U1,U2,U3}|Is], Acc, D, Fb) ->
replace_labels_1(Is, [{make_fun2,{f,label(Lbl, D, Fb)},U1,U2,U3}|Acc], D, Fb);
replace_labels_1([{bs_init,{f,Lbl},Info,Live,Ss,Dst}|Is], Acc, D, Fb) when Lbl =/= 0 ->
replace_labels_1(Is, [{bs_init,{f,label(Lbl, D, Fb)},Info,Live,Ss,Dst}|Acc], D, Fb);
replace_labels_1([{bs_put,{f,Lbl},Info,Ss}|Is], Acc, D, Fb) when Lbl =/= 0 ->
replace_labels_1(Is, [{bs_put,{f,label(Lbl, D, Fb)},Info,Ss}|Acc], D, Fb);
replace_labels_1([{put_map=I,{f,Lbl},Op,Src,Dst,Live,List}|Is], Acc, D, Fb)
when Lbl =/= 0 ->
replace_labels_1(Is, [{I,{f,label(Lbl, D, Fb)},Op,Src,Dst,Live,List}|Acc], D, Fb);
replace_labels_1([{get_map_elements=I,{f,Lbl},Src,List}|Is], Acc, D, Fb) when Lbl =/= 0 ->
replace_labels_1(Is, [{I,{f,label(Lbl, D, Fb)},Src,List}|Acc], D, Fb);
replace_labels_1([I|Is], Acc, D, Fb) ->
replace_labels_1(Is, [I|Acc], D, Fb);
replace_labels_1([], Acc, _, _) -> Acc.
label(Old, D, Fb) ->
case D of
#{Old := New} -> New;
_ -> Fb(Old)
end.
%% live_opt/4.
split_even([], Ss, Ds) ->
{reverse(Ss),reverse(Ds)};
split_even([S,D|Rs], Ss, Ds) ->
split_even(Rs, [S|Ss], [D|Ds]).