aboutsummaryrefslogtreecommitdiffstats
path: root/include/lldb/Target/Thread.h
blob: 7c5ff6093baf54a4047bd95d4623cb632a3a622e (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
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
//===-- Thread.h ------------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef liblldb_Thread_h_
#define liblldb_Thread_h_

#include <memory>
#include <mutex>
#include <string>
#include <vector>

#include "lldb/Core/UserSettingsController.h"
#include "lldb/Target/ExecutionContextScope.h"
#include "lldb/Target/RegisterCheckpoint.h"
#include "lldb/Target/StackFrameList.h"
#include "lldb/Utility/Broadcaster.h"
#include "lldb/Utility/Event.h"
#include "lldb/Utility/StructuredData.h"
#include "lldb/Utility/UserID.h"
#include "lldb/lldb-private.h"

#define LLDB_THREAD_MAX_STOP_EXC_DATA 8

namespace lldb_private {

class ThreadProperties : public Properties {
public:
  ThreadProperties(bool is_global);

  ~ThreadProperties() override;

  /// The regular expression returned determines symbols that this
  /// thread won't stop in during "step-in" operations.
  ///
  /// \return
  ///    A pointer to a regular expression to compare against symbols,
  ///    or nullptr if all symbols are allowed.
  ///
  const RegularExpression *GetSymbolsToAvoidRegexp();

  FileSpecList GetLibrariesToAvoid() const;

  bool GetTraceEnabledState() const;

  bool GetStepInAvoidsNoDebug() const;

  bool GetStepOutAvoidsNoDebug() const;

  uint64_t GetMaxBacktraceDepth() const;
};

typedef std::shared_ptr<ThreadProperties> ThreadPropertiesSP;

class Thread : public std::enable_shared_from_this<Thread>,
               public ThreadProperties,
               public UserID,
               public ExecutionContextScope,
               public Broadcaster {
public:
  /// Broadcaster event bits definitions.
  enum {
    eBroadcastBitStackChanged = (1 << 0),
    eBroadcastBitThreadSuspended = (1 << 1),
    eBroadcastBitThreadResumed = (1 << 2),
    eBroadcastBitSelectedFrameChanged = (1 << 3),
    eBroadcastBitThreadSelected = (1 << 4)
  };

  static ConstString &GetStaticBroadcasterClass();

  ConstString &GetBroadcasterClass() const override {
    return GetStaticBroadcasterClass();
  }

  class ThreadEventData : public EventData {
  public:
    ThreadEventData(const lldb::ThreadSP thread_sp);

    ThreadEventData(const lldb::ThreadSP thread_sp, const StackID &stack_id);

    ThreadEventData();

    ~ThreadEventData() override;

    static ConstString GetFlavorString();

    ConstString GetFlavor() const override {
      return ThreadEventData::GetFlavorString();
    }

    void Dump(Stream *s) const override;

    static const ThreadEventData *GetEventDataFromEvent(const Event *event_ptr);

    static lldb::ThreadSP GetThreadFromEvent(const Event *event_ptr);

    static StackID GetStackIDFromEvent(const Event *event_ptr);

    static lldb::StackFrameSP GetStackFrameFromEvent(const Event *event_ptr);

    lldb::ThreadSP GetThread() const { return m_thread_sp; }

    StackID GetStackID() const { return m_stack_id; }

  private:
    lldb::ThreadSP m_thread_sp;
    StackID m_stack_id;

    DISALLOW_COPY_AND_ASSIGN(ThreadEventData);
  };

  struct ThreadStateCheckpoint {
    uint32_t orig_stop_id; // Dunno if I need this yet but it is an interesting
                           // bit of data.
    lldb::StopInfoSP stop_info_sp; // You have to restore the stop info or you
                                   // might continue with the wrong signals.
    std::vector<lldb::ThreadPlanSP> m_completed_plan_stack;
    lldb::RegisterCheckpointSP
        register_backup_sp; // You need to restore the registers, of course...
    uint32_t current_inlined_depth;
    lldb::addr_t current_inlined_pc;
  };

  /// Constructor
  ///
  /// \param [in] process
  ///
  /// \param [in] tid
  ///
  /// \param [in] use_invalid_index_id
  ///     Optional parameter, defaults to false.  The only subclass that
  ///     is likely to set use_invalid_index_id == true is the HistoryThread
  ///     class.  In that case, the Thread we are constructing represents
  ///     a thread from earlier in the program execution.  We may have the
  ///     tid of the original thread that they represent but we don't want
  ///     to reuse the IndexID of that thread, or create a new one.  If a
  ///     client wants to know the original thread's IndexID, they should use
  ///     Thread::GetExtendedBacktraceOriginatingIndexID().
  Thread(Process &process, lldb::tid_t tid, bool use_invalid_index_id = false);

  ~Thread() override;

  static void SettingsInitialize();

  static void SettingsTerminate();

  static const ThreadPropertiesSP &GetGlobalProperties();

  lldb::ProcessSP GetProcess() const { return m_process_wp.lock(); }

  int GetResumeSignal() const { return m_resume_signal; }

  void SetResumeSignal(int signal) { m_resume_signal = signal; }

  lldb::StateType GetState() const;

  void SetState(lldb::StateType state);

  /// Sets the USER resume state for this thread.  If you set a thread to
  /// suspended with
  /// this API, it won't take part in any of the arbitration for ShouldResume,
  /// and will stay
  /// suspended even when other threads do get to run.
  ///
  /// N.B. This is not the state that is used internally by thread plans to
  /// implement
  /// staying on one thread while stepping over a breakpoint, etc.  The is the
  /// TemporaryResume state, and if you are implementing some bit of strategy in
  /// the stepping
  /// machinery you should be using that state and not the user resume state.
  ///
  /// If you are just preparing all threads to run, you should not override the
  /// threads that are
  /// marked as suspended by the debugger.  In that case, pass override_suspend
  /// = false.  If you want
  /// to force the thread to run (e.g. the "thread continue" command, or are
  /// resetting the state
  /// (e.g. in SBThread::Resume()), then pass true to override_suspend.
  /// \return
  ///    The User resume state for this thread.
  void SetResumeState(lldb::StateType state, bool override_suspend = false) {
    if (m_resume_state == lldb::eStateSuspended && !override_suspend)
      return;
    m_resume_state = state;
  }

  /// Gets the USER resume state for this thread.  This is not the same as what
  /// this thread is going to do for any particular step, however if this thread
  /// returns eStateSuspended, then the process control logic will never allow
  /// this
  /// thread to run.
  ///
  /// \return
  ///    The User resume state for this thread.
  lldb::StateType GetResumeState() const { return m_resume_state; }

  // This function is called on all the threads before "ShouldResume" and
  // "WillResume" in case a thread needs to change its state before the
  // ThreadList polls all the threads to figure out which ones actually will
  // get to run and how.
  void SetupForResume();

  // Do not override this function, it is for thread plan logic only
  bool ShouldResume(lldb::StateType resume_state);

  // Override this to do platform specific tasks before resume.
  virtual void WillResume(lldb::StateType resume_state) {}

  // This clears generic thread state after a resume.  If you subclass this, be
  // sure to call it.
  virtual void DidResume();

  // This notifies the thread when a private stop occurs.
  virtual void DidStop();

  virtual void RefreshStateAfterStop() = 0;

  void WillStop();

  bool ShouldStop(Event *event_ptr);

  Vote ShouldReportStop(Event *event_ptr);

  Vote ShouldReportRun(Event *event_ptr);

  void Flush();

  // Return whether this thread matches the specification in ThreadSpec.  This
  // is a virtual method because at some point we may extend the thread spec
  // with a platform specific dictionary of attributes, which then only the
  // platform specific Thread implementation would know how to match.  For now,
  // this just calls through to the ThreadSpec's ThreadPassesBasicTests method.
  virtual bool MatchesSpec(const ThreadSpec *spec);

  lldb::StopInfoSP GetStopInfo();

  lldb::StopReason GetStopReason();

  bool StopInfoIsUpToDate() const;

  // This sets the stop reason to a "blank" stop reason, so you can call
  // functions on the thread without having the called function run with
  // whatever stop reason you stopped with.
  void SetStopInfoToNothing();

  bool ThreadStoppedForAReason();

  static const char *RunModeAsCString(lldb::RunMode mode);

  static const char *StopReasonAsCString(lldb::StopReason reason);

  virtual const char *GetInfo() { return nullptr; }

  /// Retrieve a dictionary of information about this thread
  ///
  /// On Mac OS X systems there may be voucher information.
  /// The top level dictionary returned will have an "activity" key and the
  /// value of the activity is a dictionary.  Keys in that dictionary will
  /// be "name" and "id", among others.
  /// There may also be "trace_messages" (an array) with each entry in that
  /// array
  /// being a dictionary (keys include "message" with the text of the trace
  /// message).
  StructuredData::ObjectSP GetExtendedInfo() {
    if (!m_extended_info_fetched) {
      m_extended_info = FetchThreadExtendedInfo();
      m_extended_info_fetched = true;
    }
    return m_extended_info;
  }

  virtual const char *GetName() { return nullptr; }

  virtual void SetName(const char *name) {}

  /// Whether this thread can be associated with a libdispatch queue
  ///
  /// The Thread may know if it is associated with a libdispatch queue,
  /// it may know definitively that it is NOT associated with a libdispatch
  /// queue, or it may be unknown whether it is associated with a libdispatch
  /// queue.
  ///
  /// \return
  ///     eLazyBoolNo if this thread is definitely not associated with a
  ///     libdispatch queue (e.g. on a non-Darwin system where GCD aka
  ///     libdispatch is not available).
  ///
  ///     eLazyBoolYes this thread is associated with a libdispatch queue.
  ///
  ///     eLazyBoolCalculate this thread may be associated with a libdispatch
  ///     queue but the thread doesn't know one way or the other.
  virtual lldb_private::LazyBool GetAssociatedWithLibdispatchQueue() {
    return eLazyBoolNo;
  }

  virtual void SetAssociatedWithLibdispatchQueue(
      lldb_private::LazyBool associated_with_libdispatch_queue) {}

  /// Retrieve the Queue ID for the queue currently using this Thread
  ///
  /// If this Thread is doing work on behalf of a libdispatch/GCD queue,
  /// retrieve the QueueID.
  ///
  /// This is a unique identifier for the libdispatch/GCD queue in a
  /// process.  Often starting at 1 for the initial system-created
  /// queues and incrementing, a QueueID will not be reused for a
  /// different queue during the lifetime of a process.
  ///
  /// \return
  ///     A QueueID if the Thread subclass implements this, else
  ///     LLDB_INVALID_QUEUE_ID.
  virtual lldb::queue_id_t GetQueueID() { return LLDB_INVALID_QUEUE_ID; }

  virtual void SetQueueID(lldb::queue_id_t new_val) {}

  /// Retrieve the Queue name for the queue currently using this Thread
  ///
  /// If this Thread is doing work on behalf of a libdispatch/GCD queue,
  /// retrieve the Queue name.
  ///
  /// \return
  ///     The Queue name, if the Thread subclass implements this, else
  ///     nullptr.
  virtual const char *GetQueueName() { return nullptr; }

  virtual void SetQueueName(const char *name) {}

  /// Retrieve the Queue kind for the queue currently using this Thread
  ///
  /// If this Thread is doing work on behalf of a libdispatch/GCD queue,
  /// retrieve the Queue kind - either eQueueKindSerial or
  /// eQueueKindConcurrent, indicating that this queue processes work
  /// items serially or concurrently.
  ///
  /// \return
  ///     The Queue kind, if the Thread subclass implements this, else
  ///     eQueueKindUnknown.
  virtual lldb::QueueKind GetQueueKind() { return lldb::eQueueKindUnknown; }

  virtual void SetQueueKind(lldb::QueueKind kind) {}

  /// Retrieve the Queue for this thread, if any.
  ///
  /// \return
  ///     A QueueSP for the queue that is currently associated with this
  ///     thread.
  ///     An empty shared pointer indicates that this thread is not
  ///     associated with a queue, or libdispatch queues are not
  ///     supported on this target.
  virtual lldb::QueueSP GetQueue() { return lldb::QueueSP(); }

  /// Retrieve the address of the libdispatch_queue_t struct for queue
  /// currently using this Thread
  ///
  /// If this Thread is doing work on behalf of a libdispatch/GCD queue,
  /// retrieve the address of the libdispatch_queue_t structure describing
  /// the queue.
  ///
  /// This address may be reused for different queues later in the Process
  /// lifetime and should not be used to identify a queue uniquely.  Use
  /// the GetQueueID() call for that.
  ///
  /// \return
  ///     The Queue's libdispatch_queue_t address if the Thread subclass
  ///     implements this, else LLDB_INVALID_ADDRESS.
  virtual lldb::addr_t GetQueueLibdispatchQueueAddress() {
    return LLDB_INVALID_ADDRESS;
  }

  virtual void SetQueueLibdispatchQueueAddress(lldb::addr_t dispatch_queue_t) {}

  /// Whether this Thread already has all the Queue information cached or not
  ///
  /// A Thread may be associated with a libdispatch work Queue at a given
  /// public stop event.  If so, the thread can satisify requests like
  /// GetQueueLibdispatchQueueAddress, GetQueueKind, GetQueueName, and
  /// GetQueueID
  /// either from information from the remote debug stub when it is initially
  /// created, or it can query the SystemRuntime for that information.
  ///
  /// This method allows the SystemRuntime to discover if a thread has this
  /// information already, instead of calling the thread to get the information
  /// and having the thread call the SystemRuntime again.
  virtual bool ThreadHasQueueInformation() const { return false; }

  virtual uint32_t GetStackFrameCount() {
    return GetStackFrameList()->GetNumFrames();
  }

  virtual lldb::StackFrameSP GetStackFrameAtIndex(uint32_t idx) {
    return GetStackFrameList()->GetFrameAtIndex(idx);
  }

  virtual lldb::StackFrameSP
  GetFrameWithConcreteFrameIndex(uint32_t unwind_idx);

  bool DecrementCurrentInlinedDepth() {
    return GetStackFrameList()->DecrementCurrentInlinedDepth();
  }

  uint32_t GetCurrentInlinedDepth() {
    return GetStackFrameList()->GetCurrentInlinedDepth();
  }

  Status ReturnFromFrameWithIndex(uint32_t frame_idx,
                                  lldb::ValueObjectSP return_value_sp,
                                  bool broadcast = false);

  Status ReturnFromFrame(lldb::StackFrameSP frame_sp,
                         lldb::ValueObjectSP return_value_sp,
                         bool broadcast = false);

  Status JumpToLine(const FileSpec &file, uint32_t line,
                    bool can_leave_function, std::string *warnings = nullptr);

  virtual lldb::StackFrameSP GetFrameWithStackID(const StackID &stack_id) {
    if (stack_id.IsValid())
      return GetStackFrameList()->GetFrameWithStackID(stack_id);
    return lldb::StackFrameSP();
  }

  uint32_t GetSelectedFrameIndex() {
    return GetStackFrameList()->GetSelectedFrameIndex();
  }

  lldb::StackFrameSP GetSelectedFrame();

  uint32_t SetSelectedFrame(lldb_private::StackFrame *frame,
                            bool broadcast = false);

  bool SetSelectedFrameByIndex(uint32_t frame_idx, bool broadcast = false);

  bool SetSelectedFrameByIndexNoisily(uint32_t frame_idx,
                                      Stream &output_stream);

  void SetDefaultFileAndLineToSelectedFrame() {
    GetStackFrameList()->SetDefaultFileAndLineToSelectedFrame();
  }

  virtual lldb::RegisterContextSP GetRegisterContext() = 0;

  virtual lldb::RegisterContextSP
  CreateRegisterContextForFrame(StackFrame *frame) = 0;

  virtual void ClearStackFrames();

  virtual bool SetBackingThread(const lldb::ThreadSP &thread_sp) {
    return false;
  }

  virtual lldb::ThreadSP GetBackingThread() const { return lldb::ThreadSP(); }

  virtual void ClearBackingThread() {
    // Subclasses can use this function if a thread is actually backed by
    // another thread. This is currently used for the OperatingSystem plug-ins
    // where they might have a thread that is in memory, yet its registers are
    // available through the lldb_private::Thread subclass for the current
    // lldb_private::Process class. Since each time the process stops the
    // backing threads for memory threads can change, we need a way to clear
    // the backing thread for all memory threads each time we stop.
  }

  // If stop_format is true, this will be the form used when we print stop
  // info. If false, it will be the form we use for thread list and co.
  void DumpUsingSettingsFormat(Stream &strm, uint32_t frame_idx,
                               bool stop_format);

  bool GetDescription(Stream &s, lldb::DescriptionLevel level,
                      bool print_json_thread, bool print_json_stopinfo);

  /// Default implementation for stepping into.
  ///
  /// This function is designed to be used by commands where the
  /// process is publicly stopped.
  ///
  /// \param[in] source_step
  ///     If true and the frame has debug info, then do a source level
  ///     step in, else do a single instruction step in.
  ///
  /// \param[in] step_in_avoids_code_without_debug_info
  ///     If \a true, then avoid stepping into code that doesn't have
  ///     debug info, else step into any code regardless of whether it
  ///     has debug info.
  ///
  /// \param[in] step_out_avoids_code_without_debug_info
  ///     If \a true, then if you step out to code with no debug info, keep
  ///     stepping out till you get to code with debug info.
  ///
  /// \return
  ///     An error that describes anything that went wrong
  virtual Status
  StepIn(bool source_step,
         LazyBool step_in_avoids_code_without_debug_info = eLazyBoolCalculate,
         LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);

  /// Default implementation for stepping over.
  ///
  /// This function is designed to be used by commands where the
  /// process is publicly stopped.
  ///
  /// \param[in] source_step
  ///     If true and the frame has debug info, then do a source level
  ///     step over, else do a single instruction step over.
  ///
  /// \return
  ///     An error that describes anything that went wrong
  virtual Status StepOver(
      bool source_step,
      LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);

  /// Default implementation for stepping out.
  ///
  /// This function is designed to be used by commands where the
  /// process is publicly stopped.
  ///
  /// \return
  ///     An error that describes anything that went wrong
  virtual Status StepOut();

  /// Retrieves the per-thread data area.
  /// Most OSs maintain a per-thread pointer (e.g. the FS register on
  /// x64), which we return the value of here.
  ///
  /// \return
  ///     LLDB_INVALID_ADDRESS if not supported, otherwise the thread
  ///     pointer value.
  virtual lldb::addr_t GetThreadPointer();

  /// Retrieves the per-module TLS block for a thread.
  ///
  /// \param[in] module
  ///     The module to query TLS data for.
  ///
  /// \param[in] tls_file_addr
  ///     The thread local address in module
  /// \return
  ///     If the thread has TLS data allocated for the
  ///     module, the address of the TLS block. Otherwise
  ///     LLDB_INVALID_ADDRESS is returned.
  virtual lldb::addr_t GetThreadLocalData(const lldb::ModuleSP module,
                                          lldb::addr_t tls_file_addr);

  /// Check whether this thread is safe to run functions
  ///
  /// The SystemRuntime may know of certain thread states (functions in
  /// process of execution, for instance) which can make it unsafe for
  /// functions to be called.
  ///
  /// \return
  ///     True if it is safe to call functions on this thread.
  ///     False if function calls should be avoided on this thread.
  virtual bool SafeToCallFunctions();

  // Thread Plan Providers:
  // This section provides the basic thread plans that the Process control
  // machinery uses to run the target.  ThreadPlan.h provides more details on
  // how this mechanism works. The thread provides accessors to a set of plans
  // that perform basic operations. The idea is that particular Platform
  // plugins can override these methods to provide the implementation of these
  // basic operations appropriate to their environment.
  //
  // NB: All the QueueThreadPlanXXX providers return Shared Pointers to
  // Thread plans.  This is useful so that you can modify the plans after
  // creation in ways specific to that plan type.  Also, it is often necessary
  // for ThreadPlans that utilize other ThreadPlans to implement their task to
  // keep a shared pointer to the sub-plan. But besides that, the shared
  // pointers should only be held onto by entities who live no longer than the
  // thread containing the ThreadPlan.
  // FIXME: If this becomes a problem, we can make a version that just returns a
  // pointer,
  // which it is clearly unsafe to hold onto, and a shared pointer version, and
  // only allow ThreadPlan and Co. to use the latter.  That is made more
  // annoying to do because there's no elegant way to friend a method to all
  // sub-classes of a given class.
  //

  /// Queues the base plan for a thread.
  /// The version returned by Process does some things that are useful,
  /// like handle breakpoints and signals, so if you return a plugin specific
  /// one you probably want to call through to the Process one for anything
  /// your plugin doesn't explicitly handle.
  ///
  /// \param[in] abort_other_plans
  ///    \b true if we discard the currently queued plans and replace them with
  ///    this one.
  ///    Otherwise this plan will go on the end of the plan stack.
  ///
  /// \return
  ///     A shared pointer to the newly queued thread plan, or nullptr if the
  ///     plan could not be queued.
  virtual lldb::ThreadPlanSP QueueFundamentalPlan(bool abort_other_plans);

  /// Queues the plan used to step one instruction from the current PC of \a
  /// thread.
  ///
  /// \param[in] step_over
  ///    \b true if we step over calls to functions, false if we step in.
  ///
  /// \param[in] abort_other_plans
  ///    \b true if we discard the currently queued plans and replace them with
  ///    this one.
  ///    Otherwise this plan will go on the end of the plan stack.
  ///
  /// \param[in] stop_other_threads
  ///    \b true if we will stop other threads while we single step this one.
  ///
  /// \param[out] status
  ///     A status with an error if queuing failed.
  ///
  /// \return
  ///     A shared pointer to the newly queued thread plan, or nullptr if the
  ///     plan could not be queued.
  virtual lldb::ThreadPlanSP QueueThreadPlanForStepSingleInstruction(
      bool step_over, bool abort_other_plans, bool stop_other_threads,
      Status &status);

  /// Queues the plan used to step through an address range, stepping  over
  /// function calls.
  ///
  /// \param[in] abort_other_plans
  ///    \b true if we discard the currently queued plans and replace them with
  ///    this one.
  ///    Otherwise this plan will go on the end of the plan stack.
  ///
  /// \param[in] type
  ///    Type of step to do, only eStepTypeInto and eStepTypeOver are supported
  ///    by this plan.
  ///
  /// \param[in] range
  ///    The address range to step through.
  ///
  /// \param[in] addr_context
  ///    When dealing with stepping through inlined functions the current PC is
  ///    not enough information to know
  ///    what "step" means.  For instance a series of nested inline functions
  ///    might start at the same address.
  //     The \a addr_context provides the current symbol context the step
  ///    is supposed to be out of.
  //   FIXME: Currently unused.
  ///
  /// \param[in] stop_other_threads
  ///    \b true if we will stop other threads while we single step this one.
  ///
  /// \param[out] status
  ///     A status with an error if queuing failed.
  ///
  /// \param[in] step_out_avoids_code_without_debug_info
  ///    If eLazyBoolYes, if the step over steps out it will continue to step
  ///    out till it comes to a frame with debug info.
  ///    If eLazyBoolCalculate, we will consult the default set in the thread.
  ///
  /// \return
  ///     A shared pointer to the newly queued thread plan, or nullptr if the
  ///     plan could not be queued.
  virtual lldb::ThreadPlanSP QueueThreadPlanForStepOverRange(
      bool abort_other_plans, const AddressRange &range,
      const SymbolContext &addr_context, lldb::RunMode stop_other_threads,
      Status &status,
      LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);

  // Helper function that takes a LineEntry to step, insted of an AddressRange.
  // This may combine multiple LineEntries of the same source line number to
  // step over a longer address range in a single operation.
  virtual lldb::ThreadPlanSP QueueThreadPlanForStepOverRange(
      bool abort_other_plans, const LineEntry &line_entry,
      const SymbolContext &addr_context, lldb::RunMode stop_other_threads,
      Status &status,
      LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);

  /// Queues the plan used to step through an address range, stepping into
  /// functions.
  ///
  /// \param[in] abort_other_plans
  ///    \b true if we discard the currently queued plans and replace them with
  ///    this one.
  ///    Otherwise this plan will go on the end of the plan stack.
  ///
  /// \param[in] type
  ///    Type of step to do, only eStepTypeInto and eStepTypeOver are supported
  ///    by this plan.
  ///
  /// \param[in] range
  ///    The address range to step through.
  ///
  /// \param[in] addr_context
  ///    When dealing with stepping through inlined functions the current PC is
  ///    not enough information to know
  ///    what "step" means.  For instance a series of nested inline functions
  ///    might start at the same address.
  //     The \a addr_context provides the current symbol context the step
  ///    is supposed to be out of.
  //   FIXME: Currently unused.
  ///
  /// \param[in] step_in_target
  ///    Name if function we are trying to step into.  We will step out if we
  ///    don't land in that function.
  ///
  /// \param[in] stop_other_threads
  ///    \b true if we will stop other threads while we single step this one.
  ///
  /// \param[out] status
  ///     A status with an error if queuing failed.
  ///
  /// \param[in] step_in_avoids_code_without_debug_info
  ///    If eLazyBoolYes we will step out if we step into code with no debug
  ///    info.
  ///    If eLazyBoolCalculate we will consult the default set in the thread.
  ///
  /// \param[in] step_out_avoids_code_without_debug_info
  ///    If eLazyBoolYes, if the step over steps out it will continue to step
  ///    out till it comes to a frame with debug info.
  ///    If eLazyBoolCalculate, it will consult the default set in the thread.
  ///
  /// \return
  ///     A shared pointer to the newly queued thread plan, or nullptr if the
  ///     plan could not be queued.
  virtual lldb::ThreadPlanSP QueueThreadPlanForStepInRange(
      bool abort_other_plans, const AddressRange &range,
      const SymbolContext &addr_context, const char *step_in_target,
      lldb::RunMode stop_other_threads, Status &status,
      LazyBool step_in_avoids_code_without_debug_info = eLazyBoolCalculate,
      LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);

  // Helper function that takes a LineEntry to step, insted of an AddressRange.
  // This may combine multiple LineEntries of the same source line number to
  // step over a longer address range in a single operation.
  virtual lldb::ThreadPlanSP QueueThreadPlanForStepInRange(
      bool abort_other_plans, const LineEntry &line_entry,
      const SymbolContext &addr_context, const char *step_in_target,
      lldb::RunMode stop_other_threads, Status &status,
      LazyBool step_in_avoids_code_without_debug_info = eLazyBoolCalculate,
      LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);

  /// Queue the plan used to step out of the function at the current PC of
  /// \a thread.
  ///
  /// \param[in] abort_other_plans
  ///    \b true if we discard the currently queued plans and replace them with
  ///    this one.
  ///    Otherwise this plan will go on the end of the plan stack.
  ///
  /// \param[in] addr_context
  ///    When dealing with stepping through inlined functions the current PC is
  ///    not enough information to know
  ///    what "step" means.  For instance a series of nested inline functions
  ///    might start at the same address.
  //     The \a addr_context provides the current symbol context the step
  ///    is supposed to be out of.
  //   FIXME: Currently unused.
  ///
  /// \param[in] first_insn
  ///     \b true if this is the first instruction of a function.
  ///
  /// \param[in] stop_other_threads
  ///    \b true if we will stop other threads while we single step this one.
  ///
  /// \param[in] stop_vote
  /// \param[in] run_vote
  ///    See standard meanings for the stop & run votes in ThreadPlan.h.
  ///
  /// \param[out] status
  ///     A status with an error if queuing failed.
  ///
  /// \param[in] step_out_avoids_code_without_debug_info
  ///    If eLazyBoolYes, if the step over steps out it will continue to step
  ///    out till it comes to a frame with debug info.
  ///    If eLazyBoolCalculate, it will consult the default set in the thread.
  ///
  /// \return
  ///     A shared pointer to the newly queued thread plan, or nullptr if the
  ///     plan could not be queued.
  virtual lldb::ThreadPlanSP QueueThreadPlanForStepOut(
      bool abort_other_plans, SymbolContext *addr_context, bool first_insn,
      bool stop_other_threads, Vote stop_vote, Vote run_vote,
      uint32_t frame_idx, Status &status,
      LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);

  /// Queue the plan used to step out of the function at the current PC of
  /// a thread.  This version does not consult the should stop here callback,
  /// and should only
  /// be used by other thread plans when they need to retain control of the step
  /// out.
  ///
  /// \param[in] abort_other_plans
  ///    \b true if we discard the currently queued plans and replace them with
  ///    this one.
  ///    Otherwise this plan will go on the end of the plan stack.
  ///
  /// \param[in] addr_context
  ///    When dealing with stepping through inlined functions the current PC is
  ///    not enough information to know
  ///    what "step" means.  For instance a series of nested inline functions
  ///    might start at the same address.
  //     The \a addr_context provides the current symbol context the step
  ///    is supposed to be out of.
  //   FIXME: Currently unused.
  ///
  /// \param[in] first_insn
  ///     \b true if this is the first instruction of a function.
  ///
  /// \param[in] stop_other_threads
  ///    \b true if we will stop other threads while we single step this one.
  ///
  /// \param[in] stop_vote
  ///
  /// \param[in] run_vote
  ///    See standard meanings for the stop & run votes in ThreadPlan.h.
  ///
  /// \param[in] frame_idx
  ///
  /// \param[out] status
  ///     A status with an error if queuing failed.
  ///
  /// \param[in] continue_to_next_branch
  ///    Normally this will enqueue a plan that will put a breakpoint on the
  ///    return address and continue
  ///    to there.  If continue_to_next_branch is true, this is an operation not
  ///    involving the user --
  ///    e.g. stepping "next" in a source line and we instruction stepped into
  ///    another function --
  ///    so instead of putting a breakpoint on the return address, advance the
  ///    breakpoint to the
  ///    end of the source line that is doing the call, or until the next flow
  ///    control instruction.
  ///    If the return value from the function call is to be retrieved /
  ///    displayed to the user, you must stop
  ///    on the return address.  The return value may be stored in volatile
  ///    registers which are overwritten
  ///    before the next branch instruction.
  ///
  /// \return
  ///     A shared pointer to the newly queued thread plan, or nullptr if the
  ///     plan could not be queued.
  virtual lldb::ThreadPlanSP QueueThreadPlanForStepOutNoShouldStop(
      bool abort_other_plans, SymbolContext *addr_context, bool first_insn,
      bool stop_other_threads, Vote stop_vote, Vote run_vote,
      uint32_t frame_idx, Status &status, bool continue_to_next_branch = false);

  /// Gets the plan used to step through the code that steps from a function
  /// call site at the current PC into the actual function call.
  ///
  /// \param[in] return_stack_id
  ///    The stack id that we will return to (by setting backstop breakpoints on
  ///    the return
  ///    address to that frame) if we fail to step through.
  ///
  /// \param[in] abort_other_plans
  ///    \b true if we discard the currently queued plans and replace them with
  ///    this one.
  ///    Otherwise this plan will go on the end of the plan stack.
  ///
  /// \param[in] stop_other_threads
  ///    \b true if we will stop other threads while we single step this one.
  ///
  /// \param[out] status
  ///     A status with an error if queuing failed.
  ///
  /// \return
  ///     A shared pointer to the newly queued thread plan, or nullptr if the
  ///     plan could not be queued.
  virtual lldb::ThreadPlanSP
  QueueThreadPlanForStepThrough(StackID &return_stack_id,
                                bool abort_other_plans, bool stop_other_threads,
                                Status &status);

  /// Gets the plan used to continue from the current PC.
  /// This is a simple plan, mostly useful as a backstop when you are continuing
  /// for some particular purpose.
  ///
  /// \param[in] abort_other_plans
  ///    \b true if we discard the currently queued plans and replace them with
  ///    this one.
  ///    Otherwise this plan will go on the end of the plan stack.
  ///
  /// \param[in] target_addr
  ///    The address to which we're running.
  ///
  /// \param[in] stop_other_threads
  ///    \b true if we will stop other threads while we single step this one.
  ///
  /// \param[out] status
  ///     A status with an error if queuing failed.
  ///
  /// \return
  ///     A shared pointer to the newly queued thread plan, or nullptr if the
  ///     plan could not be queued.
  virtual lldb::ThreadPlanSP
  QueueThreadPlanForRunToAddress(bool abort_other_plans, Address &target_addr,
                                 bool stop_other_threads, Status &status);

  virtual lldb::ThreadPlanSP QueueThreadPlanForStepUntil(
      bool abort_other_plans, lldb::addr_t *address_list, size_t num_addresses,
      bool stop_others, uint32_t frame_idx, Status &status);

  virtual lldb::ThreadPlanSP
  QueueThreadPlanForStepScripted(bool abort_other_plans, const char *class_name,
                                 StructuredData::ObjectSP extra_args_sp,  
                                 bool stop_other_threads, Status &status);

  // Thread Plan accessors:

  /// Gets the plan which will execute next on the plan stack.
  ///
  /// \return
  ///     A pointer to the next executed plan.
  ThreadPlan *GetCurrentPlan();

  /// Unwinds the thread stack for the innermost expression plan currently
  /// on the thread plan stack.
  ///
  /// \return
  ///     An error if the thread plan could not be unwound.

  Status UnwindInnermostExpression();

  /// Gets the outer-most plan that was popped off the plan stack in the
  /// most recent stop.  Useful for printing the stop reason accurately.
  ///
  /// \return
  ///     A pointer to the last completed plan.
  lldb::ThreadPlanSP GetCompletedPlan();

  /// Gets the outer-most return value from the completed plans
  ///
  /// \return
  ///     A ValueObjectSP, either empty if there is no return value,
  ///     or containing the return value.
  lldb::ValueObjectSP GetReturnValueObject();

  /// Gets the outer-most expression variable from the completed plans
  ///
  /// \return
  ///     A ExpressionVariableSP, either empty if there is no
  ///     plan completed an expression during the current stop
  ///     or the expression variable that was made for the completed expression.
  lldb::ExpressionVariableSP GetExpressionVariable();

  ///  Checks whether the given plan is in the completed plans for this
  ///  stop.
  ///
  /// \param[in] plan
  ///     Pointer to the plan you're checking.
  ///
  /// \return
  ///     Returns true if the input plan is in the completed plan stack,
  ///     false otherwise.
  bool IsThreadPlanDone(ThreadPlan *plan);

  ///  Checks whether the given plan is in the discarded plans for this
  ///  stop.
  ///
  /// \param[in] plan
  ///     Pointer to the plan you're checking.
  ///
  /// \return
  ///     Returns true if the input plan is in the discarded plan stack,
  ///     false otherwise.
  bool WasThreadPlanDiscarded(ThreadPlan *plan);

  /// Check if we have completed plan to override breakpoint stop reason
  ///
  /// \return
  ///     Returns true if completed plan stack is not empty
  ///     false otherwise.
  bool CompletedPlanOverridesBreakpoint();

  /// Queues a generic thread plan.
  ///
  /// \param[in] plan_sp
  ///    The plan to queue.
  ///
  /// \param[in] abort_other_plans
  ///    \b true if we discard the currently queued plans and replace them with
  ///    this one.
  ///    Otherwise this plan will go on the end of the plan stack.
  ///
  /// \return
  ///     A pointer to the last completed plan.
  Status QueueThreadPlan(lldb::ThreadPlanSP &plan_sp, bool abort_other_plans);

  /// Discards the plans queued on the plan stack of the current thread.  This
  /// is
  /// arbitrated by the "Master" ThreadPlans, using the "OkayToDiscard" call.
  //  But if \a force is true, all thread plans are discarded.
  void DiscardThreadPlans(bool force);

  /// Discards the plans queued on the plan stack of the current thread up to
  /// and
  /// including up_to_plan_sp.
  //
  // \param[in] up_to_plan_sp
  //   Discard all plans up to and including this one.
  void DiscardThreadPlansUpToPlan(lldb::ThreadPlanSP &up_to_plan_sp);

  void DiscardThreadPlansUpToPlan(ThreadPlan *up_to_plan_ptr);

  /// Discards the plans queued on the plan stack of the current thread up to
  /// and
  /// including the plan in that matches \a thread_index counting only
  /// the non-Private plans.
  ///
  /// \param[in] up_to_plan_sp
  ///   Discard all plans up to and including this user plan given by this
  ///   index.
  ///
  /// \return
  ///    \b true if there was a thread plan with that user index, \b false
  ///    otherwise.
  bool DiscardUserThreadPlansUpToIndex(uint32_t thread_index);

  /// Prints the current plan stack.
  ///
  /// \param[in] s
  ///    The stream to which to dump the plan stack info.
  ///
  void DumpThreadPlans(
      Stream *s,
      lldb::DescriptionLevel desc_level = lldb::eDescriptionLevelVerbose,
      bool include_internal = true, bool ignore_boring = false) const;

  virtual bool CheckpointThreadState(ThreadStateCheckpoint &saved_state);

  virtual bool
  RestoreRegisterStateFromCheckpoint(ThreadStateCheckpoint &saved_state);

  virtual bool
  RestoreThreadStateFromCheckpoint(ThreadStateCheckpoint &saved_state);

  void EnableTracer(bool value, bool single_step);

  void SetTracer(lldb::ThreadPlanTracerSP &tracer_sp);

  // Get the thread index ID. The index ID that is guaranteed to not be re-used
  // by a process. They start at 1 and increase with each new thread. This
  // allows easy command line access by a unique ID that is easier to type than
  // the actual system thread ID.
  uint32_t GetIndexID() const;

  // Get the originating thread's index ID.
  // In the case of an "extended" thread -- a thread which represents the stack
  // that enqueued/spawned work that is currently executing -- we need to
  // provide the IndexID of the thread that actually did this work.  We don't
  // want to just masquerade as that thread's IndexID by using it in our own
  // IndexID because that way leads to madness - but the driver program which
  // is iterating over extended threads may ask for the OriginatingThreadID to
  // display that information to the user.
  // Normal threads will return the same thing as GetIndexID();
  virtual uint32_t GetExtendedBacktraceOriginatingIndexID() {
    return GetIndexID();
  }

  // The API ID is often the same as the Thread::GetID(), but not in all cases.
  // Thread::GetID() is the user visible thread ID that clients would want to
  // see. The API thread ID is the thread ID that is used when sending data
  // to/from the debugging protocol.
  virtual lldb::user_id_t GetProtocolID() const { return GetID(); }

  // lldb::ExecutionContextScope pure virtual functions
  lldb::TargetSP CalculateTarget() override;

  lldb::ProcessSP CalculateProcess() override;

  lldb::ThreadSP CalculateThread() override;

  lldb::StackFrameSP CalculateStackFrame() override;

  void CalculateExecutionContext(ExecutionContext &exe_ctx) override;

  lldb::StackFrameSP
  GetStackFrameSPForStackFramePtr(StackFrame *stack_frame_ptr);

  size_t GetStatus(Stream &strm, uint32_t start_frame, uint32_t num_frames,
                   uint32_t num_frames_with_source, bool stop_format,
                   bool only_stacks = false);

  size_t GetStackFrameStatus(Stream &strm, uint32_t first_frame,
                             uint32_t num_frames, bool show_frame_info,
                             uint32_t num_frames_with_source);

  // We need a way to verify that even though we have a thread in a shared
  // pointer that the object itself is still valid. Currently this won't be the
  // case if DestroyThread() was called. DestroyThread is called when a thread
  // has been removed from the Process' thread list.
  bool IsValid() const { return !m_destroy_called; }

  // Sets and returns a valid stop info based on the process stop ID and the
  // current thread plan. If the thread stop ID does not match the process'
  // stop ID, the private stop reason is not set and an invalid StopInfoSP may
  // be returned.
  //
  // NOTE: This function must be called before the current thread plan is
  // moved to the completed plan stack (in Thread::ShouldStop()).
  //
  // NOTE: If subclasses override this function, ensure they do not overwrite
  // the m_actual_stop_info if it is valid.  The stop info may be a
  // "checkpointed and restored" stop info, so if it is still around it is
  // right even if you have not calculated this yourself, or if it disagrees
  // with what you might have calculated.
  virtual lldb::StopInfoSP GetPrivateStopInfo();
  
  // Calculate the stop info that will be shown to lldb clients.  For instance,
  // a "step out" is implemented by running to a breakpoint on the function 
  // return PC, so the process plugin initially sets the stop info to a
  // StopInfoBreakpoint. But once we've run the ShouldStop machinery, we
  // discover that there's a completed ThreadPlanStepOut, and that's really
  // the StopInfo we want to show.  That will happen naturally the next
  // time GetStopInfo is called, but if you want to force the replacement,
  // you can call this.

  void CalculatePublicStopInfo();

  // Ask the thread subclass to set its stop info.
  //
  // Thread subclasses should call Thread::SetStopInfo(...) with the reason the
  // thread stopped.
  //
  // \return
  //      True if Thread::SetStopInfo(...) was called, false otherwise.
  virtual bool CalculateStopInfo() = 0;

  // Gets the temporary resume state for a thread.
  //
  // This value gets set in each thread by complex debugger logic in
  // Thread::ShouldResume() and an appropriate thread resume state will get set
  // in each thread every time the process is resumed prior to calling
  // Process::DoResume(). The lldb_private::Process subclass should adhere to
  // the thread resume state request which will be one of:
  //
  //  eStateRunning   - thread will resume when process is resumed
  //  eStateStepping  - thread should step 1 instruction and stop when process
  //                    is resumed
  //  eStateSuspended - thread should not execute any instructions when
  //                    process is resumed
  lldb::StateType GetTemporaryResumeState() const {
    return m_temporary_resume_state;
  }

  void SetStopInfo(const lldb::StopInfoSP &stop_info_sp);

  void ResetStopInfo();

  void SetShouldReportStop(Vote vote);

  /// Sets the extended backtrace token for this thread
  ///
  /// Some Thread subclasses may maintain a token to help with providing
  /// an extended backtrace.  The SystemRuntime plugin will set/request this.
  ///
  /// \param [in] token
  virtual void SetExtendedBacktraceToken(uint64_t token) {}

  /// Gets the extended backtrace token for this thread
  ///
  /// Some Thread subclasses may maintain a token to help with providing
  /// an extended backtrace.  The SystemRuntime plugin will set/request this.
  ///
  /// \return
  ///     The token needed by the SystemRuntime to create an extended backtrace.
  ///     LLDB_INVALID_ADDRESS is returned if no token is available.
  virtual uint64_t GetExtendedBacktraceToken() { return LLDB_INVALID_ADDRESS; }

  lldb::ValueObjectSP GetCurrentException();

  lldb::ThreadSP GetCurrentExceptionBacktrace();

protected:
  friend class ThreadPlan;
  friend class ThreadList;
  friend class ThreadEventData;
  friend class StackFrameList;
  friend class StackFrame;
  friend class OperatingSystem;

  // This is necessary to make sure thread assets get destroyed while the
  // thread is still in good shape to call virtual thread methods.  This must
  // be called by classes that derive from Thread in their destructor.
  virtual void DestroyThread();

  void PushPlan(lldb::ThreadPlanSP &plan_sp);

  void PopPlan();

  void DiscardPlan();

  ThreadPlan *GetPreviousPlan(ThreadPlan *plan);

  typedef std::vector<lldb::ThreadPlanSP> plan_stack;

  virtual lldb_private::Unwind *GetUnwinder();

  // Check to see whether the thread is still at the last breakpoint hit that
  // stopped it.
  virtual bool IsStillAtLastBreakpointHit();

  // Some threads are threads that are made up by OperatingSystem plugins that
  // are threads that exist and are context switched out into memory. The
  // OperatingSystem plug-in need a ways to know if a thread is "real" or made
  // up.
  virtual bool IsOperatingSystemPluginThread() const { return false; }

  // Subclasses that have a way to get an extended info dictionary for this
  // thread should fill
  virtual lldb_private::StructuredData::ObjectSP FetchThreadExtendedInfo() {
    return StructuredData::ObjectSP();
  }

  lldb::StackFrameListSP GetStackFrameList();

  void SetTemporaryResumeState(lldb::StateType new_state) {
    m_temporary_resume_state = new_state;
  }

  void FunctionOptimizationWarning(lldb_private::StackFrame *frame);

  // Classes that inherit from Process can see and modify these
  lldb::ProcessWP m_process_wp;    ///< The process that owns this thread.
  lldb::StopInfoSP m_stop_info_sp; ///< The private stop reason for this thread
  uint32_t m_stop_info_stop_id; // This is the stop id for which the StopInfo is
                                // valid.  Can use this so you know that
  // the thread's m_stop_info_sp is current and you don't have to fetch it
  // again
  uint32_t m_stop_info_override_stop_id; // The stop ID containing the last time
                                         // the stop info was checked against
                                         // the stop info override
  const uint32_t m_index_id; ///< A unique 1 based index assigned to each thread
                             ///for easy UI/command line access.
  lldb::RegisterContextSP m_reg_context_sp; ///< The register context for this
                                            ///thread's current register state.
  lldb::StateType m_state;                  ///< The state of our process.
  mutable std::recursive_mutex
      m_state_mutex;       ///< Multithreaded protection for m_state.
  plan_stack m_plan_stack; ///< The stack of plans this thread is executing.
  plan_stack m_completed_plan_stack; ///< Plans that have been completed by this
                                     ///stop.  They get deleted when the thread
                                     ///resumes.
  plan_stack m_discarded_plan_stack; ///< Plans that have been discarded by this
                                     ///stop.  They get deleted when the thread
                                     ///resumes.
  mutable std::recursive_mutex
      m_frame_mutex; ///< Multithreaded protection for m_state.
  lldb::StackFrameListSP m_curr_frames_sp; ///< The stack frames that get lazily
                                           ///populated after a thread stops.
  lldb::StackFrameListSP m_prev_frames_sp; ///< The previous stack frames from
                                           ///the last time this thread stopped.
  int m_resume_signal; ///< The signal that should be used when continuing this
                       ///thread.
  lldb::StateType m_resume_state; ///< This state is used to force a thread to
                                  ///be suspended from outside the ThreadPlan
                                  ///logic.
  lldb::StateType m_temporary_resume_state; ///< This state records what the
                                            ///thread was told to do by the
                                            ///thread plan logic for the current
                                            ///resume.
  /// It gets set in Thread::ShouldResume.
  std::unique_ptr<lldb_private::Unwind> m_unwinder_up;
  bool m_destroy_called; // This is used internally to make sure derived Thread
                         // classes call DestroyThread.
  LazyBool m_override_should_notify;

private:
  bool m_extended_info_fetched; // Have we tried to retrieve the m_extended_info
                                // for this thread?
  StructuredData::ObjectSP m_extended_info; // The extended info for this thread

private:
  bool PlanIsBasePlan(ThreadPlan *plan_ptr);

  void BroadcastSelectedFrameChange(StackID &new_frame_id);

  DISALLOW_COPY_AND_ASSIGN(Thread);
};

} // namespace lldb_private

#endif // liblldb_Thread_h_