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      1 //===-- Thread.cpp ----------------------------------------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #include "lldb/lldb-python.h"
     11 
     12 #include "lldb/lldb-private-log.h"
     13 #include "lldb/Breakpoint/BreakpointLocation.h"
     14 #include "lldb/Core/Debugger.h"
     15 #include "lldb/Core/Log.h"
     16 #include "lldb/Core/State.h"
     17 #include "lldb/Core/Stream.h"
     18 #include "lldb/Core/StreamString.h"
     19 #include "lldb/Core/RegularExpression.h"
     20 #include "lldb/Host/Host.h"
     21 #include "lldb/Symbol/Function.h"
     22 #include "lldb/Target/DynamicLoader.h"
     23 #include "lldb/Target/ExecutionContext.h"
     24 #include "lldb/Target/ObjCLanguageRuntime.h"
     25 #include "lldb/Target/Process.h"
     26 #include "lldb/Target/RegisterContext.h"
     27 #include "lldb/Target/StopInfo.h"
     28 #include "lldb/Target/Target.h"
     29 #include "lldb/Target/Thread.h"
     30 #include "lldb/Target/ThreadPlan.h"
     31 #include "lldb/Target/ThreadPlanCallFunction.h"
     32 #include "lldb/Target/ThreadPlanBase.h"
     33 #include "lldb/Target/ThreadPlanStepInstruction.h"
     34 #include "lldb/Target/ThreadPlanStepOut.h"
     35 #include "lldb/Target/ThreadPlanStepOverBreakpoint.h"
     36 #include "lldb/Target/ThreadPlanStepThrough.h"
     37 #include "lldb/Target/ThreadPlanStepInRange.h"
     38 #include "lldb/Target/ThreadPlanStepOverRange.h"
     39 #include "lldb/Target/ThreadPlanRunToAddress.h"
     40 #include "lldb/Target/ThreadPlanStepUntil.h"
     41 #include "lldb/Target/ThreadSpec.h"
     42 #include "lldb/Target/Unwind.h"
     43 #include "Plugins/Process/Utility/UnwindLLDB.h"
     44 #include "UnwindMacOSXFrameBackchain.h"
     45 
     46 
     47 using namespace lldb;
     48 using namespace lldb_private;
     49 
     50 
     51 const ThreadPropertiesSP &
     52 Thread::GetGlobalProperties()
     53 {
     54     static ThreadPropertiesSP g_settings_sp;
     55     if (!g_settings_sp)
     56         g_settings_sp.reset (new ThreadProperties (true));
     57     return g_settings_sp;
     58 }
     59 
     60 static PropertyDefinition
     61 g_properties[] =
     62 {
     63     { "step-avoid-regexp",  OptionValue::eTypeRegex  , true , REG_EXTENDED, "^std::", NULL, "A regular expression defining functions step-in won't stop in." },
     64     { "trace-thread",       OptionValue::eTypeBoolean, false, false, NULL, NULL, "If true, this thread will single-step and log execution." },
     65     {  NULL               , OptionValue::eTypeInvalid, false, 0    , NULL, NULL, NULL  }
     66 };
     67 
     68 enum {
     69     ePropertyStepAvoidRegex,
     70     ePropertyEnableThreadTrace
     71 };
     72 
     73 
     74 class ThreadOptionValueProperties : public OptionValueProperties
     75 {
     76 public:
     77     ThreadOptionValueProperties (const ConstString &name) :
     78         OptionValueProperties (name)
     79     {
     80     }
     81 
     82     // This constructor is used when creating ThreadOptionValueProperties when it
     83     // is part of a new lldb_private::Thread instance. It will copy all current
     84     // global property values as needed
     85     ThreadOptionValueProperties (ThreadProperties *global_properties) :
     86         OptionValueProperties(*global_properties->GetValueProperties())
     87     {
     88     }
     89 
     90     virtual const Property *
     91     GetPropertyAtIndex (const ExecutionContext *exe_ctx, bool will_modify, uint32_t idx) const
     92     {
     93         // When gettings the value for a key from the thread options, we will always
     94         // try and grab the setting from the current thread if there is one. Else we just
     95         // use the one from this instance.
     96         if (exe_ctx)
     97         {
     98             Thread *thread = exe_ctx->GetThreadPtr();
     99             if (thread)
    100             {
    101                 ThreadOptionValueProperties *instance_properties = static_cast<ThreadOptionValueProperties *>(thread->GetValueProperties().get());
    102                 if (this != instance_properties)
    103                     return instance_properties->ProtectedGetPropertyAtIndex (idx);
    104             }
    105         }
    106         return ProtectedGetPropertyAtIndex (idx);
    107     }
    108 };
    109 
    110 
    111 
    112 ThreadProperties::ThreadProperties (bool is_global) :
    113     Properties ()
    114 {
    115     if (is_global)
    116     {
    117         m_collection_sp.reset (new ThreadOptionValueProperties(ConstString("thread")));
    118         m_collection_sp->Initialize(g_properties);
    119     }
    120     else
    121         m_collection_sp.reset (new ThreadOptionValueProperties(Thread::GetGlobalProperties().get()));
    122 }
    123 
    124 ThreadProperties::~ThreadProperties()
    125 {
    126 }
    127 
    128 const RegularExpression *
    129 ThreadProperties::GetSymbolsToAvoidRegexp()
    130 {
    131     const uint32_t idx = ePropertyStepAvoidRegex;
    132     return m_collection_sp->GetPropertyAtIndexAsOptionValueRegex (NULL, idx);
    133 }
    134 
    135 bool
    136 ThreadProperties::GetTraceEnabledState() const
    137 {
    138     const uint32_t idx = ePropertyEnableThreadTrace;
    139     return m_collection_sp->GetPropertyAtIndexAsBoolean (NULL, idx, g_properties[idx].default_uint_value != 0);
    140 }
    141 
    142 //------------------------------------------------------------------
    143 // Thread Event Data
    144 //------------------------------------------------------------------
    145 
    146 
    147 const ConstString &
    148 Thread::ThreadEventData::GetFlavorString ()
    149 {
    150     static ConstString g_flavor ("Thread::ThreadEventData");
    151     return g_flavor;
    152 }
    153 
    154 Thread::ThreadEventData::ThreadEventData (const lldb::ThreadSP thread_sp) :
    155     m_thread_sp (thread_sp),
    156     m_stack_id ()
    157 {
    158 }
    159 
    160 Thread::ThreadEventData::ThreadEventData (const lldb::ThreadSP thread_sp, const StackID &stack_id) :
    161     m_thread_sp (thread_sp),
    162     m_stack_id (stack_id)
    163 {
    164 }
    165 
    166 Thread::ThreadEventData::ThreadEventData () :
    167     m_thread_sp (),
    168     m_stack_id ()
    169 {
    170 }
    171 
    172 Thread::ThreadEventData::~ThreadEventData ()
    173 {
    174 }
    175 
    176 void
    177 Thread::ThreadEventData::Dump (Stream *s) const
    178 {
    179 
    180 }
    181 
    182 const Thread::ThreadEventData *
    183 Thread::ThreadEventData::GetEventDataFromEvent (const Event *event_ptr)
    184 {
    185     if (event_ptr)
    186     {
    187         const EventData *event_data = event_ptr->GetData();
    188         if (event_data && event_data->GetFlavor() == ThreadEventData::GetFlavorString())
    189             return static_cast <const ThreadEventData *> (event_ptr->GetData());
    190     }
    191     return NULL;
    192 }
    193 
    194 ThreadSP
    195 Thread::ThreadEventData::GetThreadFromEvent (const Event *event_ptr)
    196 {
    197     ThreadSP thread_sp;
    198     const ThreadEventData *event_data = GetEventDataFromEvent (event_ptr);
    199     if (event_data)
    200         thread_sp = event_data->GetThread();
    201     return thread_sp;
    202 }
    203 
    204 StackID
    205 Thread::ThreadEventData::GetStackIDFromEvent (const Event *event_ptr)
    206 {
    207     StackID stack_id;
    208     const ThreadEventData *event_data = GetEventDataFromEvent (event_ptr);
    209     if (event_data)
    210         stack_id = event_data->GetStackID();
    211     return stack_id;
    212 }
    213 
    214 StackFrameSP
    215 Thread::ThreadEventData::GetStackFrameFromEvent (const Event *event_ptr)
    216 {
    217     const ThreadEventData *event_data = GetEventDataFromEvent (event_ptr);
    218     StackFrameSP frame_sp;
    219     if (event_data)
    220     {
    221         ThreadSP thread_sp = event_data->GetThread();
    222         if (thread_sp)
    223         {
    224             frame_sp = thread_sp->GetStackFrameList()->GetFrameWithStackID (event_data->GetStackID());
    225         }
    226     }
    227     return frame_sp;
    228 }
    229 
    230 //------------------------------------------------------------------
    231 // Thread class
    232 //------------------------------------------------------------------
    233 
    234 ConstString &
    235 Thread::GetStaticBroadcasterClass ()
    236 {
    237     static ConstString class_name ("lldb.thread");
    238     return class_name;
    239 }
    240 
    241 Thread::Thread (Process &process, lldb::tid_t tid) :
    242     ThreadProperties (false),
    243     UserID (tid),
    244     Broadcaster(&process.GetTarget().GetDebugger(), Thread::GetStaticBroadcasterClass().AsCString()),
    245     m_process_wp (process.shared_from_this()),
    246     m_stop_info_sp (),
    247     m_stop_info_stop_id (0),
    248     m_index_id (process.GetNextThreadIndexID(tid)),
    249     m_reg_context_sp (),
    250     m_state (eStateUnloaded),
    251     m_state_mutex (Mutex::eMutexTypeRecursive),
    252     m_plan_stack (),
    253     m_completed_plan_stack(),
    254     m_frame_mutex (Mutex::eMutexTypeRecursive),
    255     m_curr_frames_sp (),
    256     m_prev_frames_sp (),
    257     m_resume_signal (LLDB_INVALID_SIGNAL_NUMBER),
    258     m_resume_state (eStateRunning),
    259     m_temporary_resume_state (eStateRunning),
    260     m_unwinder_ap (),
    261     m_destroy_called (false),
    262     m_override_should_notify (eLazyBoolCalculate)
    263 {
    264     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_OBJECT));
    265     if (log)
    266         log->Printf ("%p Thread::Thread(tid = 0x%4.4" PRIx64 ")", this, GetID());
    267 
    268     CheckInWithManager();
    269     QueueFundamentalPlan(true);
    270 }
    271 
    272 
    273 Thread::~Thread()
    274 {
    275     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_OBJECT));
    276     if (log)
    277         log->Printf ("%p Thread::~Thread(tid = 0x%4.4" PRIx64 ")", this, GetID());
    278     /// If you hit this assert, it means your derived class forgot to call DoDestroy in its destructor.
    279     assert (m_destroy_called);
    280 }
    281 
    282 void
    283 Thread::DestroyThread ()
    284 {
    285     // Tell any plans on the plan stack that the thread is being destroyed since
    286     // any active plans that have a thread go away in the middle of might need
    287     // to do cleanup.
    288     for (auto plan : m_plan_stack)
    289         plan->ThreadDestroyed();
    290 
    291     m_destroy_called = true;
    292     m_plan_stack.clear();
    293     m_discarded_plan_stack.clear();
    294     m_completed_plan_stack.clear();
    295 
    296     // Push a ThreadPlanNull on the plan stack.  That way we can continue assuming that the
    297     // plan stack is never empty, but if somebody errantly asks questions of a destroyed thread
    298     // without checking first whether it is destroyed, they won't crash.
    299     ThreadPlanSP null_plan_sp(new ThreadPlanNull (*this));
    300     m_plan_stack.push_back (null_plan_sp);
    301 
    302     m_stop_info_sp.reset();
    303     m_reg_context_sp.reset();
    304     m_unwinder_ap.reset();
    305     Mutex::Locker locker(m_frame_mutex);
    306     m_curr_frames_sp.reset();
    307     m_prev_frames_sp.reset();
    308 }
    309 
    310 void
    311 Thread::BroadcastSelectedFrameChange(StackID &new_frame_id)
    312 {
    313     if (EventTypeHasListeners(eBroadcastBitSelectedFrameChanged))
    314         BroadcastEvent(eBroadcastBitSelectedFrameChanged, new ThreadEventData (this->shared_from_this(), new_frame_id));
    315 }
    316 
    317 uint32_t
    318 Thread::SetSelectedFrame (lldb_private::StackFrame *frame, bool broadcast)
    319 {
    320     uint32_t ret_value = GetStackFrameList()->SetSelectedFrame(frame);
    321     if (broadcast)
    322         BroadcastSelectedFrameChange(frame->GetStackID());
    323     return ret_value;
    324 }
    325 
    326 bool
    327 Thread::SetSelectedFrameByIndex (uint32_t frame_idx, bool broadcast)
    328 {
    329     StackFrameSP frame_sp(GetStackFrameList()->GetFrameAtIndex (frame_idx));
    330     if (frame_sp)
    331     {
    332         GetStackFrameList()->SetSelectedFrame(frame_sp.get());
    333         if (broadcast)
    334             BroadcastSelectedFrameChange(frame_sp->GetStackID());
    335         return true;
    336     }
    337     else
    338         return false;
    339 }
    340 
    341 bool
    342 Thread::SetSelectedFrameByIndexNoisily (uint32_t frame_idx, Stream &output_stream)
    343 {
    344     const bool broadcast = true;
    345     bool success = SetSelectedFrameByIndex (frame_idx, broadcast);
    346     if (success)
    347     {
    348         StackFrameSP frame_sp = GetSelectedFrame();
    349         if (frame_sp)
    350         {
    351             bool already_shown = false;
    352             SymbolContext frame_sc(frame_sp->GetSymbolContext(eSymbolContextLineEntry));
    353             if (GetProcess()->GetTarget().GetDebugger().GetUseExternalEditor() && frame_sc.line_entry.file && frame_sc.line_entry.line != 0)
    354             {
    355                 already_shown = Host::OpenFileInExternalEditor (frame_sc.line_entry.file, frame_sc.line_entry.line);
    356             }
    357 
    358             bool show_frame_info = true;
    359             bool show_source = !already_shown;
    360             return frame_sp->GetStatus (output_stream, show_frame_info, show_source);
    361         }
    362         return false;
    363     }
    364     else
    365         return false;
    366 }
    367 
    368 
    369 lldb::StopInfoSP
    370 Thread::GetStopInfo ()
    371 {
    372     if (m_destroy_called)
    373         return m_stop_info_sp;
    374 
    375     ThreadPlanSP plan_sp (GetCompletedPlan());
    376     ProcessSP process_sp (GetProcess());
    377     const uint32_t stop_id = process_sp ? process_sp->GetStopID() : UINT32_MAX;
    378     if (plan_sp && plan_sp->PlanSucceeded())
    379     {
    380         return StopInfo::CreateStopReasonWithPlan (plan_sp, GetReturnValueObject());
    381     }
    382     else
    383     {
    384         if ((m_stop_info_stop_id == stop_id) ||   // Stop info is valid, just return what we have (even if empty)
    385             (m_stop_info_sp && m_stop_info_sp->IsValid()))  // Stop info is valid, just return what we have
    386         {
    387             return m_stop_info_sp;
    388         }
    389         else
    390         {
    391             GetPrivateStopInfo ();
    392             return m_stop_info_sp;
    393         }
    394     }
    395 }
    396 
    397 lldb::StopInfoSP
    398 Thread::GetPrivateStopInfo ()
    399 {
    400     if (m_destroy_called)
    401         return m_stop_info_sp;
    402 
    403     ProcessSP process_sp (GetProcess());
    404     if (process_sp)
    405     {
    406         const uint32_t process_stop_id = process_sp->GetStopID();
    407         if (m_stop_info_stop_id != process_stop_id)
    408         {
    409             if (m_stop_info_sp)
    410             {
    411                 if (m_stop_info_sp->IsValid()
    412                     || IsStillAtLastBreakpointHit()
    413                     || GetCurrentPlan()->IsVirtualStep())
    414                     SetStopInfo (m_stop_info_sp);
    415                 else
    416                     m_stop_info_sp.reset();
    417             }
    418 
    419             if (!m_stop_info_sp)
    420             {
    421                 if (CalculateStopInfo() == false)
    422                     SetStopInfo (StopInfoSP());
    423             }
    424         }
    425     }
    426     return m_stop_info_sp;
    427 }
    428 
    429 
    430 lldb::StopReason
    431 Thread::GetStopReason()
    432 {
    433     lldb::StopInfoSP stop_info_sp (GetStopInfo ());
    434     if (stop_info_sp)
    435         return stop_info_sp->GetStopReason();
    436     return eStopReasonNone;
    437 }
    438 
    439 
    440 
    441 void
    442 Thread::SetStopInfo (const lldb::StopInfoSP &stop_info_sp)
    443 {
    444     m_stop_info_sp = stop_info_sp;
    445     if (m_stop_info_sp)
    446     {
    447         m_stop_info_sp->MakeStopInfoValid();
    448         // If we are overriding the ShouldReportStop, do that here:
    449         if (m_override_should_notify != eLazyBoolCalculate)
    450             m_stop_info_sp->OverrideShouldNotify (m_override_should_notify == eLazyBoolYes);
    451     }
    452 
    453     ProcessSP process_sp (GetProcess());
    454     if (process_sp)
    455         m_stop_info_stop_id = process_sp->GetStopID();
    456     else
    457         m_stop_info_stop_id = UINT32_MAX;
    458     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_THREAD));
    459     if (log)
    460         log->Printf("%p: tid = 0x%" PRIx64 ": stop info = %s (stop_id = %u)\n", this, GetID(), stop_info_sp ? stop_info_sp->GetDescription() : "<NULL>", m_stop_info_stop_id);
    461 }
    462 
    463 void
    464 Thread::SetShouldReportStop (Vote vote)
    465 {
    466     if (vote == eVoteNoOpinion)
    467         return;
    468     else
    469     {
    470         m_override_should_notify = (vote == eVoteYes ? eLazyBoolYes : eLazyBoolNo);
    471         if (m_stop_info_sp)
    472             m_stop_info_sp->OverrideShouldNotify (m_override_should_notify == eLazyBoolYes);
    473     }
    474 }
    475 
    476 void
    477 Thread::SetStopInfoToNothing()
    478 {
    479     // Note, we can't just NULL out the private reason, or the native thread implementation will try to
    480     // go calculate it again.  For now, just set it to a Unix Signal with an invalid signal number.
    481     SetStopInfo (StopInfo::CreateStopReasonWithSignal (*this,  LLDB_INVALID_SIGNAL_NUMBER));
    482 }
    483 
    484 bool
    485 Thread::ThreadStoppedForAReason (void)
    486 {
    487     return (bool) GetPrivateStopInfo ();
    488 }
    489 
    490 bool
    491 Thread::CheckpointThreadState (ThreadStateCheckpoint &saved_state)
    492 {
    493     if (!SaveFrameZeroState(saved_state.register_backup))
    494         return false;
    495 
    496     saved_state.stop_info_sp = GetStopInfo();
    497     ProcessSP process_sp (GetProcess());
    498     if (process_sp)
    499         saved_state.orig_stop_id = process_sp->GetStopID();
    500     saved_state.current_inlined_depth = GetCurrentInlinedDepth();
    501 
    502     return true;
    503 }
    504 
    505 bool
    506 Thread::RestoreRegisterStateFromCheckpoint (ThreadStateCheckpoint &saved_state)
    507 {
    508     RestoreSaveFrameZero(saved_state.register_backup);
    509     return true;
    510 }
    511 
    512 bool
    513 Thread::RestoreThreadStateFromCheckpoint (ThreadStateCheckpoint &saved_state)
    514 {
    515     if (saved_state.stop_info_sp)
    516         saved_state.stop_info_sp->MakeStopInfoValid();
    517     SetStopInfo(saved_state.stop_info_sp);
    518     GetStackFrameList()->SetCurrentInlinedDepth (saved_state.current_inlined_depth);
    519     return true;
    520 }
    521 
    522 StateType
    523 Thread::GetState() const
    524 {
    525     // If any other threads access this we will need a mutex for it
    526     Mutex::Locker locker(m_state_mutex);
    527     return m_state;
    528 }
    529 
    530 void
    531 Thread::SetState(StateType state)
    532 {
    533     Mutex::Locker locker(m_state_mutex);
    534     m_state = state;
    535 }
    536 
    537 void
    538 Thread::WillStop()
    539 {
    540     ThreadPlan *current_plan = GetCurrentPlan();
    541 
    542     // FIXME: I may decide to disallow threads with no plans.  In which
    543     // case this should go to an assert.
    544 
    545     if (!current_plan)
    546         return;
    547 
    548     current_plan->WillStop();
    549 }
    550 
    551 void
    552 Thread::SetupForResume ()
    553 {
    554     if (GetResumeState() != eStateSuspended)
    555     {
    556 
    557         // If we're at a breakpoint push the step-over breakpoint plan.  Do this before
    558         // telling the current plan it will resume, since we might change what the current
    559         // plan is.
    560 
    561 //      StopReason stop_reason = lldb::eStopReasonInvalid;
    562 //      StopInfoSP stop_info_sp = GetStopInfo();
    563 //      if (stop_info_sp.get())
    564 //          stop_reason = stop_info_sp->GetStopReason();
    565 //      if (stop_reason == lldb::eStopReasonBreakpoint)
    566         lldb::RegisterContextSP reg_ctx_sp (GetRegisterContext());
    567         if (reg_ctx_sp)
    568         {
    569             BreakpointSiteSP bp_site_sp = GetProcess()->GetBreakpointSiteList().FindByAddress(reg_ctx_sp->GetPC());
    570             if (bp_site_sp)
    571             {
    572                 // Note, don't assume there's a ThreadPlanStepOverBreakpoint, the target may not require anything
    573                 // special to step over a breakpoint.
    574 
    575                 ThreadPlan *cur_plan = GetCurrentPlan();
    576 
    577                 if (cur_plan->GetKind() != ThreadPlan::eKindStepOverBreakpoint)
    578                 {
    579                     ThreadPlanStepOverBreakpoint *step_bp_plan = new ThreadPlanStepOverBreakpoint (*this);
    580                     if (step_bp_plan)
    581                     {
    582                         ThreadPlanSP step_bp_plan_sp;
    583                         step_bp_plan->SetPrivate (true);
    584 
    585                         if (GetCurrentPlan()->RunState() != eStateStepping)
    586                         {
    587                             step_bp_plan->SetAutoContinue(true);
    588                         }
    589                         step_bp_plan_sp.reset (step_bp_plan);
    590                         QueueThreadPlan (step_bp_plan_sp, false);
    591                     }
    592                 }
    593             }
    594         }
    595     }
    596 }
    597 
    598 bool
    599 Thread::ShouldResume (StateType resume_state)
    600 {
    601     // At this point clear the completed plan stack.
    602     m_completed_plan_stack.clear();
    603     m_discarded_plan_stack.clear();
    604     m_override_should_notify = eLazyBoolCalculate;
    605 
    606     m_temporary_resume_state = resume_state;
    607 
    608     lldb::ThreadSP backing_thread_sp (GetBackingThread ());
    609     if (backing_thread_sp)
    610         backing_thread_sp->m_temporary_resume_state = resume_state;
    611 
    612     // Make sure m_stop_info_sp is valid
    613     GetPrivateStopInfo();
    614 
    615     // This is a little dubious, but we are trying to limit how often we actually fetch stop info from
    616     // the target, 'cause that slows down single stepping.  So assume that if we got to the point where
    617     // we're about to resume, and we haven't yet had to fetch the stop reason, then it doesn't need to know
    618     // about the fact that we are resuming...
    619         const uint32_t process_stop_id = GetProcess()->GetStopID();
    620     if (m_stop_info_stop_id == process_stop_id &&
    621         (m_stop_info_sp && m_stop_info_sp->IsValid()))
    622     {
    623         StopInfo *stop_info = GetPrivateStopInfo().get();
    624         if (stop_info)
    625             stop_info->WillResume (resume_state);
    626     }
    627 
    628     // Tell all the plans that we are about to resume in case they need to clear any state.
    629     // We distinguish between the plan on the top of the stack and the lower
    630     // plans in case a plan needs to do any special business before it runs.
    631 
    632     bool need_to_resume = false;
    633     ThreadPlan *plan_ptr = GetCurrentPlan();
    634     if (plan_ptr)
    635     {
    636         need_to_resume = plan_ptr->WillResume(resume_state, true);
    637 
    638         while ((plan_ptr = GetPreviousPlan(plan_ptr)) != NULL)
    639         {
    640             plan_ptr->WillResume (resume_state, false);
    641         }
    642 
    643         // If the WillResume for the plan says we are faking a resume, then it will have set an appropriate stop info.
    644         // In that case, don't reset it here.
    645 
    646         if (need_to_resume && resume_state != eStateSuspended)
    647         {
    648             m_stop_info_sp.reset();
    649         }
    650     }
    651 
    652     if (need_to_resume)
    653     {
    654         ClearStackFrames();
    655         // Let Thread subclasses do any special work they need to prior to resuming
    656         WillResume (resume_state);
    657     }
    658 
    659     return need_to_resume;
    660 }
    661 
    662 void
    663 Thread::DidResume ()
    664 {
    665     SetResumeSignal (LLDB_INVALID_SIGNAL_NUMBER);
    666 }
    667 
    668 void
    669 Thread::DidStop ()
    670 {
    671     SetState (eStateStopped);
    672 }
    673 
    674 bool
    675 Thread::ShouldStop (Event* event_ptr)
    676 {
    677     ThreadPlan *current_plan = GetCurrentPlan();
    678 
    679     bool should_stop = true;
    680 
    681     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
    682 
    683     if (GetResumeState () == eStateSuspended)
    684     {
    685         if (log)
    686             log->Printf ("Thread::%s for tid = 0x%4.4" PRIx64 " 0x%4.4" PRIx64 ", should_stop = 0 (ignore since thread was suspended)",
    687                          __FUNCTION__,
    688                          GetID (),
    689                          GetProtocolID());
    690         return false;
    691     }
    692 
    693     if (GetTemporaryResumeState () == eStateSuspended)
    694     {
    695         if (log)
    696             log->Printf ("Thread::%s for tid = 0x%4.4" PRIx64 " 0x%4.4" PRIx64 ", should_stop = 0 (ignore since thread was suspended)",
    697                          __FUNCTION__,
    698                          GetID (),
    699                          GetProtocolID());
    700         return false;
    701     }
    702 
    703     // Based on the current thread plan and process stop info, check if this
    704     // thread caused the process to stop. NOTE: this must take place before
    705     // the plan is moved from the current plan stack to the completed plan
    706     // stack.
    707     if (ThreadStoppedForAReason() == false)
    708     {
    709         if (log)
    710             log->Printf ("Thread::%s for tid = 0x%4.4" PRIx64 " 0x%4.4" PRIx64 ", pc = 0x%16.16" PRIx64 ", should_stop = 0 (ignore since no stop reason)",
    711                          __FUNCTION__,
    712                          GetID (),
    713                          GetProtocolID(),
    714                          GetRegisterContext() ? GetRegisterContext()->GetPC() : LLDB_INVALID_ADDRESS);
    715         return false;
    716     }
    717 
    718     if (log)
    719     {
    720         log->Printf ("Thread::%s(%p) for tid = 0x%4.4" PRIx64 " 0x%4.4" PRIx64 ", pc = 0x%16.16" PRIx64,
    721                      __FUNCTION__,
    722                      this,
    723                      GetID (),
    724                      GetProtocolID (),
    725                      GetRegisterContext() ? GetRegisterContext()->GetPC() : LLDB_INVALID_ADDRESS);
    726         log->Printf ("^^^^^^^^ Thread::ShouldStop Begin ^^^^^^^^");
    727         StreamString s;
    728         s.IndentMore();
    729         DumpThreadPlans(&s);
    730         log->Printf ("Plan stack initial state:\n%s", s.GetData());
    731     }
    732 
    733     // The top most plan always gets to do the trace log...
    734     current_plan->DoTraceLog ();
    735 
    736     // First query the stop info's ShouldStopSynchronous.  This handles "synchronous" stop reasons, for example the breakpoint
    737     // command on internal breakpoints.  If a synchronous stop reason says we should not stop, then we don't have to
    738     // do any more work on this stop.
    739     StopInfoSP private_stop_info (GetPrivateStopInfo());
    740     if (private_stop_info && private_stop_info->ShouldStopSynchronous(event_ptr) == false)
    741     {
    742         if (log)
    743             log->Printf ("StopInfo::ShouldStop async callback says we should not stop, returning ShouldStop of false.");
    744         return false;
    745     }
    746 
    747     // If we've already been restarted, don't query the plans since the state they would examine is not current.
    748     if (Process::ProcessEventData::GetRestartedFromEvent(event_ptr))
    749         return false;
    750 
    751     // Before the plans see the state of the world, calculate the current inlined depth.
    752     GetStackFrameList()->CalculateCurrentInlinedDepth();
    753 
    754     // If the base plan doesn't understand why we stopped, then we have to find a plan that does.
    755     // If that plan is still working, then we don't need to do any more work.  If the plan that explains
    756     // the stop is done, then we should pop all the plans below it, and pop it, and then let the plans above it decide
    757     // whether they still need to do more work.
    758 
    759     bool done_processing_current_plan = false;
    760 
    761     if (!current_plan->PlanExplainsStop(event_ptr))
    762     {
    763         if (current_plan->TracerExplainsStop())
    764         {
    765             done_processing_current_plan = true;
    766             should_stop = false;
    767         }
    768         else
    769         {
    770             // If the current plan doesn't explain the stop, then find one that
    771             // does and let it handle the situation.
    772             ThreadPlan *plan_ptr = current_plan;
    773             while ((plan_ptr = GetPreviousPlan(plan_ptr)) != NULL)
    774             {
    775                 if (plan_ptr->PlanExplainsStop(event_ptr))
    776                 {
    777                     should_stop = plan_ptr->ShouldStop (event_ptr);
    778 
    779                     // plan_ptr explains the stop, next check whether plan_ptr is done, if so, then we should take it
    780                     // and all the plans below it off the stack.
    781 
    782                     if (plan_ptr->MischiefManaged())
    783                     {
    784                         // We're going to pop the plans up to and including the plan that explains the stop.
    785                         ThreadPlan *prev_plan_ptr = GetPreviousPlan (plan_ptr);
    786 
    787                         do
    788                         {
    789                             if (should_stop)
    790                                 current_plan->WillStop();
    791                             PopPlan();
    792                         }
    793                         while ((current_plan = GetCurrentPlan()) != prev_plan_ptr);
    794                         // Now, if the responsible plan was not "Okay to discard" then we're done,
    795                         // otherwise we forward this to the next plan in the stack below.
    796                         if (plan_ptr->IsMasterPlan() && !plan_ptr->OkayToDiscard())
    797                             done_processing_current_plan = true;
    798                         else
    799                             done_processing_current_plan = false;
    800                     }
    801                     else
    802                         done_processing_current_plan = true;
    803 
    804                     break;
    805                 }
    806 
    807             }
    808         }
    809     }
    810 
    811     if (!done_processing_current_plan)
    812     {
    813         bool over_ride_stop = current_plan->ShouldAutoContinue(event_ptr);
    814 
    815         if (log)
    816             log->Printf("Plan %s explains stop, auto-continue %i.", current_plan->GetName(), over_ride_stop);
    817 
    818         // We're starting from the base plan, so just let it decide;
    819         if (PlanIsBasePlan(current_plan))
    820         {
    821             should_stop = current_plan->ShouldStop (event_ptr);
    822             if (log)
    823                 log->Printf("Base plan says should stop: %i.", should_stop);
    824         }
    825         else
    826         {
    827             // Otherwise, don't let the base plan override what the other plans say to do, since
    828             // presumably if there were other plans they would know what to do...
    829             while (1)
    830             {
    831                 if (PlanIsBasePlan(current_plan))
    832                     break;
    833 
    834                 should_stop = current_plan->ShouldStop(event_ptr);
    835                 if (log)
    836                     log->Printf("Plan %s should stop: %d.", current_plan->GetName(), should_stop);
    837                 if (current_plan->MischiefManaged())
    838                 {
    839                     if (should_stop)
    840                         current_plan->WillStop();
    841 
    842                     // If a Master Plan wants to stop, and wants to stick on the stack, we let it.
    843                     // Otherwise, see if the plan's parent wants to stop.
    844 
    845                     if (should_stop && current_plan->IsMasterPlan() && !current_plan->OkayToDiscard())
    846                     {
    847                         PopPlan();
    848                         break;
    849                     }
    850                     else
    851                     {
    852 
    853                         PopPlan();
    854 
    855                         current_plan = GetCurrentPlan();
    856                         if (current_plan == NULL)
    857                         {
    858                             break;
    859                         }
    860                     }
    861                 }
    862                 else
    863                 {
    864                     break;
    865                 }
    866             }
    867         }
    868 
    869         if (over_ride_stop)
    870             should_stop = false;
    871 
    872         // One other potential problem is that we set up a master plan, then stop in before it is complete - for instance
    873         // by hitting a breakpoint during a step-over - then do some step/finish/etc operations that wind up
    874         // past the end point condition of the initial plan.  We don't want to strand the original plan on the stack,
    875         // This code clears stale plans off the stack.
    876 
    877         if (should_stop)
    878         {
    879             ThreadPlan *plan_ptr = GetCurrentPlan();
    880             while (!PlanIsBasePlan(plan_ptr))
    881             {
    882                 bool stale = plan_ptr->IsPlanStale ();
    883                 ThreadPlan *examined_plan = plan_ptr;
    884                 plan_ptr = GetPreviousPlan (examined_plan);
    885 
    886                 if (stale)
    887                 {
    888                     if (log)
    889                         log->Printf("Plan %s being discarded in cleanup, it says it is already done.", examined_plan->GetName());
    890                     DiscardThreadPlansUpToPlan(examined_plan);
    891                 }
    892             }
    893         }
    894 
    895     }
    896 
    897     if (log)
    898     {
    899         StreamString s;
    900         s.IndentMore();
    901         DumpThreadPlans(&s);
    902         log->Printf ("Plan stack final state:\n%s", s.GetData());
    903         log->Printf ("vvvvvvvv Thread::ShouldStop End (returning %i) vvvvvvvv", should_stop);
    904     }
    905     return should_stop;
    906 }
    907 
    908 Vote
    909 Thread::ShouldReportStop (Event* event_ptr)
    910 {
    911     StateType thread_state = GetResumeState ();
    912     StateType temp_thread_state = GetTemporaryResumeState();
    913 
    914     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
    915 
    916     if (thread_state == eStateSuspended || thread_state == eStateInvalid)
    917     {
    918         if (log)
    919             log->Printf ("Thread::ShouldReportStop() tid = 0x%4.4" PRIx64 ": returning vote %i (state was suspended or invalid)", GetID(), eVoteNoOpinion);
    920         return eVoteNoOpinion;
    921     }
    922 
    923     if (temp_thread_state == eStateSuspended || temp_thread_state == eStateInvalid)
    924     {
    925         if (log)
    926             log->Printf ("Thread::ShouldReportStop() tid = 0x%4.4" PRIx64 ": returning vote %i (temporary state was suspended or invalid)", GetID(), eVoteNoOpinion);
    927         return eVoteNoOpinion;
    928     }
    929 
    930     if (!ThreadStoppedForAReason())
    931     {
    932         if (log)
    933             log->Printf ("Thread::ShouldReportStop() tid = 0x%4.4" PRIx64 ": returning vote %i (thread didn't stop for a reason.)", GetID(), eVoteNoOpinion);
    934         return eVoteNoOpinion;
    935     }
    936 
    937     if (m_completed_plan_stack.size() > 0)
    938     {
    939         // Don't use GetCompletedPlan here, since that suppresses private plans.
    940         if (log)
    941             log->Printf ("Thread::ShouldReportStop() tid = 0x%4.4" PRIx64 ": returning vote  for complete stack's back plan", GetID());
    942         return m_completed_plan_stack.back()->ShouldReportStop (event_ptr);
    943     }
    944     else
    945     {
    946         Vote thread_vote = eVoteNoOpinion;
    947         ThreadPlan *plan_ptr = GetCurrentPlan();
    948         while (1)
    949         {
    950             if (plan_ptr->PlanExplainsStop(event_ptr))
    951             {
    952                 thread_vote = plan_ptr->ShouldReportStop(event_ptr);
    953                 break;
    954             }
    955             if (PlanIsBasePlan(plan_ptr))
    956                 break;
    957             else
    958                 plan_ptr = GetPreviousPlan(plan_ptr);
    959         }
    960         if (log)
    961             log->Printf ("Thread::ShouldReportStop() tid = 0x%4.4" PRIx64 ": returning vote %i for current plan", GetID(), thread_vote);
    962 
    963         return thread_vote;
    964     }
    965 }
    966 
    967 Vote
    968 Thread::ShouldReportRun (Event* event_ptr)
    969 {
    970     StateType thread_state = GetResumeState ();
    971 
    972     if (thread_state == eStateSuspended
    973             || thread_state == eStateInvalid)
    974     {
    975         return eVoteNoOpinion;
    976     }
    977 
    978     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
    979     if (m_completed_plan_stack.size() > 0)
    980     {
    981         // Don't use GetCompletedPlan here, since that suppresses private plans.
    982         if (log)
    983             log->Printf ("Current Plan for thread %d(%p) (0x%4.4" PRIx64 ", %s): %s being asked whether we should report run.",
    984                          GetIndexID(),
    985                          this,
    986                          GetID(),
    987                          StateAsCString(GetTemporaryResumeState()),
    988                          m_completed_plan_stack.back()->GetName());
    989 
    990         return m_completed_plan_stack.back()->ShouldReportRun (event_ptr);
    991     }
    992     else
    993     {
    994         if (log)
    995             log->Printf ("Current Plan for thread %d(%p) (0x%4.4" PRIx64 ", %s): %s being asked whether we should report run.",
    996                          GetIndexID(),
    997                          this,
    998                          GetID(),
    999                          StateAsCString(GetTemporaryResumeState()),
   1000                          GetCurrentPlan()->GetName());
   1001 
   1002         return GetCurrentPlan()->ShouldReportRun (event_ptr);
   1003      }
   1004 }
   1005 
   1006 bool
   1007 Thread::MatchesSpec (const ThreadSpec *spec)
   1008 {
   1009     if (spec == NULL)
   1010         return true;
   1011 
   1012     return spec->ThreadPassesBasicTests(*this);
   1013 }
   1014 
   1015 void
   1016 Thread::PushPlan (ThreadPlanSP &thread_plan_sp)
   1017 {
   1018     if (thread_plan_sp)
   1019     {
   1020         // If the thread plan doesn't already have a tracer, give it its parent's tracer:
   1021         if (!thread_plan_sp->GetThreadPlanTracer())
   1022             thread_plan_sp->SetThreadPlanTracer(m_plan_stack.back()->GetThreadPlanTracer());
   1023         m_plan_stack.push_back (thread_plan_sp);
   1024 
   1025         thread_plan_sp->DidPush();
   1026 
   1027         Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
   1028         if (log)
   1029         {
   1030             StreamString s;
   1031             thread_plan_sp->GetDescription (&s, lldb::eDescriptionLevelFull);
   1032             log->Printf("Thread::PushPlan(0x%p): \"%s\", tid = 0x%4.4" PRIx64 ".",
   1033                         this,
   1034                         s.GetData(),
   1035                         thread_plan_sp->GetThread().GetID());
   1036         }
   1037     }
   1038 }
   1039 
   1040 void
   1041 Thread::PopPlan ()
   1042 {
   1043     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
   1044 
   1045     if (m_plan_stack.size() <= 1)
   1046         return;
   1047     else
   1048     {
   1049         ThreadPlanSP &plan = m_plan_stack.back();
   1050         if (log)
   1051         {
   1052             log->Printf("Popping plan: \"%s\", tid = 0x%4.4" PRIx64 ".", plan->GetName(), plan->GetThread().GetID());
   1053         }
   1054         m_completed_plan_stack.push_back (plan);
   1055         plan->WillPop();
   1056         m_plan_stack.pop_back();
   1057     }
   1058 }
   1059 
   1060 void
   1061 Thread::DiscardPlan ()
   1062 {
   1063     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
   1064     if (m_plan_stack.size() > 1)
   1065     {
   1066         ThreadPlanSP &plan = m_plan_stack.back();
   1067         if (log)
   1068             log->Printf("Discarding plan: \"%s\", tid = 0x%4.4" PRIx64 ".", plan->GetName(), plan->GetThread().GetID());
   1069 
   1070         m_discarded_plan_stack.push_back (plan);
   1071         plan->WillPop();
   1072         m_plan_stack.pop_back();
   1073     }
   1074 }
   1075 
   1076 ThreadPlan *
   1077 Thread::GetCurrentPlan ()
   1078 {
   1079     // There will always be at least the base plan.  If somebody is mucking with a
   1080     // thread with an empty plan stack, we should assert right away.
   1081     if (m_plan_stack.empty())
   1082         return NULL;
   1083     return m_plan_stack.back().get();
   1084 }
   1085 
   1086 ThreadPlanSP
   1087 Thread::GetCompletedPlan ()
   1088 {
   1089     ThreadPlanSP empty_plan_sp;
   1090     if (!m_completed_plan_stack.empty())
   1091     {
   1092         for (int i = m_completed_plan_stack.size() - 1; i >= 0; i--)
   1093         {
   1094             ThreadPlanSP completed_plan_sp;
   1095             completed_plan_sp = m_completed_plan_stack[i];
   1096             if (!completed_plan_sp->GetPrivate ())
   1097             return completed_plan_sp;
   1098         }
   1099     }
   1100     return empty_plan_sp;
   1101 }
   1102 
   1103 ValueObjectSP
   1104 Thread::GetReturnValueObject ()
   1105 {
   1106     if (!m_completed_plan_stack.empty())
   1107     {
   1108         for (int i = m_completed_plan_stack.size() - 1; i >= 0; i--)
   1109         {
   1110             ValueObjectSP return_valobj_sp;
   1111             return_valobj_sp = m_completed_plan_stack[i]->GetReturnValueObject();
   1112             if (return_valobj_sp)
   1113             return return_valobj_sp;
   1114         }
   1115     }
   1116     return ValueObjectSP();
   1117 }
   1118 
   1119 bool
   1120 Thread::IsThreadPlanDone (ThreadPlan *plan)
   1121 {
   1122     if (!m_completed_plan_stack.empty())
   1123     {
   1124         for (int i = m_completed_plan_stack.size() - 1; i >= 0; i--)
   1125         {
   1126             if (m_completed_plan_stack[i].get() == plan)
   1127                 return true;
   1128         }
   1129     }
   1130     return false;
   1131 }
   1132 
   1133 bool
   1134 Thread::WasThreadPlanDiscarded (ThreadPlan *plan)
   1135 {
   1136     if (!m_discarded_plan_stack.empty())
   1137     {
   1138         for (int i = m_discarded_plan_stack.size() - 1; i >= 0; i--)
   1139         {
   1140             if (m_discarded_plan_stack[i].get() == plan)
   1141                 return true;
   1142         }
   1143     }
   1144     return false;
   1145 }
   1146 
   1147 ThreadPlan *
   1148 Thread::GetPreviousPlan (ThreadPlan *current_plan)
   1149 {
   1150     if (current_plan == NULL)
   1151         return NULL;
   1152 
   1153     int stack_size = m_completed_plan_stack.size();
   1154     for (int i = stack_size - 1; i > 0; i--)
   1155     {
   1156         if (current_plan == m_completed_plan_stack[i].get())
   1157             return m_completed_plan_stack[i-1].get();
   1158     }
   1159 
   1160     if (stack_size > 0 && m_completed_plan_stack[0].get() == current_plan)
   1161     {
   1162         if (m_plan_stack.size() > 0)
   1163             return m_plan_stack.back().get();
   1164         else
   1165             return NULL;
   1166     }
   1167 
   1168     stack_size = m_plan_stack.size();
   1169     for (int i = stack_size - 1; i > 0; i--)
   1170     {
   1171         if (current_plan == m_plan_stack[i].get())
   1172             return m_plan_stack[i-1].get();
   1173     }
   1174     return NULL;
   1175 }
   1176 
   1177 void
   1178 Thread::QueueThreadPlan (ThreadPlanSP &thread_plan_sp, bool abort_other_plans)
   1179 {
   1180     if (abort_other_plans)
   1181        DiscardThreadPlans(true);
   1182 
   1183     PushPlan (thread_plan_sp);
   1184 }
   1185 
   1186 
   1187 void
   1188 Thread::EnableTracer (bool value, bool single_stepping)
   1189 {
   1190     int stack_size = m_plan_stack.size();
   1191     for (int i = 0; i < stack_size; i++)
   1192     {
   1193         if (m_plan_stack[i]->GetThreadPlanTracer())
   1194         {
   1195             m_plan_stack[i]->GetThreadPlanTracer()->EnableTracing(value);
   1196             m_plan_stack[i]->GetThreadPlanTracer()->EnableSingleStep(single_stepping);
   1197         }
   1198     }
   1199 }
   1200 
   1201 void
   1202 Thread::SetTracer (lldb::ThreadPlanTracerSP &tracer_sp)
   1203 {
   1204     int stack_size = m_plan_stack.size();
   1205     for (int i = 0; i < stack_size; i++)
   1206         m_plan_stack[i]->SetThreadPlanTracer(tracer_sp);
   1207 }
   1208 
   1209 void
   1210 Thread::DiscardThreadPlansUpToPlan (lldb::ThreadPlanSP &up_to_plan_sp)
   1211 {
   1212     DiscardThreadPlansUpToPlan (up_to_plan_sp.get());
   1213 }
   1214 
   1215 void
   1216 Thread::DiscardThreadPlansUpToPlan (ThreadPlan *up_to_plan_ptr)
   1217 {
   1218     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
   1219     if (log)
   1220     {
   1221         log->Printf("Discarding thread plans for thread tid = 0x%4.4" PRIx64 ", up to %p", GetID(), up_to_plan_ptr);
   1222     }
   1223 
   1224     int stack_size = m_plan_stack.size();
   1225 
   1226     // If the input plan is NULL, discard all plans.  Otherwise make sure this plan is in the
   1227     // stack, and if so discard up to and including it.
   1228 
   1229     if (up_to_plan_ptr == NULL)
   1230     {
   1231         for (int i = stack_size - 1; i > 0; i--)
   1232             DiscardPlan();
   1233     }
   1234     else
   1235     {
   1236         bool found_it = false;
   1237         for (int i = stack_size - 1; i > 0; i--)
   1238         {
   1239             if (m_plan_stack[i].get() == up_to_plan_ptr)
   1240                 found_it = true;
   1241         }
   1242         if (found_it)
   1243         {
   1244             bool last_one = false;
   1245             for (int i = stack_size - 1; i > 0 && !last_one ; i--)
   1246             {
   1247                 if (GetCurrentPlan() == up_to_plan_ptr)
   1248                     last_one = true;
   1249                 DiscardPlan();
   1250             }
   1251         }
   1252     }
   1253     return;
   1254 }
   1255 
   1256 void
   1257 Thread::DiscardThreadPlans(bool force)
   1258 {
   1259     Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
   1260     if (log)
   1261     {
   1262         log->Printf("Discarding thread plans for thread (tid = 0x%4.4" PRIx64 ", force %d)", GetID(), force);
   1263     }
   1264 
   1265     if (force)
   1266     {
   1267         int stack_size = m_plan_stack.size();
   1268         for (int i = stack_size - 1; i > 0; i--)
   1269         {
   1270             DiscardPlan();
   1271         }
   1272         return;
   1273     }
   1274 
   1275     while (1)
   1276     {
   1277 
   1278         int master_plan_idx;
   1279         bool discard = true;
   1280 
   1281         // Find the first master plan, see if it wants discarding, and if yes discard up to it.
   1282         for (master_plan_idx = m_plan_stack.size() - 1; master_plan_idx >= 0; master_plan_idx--)
   1283         {
   1284             if (m_plan_stack[master_plan_idx]->IsMasterPlan())
   1285             {
   1286                 discard = m_plan_stack[master_plan_idx]->OkayToDiscard();
   1287                 break;
   1288             }
   1289         }
   1290 
   1291         if (discard)
   1292         {
   1293             // First pop all the dependent plans:
   1294             for (int i = m_plan_stack.size() - 1; i > master_plan_idx; i--)
   1295             {
   1296 
   1297                 // FIXME: Do we need a finalize here, or is the rule that "PrepareForStop"
   1298                 // for the plan leaves it in a state that it is safe to pop the plan
   1299                 // with no more notice?
   1300                 DiscardPlan();
   1301             }
   1302 
   1303             // Now discard the master plan itself.
   1304             // The bottom-most plan never gets discarded.  "OkayToDiscard" for it means
   1305             // discard it's dependent plans, but not it...
   1306             if (master_plan_idx > 0)
   1307             {
   1308                 DiscardPlan();
   1309             }
   1310         }
   1311         else
   1312         {
   1313             // If the master plan doesn't want to get discarded, then we're done.
   1314             break;
   1315         }
   1316 
   1317     }
   1318 }
   1319 
   1320 bool
   1321 Thread::PlanIsBasePlan (ThreadPlan *plan_ptr)
   1322 {
   1323     if (plan_ptr->IsBasePlan())
   1324         return true;
   1325     else if (m_plan_stack.size() == 0)
   1326         return false;
   1327     else
   1328        return m_plan_stack[0].get() == plan_ptr;
   1329 }
   1330 
   1331 Error
   1332 Thread::UnwindInnermostExpression()
   1333 {
   1334     Error error;
   1335     int stack_size = m_plan_stack.size();
   1336 
   1337     // If the input plan is NULL, discard all plans.  Otherwise make sure this plan is in the
   1338     // stack, and if so discard up to and including it.
   1339 
   1340     for (int i = stack_size - 1; i > 0; i--)
   1341     {
   1342         if (m_plan_stack[i]->GetKind() == ThreadPlan::eKindCallFunction)
   1343         {
   1344             DiscardThreadPlansUpToPlan(m_plan_stack[i].get());
   1345             return error;
   1346         }
   1347     }
   1348     error.SetErrorString("No expressions currently active on this thread");
   1349     return error;
   1350 }
   1351 
   1352 
   1353 ThreadPlanSP
   1354 Thread::QueueFundamentalPlan (bool abort_other_plans)
   1355 {
   1356     ThreadPlanSP thread_plan_sp (new ThreadPlanBase(*this));
   1357     QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1358     return thread_plan_sp;
   1359 }
   1360 
   1361 ThreadPlanSP
   1362 Thread::QueueThreadPlanForStepSingleInstruction
   1363 (
   1364     bool step_over,
   1365     bool abort_other_plans,
   1366     bool stop_other_threads
   1367 )
   1368 {
   1369     ThreadPlanSP thread_plan_sp (new ThreadPlanStepInstruction (*this, step_over, stop_other_threads, eVoteNoOpinion, eVoteNoOpinion));
   1370     QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1371     return thread_plan_sp;
   1372 }
   1373 
   1374 ThreadPlanSP
   1375 Thread::QueueThreadPlanForStepOverRange
   1376 (
   1377     bool abort_other_plans,
   1378     const AddressRange &range,
   1379     const SymbolContext &addr_context,
   1380     lldb::RunMode stop_other_threads
   1381 )
   1382 {
   1383     ThreadPlanSP thread_plan_sp;
   1384     thread_plan_sp.reset (new ThreadPlanStepOverRange (*this, range, addr_context, stop_other_threads));
   1385 
   1386     QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1387     return thread_plan_sp;
   1388 }
   1389 
   1390 ThreadPlanSP
   1391 Thread::QueueThreadPlanForStepInRange
   1392 (
   1393     bool abort_other_plans,
   1394     const AddressRange &range,
   1395     const SymbolContext &addr_context,
   1396     const char *step_in_target,
   1397     lldb::RunMode stop_other_threads,
   1398     bool avoid_code_without_debug_info
   1399 )
   1400 {
   1401     ThreadPlanSP thread_plan_sp;
   1402     ThreadPlanStepInRange *plan = new ThreadPlanStepInRange (*this, range, addr_context, stop_other_threads);
   1403     if (avoid_code_without_debug_info)
   1404         plan->GetFlags().Set (ThreadPlanShouldStopHere::eAvoidNoDebug);
   1405     else
   1406         plan->GetFlags().Clear (ThreadPlanShouldStopHere::eAvoidNoDebug);
   1407     if (step_in_target)
   1408         plan->SetStepInTarget(step_in_target);
   1409     thread_plan_sp.reset (plan);
   1410 
   1411     QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1412     return thread_plan_sp;
   1413 }
   1414 
   1415 
   1416 ThreadPlanSP
   1417 Thread::QueueThreadPlanForStepOverBreakpointPlan (bool abort_other_plans)
   1418 {
   1419     ThreadPlanSP thread_plan_sp (new ThreadPlanStepOverBreakpoint (*this));
   1420     QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1421     return thread_plan_sp;
   1422 }
   1423 
   1424 ThreadPlanSP
   1425 Thread::QueueThreadPlanForStepOut
   1426 (
   1427     bool abort_other_plans,
   1428     SymbolContext *addr_context,
   1429     bool first_insn,
   1430     bool stop_other_threads,
   1431     Vote stop_vote,
   1432     Vote run_vote,
   1433     uint32_t frame_idx
   1434 )
   1435 {
   1436     ThreadPlanSP thread_plan_sp (new ThreadPlanStepOut (*this,
   1437                                                         addr_context,
   1438                                                         first_insn,
   1439                                                         stop_other_threads,
   1440                                                         stop_vote,
   1441                                                         run_vote,
   1442                                                         frame_idx));
   1443 
   1444     if (thread_plan_sp->ValidatePlan(NULL))
   1445     {
   1446         QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1447         return thread_plan_sp;
   1448     }
   1449     else
   1450     {
   1451         return ThreadPlanSP();
   1452     }
   1453 }
   1454 
   1455 ThreadPlanSP
   1456 Thread::QueueThreadPlanForStepThrough (StackID &return_stack_id, bool abort_other_plans, bool stop_other_threads)
   1457 {
   1458     ThreadPlanSP thread_plan_sp(new ThreadPlanStepThrough (*this, return_stack_id, stop_other_threads));
   1459     if (!thread_plan_sp || !thread_plan_sp->ValidatePlan (NULL))
   1460         return ThreadPlanSP();
   1461 
   1462     QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1463     return thread_plan_sp;
   1464 }
   1465 
   1466 ThreadPlanSP
   1467 Thread::QueueThreadPlanForCallFunction (bool abort_other_plans,
   1468                                         Address& function,
   1469                                         lldb::addr_t arg,
   1470                                         bool stop_other_threads,
   1471                                         bool unwind_on_error,
   1472                                         bool ignore_breakpoints)
   1473 {
   1474     ThreadPlanSP thread_plan_sp (new ThreadPlanCallFunction (*this,
   1475                                                              function,
   1476                                                              ClangASTType(),
   1477                                                              arg,
   1478                                                              stop_other_threads,
   1479                                                              unwind_on_error,
   1480                                                              ignore_breakpoints));
   1481     QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1482     return thread_plan_sp;
   1483 }
   1484 
   1485 ThreadPlanSP
   1486 Thread::QueueThreadPlanForRunToAddress (bool abort_other_plans,
   1487                                         Address &target_addr,
   1488                                         bool stop_other_threads)
   1489 {
   1490     ThreadPlanSP thread_plan_sp (new ThreadPlanRunToAddress (*this, target_addr, stop_other_threads));
   1491     QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1492     return thread_plan_sp;
   1493 }
   1494 
   1495 ThreadPlanSP
   1496 Thread::QueueThreadPlanForStepUntil (bool abort_other_plans,
   1497                                      lldb::addr_t *address_list,
   1498                                      size_t num_addresses,
   1499                                      bool stop_other_threads,
   1500                                      uint32_t frame_idx)
   1501 {
   1502     ThreadPlanSP thread_plan_sp (new ThreadPlanStepUntil (*this, address_list, num_addresses, stop_other_threads, frame_idx));
   1503     QueueThreadPlan (thread_plan_sp, abort_other_plans);
   1504     return thread_plan_sp;
   1505 
   1506 }
   1507 
   1508 uint32_t
   1509 Thread::GetIndexID () const
   1510 {
   1511     return m_index_id;
   1512 }
   1513 
   1514 void
   1515 Thread::DumpThreadPlans (lldb_private::Stream *s) const
   1516 {
   1517     uint32_t stack_size = m_plan_stack.size();
   1518     int i;
   1519     s->Indent();
   1520     s->Printf ("Plan Stack for thread #%u: tid = 0x%4.4" PRIx64 ", stack_size = %d\n", GetIndexID(), GetID(), stack_size);
   1521     for (i = stack_size - 1; i >= 0; i--)
   1522     {
   1523         s->IndentMore();
   1524         s->Indent();
   1525         s->Printf ("Element %d: ", i);
   1526         m_plan_stack[i]->GetDescription (s, eDescriptionLevelFull);
   1527         s->EOL();
   1528         s->IndentLess();
   1529     }
   1530 
   1531     stack_size = m_completed_plan_stack.size();
   1532     if (stack_size > 0)
   1533     {
   1534         s->Indent();
   1535         s->Printf ("Completed Plan Stack: %d elements.\n", stack_size);
   1536         for (i = stack_size - 1; i >= 0; i--)
   1537         {
   1538             s->IndentMore();
   1539             s->Indent();
   1540             s->Printf ("Element %d: ", i);
   1541             m_completed_plan_stack[i]->GetDescription (s, eDescriptionLevelFull);
   1542             s->EOL();
   1543             s->IndentLess();
   1544         }
   1545     }
   1546 
   1547     stack_size = m_discarded_plan_stack.size();
   1548     if (stack_size > 0)
   1549     {
   1550         s->Indent();
   1551         s->Printf ("Discarded Plan Stack: %d elements.\n", stack_size);
   1552         for (i = stack_size - 1; i >= 0; i--)
   1553         {
   1554             s->IndentMore();
   1555             s->Indent();
   1556             s->Printf ("Element %d: ", i);
   1557             m_discarded_plan_stack[i]->GetDescription (s, eDescriptionLevelFull);
   1558             s->EOL();
   1559             s->IndentLess();
   1560         }
   1561     }
   1562 
   1563 }
   1564 
   1565 TargetSP
   1566 Thread::CalculateTarget ()
   1567 {
   1568     TargetSP target_sp;
   1569     ProcessSP process_sp(GetProcess());
   1570     if (process_sp)
   1571         target_sp = process_sp->CalculateTarget();
   1572     return target_sp;
   1573 
   1574 }
   1575 
   1576 ProcessSP
   1577 Thread::CalculateProcess ()
   1578 {
   1579     return GetProcess();
   1580 }
   1581 
   1582 ThreadSP
   1583 Thread::CalculateThread ()
   1584 {
   1585     return shared_from_this();
   1586 }
   1587 
   1588 StackFrameSP
   1589 Thread::CalculateStackFrame ()
   1590 {
   1591     return StackFrameSP();
   1592 }
   1593 
   1594 void
   1595 Thread::CalculateExecutionContext (ExecutionContext &exe_ctx)
   1596 {
   1597     exe_ctx.SetContext (shared_from_this());
   1598 }
   1599 
   1600 
   1601 StackFrameListSP
   1602 Thread::GetStackFrameList ()
   1603 {
   1604     StackFrameListSP frame_list_sp;
   1605     Mutex::Locker locker(m_frame_mutex);
   1606     if (m_curr_frames_sp)
   1607     {
   1608         frame_list_sp = m_curr_frames_sp;
   1609     }
   1610     else
   1611     {
   1612         frame_list_sp.reset(new StackFrameList (*this, m_prev_frames_sp, true));
   1613         m_curr_frames_sp = frame_list_sp;
   1614     }
   1615     return frame_list_sp;
   1616 }
   1617 
   1618 void
   1619 Thread::ClearStackFrames ()
   1620 {
   1621     Mutex::Locker locker(m_frame_mutex);
   1622 
   1623     Unwind *unwinder = GetUnwinder ();
   1624     if (unwinder)
   1625         unwinder->Clear();
   1626 
   1627     // Only store away the old "reference" StackFrameList if we got all its frames:
   1628     // FIXME: At some point we can try to splice in the frames we have fetched into
   1629     // the new frame as we make it, but let's not try that now.
   1630     if (m_curr_frames_sp && m_curr_frames_sp->GetAllFramesFetched())
   1631         m_prev_frames_sp.swap (m_curr_frames_sp);
   1632     m_curr_frames_sp.reset();
   1633 }
   1634 
   1635 lldb::StackFrameSP
   1636 Thread::GetFrameWithConcreteFrameIndex (uint32_t unwind_idx)
   1637 {
   1638     return GetStackFrameList()->GetFrameWithConcreteFrameIndex (unwind_idx);
   1639 }
   1640 
   1641 
   1642 Error
   1643 Thread::ReturnFromFrameWithIndex (uint32_t frame_idx, lldb::ValueObjectSP return_value_sp, bool broadcast)
   1644 {
   1645     StackFrameSP frame_sp = GetStackFrameAtIndex (frame_idx);
   1646     Error return_error;
   1647 
   1648     if (!frame_sp)
   1649     {
   1650         return_error.SetErrorStringWithFormat("Could not find frame with index %d in thread 0x%" PRIx64 ".", frame_idx, GetID());
   1651     }
   1652 
   1653     return ReturnFromFrame(frame_sp, return_value_sp, broadcast);
   1654 }
   1655 
   1656 Error
   1657 Thread::ReturnFromFrame (lldb::StackFrameSP frame_sp, lldb::ValueObjectSP return_value_sp, bool broadcast)
   1658 {
   1659     Error return_error;
   1660 
   1661     if (!frame_sp)
   1662     {
   1663         return_error.SetErrorString("Can't return to a null frame.");
   1664         return return_error;
   1665     }
   1666 
   1667     Thread *thread = frame_sp->GetThread().get();
   1668     uint32_t older_frame_idx = frame_sp->GetFrameIndex() + 1;
   1669     StackFrameSP older_frame_sp = thread->GetStackFrameAtIndex(older_frame_idx);
   1670     if (!older_frame_sp)
   1671     {
   1672         return_error.SetErrorString("No older frame to return to.");
   1673         return return_error;
   1674     }
   1675 
   1676     if (return_value_sp)
   1677     {
   1678         lldb::ABISP abi = thread->GetProcess()->GetABI();
   1679         if (!abi)
   1680         {
   1681             return_error.SetErrorString("Could not find ABI to set return value.");
   1682             return return_error;
   1683         }
   1684         SymbolContext sc = frame_sp->GetSymbolContext(eSymbolContextFunction);
   1685 
   1686         // FIXME: ValueObject::Cast doesn't currently work correctly, at least not for scalars.
   1687         // Turn that back on when that works.
   1688         if (0 && sc.function != NULL)
   1689         {
   1690             Type *function_type = sc.function->GetType();
   1691             if (function_type)
   1692             {
   1693                 ClangASTType return_type = sc.function->GetClangType().GetFunctionReturnType();
   1694                 if (return_type)
   1695                 {
   1696                     StreamString s;
   1697                     return_type.DumpTypeDescription(&s);
   1698                     ValueObjectSP cast_value_sp = return_value_sp->Cast(return_type);
   1699                     if (cast_value_sp)
   1700                     {
   1701                         cast_value_sp->SetFormat(eFormatHex);
   1702                         return_value_sp = cast_value_sp;
   1703                     }
   1704                 }
   1705             }
   1706         }
   1707 
   1708         return_error = abi->SetReturnValueObject(older_frame_sp, return_value_sp);
   1709         if (!return_error.Success())
   1710             return return_error;
   1711     }
   1712 
   1713     // Now write the return registers for the chosen frame:
   1714     // Note, we can't use ReadAllRegisterValues->WriteAllRegisterValues, since the read & write
   1715     // cook their data
   1716 
   1717     StackFrameSP youngest_frame_sp = thread->GetStackFrameAtIndex(0);
   1718     if (youngest_frame_sp)
   1719     {
   1720         lldb::RegisterContextSP reg_ctx_sp (youngest_frame_sp->GetRegisterContext());
   1721         if (reg_ctx_sp)
   1722         {
   1723             bool copy_success = reg_ctx_sp->CopyFromRegisterContext(older_frame_sp->GetRegisterContext());
   1724             if (copy_success)
   1725             {
   1726                 thread->DiscardThreadPlans(true);
   1727                 thread->ClearStackFrames();
   1728                 if (broadcast && EventTypeHasListeners(eBroadcastBitStackChanged))
   1729                     BroadcastEvent(eBroadcastBitStackChanged, new ThreadEventData (this->shared_from_this()));
   1730             }
   1731             else
   1732             {
   1733                 return_error.SetErrorString("Could not reset register values.");
   1734             }
   1735         }
   1736         else
   1737         {
   1738             return_error.SetErrorString("Frame has no register context.");
   1739         }
   1740     }
   1741     else
   1742     {
   1743         return_error.SetErrorString("Returned past top frame.");
   1744     }
   1745     return return_error;
   1746 }
   1747 
   1748 void
   1749 Thread::DumpUsingSettingsFormat (Stream &strm, uint32_t frame_idx)
   1750 {
   1751     ExecutionContext exe_ctx (shared_from_this());
   1752     Process *process = exe_ctx.GetProcessPtr();
   1753     if (process == NULL)
   1754         return;
   1755 
   1756     StackFrameSP frame_sp;
   1757     SymbolContext frame_sc;
   1758     if (frame_idx != LLDB_INVALID_INDEX32)
   1759     {
   1760         frame_sp = GetStackFrameAtIndex (frame_idx);
   1761         if (frame_sp)
   1762         {
   1763             exe_ctx.SetFrameSP(frame_sp);
   1764             frame_sc = frame_sp->GetSymbolContext(eSymbolContextEverything);
   1765         }
   1766     }
   1767 
   1768     const char *thread_format = exe_ctx.GetTargetRef().GetDebugger().GetThreadFormat();
   1769     assert (thread_format);
   1770     Debugger::FormatPrompt (thread_format,
   1771                             frame_sp ? &frame_sc : NULL,
   1772                             &exe_ctx,
   1773                             NULL,
   1774                             strm);
   1775 }
   1776 
   1777 void
   1778 Thread::SettingsInitialize ()
   1779 {
   1780 }
   1781 
   1782 void
   1783 Thread::SettingsTerminate ()
   1784 {
   1785 }
   1786 
   1787 lldb::StackFrameSP
   1788 Thread::GetStackFrameSPForStackFramePtr (StackFrame *stack_frame_ptr)
   1789 {
   1790     return GetStackFrameList()->GetStackFrameSPForStackFramePtr (stack_frame_ptr);
   1791 }
   1792 
   1793 const char *
   1794 Thread::StopReasonAsCString (lldb::StopReason reason)
   1795 {
   1796     switch (reason)
   1797     {
   1798     case eStopReasonInvalid:       return "invalid";
   1799     case eStopReasonNone:          return "none";
   1800     case eStopReasonTrace:         return "trace";
   1801     case eStopReasonBreakpoint:    return "breakpoint";
   1802     case eStopReasonWatchpoint:    return "watchpoint";
   1803     case eStopReasonSignal:        return "signal";
   1804     case eStopReasonException:     return "exception";
   1805     case eStopReasonExec:          return "exec";
   1806     case eStopReasonPlanComplete:  return "plan complete";
   1807     case eStopReasonThreadExiting: return "thread exiting";
   1808     }
   1809 
   1810 
   1811     static char unknown_state_string[64];
   1812     snprintf(unknown_state_string, sizeof (unknown_state_string), "StopReason = %i", reason);
   1813     return unknown_state_string;
   1814 }
   1815 
   1816 const char *
   1817 Thread::RunModeAsCString (lldb::RunMode mode)
   1818 {
   1819     switch (mode)
   1820     {
   1821     case eOnlyThisThread:     return "only this thread";
   1822     case eAllThreads:         return "all threads";
   1823     case eOnlyDuringStepping: return "only during stepping";
   1824     }
   1825 
   1826     static char unknown_state_string[64];
   1827     snprintf(unknown_state_string, sizeof (unknown_state_string), "RunMode = %i", mode);
   1828     return unknown_state_string;
   1829 }
   1830 
   1831 size_t
   1832 Thread::GetStatus (Stream &strm, uint32_t start_frame, uint32_t num_frames, uint32_t num_frames_with_source)
   1833 {
   1834     ExecutionContext exe_ctx (shared_from_this());
   1835     Target *target = exe_ctx.GetTargetPtr();
   1836     Process *process = exe_ctx.GetProcessPtr();
   1837     size_t num_frames_shown = 0;
   1838     strm.Indent();
   1839     bool is_selected = false;
   1840     if (process)
   1841     {
   1842         if (process->GetThreadList().GetSelectedThread().get() == this)
   1843             is_selected = true;
   1844     }
   1845     strm.Printf("%c ", is_selected ? '*' : ' ');
   1846     if (target && target->GetDebugger().GetUseExternalEditor())
   1847     {
   1848         StackFrameSP frame_sp = GetStackFrameAtIndex(start_frame);
   1849         if (frame_sp)
   1850         {
   1851             SymbolContext frame_sc(frame_sp->GetSymbolContext (eSymbolContextLineEntry));
   1852             if (frame_sc.line_entry.line != 0 && frame_sc.line_entry.file)
   1853             {
   1854                 Host::OpenFileInExternalEditor (frame_sc.line_entry.file, frame_sc.line_entry.line);
   1855             }
   1856         }
   1857     }
   1858 
   1859     DumpUsingSettingsFormat (strm, start_frame);
   1860 
   1861     if (num_frames > 0)
   1862     {
   1863         strm.IndentMore();
   1864 
   1865         const bool show_frame_info = true;
   1866         strm.IndentMore ();
   1867         num_frames_shown = GetStackFrameList ()->GetStatus (strm,
   1868                                                             start_frame,
   1869                                                             num_frames,
   1870                                                             show_frame_info,
   1871                                                             num_frames_with_source);
   1872         strm.IndentLess();
   1873         strm.IndentLess();
   1874     }
   1875     return num_frames_shown;
   1876 }
   1877 
   1878 size_t
   1879 Thread::GetStackFrameStatus (Stream& strm,
   1880                              uint32_t first_frame,
   1881                              uint32_t num_frames,
   1882                              bool show_frame_info,
   1883                              uint32_t num_frames_with_source)
   1884 {
   1885     return GetStackFrameList()->GetStatus (strm,
   1886                                            first_frame,
   1887                                            num_frames,
   1888                                            show_frame_info,
   1889                                            num_frames_with_source);
   1890 }
   1891 
   1892 bool
   1893 Thread::SaveFrameZeroState (RegisterCheckpoint &checkpoint)
   1894 {
   1895     lldb::StackFrameSP frame_sp(GetStackFrameAtIndex (0));
   1896     if (frame_sp)
   1897     {
   1898         checkpoint.SetStackID(frame_sp->GetStackID());
   1899         lldb::RegisterContextSP reg_ctx_sp (frame_sp->GetRegisterContext());
   1900         if (reg_ctx_sp)
   1901             return reg_ctx_sp->ReadAllRegisterValues (checkpoint.GetData());
   1902     }
   1903     return false;
   1904 }
   1905 
   1906 bool
   1907 Thread::RestoreSaveFrameZero (const RegisterCheckpoint &checkpoint)
   1908 {
   1909     return ResetFrameZeroRegisters (checkpoint.GetData());
   1910 }
   1911 
   1912 bool
   1913 Thread::ResetFrameZeroRegisters (lldb::DataBufferSP register_data_sp)
   1914 {
   1915     lldb::StackFrameSP frame_sp(GetStackFrameAtIndex (0));
   1916     if (frame_sp)
   1917     {
   1918         lldb::RegisterContextSP reg_ctx_sp (frame_sp->GetRegisterContext());
   1919         if (reg_ctx_sp)
   1920         {
   1921             bool ret = reg_ctx_sp->WriteAllRegisterValues (register_data_sp);
   1922 
   1923             // Clear out all stack frames as our world just changed.
   1924             ClearStackFrames();
   1925             reg_ctx_sp->InvalidateIfNeeded(true);
   1926             if (m_unwinder_ap.get())
   1927                 m_unwinder_ap->Clear();
   1928             return ret;
   1929         }
   1930     }
   1931     return false;
   1932 }
   1933 
   1934 Unwind *
   1935 Thread::GetUnwinder ()
   1936 {
   1937     if (m_unwinder_ap.get() == NULL)
   1938     {
   1939         const ArchSpec target_arch (CalculateTarget()->GetArchitecture ());
   1940         const llvm::Triple::ArchType machine = target_arch.GetMachine();
   1941         switch (machine)
   1942         {
   1943             case llvm::Triple::x86_64:
   1944             case llvm::Triple::x86:
   1945             case llvm::Triple::arm:
   1946             case llvm::Triple::thumb:
   1947                 m_unwinder_ap.reset (new UnwindLLDB (*this));
   1948                 break;
   1949 
   1950             default:
   1951                 if (target_arch.GetTriple().getVendor() == llvm::Triple::Apple)
   1952                     m_unwinder_ap.reset (new UnwindMacOSXFrameBackchain (*this));
   1953                 break;
   1954         }
   1955     }
   1956     return m_unwinder_ap.get();
   1957 }
   1958 
   1959 
   1960 void
   1961 Thread::Flush ()
   1962 {
   1963     ClearStackFrames ();
   1964     m_reg_context_sp.reset();
   1965 }
   1966 
   1967 bool
   1968 Thread::IsStillAtLastBreakpointHit ()
   1969 {
   1970     // If we are currently stopped at a breakpoint, always return that stopinfo and don't reset it.
   1971     // This allows threads to maintain their breakpoint stopinfo, such as when thread-stepping in
   1972     // multithreaded programs.
   1973     if (m_stop_info_sp) {
   1974         StopReason stop_reason = m_stop_info_sp->GetStopReason();
   1975         if (stop_reason == lldb::eStopReasonBreakpoint) {
   1976             uint64_t value = m_stop_info_sp->GetValue();
   1977             lldb::RegisterContextSP reg_ctx_sp (GetRegisterContext());
   1978             if (reg_ctx_sp)
   1979             {
   1980                 lldb::addr_t pc = reg_ctx_sp->GetPC();
   1981                 BreakpointSiteSP bp_site_sp = GetProcess()->GetBreakpointSiteList().FindByAddress(pc);
   1982                 if (bp_site_sp && value == bp_site_sp->GetID())
   1983                     return true;
   1984             }
   1985         }
   1986     }
   1987     return false;
   1988 }
   1989