xref: /llvm-project-15.0.7/lldb/source/Breakpoint/Breakpoint.cpp (revision 498ee00a)

//===-- Breakpoint.cpp ------------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// C Includes
// C++ Includes
// Other libraries and framework includes
#include "llvm/Support/Casting.h"

// Project includes
#include "lldb/Breakpoint/Breakpoint.h"
#include "lldb/Breakpoint/BreakpointLocation.h"
#include "lldb/Breakpoint/BreakpointLocationCollection.h"
#include "lldb/Breakpoint/BreakpointResolver.h"
#include "lldb/Breakpoint/BreakpointResolverFileLine.h"
#include "lldb/Core/Address.h"
#include "lldb/Core/Log.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/ModuleList.h"
#include "lldb/Core/SearchFilter.h"
#include "lldb/Core/Section.h"
#include "lldb/Core/Stream.h"
#include "lldb/Core/StreamString.h"
#include "lldb/Symbol/CompileUnit.h"
#include "lldb/Symbol/Function.h"
#include "lldb/Symbol/SymbolContext.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/ThreadSpec.h"

using namespace lldb;
using namespace lldb_private;
using namespace llvm;

const ConstString &Breakpoint::GetEventIdentifier() {
  static ConstString g_identifier("event-identifier.breakpoint.changed");
  return g_identifier;
}

const char *Breakpoint::g_option_names[static_cast<uint32_t>(
    Breakpoint::OptionNames::LastOptionName)]{"Names", "Hardware"};

//----------------------------------------------------------------------
// Breakpoint constructor
//----------------------------------------------------------------------
Breakpoint::Breakpoint(Target &target, SearchFilterSP &filter_sp,
                       BreakpointResolverSP &resolver_sp, bool hardware,
                       bool resolve_indirect_symbols)
    : m_being_created(true), m_hardware(hardware), m_target(target),
      m_filter_sp(filter_sp), m_resolver_sp(resolver_sp),
      m_options_up(new BreakpointOptions()), m_locations(*this),
      m_resolve_indirect_symbols(resolve_indirect_symbols), m_hit_count(0) {
  m_being_created = false;
}

Breakpoint::Breakpoint(Target &new_target, Breakpoint &source_bp)
    : m_being_created(true), m_hardware(source_bp.m_hardware),
      m_target(new_target), m_name_list(source_bp.m_name_list),
      m_options_up(new BreakpointOptions(*source_bp.m_options_up.get())),
      m_locations(*this),
      m_resolve_indirect_symbols(source_bp.m_resolve_indirect_symbols),
      m_hit_count(0) {
  // Now go through and copy the filter & resolver:
  m_resolver_sp = source_bp.m_resolver_sp->CopyForBreakpoint(*this);
  m_filter_sp = source_bp.m_filter_sp->CopyForBreakpoint(*this);
}

//----------------------------------------------------------------------
// Destructor
//----------------------------------------------------------------------
Breakpoint::~Breakpoint() = default;

//----------------------------------------------------------------------
// Serialization
//----------------------------------------------------------------------
StructuredData::ObjectSP Breakpoint::SerializeToStructuredData() {
  // Serialize the resolver:
  StructuredData::DictionarySP breakpoint_dict_sp(
      new StructuredData::Dictionary());
  StructuredData::DictionarySP breakpoint_contents_sp(
      new StructuredData::Dictionary());

  if (!m_name_list.empty()) {
    StructuredData::ArraySP names_array_sp(new StructuredData::Array());
    for (auto name : m_name_list) {
      names_array_sp->AddItem(
          StructuredData::StringSP(new StructuredData::String(name)));
    }
    breakpoint_contents_sp->AddItem(Breakpoint::GetKey(OptionNames::Names),
                                    names_array_sp);
  }

  breakpoint_contents_sp->AddBooleanItem(
      Breakpoint::GetKey(OptionNames::Hardware), m_hardware);

  StructuredData::ObjectSP resolver_dict_sp(
      m_resolver_sp->SerializeToStructuredData());
  if (!resolver_dict_sp)
    return StructuredData::ObjectSP();

  breakpoint_contents_sp->AddItem(BreakpointResolver::GetSerializationKey(),
                                  resolver_dict_sp);

  StructuredData::ObjectSP filter_dict_sp(
      m_filter_sp->SerializeToStructuredData());
  if (!filter_dict_sp)
    return StructuredData::ObjectSP();

  breakpoint_contents_sp->AddItem(SearchFilter::GetSerializationKey(),
                                  filter_dict_sp);

  StructuredData::ObjectSP options_dict_sp(
      m_options_up->SerializeToStructuredData());
  if (!options_dict_sp)
    return StructuredData::ObjectSP();

  breakpoint_contents_sp->AddItem(BreakpointOptions::GetSerializationKey(),
                                  options_dict_sp);

  breakpoint_dict_sp->AddItem(GetSerializationKey(), breakpoint_contents_sp);
  return breakpoint_dict_sp;
}

lldb::BreakpointSP Breakpoint::CreateFromStructuredData(
    Target &target, StructuredData::ObjectSP &object_data, Error &error) {
  BreakpointSP result_sp;

  StructuredData::Dictionary *breakpoint_dict = object_data->GetAsDictionary();

  if (!breakpoint_dict || !breakpoint_dict->IsValid()) {
    error.SetErrorString("Can't deserialize from an invalid data object.");
    return result_sp;
  }

  StructuredData::Dictionary *resolver_dict;
  bool success = breakpoint_dict->GetValueForKeyAsDictionary(
      BreakpointResolver::GetSerializationKey(), resolver_dict);
  if (!success) {
    error.SetErrorStringWithFormat(
        "Breakpoint data missing toplevel resolver key");
    return result_sp;
  }

  Error create_error;
  BreakpointResolverSP resolver_sp =
      BreakpointResolver::CreateFromStructuredData(*resolver_dict,
                                                   create_error);
  if (create_error.Fail()) {
    error.SetErrorStringWithFormat(
        "Error creating breakpoint resolver from data: %s.",
        create_error.AsCString());
    return result_sp;
  }

  StructuredData::Dictionary *filter_dict;
  success = breakpoint_dict->GetValueForKeyAsDictionary(
      SearchFilter::GetSerializationKey(), filter_dict);
  SearchFilterSP filter_sp;
  if (!success)
    filter_sp.reset(
        new SearchFilterForUnconstrainedSearches(target.shared_from_this()));
  else {
    filter_sp = SearchFilter::CreateFromStructuredData(target, *filter_dict,
                                                       create_error);
    if (create_error.Fail()) {
      error.SetErrorStringWithFormat(
          "Error creating breakpoint filter from data: %s.",
          create_error.AsCString());
      return result_sp;
    }
  }

  std::unique_ptr<BreakpointOptions> options_up;
  StructuredData::Dictionary *options_dict;
  success = breakpoint_dict->GetValueForKeyAsDictionary(
      BreakpointOptions::GetSerializationKey(), options_dict);
  if (success) {
    options_up = BreakpointOptions::CreateFromStructuredData(
        target, *options_dict, create_error);
    if (create_error.Fail()) {
      error.SetErrorStringWithFormat(
          "Error creating breakpoint options from data: %s.",
          create_error.AsCString());
      return result_sp;
    }
  }

  bool hardware = false;
  success = breakpoint_dict->GetValueForKeyAsBoolean(
      Breakpoint::GetKey(OptionNames::Hardware), hardware);

  result_sp =
      target.CreateBreakpoint(filter_sp, resolver_sp, false, hardware, true);

  if (result_sp && options_up) {
    result_sp->m_options_up = std::move(options_up);
  }

  StructuredData::Array *names_array;
  success = breakpoint_dict->GetValueForKeyAsArray(
      Breakpoint::GetKey(OptionNames::Names), names_array);
  if (success && names_array) {
    size_t num_names = names_array->GetSize();
    for (size_t i = 0; i < num_names; i++) {
      std::string name;
      Error error;
      success = names_array->GetItemAtIndexAsString(i, name);
      result_sp->AddName(name.c_str(), error);
    }
  }

  return result_sp;
}

bool Breakpoint::SerializedBreakpointMatchesNames(
    StructuredData::ObjectSP &bkpt_object_sp, std::vector<std::string> &names) {
  if (!bkpt_object_sp)
    return false;

  StructuredData::Dictionary *bkpt_dict = bkpt_object_sp->GetAsDictionary();
  if (!bkpt_dict)
    return false;

  if (names.empty())
    return true;

  StructuredData::Array *names_array;

  bool success =
      bkpt_dict->GetValueForKeyAsArray(GetKey(OptionNames::Names), names_array);
  // If there are no names, it can't match these names;
  if (!success)
    return false;

  size_t num_names = names_array->GetSize();
  std::vector<std::string>::iterator begin = names.begin();
  std::vector<std::string>::iterator end = names.end();

  for (size_t i = 0; i < num_names; i++) {
    std::string name;
    if (names_array->GetItemAtIndexAsString(i, name)) {
      if (std::find(begin, end, name) != end) {
        return true;
      }
    }
  }
  return false;
}

const lldb::TargetSP Breakpoint::GetTargetSP() {
  return m_target.shared_from_this();
}

bool Breakpoint::IsInternal() const { return LLDB_BREAK_ID_IS_INTERNAL(m_bid); }

BreakpointLocationSP Breakpoint::AddLocation(const Address &addr,
                                             bool *new_location) {
  return m_locations.AddLocation(addr, m_resolve_indirect_symbols,
                                 new_location);
}

BreakpointLocationSP Breakpoint::FindLocationByAddress(const Address &addr) {
  return m_locations.FindByAddress(addr);
}

break_id_t Breakpoint::FindLocationIDByAddress(const Address &addr) {
  return m_locations.FindIDByAddress(addr);
}

BreakpointLocationSP Breakpoint::FindLocationByID(break_id_t bp_loc_id) {
  return m_locations.FindByID(bp_loc_id);
}

BreakpointLocationSP Breakpoint::GetLocationAtIndex(size_t index) {
  return m_locations.GetByIndex(index);
}

void Breakpoint::RemoveInvalidLocations(const ArchSpec &arch) {
  m_locations.RemoveInvalidLocations(arch);
}

// For each of the overall options we need to decide how they propagate to
// the location options.  This will determine the precedence of options on
// the breakpoint vs. its locations.

// Disable at the breakpoint level should override the location settings.
// That way you can conveniently turn off a whole breakpoint without messing
// up the individual settings.

void Breakpoint::SetEnabled(bool enable) {
  if (enable == m_options_up->IsEnabled())
    return;

  m_options_up->SetEnabled(enable);
  if (enable)
    m_locations.ResolveAllBreakpointSites();
  else
    m_locations.ClearAllBreakpointSites();

  SendBreakpointChangedEvent(enable ? eBreakpointEventTypeEnabled
                                    : eBreakpointEventTypeDisabled);
}

bool Breakpoint::IsEnabled() { return m_options_up->IsEnabled(); }

void Breakpoint::SetIgnoreCount(uint32_t n) {
  if (m_options_up->GetIgnoreCount() == n)
    return;

  m_options_up->SetIgnoreCount(n);
  SendBreakpointChangedEvent(eBreakpointEventTypeIgnoreChanged);
}

void Breakpoint::DecrementIgnoreCount() {
  uint32_t ignore = m_options_up->GetIgnoreCount();
  if (ignore != 0)
    m_options_up->SetIgnoreCount(ignore - 1);
}

uint32_t Breakpoint::GetIgnoreCount() const {
  return m_options_up->GetIgnoreCount();
}

bool Breakpoint::IgnoreCountShouldStop() {
  uint32_t ignore = GetIgnoreCount();
  if (ignore != 0) {
    // When we get here we know the location that caused the stop doesn't have
    // an ignore count,
    // since by contract we call it first...  So we don't have to find &
    // decrement it, we only have
    // to decrement our own ignore count.
    DecrementIgnoreCount();
    return false;
  } else
    return true;
}

uint32_t Breakpoint::GetHitCount() const { return m_hit_count; }

bool Breakpoint::IsOneShot() const { return m_options_up->IsOneShot(); }

void Breakpoint::SetOneShot(bool one_shot) {
  m_options_up->SetOneShot(one_shot);
}

void Breakpoint::SetThreadID(lldb::tid_t thread_id) {
  if (m_options_up->GetThreadSpec()->GetTID() == thread_id)
    return;

  m_options_up->GetThreadSpec()->SetTID(thread_id);
  SendBreakpointChangedEvent(eBreakpointEventTypeThreadChanged);
}

lldb::tid_t Breakpoint::GetThreadID() const {
  if (m_options_up->GetThreadSpecNoCreate() == nullptr)
    return LLDB_INVALID_THREAD_ID;
  else
    return m_options_up->GetThreadSpecNoCreate()->GetTID();
}

void Breakpoint::SetThreadIndex(uint32_t index) {
  if (m_options_up->GetThreadSpec()->GetIndex() == index)
    return;

  m_options_up->GetThreadSpec()->SetIndex(index);
  SendBreakpointChangedEvent(eBreakpointEventTypeThreadChanged);
}

uint32_t Breakpoint::GetThreadIndex() const {
  if (m_options_up->GetThreadSpecNoCreate() == nullptr)
    return 0;
  else
    return m_options_up->GetThreadSpecNoCreate()->GetIndex();
}

void Breakpoint::SetThreadName(const char *thread_name) {
  if (m_options_up->GetThreadSpec()->GetName() != nullptr &&
      ::strcmp(m_options_up->GetThreadSpec()->GetName(), thread_name) == 0)
    return;

  m_options_up->GetThreadSpec()->SetName(thread_name);
  SendBreakpointChangedEvent(eBreakpointEventTypeThreadChanged);
}

const char *Breakpoint::GetThreadName() const {
  if (m_options_up->GetThreadSpecNoCreate() == nullptr)
    return nullptr;
  else
    return m_options_up->GetThreadSpecNoCreate()->GetName();
}

void Breakpoint::SetQueueName(const char *queue_name) {
  if (m_options_up->GetThreadSpec()->GetQueueName() != nullptr &&
      ::strcmp(m_options_up->GetThreadSpec()->GetQueueName(), queue_name) == 0)
    return;

  m_options_up->GetThreadSpec()->SetQueueName(queue_name);
  SendBreakpointChangedEvent(eBreakpointEventTypeThreadChanged);
}

const char *Breakpoint::GetQueueName() const {
  if (m_options_up->GetThreadSpecNoCreate() == nullptr)
    return nullptr;
  else
    return m_options_up->GetThreadSpecNoCreate()->GetQueueName();
}

void Breakpoint::SetCondition(const char *condition) {
  m_options_up->SetCondition(condition);
  SendBreakpointChangedEvent(eBreakpointEventTypeConditionChanged);
}

const char *Breakpoint::GetConditionText() const {
  return m_options_up->GetConditionText();
}

// This function is used when "baton" doesn't need to be freed
void Breakpoint::SetCallback(BreakpointHitCallback callback, void *baton,
                             bool is_synchronous) {
  // The default "Baton" class will keep a copy of "baton" and won't free
  // or delete it when it goes goes out of scope.
  m_options_up->SetCallback(callback, std::make_shared<UntypedBaton>(baton),
                            is_synchronous);

  SendBreakpointChangedEvent(eBreakpointEventTypeCommandChanged);
}

// This function is used when a baton needs to be freed and therefore is
// contained in a "Baton" subclass.
void Breakpoint::SetCallback(BreakpointHitCallback callback,
                             const BatonSP &callback_baton_sp,
                             bool is_synchronous) {
  m_options_up->SetCallback(callback, callback_baton_sp, is_synchronous);
}

void Breakpoint::ClearCallback() { m_options_up->ClearCallback(); }

bool Breakpoint::InvokeCallback(StoppointCallbackContext *context,
                                break_id_t bp_loc_id) {
  return m_options_up->InvokeCallback(context, GetID(), bp_loc_id);
}

BreakpointOptions *Breakpoint::GetOptions() { return m_options_up.get(); }

void Breakpoint::ResolveBreakpoint() {
  if (m_resolver_sp)
    m_resolver_sp->ResolveBreakpoint(*m_filter_sp);
}

void Breakpoint::ResolveBreakpointInModules(
    ModuleList &module_list, BreakpointLocationCollection &new_locations) {
  m_locations.StartRecordingNewLocations(new_locations);

  m_resolver_sp->ResolveBreakpointInModules(*m_filter_sp, module_list);

  m_locations.StopRecordingNewLocations();
}

void Breakpoint::ResolveBreakpointInModules(ModuleList &module_list,
                                            bool send_event) {
  if (m_resolver_sp) {
    // If this is not an internal breakpoint, set up to record the new
    // locations, then dispatch
    // an event with the new locations.
    if (!IsInternal() && send_event) {
      BreakpointEventData *new_locations_event = new BreakpointEventData(
          eBreakpointEventTypeLocationsAdded, shared_from_this());

      ResolveBreakpointInModules(
          module_list, new_locations_event->GetBreakpointLocationCollection());

      if (new_locations_event->GetBreakpointLocationCollection().GetSize() !=
          0) {
        SendBreakpointChangedEvent(new_locations_event);
      } else
        delete new_locations_event;
    } else {
      m_resolver_sp->ResolveBreakpointInModules(*m_filter_sp, module_list);
    }
  }
}

void Breakpoint::ClearAllBreakpointSites() {
  m_locations.ClearAllBreakpointSites();
}

//----------------------------------------------------------------------
// ModulesChanged: Pass in a list of new modules, and
//----------------------------------------------------------------------

void Breakpoint::ModulesChanged(ModuleList &module_list, bool load,
                                bool delete_locations) {
  Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_BREAKPOINTS));
  if (log)
    log->Printf("Breakpoint::ModulesChanged: num_modules: %zu load: %i "
                "delete_locations: %i\n",
                module_list.GetSize(), load, delete_locations);

  std::lock_guard<std::recursive_mutex> guard(module_list.GetMutex());
  if (load) {
    // The logic for handling new modules is:
    // 1) If the filter rejects this module, then skip it.
    // 2) Run through the current location list and if there are any locations
    //    for that module, we mark the module as "seen" and we don't try to
    //    re-resolve
    //    breakpoint locations for that module.
    //    However, we do add breakpoint sites to these locations if needed.
    // 3) If we don't see this module in our breakpoint location list, call
    // ResolveInModules.

    ModuleList new_modules; // We'll stuff the "unseen" modules in this list,
                            // and then resolve
    // them after the locations pass.  Have to do it this way because
    // resolving breakpoints will add new locations potentially.

    for (ModuleSP module_sp : module_list.ModulesNoLocking()) {
      bool seen = false;
      if (!m_filter_sp->ModulePasses(module_sp))
        continue;

      for (BreakpointLocationSP break_loc_sp :
           m_locations.BreakpointLocations()) {
        if (!break_loc_sp->IsEnabled())
          continue;
        SectionSP section_sp(break_loc_sp->GetAddress().GetSection());
        if (!section_sp || section_sp->GetModule() == module_sp) {
          if (!seen)
            seen = true;

          if (!break_loc_sp->ResolveBreakpointSite()) {
            if (log)
              log->Printf("Warning: could not set breakpoint site for "
                          "breakpoint location %d of breakpoint %d.\n",
                          break_loc_sp->GetID(), GetID());
          }
        }
      }

      if (!seen)
        new_modules.AppendIfNeeded(module_sp);
    }

    if (new_modules.GetSize() > 0) {
      ResolveBreakpointInModules(new_modules);
    }
  } else {
    // Go through the currently set locations and if any have breakpoints in
    // the module list, then remove their breakpoint sites, and their locations
    // if asked to.

    BreakpointEventData *removed_locations_event;
    if (!IsInternal())
      removed_locations_event = new BreakpointEventData(
          eBreakpointEventTypeLocationsRemoved, shared_from_this());
    else
      removed_locations_event = nullptr;

    size_t num_modules = module_list.GetSize();
    for (size_t i = 0; i < num_modules; i++) {
      ModuleSP module_sp(module_list.GetModuleAtIndexUnlocked(i));
      if (m_filter_sp->ModulePasses(module_sp)) {
        size_t loc_idx = 0;
        size_t num_locations = m_locations.GetSize();
        BreakpointLocationCollection locations_to_remove;
        for (loc_idx = 0; loc_idx < num_locations; loc_idx++) {
          BreakpointLocationSP break_loc_sp(m_locations.GetByIndex(loc_idx));
          SectionSP section_sp(break_loc_sp->GetAddress().GetSection());
          if (section_sp && section_sp->GetModule() == module_sp) {
            // Remove this breakpoint since the shared library is
            // unloaded, but keep the breakpoint location around
            // so we always get complete hit count and breakpoint
            // lifetime info
            break_loc_sp->ClearBreakpointSite();
            if (removed_locations_event) {
              removed_locations_event->GetBreakpointLocationCollection().Add(
                  break_loc_sp);
            }
            if (delete_locations)
              locations_to_remove.Add(break_loc_sp);
          }
        }

        if (delete_locations) {
          size_t num_locations_to_remove = locations_to_remove.GetSize();
          for (loc_idx = 0; loc_idx < num_locations_to_remove; loc_idx++)
            m_locations.RemoveLocation(locations_to_remove.GetByIndex(loc_idx));
        }
      }
    }
    SendBreakpointChangedEvent(removed_locations_event);
  }
}

namespace {
static bool SymbolContextsMightBeEquivalent(SymbolContext &old_sc,
                                            SymbolContext &new_sc) {
  bool equivalent_scs = false;

  if (old_sc.module_sp.get() == new_sc.module_sp.get()) {
    // If these come from the same module, we can directly compare the pointers:
    if (old_sc.comp_unit && new_sc.comp_unit &&
        (old_sc.comp_unit == new_sc.comp_unit)) {
      if (old_sc.function && new_sc.function &&
          (old_sc.function == new_sc.function)) {
        equivalent_scs = true;
      }
    } else if (old_sc.symbol && new_sc.symbol &&
               (old_sc.symbol == new_sc.symbol)) {
      equivalent_scs = true;
    }
  } else {
    // Otherwise we will compare by name...
    if (old_sc.comp_unit && new_sc.comp_unit) {
      if (FileSpec::Equal(*old_sc.comp_unit, *new_sc.comp_unit, true)) {
        // Now check the functions:
        if (old_sc.function && new_sc.function &&
            (old_sc.function->GetName() == new_sc.function->GetName())) {
          equivalent_scs = true;
        }
      }
    } else if (old_sc.symbol && new_sc.symbol) {
      if (Mangled::Compare(old_sc.symbol->GetMangled(),
                           new_sc.symbol->GetMangled()) == 0) {
        equivalent_scs = true;
      }
    }
  }
  return equivalent_scs;
}
} // anonymous namespace

void Breakpoint::ModuleReplaced(ModuleSP old_module_sp,
                                ModuleSP new_module_sp) {
  Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_BREAKPOINTS));
  if (log)
    log->Printf("Breakpoint::ModulesReplaced for %s\n",
                old_module_sp->GetSpecificationDescription().c_str());
  // First find all the locations that are in the old module

  BreakpointLocationCollection old_break_locs;
  for (BreakpointLocationSP break_loc_sp : m_locations.BreakpointLocations()) {
    SectionSP section_sp = break_loc_sp->GetAddress().GetSection();
    if (section_sp && section_sp->GetModule() == old_module_sp) {
      old_break_locs.Add(break_loc_sp);
    }
  }

  size_t num_old_locations = old_break_locs.GetSize();

  if (num_old_locations == 0) {
    // There were no locations in the old module, so we just need to check if
    // there were any in the new module.
    ModuleList temp_list;
    temp_list.Append(new_module_sp);
    ResolveBreakpointInModules(temp_list);
  } else {
    // First search the new module for locations.
    // Then compare this with the old list, copy over locations that "look the
    // same"
    // Then delete the old locations.
    // Finally remember to post the creation event.
    //
    // Two locations are the same if they have the same comp unit & function (by
    // name) and there are the same number
    // of locations in the old function as in the new one.

    ModuleList temp_list;
    temp_list.Append(new_module_sp);
    BreakpointLocationCollection new_break_locs;
    ResolveBreakpointInModules(temp_list, new_break_locs);
    BreakpointLocationCollection locations_to_remove;
    BreakpointLocationCollection locations_to_announce;

    size_t num_new_locations = new_break_locs.GetSize();

    if (num_new_locations > 0) {
      // Break out the case of one location -> one location since that's the
      // most common one, and there's no need
      // to build up the structures needed for the merge in that case.
      if (num_new_locations == 1 && num_old_locations == 1) {
        bool equivalent_locations = false;
        SymbolContext old_sc, new_sc;
        // The only way the old and new location can be equivalent is if they
        // have the same amount of information:
        BreakpointLocationSP old_loc_sp = old_break_locs.GetByIndex(0);
        BreakpointLocationSP new_loc_sp = new_break_locs.GetByIndex(0);

        if (old_loc_sp->GetAddress().CalculateSymbolContext(&old_sc) ==
            new_loc_sp->GetAddress().CalculateSymbolContext(&new_sc)) {
          equivalent_locations =
              SymbolContextsMightBeEquivalent(old_sc, new_sc);
        }

        if (equivalent_locations) {
          m_locations.SwapLocation(old_loc_sp, new_loc_sp);
        } else {
          locations_to_remove.Add(old_loc_sp);
          locations_to_announce.Add(new_loc_sp);
        }
      } else {
        // We don't want to have to keep computing the SymbolContexts for these
        // addresses over and over,
        // so lets get them up front:

        typedef std::map<lldb::break_id_t, SymbolContext> IDToSCMap;
        IDToSCMap old_sc_map;
        for (size_t idx = 0; idx < num_old_locations; idx++) {
          SymbolContext sc;
          BreakpointLocationSP bp_loc_sp = old_break_locs.GetByIndex(idx);
          lldb::break_id_t loc_id = bp_loc_sp->GetID();
          bp_loc_sp->GetAddress().CalculateSymbolContext(&old_sc_map[loc_id]);
        }

        std::map<lldb::break_id_t, SymbolContext> new_sc_map;
        for (size_t idx = 0; idx < num_new_locations; idx++) {
          SymbolContext sc;
          BreakpointLocationSP bp_loc_sp = new_break_locs.GetByIndex(idx);
          lldb::break_id_t loc_id = bp_loc_sp->GetID();
          bp_loc_sp->GetAddress().CalculateSymbolContext(&new_sc_map[loc_id]);
        }
        // Take an element from the old Symbol Contexts
        while (old_sc_map.size() > 0) {
          lldb::break_id_t old_id = old_sc_map.begin()->first;
          SymbolContext &old_sc = old_sc_map.begin()->second;

          // Count the number of entries equivalent to this SC for the old list:
          std::vector<lldb::break_id_t> old_id_vec;
          old_id_vec.push_back(old_id);

          IDToSCMap::iterator tmp_iter;
          for (tmp_iter = ++old_sc_map.begin(); tmp_iter != old_sc_map.end();
               tmp_iter++) {
            if (SymbolContextsMightBeEquivalent(old_sc, tmp_iter->second))
              old_id_vec.push_back(tmp_iter->first);
          }

          // Now find all the equivalent locations in the new list.
          std::vector<lldb::break_id_t> new_id_vec;
          for (tmp_iter = new_sc_map.begin(); tmp_iter != new_sc_map.end();
               tmp_iter++) {
            if (SymbolContextsMightBeEquivalent(old_sc, tmp_iter->second))
              new_id_vec.push_back(tmp_iter->first);
          }

          // Alright, if we have the same number of potentially equivalent
          // locations in the old
          // and new modules, we'll just map them one to one in ascending ID
          // order (assuming the
          // resolver's order would match the equivalent ones.
          // Otherwise, we'll dump all the old ones, and just take the new ones,
          // erasing the elements
          // from both maps as we go.

          if (old_id_vec.size() == new_id_vec.size()) {
            sort(old_id_vec.begin(), old_id_vec.end());
            sort(new_id_vec.begin(), new_id_vec.end());
            size_t num_elements = old_id_vec.size();
            for (size_t idx = 0; idx < num_elements; idx++) {
              BreakpointLocationSP old_loc_sp =
                  old_break_locs.FindByIDPair(GetID(), old_id_vec[idx]);
              BreakpointLocationSP new_loc_sp =
                  new_break_locs.FindByIDPair(GetID(), new_id_vec[idx]);
              m_locations.SwapLocation(old_loc_sp, new_loc_sp);
              old_sc_map.erase(old_id_vec[idx]);
              new_sc_map.erase(new_id_vec[idx]);
            }
          } else {
            for (lldb::break_id_t old_id : old_id_vec) {
              locations_to_remove.Add(
                  old_break_locs.FindByIDPair(GetID(), old_id));
              old_sc_map.erase(old_id);
            }
            for (lldb::break_id_t new_id : new_id_vec) {
              locations_to_announce.Add(
                  new_break_locs.FindByIDPair(GetID(), new_id));
              new_sc_map.erase(new_id);
            }
          }
        }
      }
    }

    // Now remove the remaining old locations, and cons up a removed locations
    // event.
    // Note, we don't put the new locations that were swapped with an old
    // location on the locations_to_remove
    // list, so we don't need to worry about telling the world about removing a
    // location we didn't tell them
    // about adding.

    BreakpointEventData *locations_event;
    if (!IsInternal())
      locations_event = new BreakpointEventData(
          eBreakpointEventTypeLocationsRemoved, shared_from_this());
    else
      locations_event = nullptr;

    for (BreakpointLocationSP loc_sp :
         locations_to_remove.BreakpointLocations()) {
      m_locations.RemoveLocation(loc_sp);
      if (locations_event)
        locations_event->GetBreakpointLocationCollection().Add(loc_sp);
    }
    SendBreakpointChangedEvent(locations_event);

    // And announce the new ones.

    if (!IsInternal()) {
      locations_event = new BreakpointEventData(
          eBreakpointEventTypeLocationsAdded, shared_from_this());
      for (BreakpointLocationSP loc_sp :
           locations_to_announce.BreakpointLocations())
        locations_event->GetBreakpointLocationCollection().Add(loc_sp);

      SendBreakpointChangedEvent(locations_event);
    }
    m_locations.Compact();
  }
}

void Breakpoint::Dump(Stream *) {}

size_t Breakpoint::GetNumResolvedLocations() const {
  // Return the number of breakpoints that are actually resolved and set
  // down in the inferior process.
  return m_locations.GetNumResolvedLocations();
}

size_t Breakpoint::GetNumLocations() const { return m_locations.GetSize(); }

bool Breakpoint::AddName(const char *new_name, Error &error) {
  if (!new_name)
    return false;
  if (!BreakpointID::StringIsBreakpointName(llvm::StringRef(new_name), error)) {
    error.SetErrorStringWithFormat("input name \"%s\" not a breakpoint name.",
                                   new_name);
    return false;
  }
  if (!error.Success())
    return false;

  m_name_list.insert(new_name);
  return true;
}

void Breakpoint::GetDescription(Stream *s, lldb::DescriptionLevel level,
                                bool show_locations) {
  assert(s != nullptr);

  if (!m_kind_description.empty()) {
    if (level == eDescriptionLevelBrief) {
      s->PutCString(GetBreakpointKind());
      return;
    } else
      s->Printf("Kind: %s\n", GetBreakpointKind());
  }

  const size_t num_locations = GetNumLocations();
  const size_t num_resolved_locations = GetNumResolvedLocations();

  // They just made the breakpoint, they don't need to be told HOW they made
  // it...
  // Also, we'll print the breakpoint number differently depending on whether
  // there is 1 or more locations.
  if (level != eDescriptionLevelInitial) {
    s->Printf("%i: ", GetID());
    GetResolverDescription(s);
    GetFilterDescription(s);
  }

  switch (level) {
  case lldb::eDescriptionLevelBrief:
  case lldb::eDescriptionLevelFull:
    if (num_locations > 0) {
      s->Printf(", locations = %" PRIu64, (uint64_t)num_locations);
      if (num_resolved_locations > 0)
        s->Printf(", resolved = %" PRIu64 ", hit count = %d",
                  (uint64_t)num_resolved_locations, GetHitCount());
    } else {
      // Don't print the pending notification for exception resolvers since we
      // don't generally
      // know how to set them until the target is run.
      if (m_resolver_sp->getResolverID() !=
          BreakpointResolver::ExceptionResolver)
        s->Printf(", locations = 0 (pending)");
    }

    GetOptions()->GetDescription(s, level);

    if (m_precondition_sp)
      m_precondition_sp->GetDescription(*s, level);

    if (level == lldb::eDescriptionLevelFull) {
      if (!m_name_list.empty()) {
        s->EOL();
        s->Indent();
        s->Printf("Names:");
        s->EOL();
        s->IndentMore();
        for (std::string name : m_name_list) {
          s->Indent();
          s->Printf("%s\n", name.c_str());
        }
        s->IndentLess();
      }
      s->IndentLess();
      s->EOL();
    }
    break;

  case lldb::eDescriptionLevelInitial:
    s->Printf("Breakpoint %i: ", GetID());
    if (num_locations == 0) {
      s->Printf("no locations (pending).");
    } else if (num_locations == 1 && !show_locations) {
      // There is only one location, so we'll just print that location
      // information.
      GetLocationAtIndex(0)->GetDescription(s, level);
    } else {
      s->Printf("%" PRIu64 " locations.", static_cast<uint64_t>(num_locations));
    }
    s->EOL();
    break;

  case lldb::eDescriptionLevelVerbose:
    // Verbose mode does a debug dump of the breakpoint
    Dump(s);
    s->EOL();
    // s->Indent();
    GetOptions()->GetDescription(s, level);
    break;

  default:
    break;
  }

  // The brief description is just the location name (1.2 or whatever).  That's
  // pointless to
  // show in the breakpoint's description, so suppress it.
  if (show_locations && level != lldb::eDescriptionLevelBrief) {
    s->IndentMore();
    for (size_t i = 0; i < num_locations; ++i) {
      BreakpointLocation *loc = GetLocationAtIndex(i).get();
      loc->GetDescription(s, level);
      s->EOL();
    }
    s->IndentLess();
  }
}

void Breakpoint::GetResolverDescription(Stream *s) {
  if (m_resolver_sp)
    m_resolver_sp->GetDescription(s);
}

bool Breakpoint::GetMatchingFileLine(const ConstString &filename,
                                     uint32_t line_number,
                                     BreakpointLocationCollection &loc_coll) {
  // TODO: To be correct, this method needs to fill the breakpoint location
  // collection
  //       with the location IDs which match the filename and line_number.
  //

  if (m_resolver_sp) {
    BreakpointResolverFileLine *resolverFileLine =
        dyn_cast<BreakpointResolverFileLine>(m_resolver_sp.get());
    if (resolverFileLine &&
        resolverFileLine->m_file_spec.GetFilename() == filename &&
        resolverFileLine->m_line_number == line_number) {
      return true;
    }
  }
  return false;
}

void Breakpoint::GetFilterDescription(Stream *s) {
  m_filter_sp->GetDescription(s);
}

bool Breakpoint::EvaluatePrecondition(StoppointCallbackContext &context) {
  if (!m_precondition_sp)
    return true;

  return m_precondition_sp->EvaluatePrecondition(context);
}

bool Breakpoint::BreakpointPrecondition::EvaluatePrecondition(
    StoppointCallbackContext &context) {
  return true;
}

void Breakpoint::BreakpointPrecondition::GetDescription(
    Stream &stream, lldb::DescriptionLevel level) {}

Error Breakpoint::BreakpointPrecondition::ConfigurePrecondition(Args &options) {
  Error error;
  error.SetErrorString("Base breakpoint precondition has no options.");
  return error;
}

void Breakpoint::SendBreakpointChangedEvent(
    lldb::BreakpointEventType eventKind) {
  if (!m_being_created && !IsInternal() &&
      GetTarget().EventTypeHasListeners(
          Target::eBroadcastBitBreakpointChanged)) {
    BreakpointEventData *data =
        new Breakpoint::BreakpointEventData(eventKind, shared_from_this());

    GetTarget().BroadcastEvent(Target::eBroadcastBitBreakpointChanged, data);
  }
}

void Breakpoint::SendBreakpointChangedEvent(BreakpointEventData *data) {
  if (data == nullptr)
    return;

  if (!m_being_created && !IsInternal() &&
      GetTarget().EventTypeHasListeners(Target::eBroadcastBitBreakpointChanged))
    GetTarget().BroadcastEvent(Target::eBroadcastBitBreakpointChanged, data);
  else
    delete data;
}

Breakpoint::BreakpointEventData::BreakpointEventData(
    BreakpointEventType sub_type, const BreakpointSP &new_breakpoint_sp)
    : EventData(), m_breakpoint_event(sub_type),
      m_new_breakpoint_sp(new_breakpoint_sp) {}

Breakpoint::BreakpointEventData::~BreakpointEventData() = default;

const ConstString &Breakpoint::BreakpointEventData::GetFlavorString() {
  static ConstString g_flavor("Breakpoint::BreakpointEventData");
  return g_flavor;
}

const ConstString &Breakpoint::BreakpointEventData::GetFlavor() const {
  return BreakpointEventData::GetFlavorString();
}

BreakpointSP &Breakpoint::BreakpointEventData::GetBreakpoint() {
  return m_new_breakpoint_sp;
}

BreakpointEventType
Breakpoint::BreakpointEventData::GetBreakpointEventType() const {
  return m_breakpoint_event;
}

void Breakpoint::BreakpointEventData::Dump(Stream *s) const {}

const Breakpoint::BreakpointEventData *
Breakpoint::BreakpointEventData::GetEventDataFromEvent(const Event *event) {
  if (event) {
    const EventData *event_data = event->GetData();
    if (event_data &&
        event_data->GetFlavor() == BreakpointEventData::GetFlavorString())
      return static_cast<const BreakpointEventData *>(event->GetData());
  }
  return nullptr;
}

BreakpointEventType
Breakpoint::BreakpointEventData::GetBreakpointEventTypeFromEvent(
    const EventSP &event_sp) {
  const BreakpointEventData *data = GetEventDataFromEvent(event_sp.get());

  if (data == nullptr)
    return eBreakpointEventTypeInvalidType;
  else
    return data->GetBreakpointEventType();
}

BreakpointSP Breakpoint::BreakpointEventData::GetBreakpointFromEvent(
    const EventSP &event_sp) {
  BreakpointSP bp_sp;

  const BreakpointEventData *data = GetEventDataFromEvent(event_sp.get());
  if (data)
    bp_sp = data->m_new_breakpoint_sp;

  return bp_sp;
}

size_t Breakpoint::BreakpointEventData::GetNumBreakpointLocationsFromEvent(
    const EventSP &event_sp) {
  const BreakpointEventData *data = GetEventDataFromEvent(event_sp.get());
  if (data)
    return data->m_locations.GetSize();

  return 0;
}

lldb::BreakpointLocationSP
Breakpoint::BreakpointEventData::GetBreakpointLocationAtIndexFromEvent(
    const lldb::EventSP &event_sp, uint32_t bp_loc_idx) {
  lldb::BreakpointLocationSP bp_loc_sp;

  const BreakpointEventData *data = GetEventDataFromEvent(event_sp.get());
  if (data) {
    bp_loc_sp = data->m_locations.GetByIndex(bp_loc_idx);
  }

  return bp_loc_sp;
}