aboutsummaryrefslogtreecommitdiffstats
path: root/lib/compiler/src/beam_ssa_bsm.erl
blob: 2efeb6b5b6d0d993a77095038f546f3ee818b0d5 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 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%
%%

%%%
%%% This pass optimizes bit syntax matching, and is centered around the concept
%%% of "match context reuse" which is best explained through example. To put it
%%% shortly we attempt to turn this:
%%%
%%%    <<0,B/bits>> = A,
%%%    <<1,C/bits>> = B,
%%%    <<D,_/bits>> = C,
%%%    D.
%%%
%%% ... Into this:
%%%
%%%    <<0,1,D,_/bits>>=A,
%%%    D.
%%%
%%% Which is much faster as it avoids the creation of intermediate terms. This
%%% is especially noticeable in loops where such garbage is generated on each
%%% iteration.
%%%
%%% The optimization itself is very simple and can be applied whenever there's
%%% matching on the tail end of a binary; instead of creating a new binary and
%%% starting a new match context on it, we reuse the match context used to
%%% extract the tail and avoid the creation of both objects.
%%%
%%% The catch is that a match context isn't a proper type and nothing outside
%%% of bit syntax match operations can handle them. We therefore need to make
%%% sure that they never "leak" into other instructions, and most of the pass
%%% revolves around getting around that limitation.
%%%
%%% Unlike most other passes we look at the whole module so we can combine
%%% matches across function boundaries, greatly increasing the performance of
%%% complex matches and loops.
%%%

-module(beam_ssa_bsm).

-export([module/2, format_error/1]).

-include("beam_ssa.hrl").

-import(lists, [member/2, reverse/1, splitwith/2, map/2, foldl/3, mapfoldl/3,
                nth/2, max/1, unzip/1]).

-spec format_error(term()) -> nonempty_string().

format_error(OptInfo) ->
    format_opt_info(OptInfo).

-spec module(Module, Options) -> Result when
      Module :: beam_ssa:b_module(),
      Options :: [compile:option()],
      Result :: {ok, beam_ssa:b_module(), list()}.

-define(PASS(N), {N,fun N/1}).

module(#b_module{body=Fs0}=Module, Opts) ->
    ModInfo = analyze_module(Module),

    %% combine_matches is repeated after accept_context_args as the control
    %% flow changes can enable further optimizations, as in the example below:
    %%
    %%    a(<<0,X/binary>>) -> a(X);
    %%    a(A) when bit_size(A) =:= 52 -> bar;
    %%    a(<<1,X/binary>>) -> X. %% Match context will be reused here when
    %%                            %% when repeated.

    {Fs, _} = compile:run_sub_passes(
                [?PASS(combine_matches),
                 ?PASS(accept_context_args),
                 ?PASS(combine_matches),
                 ?PASS(allow_context_passthrough),
                 ?PASS(skip_outgoing_tail_extraction),
                 ?PASS(annotate_context_parameters)],
                {Fs0, ModInfo}),

    Ws = case proplists:get_bool(bin_opt_info, Opts) of
             true -> collect_opt_info(Fs);
             false -> []
         end,

    {ok, Module#b_module{body=Fs}, Ws}.

-type module_info() :: #{ func_id() => func_info() }.

-type func_id() :: {Name :: atom(), Arity :: non_neg_integer()}.

-type func_info() :: #{ has_bsm_ops => boolean(),
                        parameters => [#b_var{}],
                        parameter_info => #{ #b_var{} => param_info() } }.

-type param_info() :: suitable_for_reuse |
                      {Problem :: atom(), Where :: term()}.

-spec analyze_module(#b_module{}) -> module_info().

analyze_module(#b_module{body=Fs}) ->
    foldl(fun(#b_function{args=Parameters}=F, I) ->
                  FuncInfo = #{ has_bsm_ops => has_bsm_ops(F),
                                parameters => Parameters,
                                parameter_info => #{} },
                  FuncId = get_fa(F),
                  I#{ FuncId => FuncInfo }
          end, #{}, Fs).

has_bsm_ops(#b_function{bs=Blocks}) ->
    hbo_blocks(maps:to_list(Blocks)).

hbo_blocks([{_,#b_blk{is=Is}} | Blocks]) ->
    case hbo_is(Is) of
        false -> hbo_blocks(Blocks);
        true -> true
    end;
hbo_blocks([]) ->
    false.

hbo_is([#b_set{op=bs_start_match} | _]) -> true;
hbo_is([_I | Is]) -> hbo_is(Is);
hbo_is([]) -> false.

%% Checks whether it's legal to make a call with the given argument as a match
%% context, returning the param_info() of the relevant parameter.
-spec check_context_call(#b_set{}, Arg, CtxChain, ModInfo) -> param_info() when
      Arg :: #b_var{},
      CtxChain :: [#b_var{}],
      ModInfo :: module_info().
check_context_call(#b_set{args=Args}, Arg, CtxChain, ModInfo) ->
    Aliases = [Arg | CtxChain],
    ccc_1(Args, Arg, Aliases, ModInfo).

ccc_1([#b_local{}=Call | Args], Ctx, Aliases, ModInfo) ->
    %% Matching operations assume that their context isn't aliased (as in
    %% pointer aliasing), so we must reject calls whose arguments contain more
    %% than one reference to the context.
    %%
    %% TODO: Try to fall back to passing binaries in these cases. Partial reuse
    %% is better than nothing.
    UseCount = foldl(fun(Arg, C) ->
                             case member(Arg, Aliases) of
                                 true -> C + 1;
                                 false -> C
                             end
                     end, 0, Args),
    if
        UseCount =:= 1 ->
            #b_local{name=#b_literal{val=Name},arity=Arity} = Call,
            Callee = {Name, Arity},

            ParamInfo = funcinfo_get(Callee, parameter_info, ModInfo),
            Parameters = funcinfo_get(Callee, parameters, ModInfo),
            Parameter = nth(1 + arg_index(Ctx, Args), Parameters),

            case maps:find(Parameter, ParamInfo) of
                {ok, suitable_for_reuse} ->
                    suitable_for_reuse;
                {ok, Other} ->
                    {unsuitable_call, {Call, Other}};
                error ->
                    {no_match_on_entry, Call}
            end;
        UseCount > 1 ->
            {multiple_uses_in_call, Call}
    end;
ccc_1([#b_remote{}=Call | _Args], _Ctx, _CtxChain, _ModInfo) ->
    {remote_call, Call};
ccc_1([Fun | _Args], _Ctx, _CtxChain, _ModInfo) ->
    %% TODO: It may be possible to support this in the future for locally
    %% defined funs, including ones with free variables.
    {fun_call, Fun}.

%% Returns the index of Var in Args.
arg_index(Var, Args) -> arg_index_1(Var, Args, 0).

arg_index_1(Var, [Var | _Args], Index) -> Index;
arg_index_1(Var, [_Arg | Args], Index) -> arg_index_1(Var, Args, Index + 1).

is_tail_binary(#b_set{op=bs_match,args=[#b_literal{val=binary} | Rest]}) ->
    member(#b_literal{val=all}, Rest);
is_tail_binary(#b_set{op=bs_get_tail}) ->
    true;
is_tail_binary(_) ->
    false.

is_tail_binary(#b_var{}=Var, Defs) ->
    case find_match_definition(Var, Defs) of
        {ok, Def} -> is_tail_binary(Def);
        _ -> false
    end;
is_tail_binary(_Literal, _Defs) ->
    false.

assert_match_context(#b_var{}=Var, Defs) ->
    case maps:find(Var, Defs) of
        {ok, #b_set{op=bs_match,args=[_,#b_var{}=Ctx|_]}} ->
            assert_match_context(Ctx, Defs);
        {ok, #b_set{op=bs_start_match}} ->
            ok
    end.

find_match_definition(#b_var{}=Var, Defs) ->
    case maps:find(Var, Defs) of
        {ok, #b_set{op=bs_extract,args=[Ctx]}} -> maps:find(Ctx, Defs);
        {ok, #b_set{op=bs_get_tail}=Def} -> {ok, Def};
        _ -> error
    end.

%% Returns a list of all contexts that were used to extract Var.
context_chain_of(#b_var{}=Var, Defs) ->
    case maps:find(Var, Defs) of
        {ok, #b_set{op=bs_match,args=[_,#b_var{}=Ctx|_]}} ->
            [Ctx | context_chain_of(Ctx, Defs)];
        {ok, #b_set{op=bs_get_tail,args=[Ctx]}} ->
            [Ctx | context_chain_of(Ctx, Defs)];
        {ok, #b_set{op=bs_extract,args=[Ctx]}} ->
            [Ctx | context_chain_of(Ctx, Defs)];
        _ ->
            []
    end.

%% Grabs the match context used to produce the given variable.
match_context_of(#b_var{}=Var, Defs) ->
    Ctx = match_context_of_1(Var, Defs),
    assert_match_context(Ctx, Defs),
    Ctx.

match_context_of_1(Var, Defs) ->
    case maps:get(Var, Defs) of
        #b_set{op=bs_extract,args=[#b_var{}=Ctx0]} ->
            #b_set{op=bs_match,
                   args=[_,#b_var{}=Ctx|_]} = maps:get(Ctx0, Defs),
            Ctx;
        #b_set{op=bs_get_tail,args=[#b_var{}=Ctx]} ->
            Ctx
    end.

funcinfo_get(#b_function{}=F, Attribute, ModInfo) ->
    funcinfo_get(get_fa(F), Attribute, ModInfo);
funcinfo_get({_,_}=Key, Attribute, ModInfo) ->
    FuncInfo = maps:get(Key, ModInfo),
    maps:get(Attribute, FuncInfo).

funcinfo_set(#b_function{}=F, Attribute, Value, ModInfo) ->
    funcinfo_set(get_fa(F), Attribute, Value, ModInfo);
funcinfo_set(Key, Attribute, Value, ModInfo) ->
    FuncInfo = maps:put(Attribute, Value, maps:get(Key, ModInfo, #{})),
    maps:put(Key, FuncInfo, ModInfo).

get_fa(#b_function{ anno = Anno }) ->
    {_,Name,Arity} = maps:get(func_info, Anno),
    {Name,Arity}.

%% Replaces matched-out binaries with aliases that are lazily converted to
%% binary form when used, allowing us to keep the "match path" free of binary
%% creation.

-spec alias_matched_binaries(Blocks, Counter, AliasMap) -> Result when
      Blocks :: beam_ssa:block_map(),
      Counter :: non_neg_integer(),
      AliasMap :: match_alias_map(),
      Result :: {Blocks, Counter}.

-type match_alias_map() ::
        #{ Binary :: #b_var{} =>
                     { %% Replace all uses of Binary with an alias after this
                       %% label.
                       AliasAfter :: beam_ssa:label(),
                       %% The match context whose tail is equal to Binary.
                       Context :: #b_var{} } }.

%% Keeps track of the promotions we need to insert. They're partially keyed by
%% location because they may not be valid on all execution paths and we may
%% need to add redundant promotions in some cases.
-type promotion_map() ::
        #{ { PromoteAt :: beam_ssa:label(),
             Variable :: #b_var{} } =>
               Instruction :: #b_set{} }.

-record(amb, { dominators :: beam_ssa:dominator_map(),
               match_aliases :: match_alias_map(),
               cnt :: non_neg_integer(),
               promotions = #{} :: promotion_map() }).

alias_matched_binaries(Blocks0, Counter, AliasMap) when AliasMap =/= #{} ->
    State0 = #amb{ dominators = beam_ssa:dominators(Blocks0),
                   match_aliases = AliasMap,
                   cnt = Counter },
    {Blocks, State} = beam_ssa:mapfold_blocks_rpo(fun amb_1/3, [0], State0,
                                                  Blocks0),
    {amb_insert_promotions(Blocks, State), State#amb.cnt};
alias_matched_binaries(Blocks, Counter, _AliasMap) ->
    {Blocks, Counter}.

amb_1(Lbl, #b_blk{is=Is0,last=Last0}=Block, State0) ->
    {Is, State1} = mapfoldl(fun(I, State) ->
                                    amb_assign_set(I, Lbl, State)
                            end, State0, Is0),
    {Last, State} = amb_assign_last(Last0, Lbl, State1),
    {Block#b_blk{is=Is,last=Last}, State}.

amb_assign_set(#b_set{op=phi,args=Args0}=I, _Lbl, State0) ->
    %% Phi node aliases are relative to their source block, not their
    %% containing block.
    {Args, State} =
        mapfoldl(fun({Arg0, Lbl}, Acc) ->
                         {Arg, State} = amb_get_alias(Arg0, Lbl, Acc),
                         {{Arg, Lbl}, State}
                 end, State0, Args0),
    {I#b_set{args=Args}, State};
amb_assign_set(#b_set{args=Args0}=I, Lbl, State0) ->
    {Args, State} = mapfoldl(fun(Arg0, Acc) ->
                                     amb_get_alias(Arg0, Lbl, Acc)
                             end, State0, Args0),
    {I#b_set{args=Args}, State}.

amb_assign_last(#b_ret{arg=Arg0}=T, Lbl, State0) ->
    {Arg, State} = amb_get_alias(Arg0, Lbl, State0),
    {T#b_ret{arg=Arg}, State};
amb_assign_last(#b_switch{arg=Arg0}=T, Lbl, State0) ->
    {Arg, State} = amb_get_alias(Arg0, Lbl, State0),
    {T#b_switch{arg=Arg}, State};
amb_assign_last(#b_br{bool=Arg0}=T, Lbl, State0) ->
    {Arg, State} = amb_get_alias(Arg0, Lbl, State0),
    {T#b_br{bool=Arg}, State}.

amb_get_alias(#b_var{}=Arg, Lbl, State) ->
    case maps:find(Arg, State#amb.match_aliases) of
        {ok, {AliasAfter, Context}} ->
            %% Our context may not have been created yet, so we skip assigning
            %% an alias unless the given block is among our dominators.
            Dominators = maps:get(Lbl, State#amb.dominators),
            case ordsets:is_element(AliasAfter, Dominators) of
                true -> amb_create_alias(Arg, Context, Lbl, State);
                false -> {Arg, State}
            end;
        error ->
            {Arg, State}
    end;
amb_get_alias(Arg, _Lbl, State) ->
    {Arg, State}.

amb_create_alias(#b_var{}=Arg0, Context, Lbl, State0) ->
    Dominators = maps:get(Lbl, State0#amb.dominators),
    Promotions0 = State0#amb.promotions,

    PrevPromotions =
        [maps:get({Dom, Arg0}, Promotions0)
         || Dom <- Dominators, is_map_key({Dom, Arg0}, Promotions0)],

    case PrevPromotions of
        [_|_] ->
            %% We've already created an alias prior to this block, so we'll
            %% grab the most recent one to minimize stack use.

            #b_set{dst=Alias} = max(PrevPromotions),
            {Alias, State0};
        [] ->
            %% If we haven't created an alias we need to do so now. The
            %% promotion will be inserted later by amb_insert_promotions/2.

            Counter = State0#amb.cnt,
            Alias = #b_var{name={'@ssa_bsm_alias', Counter}},
            Promotion = #b_set{op=bs_get_tail,dst=Alias,args=[Context]},

            Promotions = maps:put({Lbl, Arg0}, Promotion, Promotions0),
            State = State0#amb{ promotions=Promotions, cnt=Counter+1 },

            {Alias, State}
    end.

amb_insert_promotions(Blocks0, State) ->
    F = fun({Lbl, #b_var{}}, Promotion, Blocks) ->
                Block = maps:get(Lbl, Blocks),

                Alias = Promotion#b_set.dst,
                {Before, After} = splitwith(fun(#b_set{args=Args}) ->
                                                    not member(Alias, Args)
                                            end, Block#b_blk.is),
                Is = Before ++ [Promotion | After],

                maps:put(Lbl, Block#b_blk{is=Is}, Blocks)
        end,
    maps:fold(F, Blocks0, State#amb.promotions).

%%%
%%% Subpasses
%%%

%% Removes superflous chained bs_start_match instructions in the same
%% function. When matching on an extracted tail binary, or on a binary we've
%% already matched on, we reuse the original match context.
%%
%% This pass runs first since it makes subsequent optimizations more effective
%% by removing spots where promotion would be required.

-type prior_match_map() ::
        #{ Binary :: #b_var{} =>
                     [{ %% The context and success label of a previous
                        %% bs_start_match made on this binary.
                        ValidAfter :: beam_ssa:label(),
                        Context :: #b_var{} }] }.

-record(cm, { definitions :: beam_ssa:definition_map(),
              dominators :: beam_ssa:dominator_map(),
              blocks :: beam_ssa:block_map(),
              match_aliases = #{} :: match_alias_map(),
              prior_matches = #{} :: prior_match_map(),
              renames = #{} :: beam_ssa:rename_map() }).

combine_matches({Fs0, ModInfo}) ->
    Fs = map(fun(F) -> combine_matches(F, ModInfo) end, Fs0),
    {Fs, ModInfo}.

combine_matches(#b_function{bs=Blocks0,cnt=Counter0}=F, ModInfo) ->
    case funcinfo_get(F, has_bsm_ops, ModInfo) of
        true ->
            {Blocks1, State} =
                beam_ssa:mapfold_blocks_rpo(
                  fun(Lbl, #b_blk{is=Is0}=Block0, State0) ->
                          {Is, State} = cm_1(Is0, [], Lbl, State0),
                          {Block0#b_blk{is=Is}, State}
                  end, [0],
                  #cm{ definitions = beam_ssa:definitions(Blocks0),
                       dominators = beam_ssa:dominators(Blocks0),
                       blocks = Blocks0 },
                  Blocks0),

            Blocks2 = beam_ssa:rename_vars(State#cm.renames, [0], Blocks1),

            {Blocks, Counter} = alias_matched_binaries(Blocks2, Counter0,
                                                       State#cm.match_aliases),

            F#b_function{ bs=Blocks, cnt=Counter };
        false ->
            F
    end.

cm_1([#b_set{ op=bs_start_match,
              dst=Ctx,
              args=[Src] },
      #b_set{ op=succeeded,
              dst=Bool,
              args=[Ctx] }]=MatchSeq, Acc0, Lbl, State0) ->
    Acc = reverse(Acc0),
    case is_tail_binary(Src, State0#cm.definitions) of
        true -> cm_combine_tail(Src, Ctx, Bool, Acc, State0);
        false -> cm_handle_priors(Src, Ctx, Bool, Acc, MatchSeq, Lbl, State0)
    end;
cm_1([I | Is], Acc, Lbl, State) ->
    cm_1(Is, [I | Acc], Lbl, State);
cm_1([], Acc, _Lbl, State) ->
    {reverse(Acc), State}.

%% If we're dominated by at least one match on the same source, we can reuse
%% the context created by that match.
cm_handle_priors(Src, DstCtx, Bool, Acc, MatchSeq, Lbl, State0) ->
    PriorCtxs = case maps:find(Src, State0#cm.prior_matches) of
                    {ok, Priors} ->
                        %% We've seen other match contexts on this source, but
                        %% we can only consider the ones whose success path
                        %% dominate us.
                        Dominators = maps:get(Lbl, State0#cm.dominators, []),
                        [Ctx || {ValidAfter, Ctx} <- Priors,
                                ordsets:is_element(ValidAfter, Dominators)];
                    error ->
                        []
                end,
    case PriorCtxs of
        [Ctx|_] ->
            Renames0 = State0#cm.renames,
            Renames = Renames0#{ Bool => #b_literal{val=true}, DstCtx => Ctx },
            {Acc, State0#cm{ renames = Renames }};
        [] ->
            %% Since we lack a prior match, we need to register this one in
            %% case we dominate another.
            State = cm_register_prior(Src, DstCtx, Lbl, State0),
            {Acc ++ MatchSeq, State}
    end.

cm_register_prior(Src, DstCtx, Lbl, State) ->
    Block = maps:get(Lbl, State#cm.blocks),
    #b_br{succ=ValidAfter} = Block#b_blk.last,

    Priors0 = maps:get(Src, State#cm.prior_matches, []),
    Priors = [{ValidAfter, DstCtx} | Priors0],

    PriorMatches = maps:put(Src, Priors, State#cm.prior_matches),
    State#cm{ prior_matches = PriorMatches }.

cm_combine_tail(Src, DstCtx, Bool, Acc, State0) ->
    SrcCtx = match_context_of(Src, State0#cm.definitions),

    %% We replace the source with a context alias as it normally won't be used
    %% on the happy path after being matched, and the added cost of conversion
    %% is negligible if it is.
    Aliases = maps:put(Src, {0, SrcCtx}, State0#cm.match_aliases),

    Renames0 = State0#cm.renames,
    Renames = Renames0#{ Bool => #b_literal{val=true}, DstCtx => SrcCtx },

    State = State0#cm{ match_aliases = Aliases, renames = Renames },

    {Acc, State}.

%% Lets functions accept match contexts as arguments. The parameter must be
%% unused before the bs_start_match instruction, and it must be matched in the
%% first block.

-record(aca, { unused_parameters :: ordsets:ordset(#b_var{}),
               counter :: non_neg_integer(),
               parameter_info = #{} :: #{ #b_var{} => param_info() },
               match_aliases = #{} :: match_alias_map() }).

accept_context_args({Fs, ModInfo}) ->
    mapfoldl(fun accept_context_args/2, ModInfo, Fs).

accept_context_args(#b_function{bs=Blocks0}=F, ModInfo0) ->
    case funcinfo_get(F, has_bsm_ops, ModInfo0) of
        true ->
            Parameters = ordsets:from_list(funcinfo_get(F, parameters, ModInfo0)),
            State0 = #aca{ unused_parameters = Parameters,
                           counter = F#b_function.cnt },

            {Blocks1, State} = aca_1(Blocks0, State0),
            {Blocks, Counter} = alias_matched_binaries(Blocks1,
                                                       State#aca.counter,
                                                       State#aca.match_aliases),

            ModInfo = funcinfo_set(F, parameter_info, State#aca.parameter_info,
                                   ModInfo0),

            {F#b_function{bs=Blocks,cnt=Counter}, ModInfo};
        false ->
            {F, ModInfo0}
    end.

aca_1(Blocks, State) ->
    %% We only handle block 0 as we don't yet support starting a match after a
    %% test. This is generally good enough as the sys_core_bsm pass makes the
    %% match instruction come first if possible, and it's rare for a function
    %% to binary-match several parameters at once.
    EntryBlock = maps:get(0, Blocks),
    aca_enable_reuse(EntryBlock#b_blk.is, EntryBlock, Blocks, [], State).

aca_enable_reuse([#b_set{op=bs_start_match,args=[Src]}=I0 | Rest],
                 EntryBlock, Blocks0, Acc, State0) ->
    case aca_is_reuse_safe(Src, State0) of
        true ->
            {I, Last, Blocks1, State} =
                aca_reuse_context(I0, EntryBlock, Blocks0, State0),

            Is = reverse([I|Acc]) ++ Rest,
            Blocks = maps:put(0, EntryBlock#b_blk{is=Is,last=Last}, Blocks1),

            {Blocks, State};
        false ->
            {Blocks0, State0}
    end;
aca_enable_reuse([I | Is], EntryBlock, Blocks, Acc, State0) ->
    UnusedParams0 = State0#aca.unused_parameters,
    case ordsets:intersection(UnusedParams0, beam_ssa:used(I)) of
        [] ->
            aca_enable_reuse(Is, EntryBlock, Blocks, [I | Acc], State0);
        PrematureUses ->
            UnusedParams = ordsets:subtract(UnusedParams0, PrematureUses),

            %% Mark the offending parameters as unsuitable for context reuse.
            ParamInfo = foldl(fun(A, Ps) ->
                                      maps:put(A, {used_before_match, I}, Ps)
                              end, State0#aca.parameter_info, PrematureUses),

            State = State0#aca{ unused_parameters = UnusedParams,
                                parameter_info = ParamInfo },
            aca_enable_reuse(Is, EntryBlock, Blocks, [I | Acc], State)
    end;
aca_enable_reuse([], _EntryBlock, Blocks, _Acc, State) ->
    {Blocks, State}.

aca_is_reuse_safe(Src, State) ->
    %% Context reuse is unsafe unless all uses are dominated by the start_match
    %% instruction. Since we only process block 0 it's enough to check if
    %% they're unused so far.
    ordsets:is_element(Src, State#aca.unused_parameters).

aca_reuse_context(#b_set{dst=Dst, args=[Src]}=I0, Block, Blocks0, State0) ->
    %% When matching fails on a reused context it needs to be converted back
    %% to a binary. We only need to do this on the success path since it can't
    %% be a context on the type failure path, but it's very common for these
    %% to converge which requires special handling.
    {State1, Last, Blocks} =
        aca_handle_convergence(Src, State0, Block#b_blk.last, Blocks0),

    Aliases = maps:put(Src, {Last#b_br.succ, Dst}, State1#aca.match_aliases),
    ParamInfo = maps:put(Src, suitable_for_reuse, State1#aca.parameter_info),

    State = State1#aca{ match_aliases = Aliases,
                        parameter_info = ParamInfo },

    I = beam_ssa:add_anno(accepts_match_contexts, true, I0),

    {I, Last, Blocks, State}.

aca_handle_convergence(Src, State0, Last0, Blocks0) ->
    #b_br{fail=Fail0,succ=Succ0} = Last0,

    SuccPath = beam_ssa:rpo([Succ0], Blocks0),
    FailPath = beam_ssa:rpo([Fail0], Blocks0),

    %% The promotion logic in alias_matched_binaries breaks down if the source
    %% is used after the fail/success paths converge, as we have no way to tell
    %% whether the source is a match context or something else past that point.
    %%
    %% We could handle this through clever insertion of phi nodes but it's
    %% far simpler to copy either branch in its entirety. It doesn't matter
    %% which one as long as they become disjoint.
    ConvergedPaths = ordsets:intersection(
                       ordsets:from_list(SuccPath),
                       ordsets:from_list(FailPath)),

    case maps:is_key(Src, beam_ssa:uses(ConvergedPaths, Blocks0)) of
        true ->
            case shortest(SuccPath, FailPath) of
                left ->
                    {Succ, Blocks, Counter} =
                        aca_copy_successors(Succ0, Blocks0, State0#aca.counter),
                    State = State0#aca{ counter = Counter },
                    {State, Last0#b_br{succ=Succ}, Blocks};
                right ->
                    {Fail, Blocks, Counter} =
                        aca_copy_successors(Fail0, Blocks0, State0#aca.counter),
                    State = State0#aca{ counter = Counter },
                    {State, Last0#b_br{fail=Fail}, Blocks}
            end;
        false ->
            {State0, Last0, Blocks0}
    end.

shortest([_|As], [_|Bs]) -> shortest(As, Bs);
shortest([], _) -> left;
shortest(_, []) -> right.

%% Copies all successor blocks of Lbl, returning the label to the entry block
%% of this copy. Since the copied blocks aren't referenced anywhere else, they
%% are all guaranteed to be dominated by Lbl.
aca_copy_successors(Lbl0, Blocks0, Counter0) ->
    %% Building the block rename map up front greatly simplifies phi node
    %% handling.
    Path = beam_ssa:rpo([Lbl0], Blocks0),
    {BRs, Counter1} = aca_cs_build_brs(Path, Counter0, #{}),
    {Blocks, Counter} = aca_cs_1(Path, Blocks0, Counter1, #{}, BRs, #{}),
    Lbl = maps:get(Lbl0, BRs),
    {Lbl, Blocks, Counter}.

aca_cs_build_brs([Lbl | Path], Counter0, Acc) ->
    aca_cs_build_brs(Path, Counter0 + 1, maps:put(Lbl, Counter0, Acc));
aca_cs_build_brs([], Counter, Acc) ->
    {Acc, Counter}.

aca_cs_1([Lbl0 | Path], Blocks, Counter0, VRs0, BRs, Acc0) ->
    Block0 = maps:get(Lbl0, Blocks),
    Lbl = maps:get(Lbl0, BRs),
    {VRs, Block, Counter} = aca_cs_block(Block0, Counter0, VRs0, BRs),
    Acc = maps:put(Lbl, Block, Acc0),
    aca_cs_1(Path, Blocks, Counter, VRs, BRs, Acc);
aca_cs_1([], Blocks, Counter, _VRs, _BRs, Acc) ->
    {maps:merge(Blocks, Acc), Counter}.

aca_cs_block(#b_blk{is=Is0,last=Last0}=Block0, Counter0, VRs0, BRs) ->
    {VRs, Is, Counter} = aca_cs_is(Is0, Counter0, VRs0, BRs, []),
    Last = aca_cs_last(Last0, VRs, BRs),
    Block = Block0#b_blk{is=Is,last=Last},
    {VRs, Block, Counter}.

aca_cs_is([#b_set{op=Op,
                  dst=Dst0,
                  args=Args0}=I0 | Is],
          Counter0, VRs0, BRs, Acc) ->
    Args = case Op of
               phi -> aca_cs_args_phi(Args0, VRs0, BRs);
               _ -> aca_cs_args(Args0, VRs0)
           end,
    Counter = Counter0 + 1,
    Dst = #b_var{name={'@ssa_bsm_aca',Counter}},
    I = I0#b_set{dst=Dst,args=Args},
    VRs = maps:put(Dst0, Dst, VRs0),
    aca_cs_is(Is, Counter, VRs, BRs, [I | Acc]);
aca_cs_is([], Counter, VRs, _BRs, Acc) ->
    {VRs, reverse(Acc), Counter}.

aca_cs_last(#b_switch{arg=Arg0,list=Switch0,fail=Fail0}=Sw, VRs, BRs) ->
    Switch = [{Literal, maps:get(Lbl, BRs)} || {Literal, Lbl} <- Switch0],
    Sw#b_switch{arg=aca_cs_arg(Arg0, VRs),
                fail=maps:get(Fail0, BRs),
                list=Switch};
aca_cs_last(#b_br{bool=Arg0,succ=Succ0,fail=Fail0}=Br, VRs, BRs) ->
    Br#b_br{bool=aca_cs_arg(Arg0, VRs),
            succ=maps:get(Succ0, BRs),
            fail=maps:get(Fail0, BRs)};
aca_cs_last(#b_ret{arg=Arg0}=Ret, VRs, _BRs) ->
    Ret#b_ret{arg=aca_cs_arg(Arg0, VRs)}.

aca_cs_args_phi([{Arg, Lbl} | Args], VRs, BRs) ->
    case BRs of
        #{ Lbl := New } ->
            [{aca_cs_arg(Arg, VRs), New} | aca_cs_args_phi(Args, VRs, BRs)];
        #{} ->
            aca_cs_args_phi(Args, VRs, BRs)
    end;
aca_cs_args_phi([], _VRs, _BRs) ->
    [].

aca_cs_args([Arg | Args], VRs) ->
    [aca_cs_arg(Arg, VRs) | aca_cs_args(Args, VRs)];
aca_cs_args([], _VRs) ->
    [].

aca_cs_arg(Arg, VRs) ->
    case VRs of
        #{ Arg := New } -> New;
        #{} -> Arg
    end.

%% Allows contexts to pass through "wrapper functions" where the context is
%% passed directly to a function that accepts match contexts (including other
%% wrappers).
%%
%% This does not alter the function in any way, it only changes parameter info
%% so that skip_outgoing_tail_extraction is aware that it's safe to pass
%% contexts to us.

allow_context_passthrough({Fs, ModInfo0}) ->
    ModInfo =
        acp_forward_params([{F, beam_ssa:uses(F#b_function.bs)} || F <- Fs],
                           ModInfo0),
    {Fs, ModInfo}.

acp_forward_params(FsUses, ModInfo0) ->
    F = fun({#b_function{args=Parameters}=Func, UseMap}, ModInfo) ->
                ParamInfo =
                    foldl(fun(Param, ParamInfo) ->
                                  Uses = maps:get(Param, UseMap, []),
                                  acp_1(Param, Uses, ModInfo, ParamInfo)
                          end,
                          funcinfo_get(Func, parameter_info, ModInfo),
                          Parameters),
                funcinfo_set(Func, parameter_info, ParamInfo, ModInfo)
        end,
    %% Allowing context passthrough on one function may make it possible to
    %% enable it on another, so it needs to be repeated for maximum effect.
    case foldl(F, ModInfo0, FsUses) of
        ModInfo0 -> ModInfo0;
        Changed -> acp_forward_params(FsUses, Changed)
    end.

%% We have no way to know if an argument is a context, so it's only safe to
%% forward them if they're passed exactly once in the first block. Any other
%% uses are unsafe, including function_clause errors.
acp_1(Param, [{0, #b_set{op=call}=I}], ModInfo, ParamInfo) ->
    %% We don't need to provide a context chain as our callers make sure that
    %% multiple arguments never reference the same context.
    case check_context_call(I, Param, [], ModInfo) of
        {no_match_on_entry, _} -> ParamInfo;
        Other -> maps:put(Param, Other, ParamInfo)
    end;
acp_1(_Param, _Uses, _ModInfo, ParamInfo) ->
    ParamInfo.

%% This is conceptually similar to combine_matches but operates across
%% functions. Whenever a tail binary is passed to a parameter that accepts
%% match contexts we'll pass the context instead, improving performance by
%% avoiding the creation of a new match context in the callee.
%%
%% We also create an alias to delay extraction until it's needed as an actual
%% binary, which is often rare on the happy path. The cost of being wrong is
%% negligible (`bs_test_unit + bs_get_tail` vs `bs_get_binary`) so we're
%% applying it unconditionally to keep things simple.

-record(sote, { definitions :: beam_ssa:definition_map(),
                mod_info :: module_info(),
                match_aliases = #{} :: match_alias_map() }).

skip_outgoing_tail_extraction({Fs0, ModInfo}) ->
    Fs = map(fun(F) -> skip_outgoing_tail_extraction(F, ModInfo) end, Fs0),
    {Fs, ModInfo}.

skip_outgoing_tail_extraction(#b_function{bs=Blocks0}=F, ModInfo) ->
    case funcinfo_get(F, has_bsm_ops, ModInfo) of
        true ->
            State0 = #sote{ definitions = beam_ssa:definitions(Blocks0),
                            mod_info = ModInfo },

            {Blocks1, State} = beam_ssa:mapfold_instrs_rpo(
                                 fun sote_rewrite_calls/2, [0], State0, Blocks0),

            {Blocks, Counter} = alias_matched_binaries(Blocks1,
                                                       F#b_function.cnt,
                                                       State#sote.match_aliases),

            F#b_function{bs=Blocks,cnt=Counter};
        false ->
            F
    end.

sote_rewrite_calls(#b_set{op=call,args=Args}=Call, State) ->
    sote_rewrite_call(Call, Args, [], State);
sote_rewrite_calls(I, State) ->
    {I, State}.

sote_rewrite_call(Call, [], ArgsOut, State) ->
    {Call#b_set{args=reverse(ArgsOut)}, State};
sote_rewrite_call(Call0, [Arg | ArgsIn], ArgsOut, State0) ->
    case is_tail_binary(Arg, State0#sote.definitions) of
        true ->
            CtxChain = context_chain_of(Arg, State0#sote.definitions),
            case check_context_call(Call0, Arg, CtxChain, State0#sote.mod_info) of
                suitable_for_reuse ->
                    Ctx = match_context_of(Arg, State0#sote.definitions),

                    MatchAliases0 = State0#sote.match_aliases,
                    MatchAliases = maps:put(Arg, {0, Ctx}, MatchAliases0),
                    State = State0#sote{ match_aliases = MatchAliases },

                    Call = beam_ssa:add_anno(bsm_info, context_reused, Call0),
                    sote_rewrite_call(Call, ArgsIn, [Ctx | ArgsOut], State);
                Other ->
                    Call = beam_ssa:add_anno(bsm_info, Other, Call0),
                    sote_rewrite_call(Call, ArgsIn, [Arg | ArgsOut], State0)
            end;
        false ->
            sote_rewrite_call(Call0, ArgsIn, [Arg | ArgsOut], State0)
    end.

%% Adds parameter_type_info annotations to help the validator determine whether
%% our optimizations were safe.

annotate_context_parameters({Fs, ModInfo}) ->
    mapfoldl(fun annotate_context_parameters/2, ModInfo, Fs).

annotate_context_parameters(F, ModInfo) ->
    ParamInfo = funcinfo_get(F, parameter_info, ModInfo),
    TypeAnno0 = beam_ssa:get_anno(parameter_type_info, F, #{}),
    TypeAnno = maps:fold(fun(K, _V, Acc) when is_map_key(K, Acc) ->
                                 %% Assertion.
                                 error(conflicting_parameter_types);
                            (K, suitable_for_reuse, Acc) ->
                                 Acc#{ K => match_context };
                            (_K, _V, Acc) ->
                                 Acc
                         end, TypeAnno0, ParamInfo),
    {beam_ssa:add_anno(parameter_type_info, TypeAnno, F), ModInfo}.

%%%
%%% +bin_opt_info
%%%

collect_opt_info(Fs) ->
    foldl(fun(#b_function{bs=Blocks}=F, Acc0) ->
                  UseMap = beam_ssa:uses(Blocks),
                  Where = beam_ssa:get_anno(location, F, []),
                  beam_ssa:fold_instrs_rpo(
                    fun(I, Acc) ->
                            collect_opt_info_1(I, Where, UseMap, Acc)
                    end, [0], Acc0, Blocks)
          end, [], Fs).

collect_opt_info_1(#b_set{op=Op,anno=Anno,dst=Dst}=I, Where, UseMap, Acc0) ->
    case is_tail_binary(I) of
        true when Op =:= bs_match ->
            %% The uses include when the context is passed raw, so we discard
            %% everything but the bs_extract instruction to limit warnings to
            %% unoptimized uses.
            Uses0 = maps:get(Dst, UseMap, []),
            case [E || {_, #b_set{op=bs_extract}=E} <- Uses0] of
                [Use] -> add_unopt_binary_info(Use, false, Where, UseMap, Acc0);
                [] -> Acc0
            end;
        true ->
            %% Add a warning for each use. Note that we don't do anything
            %% special if unused as a later pass will remove this instruction
            %% anyway.
            Uses = maps:get(Dst, UseMap, []),
            foldl(fun({_Lbl, Use}, Acc) ->
                          add_unopt_binary_info(Use, false, Where, UseMap, Acc)
                  end, Acc0, Uses);
        false ->
            add_opt_info(Anno, Where, Acc0)
    end;
collect_opt_info_1(#b_ret{anno=Anno}, Where, _UseMap, Acc) ->
    add_opt_info(Anno, Where, Acc);
collect_opt_info_1(_I, _Where, _Uses, Acc) ->
    Acc.

add_opt_info(Anno, Where, Acc) ->
    case maps:find(bsm_info, Anno) of
        {ok, Term} -> [make_warning(Term, Anno, Where) | Acc];
        error -> Acc
    end.

%% When an alias is promoted we need to figure out where it goes to ignore
%% warnings for compiler-generated things, and provide more useful warnings in
%% general.
%%
%% We track whether the binary has been used to build another term because it
%% can be helpful when there's no line information.

add_unopt_binary_info(#b_set{op=Follow,dst=Dst}, _Nested, Where, UseMap, Acc0)
  when Follow =:= put_tuple;
       Follow =:= put_list;
       Follow =:= put_map ->
    %% Term-building instructions.
    {_, Uses} = unzip(maps:get(Dst, UseMap, [])),
    foldl(fun(Use, Acc) ->
                  add_unopt_binary_info(Use, true, Where, UseMap, Acc)
          end, Acc0, Uses);
add_unopt_binary_info(#b_set{op=Follow,dst=Dst}, Nested, Where, UseMap, Acc0)
  when Follow =:= bs_extract;
       Follow =:= phi ->
    %% Non-building instructions that need to be followed.
    {_, Uses} = unzip(maps:get(Dst, UseMap, [])),
    foldl(fun(Use, Acc) ->
                  add_unopt_binary_info(Use, Nested, Where, UseMap, Acc)
          end, Acc0, Uses);
add_unopt_binary_info(#b_set{op=call,
                             args=[#b_remote{mod=#b_literal{val=erlang},
                                             name=#b_literal{val=error}} |
                                   _Ignored]},
                      _Nested, _Where, _UseMap, Acc) ->
    %% There's no nice way to tell compiler-generated exceptions apart from
    %% user ones so we ignore them all. I doubt anyone cares.
    Acc;
add_unopt_binary_info(#b_switch{anno=Anno}=I, Nested, Where, _UseMap, Acc) ->
    [make_promotion_warning(I, Nested, Anno, Where) | Acc];
add_unopt_binary_info(#b_set{anno=Anno}=I, Nested, Where, _UseMap, Acc) ->
    [make_promotion_warning(I, Nested, Anno, Where) | Acc];
add_unopt_binary_info(#b_ret{anno=Anno}=I, Nested, Where, _UseMap, Acc) ->
    [make_promotion_warning(I, Nested, Anno, Where) | Acc];
add_unopt_binary_info(#b_br{anno=Anno}=I, Nested, Where, _UseMap, Acc) ->
    [make_promotion_warning(I, Nested, Anno, Where) | Acc].

make_promotion_warning(I, Nested, Anno, Where) ->
    make_warning({binary_created, I, Nested}, Anno, Where).

make_warning(Term, Anno, Where) ->
    {File, Line} = maps:get(location, Anno, Where),
    {File,[{Line,?MODULE,Term}]}.

format_opt_info(context_reused) ->
    "OPTIMIZED: match context reused";
format_opt_info({binary_created, _, _}=Promotion) ->
    io_lib:format("BINARY CREATED: ~s", [format_opt_info_1(Promotion)]);
format_opt_info(Other) ->
    io_lib:format("NOT OPTIMIZED: ~s", [format_opt_info_1(Other)]).

format_opt_info_1({binary_created, #b_set{op=call,args=[Call|_]}, false}) ->
    io_lib:format("binary is used in call to ~s which doesn't support "
                  "context reuse", [format_call(Call)]);
format_opt_info_1({binary_created, #b_set{op=call,args=[Call|_]}, true}) ->
    io_lib:format("binary is used in term passed to ~s",
                  [format_call(Call)]);
format_opt_info_1({binary_created, #b_set{op={bif, BIF},args=Args}, false}) ->
    io_lib:format("binary is used in ~p/~p which doesn't support context "
                  "reuse", [BIF, length(Args)]);
format_opt_info_1({binary_created, #b_set{op={bif, BIF},args=Args}, true}) ->
    io_lib:format("binary is used in term passed to ~p/~p",
                  [BIF, length(Args)]);
format_opt_info_1({binary_created, #b_set{op=Op}, false}) ->
    io_lib:format("binary is used in '~p' which doesn't support context "
                  "reuse", [Op]);
format_opt_info_1({binary_created, #b_set{op=Op}, true}) ->
    io_lib:format("binary is used in term passed to '~p'", [Op]);
format_opt_info_1({binary_created, #b_ret{}, false}) ->
    io_lib:format("binary is returned from the function", []);
format_opt_info_1({binary_created, #b_ret{}, true}) ->
    io_lib:format("binary is used in a term that is returned from the "
                  "function", []);
format_opt_info_1({unsuitable_call, {Call, Inner}}) ->
    io_lib:format("binary used in call to ~s, where ~s",
                  [format_call(Call), format_opt_info_1(Inner)]);
format_opt_info_1({remote_call, Call}) ->
    io_lib:format("binary is used in remote call to ~s", [format_call(Call)]);
format_opt_info_1({fun_call, Call}) ->
    io_lib:format("binary is used in fun call (~s)",
                  [format_call(Call)]);
format_opt_info_1({multiple_uses_in_call, Call}) ->
    io_lib:format("binary is passed as multiple arguments to ~s",
                  [format_call(Call)]);
format_opt_info_1({no_match_on_entry, Call}) ->
    io_lib:format("binary is used in call to ~s which does not begin with a "
                  "suitable binary match", [format_call(Call)]);
format_opt_info_1({used_before_match, #b_set{op=call,args=[Call|_]}}) ->
    io_lib:format("binary is used in call to ~s before being matched",
                  [format_call(Call)]);
format_opt_info_1({used_before_match, #b_set{op={bif, BIF},args=Args}}) ->
    io_lib:format("binary is used in ~p/~p before being matched",
                  [BIF, length(Args)]);
format_opt_info_1({used_before_match, #b_set{op=phi}}) ->
    io_lib:format("binary is returned from an expression before being "
                  "matched", []);
format_opt_info_1({used_before_match, #b_set{op=Op}}) ->
    io_lib:format("binary is used in '~p' before being matched",[Op]);
format_opt_info_1(Term) ->
    io_lib:format("~w", [Term]).

format_call(#b_local{name=#b_literal{val=F},arity=A}) ->
    io_lib:format("~p/~p", [F, A]);
format_call(#b_remote{mod=#b_literal{val=M},name=#b_literal{val=F},arity=A}) ->
    io_lib:format("~p:~p/~p", [M, F, A]);
format_call(Fun) ->
    io_lib:format("~p", [Fun]).