Debugger: move implementation to a separate folder.

src/debug.cc

-// Copyright 2012 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "src/v8.h"
-
-#include "src/api.h"
-#include "src/arguments.h"
-#include "src/bootstrapper.h"
-#include "src/code-stubs.h"
-#include "src/codegen.h"
-#include "src/compilation-cache.h"
-#include "src/compiler.h"
-#include "src/debug.h"
-#include "src/deoptimizer.h"
-#include "src/execution.h"
-#include "src/full-codegen/full-codegen.h"
-#include "src/global-handles.h"
-#include "src/list.h"
-#include "src/log.h"
-#include "src/messages.h"
-#include "src/snapshot/natives.h"
-
-#include "include/v8-debug.h"
-
-namespace v8 {
-namespace internal {
-
-Debug::Debug(Isolate* isolate)
-    : debug_context_(Handle<Context>()),
-      event_listener_(Handle<Object>()),
-      event_listener_data_(Handle<Object>()),
-      message_handler_(NULL),
-      command_received_(0),
-      command_queue_(isolate->logger(), kQueueInitialSize),
-      is_active_(false),
-      is_suppressed_(false),
-      live_edit_enabled_(true),  // TODO(yangguo): set to false by default.
-      break_disabled_(false),
-      in_debug_event_listener_(false),
-      break_on_exception_(false),
-      break_on_uncaught_exception_(false),
-      script_cache_(NULL),
-      debug_info_list_(NULL),
-      isolate_(isolate) {
-  ThreadInit();
-}
-
-
-static v8::Local<v8::Context> GetDebugEventContext(Isolate* isolate) {
-  Handle<Context> context = isolate->debug()->debugger_entry()->GetContext();
-  // Isolate::context() may have been NULL when "script collected" event
-  // occured.
-  if (context.is_null()) return v8::Local<v8::Context>();
-  Handle<Context> native_context(context->native_context());
-  return v8::Utils::ToLocal(native_context);
-}
-
-
-BreakLocation::BreakLocation(Handle<DebugInfo> debug_info, RelocInfo* rinfo,
-                             int position, int statement_position)
-    : debug_info_(debug_info),
-      pc_offset_(static_cast<int>(rinfo->pc() - debug_info->code()->entry())),
-      rmode_(rinfo->rmode()),
-      data_(rinfo->data()),
-      position_(position),
-      statement_position_(statement_position) {}
-
-
-BreakLocation::Iterator::Iterator(Handle<DebugInfo> debug_info,
-                                  BreakLocatorType type)
-    : debug_info_(debug_info),
-      reloc_iterator_(debug_info->code(), GetModeMask(type)),
-      break_index_(-1),
-      position_(1),
-      statement_position_(1) {
-  if (!Done()) Next();
-}
-
-
-int BreakLocation::Iterator::GetModeMask(BreakLocatorType type) {
-  int mask = 0;
-  mask |= RelocInfo::ModeMask(RelocInfo::POSITION);
-  mask |= RelocInfo::ModeMask(RelocInfo::STATEMENT_POSITION);
-  mask |= RelocInfo::ModeMask(RelocInfo::DEBUG_BREAK_SLOT_AT_RETURN);
-  mask |= RelocInfo::ModeMask(RelocInfo::DEBUG_BREAK_SLOT_AT_CALL);
-  mask |= RelocInfo::ModeMask(RelocInfo::DEBUG_BREAK_SLOT_AT_CONSTRUCT_CALL);
-  if (type == ALL_BREAK_LOCATIONS) {
-    mask |= RelocInfo::ModeMask(RelocInfo::DEBUG_BREAK_SLOT_AT_POSITION);
-    mask |= RelocInfo::ModeMask(RelocInfo::DEBUGGER_STATEMENT);
-  }
-  return mask;
-}
-
-
-void BreakLocation::Iterator::Next() {
-  DisallowHeapAllocation no_gc;
-  DCHECK(!Done());
-
-  // Iterate through reloc info for code and original code stopping at each
-  // breakable code target.
-  bool first = break_index_ == -1;
-  while (!Done()) {
-    if (!first) reloc_iterator_.next();
-    first = false;
-    if (Done()) return;
-
-    // Whenever a statement position or (plain) position is passed update the
-    // current value of these.
-    if (RelocInfo::IsPosition(rmode())) {
-      if (RelocInfo::IsStatementPosition(rmode())) {
-        statement_position_ = static_cast<int>(
-            rinfo()->data() - debug_info_->shared()->start_position());
-      }
-      // Always update the position as we don't want that to be before the
-      // statement position.
-      position_ = static_cast<int>(rinfo()->data() -
-                                   debug_info_->shared()->start_position());
-      DCHECK(position_ >= 0);
-      DCHECK(statement_position_ >= 0);
-      continue;
-    }
-
-    DCHECK(RelocInfo::IsDebugBreakSlot(rmode()) ||
-           RelocInfo::IsDebuggerStatement(rmode()));
-
-    if (RelocInfo::IsDebugBreakSlotAtReturn(rmode())) {
-      // Set the positions to the end of the function.
-      if (debug_info_->shared()->HasSourceCode()) {
-        position_ = debug_info_->shared()->end_position() -
-                    debug_info_->shared()->start_position() - 1;
-      } else {
-        position_ = 0;
-      }
-      statement_position_ = position_;
-    }
-
-    break;
-  }
-  break_index_++;
-}
-
-
-// Find the break point at the supplied address, or the closest one before
-// the address.
-BreakLocation BreakLocation::FromAddress(Handle<DebugInfo> debug_info,
-                                         BreakLocatorType type, Address pc) {
-  Iterator it(debug_info, type);
-  it.SkipTo(BreakIndexFromAddress(debug_info, type, pc));
-  return it.GetBreakLocation();
-}
-
-
-// Find the break point at the supplied address, or the closest one before
-// the address.
-void BreakLocation::FromAddressSameStatement(Handle<DebugInfo> debug_info,
-                                             BreakLocatorType type, Address pc,
-                                             List<BreakLocation>* result_out) {
-  int break_index = BreakIndexFromAddress(debug_info, type, pc);
-  Iterator it(debug_info, type);
-  it.SkipTo(break_index);
-  int statement_position = it.statement_position();
-  while (!it.Done() && it.statement_position() == statement_position) {
-    result_out->Add(it.GetBreakLocation());
-    it.Next();
-  }
-}
-
-
-int BreakLocation::BreakIndexFromAddress(Handle<DebugInfo> debug_info,
-                                         BreakLocatorType type, Address pc) {
-  // Run through all break points to locate the one closest to the address.
-  int closest_break = 0;
-  int distance = kMaxInt;
-  for (Iterator it(debug_info, type); !it.Done(); it.Next()) {
-    // Check if this break point is closer that what was previously found.
-    if (it.pc() <= pc && pc - it.pc() < distance) {
-      closest_break = it.break_index();
-      distance = static_cast<int>(pc - it.pc());
-      // Check whether we can't get any closer.
-      if (distance == 0) break;
-    }
-  }
-  return closest_break;
-}
-
-
-BreakLocation BreakLocation::FromPosition(Handle<DebugInfo> debug_info,
-                                          BreakLocatorType type, int position,
-                                          BreakPositionAlignment alignment) {
-  // Run through all break points to locate the one closest to the source
-  // position.
-  int closest_break = 0;
-  int distance = kMaxInt;
-
-  for (Iterator it(debug_info, type); !it.Done(); it.Next()) {
-    int next_position;
-    if (alignment == STATEMENT_ALIGNED) {
-      next_position = it.statement_position();
-    } else {
-      DCHECK(alignment == BREAK_POSITION_ALIGNED);
-      next_position = it.position();
-    }
-    if (position <= next_position && next_position - position < distance) {
-      closest_break = it.break_index();
-      distance = next_position - position;
-      // Check whether we can't get any closer.
-      if (distance == 0) break;
-    }
-  }
-
-  Iterator it(debug_info, type);
-  it.SkipTo(closest_break);
-  return it.GetBreakLocation();
-}
-
-
-void BreakLocation::SetBreakPoint(Handle<Object> break_point_object) {
-  // If there is not already a real break point here patch code with debug
-  // break.
-  if (!HasBreakPoint()) SetDebugBreak();
-  DCHECK(IsDebugBreak() || IsDebuggerStatement());
-  // Set the break point information.
-  DebugInfo::SetBreakPoint(debug_info_, pc_offset_, position_,
-                           statement_position_, break_point_object);
-}
-
-
-void BreakLocation::ClearBreakPoint(Handle<Object> break_point_object) {
-  // Clear the break point information.
-  DebugInfo::ClearBreakPoint(debug_info_, pc_offset_, break_point_object);
-  // If there are no more break points here remove the debug break.
-  if (!HasBreakPoint()) {
-    ClearDebugBreak();
-    DCHECK(!IsDebugBreak());
-  }
-}
-
-
-void BreakLocation::SetOneShot() {
-  // Debugger statement always calls debugger. No need to modify it.
-  if (IsDebuggerStatement()) return;
-
-  // If there is a real break point here no more to do.
-  if (HasBreakPoint()) {
-    DCHECK(IsDebugBreak());
-    return;
-  }
-
-  // Patch code with debug break.
-  SetDebugBreak();
-}
-
-
-void BreakLocation::ClearOneShot() {
-  // Debugger statement always calls debugger. No need to modify it.
-  if (IsDebuggerStatement()) return;
-
-  // If there is a real break point here no more to do.
-  if (HasBreakPoint()) {
-    DCHECK(IsDebugBreak());
-    return;
-  }
-
-  // Patch code removing debug break.
-  ClearDebugBreak();
-  DCHECK(!IsDebugBreak());
-}
-
-
-void BreakLocation::SetDebugBreak() {
-  // Debugger statement always calls debugger. No need to modify it.
-  if (IsDebuggerStatement()) return;
-
-  // If there is already a break point here just return. This might happen if
-  // the same code is flooded with break points twice. Flooding the same
-  // function twice might happen when stepping in a function with an exception
-  // handler as the handler and the function is the same.
-  if (IsDebugBreak()) return;
-
-  DCHECK(IsDebugBreakSlot());
-  Builtins* builtins = debug_info_->GetIsolate()->builtins();
-  Handle<Code> target =
-      IsReturn() ? builtins->Return_DebugBreak() : builtins->Slot_DebugBreak();
-  DebugCodegen::PatchDebugBreakSlot(pc(), target);
-  DCHECK(IsDebugBreak());
-}
-
-
-void BreakLocation::ClearDebugBreak() {
-  // Debugger statement always calls debugger. No need to modify it.
-  if (IsDebuggerStatement()) return;
-
-  DCHECK(IsDebugBreakSlot());
-  DebugCodegen::ClearDebugBreakSlot(pc());
-  DCHECK(!IsDebugBreak());
-}
-
-
-bool BreakLocation::IsStepInLocation() const {
-  return IsConstructCall() || IsCall();
-}
-
-
-bool BreakLocation::IsDebugBreak() const {
-  if (IsDebugBreakSlot()) {
-    return rinfo().IsPatchedDebugBreakSlotSequence();
-  }
-  return false;
-}
-
-
-Handle<Object> BreakLocation::BreakPointObjects() const {
-  return debug_info_->GetBreakPointObjects(pc_offset_);
-}
-
-
-// Threading support.
-void Debug::ThreadInit() {
-  thread_local_.break_count_ = 0;
-  thread_local_.break_id_ = 0;
-  thread_local_.break_frame_id_ = StackFrame::NO_ID;
-  thread_local_.last_step_action_ = StepNone;
-  thread_local_.last_statement_position_ = RelocInfo::kNoPosition;
-  thread_local_.step_count_ = 0;
-  thread_local_.last_fp_ = 0;
-  thread_local_.queued_step_count_ = 0;
-  thread_local_.step_into_fp_ = 0;
-  thread_local_.step_out_fp_ = 0;
-  // TODO(isolates): frames_are_dropped_?
-  base::NoBarrier_Store(&thread_local_.current_debug_scope_,
-                        static_cast<base::AtomicWord>(0));
-  thread_local_.restarter_frame_function_pointer_ = NULL;
-}
-
-
-char* Debug::ArchiveDebug(char* storage) {
-  char* to = storage;
-  MemCopy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
-  ThreadInit();
-  return storage + ArchiveSpacePerThread();
-}
-
-
-char* Debug::RestoreDebug(char* storage) {
-  char* from = storage;
-  MemCopy(reinterpret_cast<char*>(&thread_local_), from, sizeof(ThreadLocal));
-  return storage + ArchiveSpacePerThread();
-}
-
-
-int Debug::ArchiveSpacePerThread() {
-  return sizeof(ThreadLocal);
-}
-
-
-ScriptCache::ScriptCache(Isolate* isolate) : isolate_(isolate) {
-  Heap* heap = isolate_->heap();
-  HandleScope scope(isolate_);
-
-  DCHECK(isolate_->debug()->is_active());
-
-  // Perform a GC to get rid of all unreferenced scripts.
-  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask, "ScriptCache");
-
-  // Scan heap for Script objects.
-  List<Handle<Script> > scripts;
-  {
-    HeapIterator iterator(heap, HeapIterator::kFilterUnreachable);
-    DisallowHeapAllocation no_allocation;
-    for (HeapObject* obj = iterator.next(); obj != NULL;
-         obj = iterator.next()) {
-      if (obj->IsScript() && Script::cast(obj)->HasValidSource()) {
-        scripts.Add(Handle<Script>(Script::cast(obj)));
-      }
-    }
-  }
-
-  GlobalHandles* global_handles = isolate_->global_handles();
-  table_ = Handle<WeakValueHashTable>::cast(global_handles->Create(
-      Object::cast(*WeakValueHashTable::New(isolate_, scripts.length()))));
-  for (int i = 0; i < scripts.length(); i++) Add(scripts[i]);
-}
-
-
-void ScriptCache::Add(Handle<Script> script) {
-  HandleScope scope(isolate_);
-  Handle<Smi> id(script->id(), isolate_);
-
-#ifdef DEBUG
-  Handle<Object> lookup(table_->LookupWeak(id), isolate_);
-  if (!lookup->IsTheHole()) {
-    Handle<Script> found = Handle<Script>::cast(lookup);
-    DCHECK(script->id() == found->id());
-    DCHECK(!script->name()->IsString() ||
-           String::cast(script->name())->Equals(String::cast(found->name())));
-  }
-#endif
-
-  Handle<WeakValueHashTable> new_table =
-      WeakValueHashTable::PutWeak(table_, id, script);
-
-  if (new_table.is_identical_to(table_)) return;
-  GlobalHandles* global_handles = isolate_->global_handles();
-  global_handles->Destroy(Handle<Object>::cast(table_).location());
-  table_ = Handle<WeakValueHashTable>::cast(
-      global_handles->Create(Object::cast(*new_table)));
-}
-
-
-ScriptCache::~ScriptCache() {
-  isolate_->global_handles()->Destroy(Handle<Object>::cast(table_).location());
-  table_ = Handle<WeakValueHashTable>();
-}
-
-
-DebugInfoListNode::DebugInfoListNode(DebugInfo* debug_info): next_(NULL) {
-  // Globalize the request debug info object and make it weak.
-  GlobalHandles* global_handles = debug_info->GetIsolate()->global_handles();
-  debug_info_ =
-      Handle<DebugInfo>::cast(global_handles->Create(debug_info)).location();
-}
-
-
-DebugInfoListNode::~DebugInfoListNode() {
-  if (debug_info_ == nullptr) return;
-  GlobalHandles::Destroy(reinterpret_cast<Object**>(debug_info_));
-  debug_info_ = nullptr;
-}
-
-
-bool Debug::CompileDebuggerScript(Isolate* isolate, int index) {
-  Factory* factory = isolate->factory();
-  HandleScope scope(isolate);
-
-  // Bail out if the index is invalid.
-  if (index == -1) return false;
-
-  // Find source and name for the requested script.
-  Handle<String> source_code =
-      isolate->bootstrapper()->SourceLookup<Natives>(index);
-  Vector<const char> name = Natives::GetScriptName(index);
-  Handle<String> script_name =
-      factory->NewStringFromAscii(name).ToHandleChecked();
-  Handle<Context> context = isolate->native_context();
-
-  // Compile the script.
-  Handle<SharedFunctionInfo> function_info;
-  function_info = Compiler::CompileScript(
-      source_code, script_name, 0, 0, ScriptOriginOptions(), Handle<Object>(),
-      context, NULL, NULL, ScriptCompiler::kNoCompileOptions, NATIVES_CODE,
-      false);
-  if (function_info.is_null()) return false;
-
-  // Execute the shared function in the debugger context.
-  Handle<JSFunction> function =
-      factory->NewFunctionFromSharedFunctionInfo(function_info, context);
-
-  MaybeHandle<Object> maybe_exception;
-  MaybeHandle<Object> result = Execution::TryCall(
-      function, handle(context->global_proxy()), 0, NULL, &maybe_exception);
-
-  // Check for caught exceptions.
-  if (result.is_null()) {
-    DCHECK(!isolate->has_pending_exception());
-    MessageLocation computed_location;
-    isolate->ComputeLocation(&computed_location);
-    Handle<JSMessageObject> message = MessageHandler::MakeMessageObject(
-        isolate, MessageTemplate::kDebuggerLoading, &computed_location,
-        isolate->factory()->undefined_value(), Handle<JSArray>());
-    DCHECK(!isolate->has_pending_exception());
-    Handle<Object> exception;
-    if (maybe_exception.ToHandle(&exception)) {
-      isolate->set_pending_exception(*exception);
-      MessageHandler::ReportMessage(isolate, NULL, message);
-    }
-    DCHECK(!maybe_exception.is_null());
-    return false;
-  }
-
-  // Mark this script as native and return successfully.
-  Handle<Script> script(Script::cast(function->shared()->script()));
-  script->set_type(Smi::FromInt(Script::TYPE_NATIVE));
-  return true;
-}
-
-
-bool Debug::Load() {
-  // Return if debugger is already loaded.
-  if (is_loaded()) return true;
-
-  // Bail out if we're already in the process of compiling the native
-  // JavaScript source code for the debugger.
-  if (is_suppressed_) return false;
-  SuppressDebug while_loading(this);
-
-  // Disable breakpoints and interrupts while compiling and running the
-  // debugger scripts including the context creation code.
-  DisableBreak disable(this, true);
-  PostponeInterruptsScope postpone(isolate_);
-
-  // Create the debugger context.
-  HandleScope scope(isolate_);
-  ExtensionConfiguration no_extensions;
-  Handle<Context> context = isolate_->bootstrapper()->CreateEnvironment(
-      MaybeHandle<JSGlobalProxy>(), v8::Local<ObjectTemplate>(),
-      &no_extensions);
-
-  // Fail if no context could be created.
-  if (context.is_null()) return false;
-
-  // Use the debugger context.
-  SaveContext save(isolate_);
-  isolate_->set_context(*context);
-
-  // Expose the builtins object in the debugger context.
-  Handle<String> key = isolate_->factory()->InternalizeOneByteString(
-      STATIC_CHAR_VECTOR("builtins"));
-  Handle<GlobalObject> global =
-      Handle<GlobalObject>(context->global_object(), isolate_);
-  Handle<JSBuiltinsObject> builtin =
-      Handle<JSBuiltinsObject>(global->builtins(), isolate_);
-  RETURN_ON_EXCEPTION_VALUE(
-      isolate_, Object::SetProperty(global, key, builtin, SLOPPY), false);
-
-  // Compile the JavaScript for the debugger in the debugger context.
-  bool caught_exception =
-      !CompileDebuggerScript(isolate_, Natives::GetIndex("mirror")) ||
-      !CompileDebuggerScript(isolate_, Natives::GetIndex("debug"));
-
-  if (FLAG_enable_liveedit) {
-    caught_exception = caught_exception ||
-        !CompileDebuggerScript(isolate_, Natives::GetIndex("liveedit"));
-  }
-  // Check for caught exceptions.
-  if (caught_exception) return false;
-
-  debug_context_ = Handle<Context>::cast(
-      isolate_->global_handles()->Create(*context));
-  return true;
-}
-
-
-void Debug::Unload() {
-  ClearAllBreakPoints();
-  ClearStepping();
-
-  // Return debugger is not loaded.
-  if (!is_loaded()) return;
-
-  // Clear the script cache.
-  if (script_cache_ != NULL) {
-    delete script_cache_;
-    script_cache_ = NULL;
-  }
-
-  // Clear debugger context global handle.
-  GlobalHandles::Destroy(Handle<Object>::cast(debug_context_).location());
-  debug_context_ = Handle<Context>();
-}
-
-
-void Debug::Break(Arguments args, JavaScriptFrame* frame) {
-  Heap* heap = isolate_->heap();
-  HandleScope scope(isolate_);
-  DCHECK(args.length() == 0);
-
-  // Initialize LiveEdit.
-  LiveEdit::InitializeThreadLocal(this);
-
-  // Just continue if breaks are disabled or debugger cannot be loaded.
-  if (break_disabled()) return;
-
-  // Enter the debugger.
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return;
-
-  // Postpone interrupt during breakpoint processing.
-  PostponeInterruptsScope postpone(isolate_);
-
-  // Get the debug info (create it if it does not exist).
-  Handle<SharedFunctionInfo> shared =
-      Handle<SharedFunctionInfo>(frame->function()->shared());
-  Handle<DebugInfo> debug_info(shared->GetDebugInfo());
-
-  // Find the break point where execution has stopped.
-  // PC points to the instruction after the current one, possibly a break
-  // location as well. So the "- 1" to exclude it from the search.
-  Address call_pc = frame->pc() - 1;
-  BreakLocation break_location =
-      BreakLocation::FromAddress(debug_info, ALL_BREAK_LOCATIONS, call_pc);
-
-  // Check whether step next reached a new statement.
-  if (!StepNextContinue(&break_location, frame)) {
-    // Decrease steps left if performing multiple steps.
-    if (thread_local_.step_count_ > 0) {
-      thread_local_.step_count_--;
-    }
-  }
-
-  // If there is one or more real break points check whether any of these are
-  // triggered.
-  Handle<Object> break_points_hit(heap->undefined_value(), isolate_);
-  if (break_location.HasBreakPoint()) {
-    Handle<Object> break_point_objects = break_location.BreakPointObjects();
-    break_points_hit = CheckBreakPoints(break_point_objects);
-  }
-
-  // If step out is active skip everything until the frame where we need to step
-  // out to is reached, unless real breakpoint is hit.
-  if (StepOutActive() &&
-      frame->fp() != thread_local_.step_out_fp_ &&
-      break_points_hit->IsUndefined() ) {
-      // Step count should always be 0 for StepOut.
-      DCHECK(thread_local_.step_count_ == 0);
-  } else if (!break_points_hit->IsUndefined() ||
-             (thread_local_.last_step_action_ != StepNone &&
-              thread_local_.step_count_ == 0)) {
-    // Notify debugger if a real break point is triggered or if performing
-    // single stepping with no more steps to perform. Otherwise do another step.
-
-    // Clear all current stepping setup.
-    ClearStepping();
-
-    if (thread_local_.queued_step_count_ > 0) {
-      // Perform queued steps
-      int step_count = thread_local_.queued_step_count_;
-
-      // Clear queue
-      thread_local_.queued_step_count_ = 0;
-
-      PrepareStep(StepNext, step_count, StackFrame::NO_ID);
-    } else {
-      // Notify the debug event listeners.
-      OnDebugBreak(break_points_hit, false);
-    }
-  } else if (thread_local_.last_step_action_ != StepNone) {
-    // Hold on to last step action as it is cleared by the call to
-    // ClearStepping.
-    StepAction step_action = thread_local_.last_step_action_;
-    int step_count = thread_local_.step_count_;
-
-    // If StepNext goes deeper in code, StepOut until original frame
-    // and keep step count queued up in the meantime.
-    if (step_action == StepNext && frame->fp() < thread_local_.last_fp_) {
-      // Count frames until target frame
-      int count = 0;
-      JavaScriptFrameIterator it(isolate_);
-      while (!it.done() && it.frame()->fp() < thread_local_.last_fp_) {
-        count++;
-        it.Advance();
-      }
-
-      // Check that we indeed found the frame we are looking for.
-      CHECK(!it.done() && (it.frame()->fp() == thread_local_.last_fp_));
-      if (step_count > 1) {
-        // Save old count and action to continue stepping after StepOut.
-        thread_local_.queued_step_count_ = step_count - 1;
-      }
-
-      // Set up for StepOut to reach target frame.
-      step_action = StepOut;
-      step_count = count;
-    }
-
-    // Clear all current stepping setup.
-    ClearStepping();
-
-    // Set up for the remaining steps.
-    PrepareStep(step_action, step_count, StackFrame::NO_ID);
-  }
-}
-
-
-// Check the break point objects for whether one or more are actually
-// triggered. This function returns a JSArray with the break point objects
-// which is triggered.
-Handle<Object> Debug::CheckBreakPoints(Handle<Object> break_point_objects) {
-  Factory* factory = isolate_->factory();
-
-  // Count the number of break points hit. If there are multiple break points
-  // they are in a FixedArray.
-  Handle<FixedArray> break_points_hit;
-  int break_points_hit_count = 0;
-  DCHECK(!break_point_objects->IsUndefined());
-  if (break_point_objects->IsFixedArray()) {
-    Handle<FixedArray> array(FixedArray::cast(*break_point_objects));
-    break_points_hit = factory->NewFixedArray(array->length());
-    for (int i = 0; i < array->length(); i++) {
-      Handle<Object> o(array->get(i), isolate_);
-      if (CheckBreakPoint(o)) {
-        break_points_hit->set(break_points_hit_count++, *o);
-      }
-    }
-  } else {
-    break_points_hit = factory->NewFixedArray(1);
-    if (CheckBreakPoint(break_point_objects)) {
-      break_points_hit->set(break_points_hit_count++, *break_point_objects);
-    }
-  }
-
-  // Return undefined if no break points were triggered.
-  if (break_points_hit_count == 0) {
-    return factory->undefined_value();
-  }
-  // Return break points hit as a JSArray.
-  Handle<JSArray> result = factory->NewJSArrayWithElements(break_points_hit);
-  result->set_length(Smi::FromInt(break_points_hit_count));
-  return result;
-}
-
-
-// Check whether a single break point object is triggered.
-bool Debug::CheckBreakPoint(Handle<Object> break_point_object) {
-  Factory* factory = isolate_->factory();
-  HandleScope scope(isolate_);
-
-  // Ignore check if break point object is not a JSObject.
-  if (!break_point_object->IsJSObject()) return true;
-
-  // Get the function IsBreakPointTriggered (defined in debug-debugger.js).
-  Handle<String> is_break_point_triggered_string =
-      factory->InternalizeOneByteString(
-          STATIC_CHAR_VECTOR("IsBreakPointTriggered"));
-  Handle<GlobalObject> debug_global(debug_context()->global_object());
-  Handle<JSFunction> check_break_point =
-    Handle<JSFunction>::cast(Object::GetProperty(
-        debug_global, is_break_point_triggered_string).ToHandleChecked());
-
-  // Get the break id as an object.
-  Handle<Object> break_id = factory->NewNumberFromInt(Debug::break_id());
-
-  // Call HandleBreakPointx.
-  Handle<Object> argv[] = { break_id, break_point_object };
-  Handle<Object> result;
-  if (!Execution::TryCall(check_break_point,
-                          isolate_->js_builtins_object(),
-                          arraysize(argv),
-                          argv).ToHandle(&result)) {
-    return false;
-  }
-
-  // Return whether the break point is triggered.
-  return result->IsTrue();
-}
-
-
-bool Debug::SetBreakPoint(Handle<JSFunction> function,
-                          Handle<Object> break_point_object,
-                          int* source_position) {
-  HandleScope scope(isolate_);
-
-  // Make sure the function is compiled and has set up the debug info.
-  Handle<SharedFunctionInfo> shared(function->shared());
-  if (!EnsureDebugInfo(shared, function)) {
-    // Return if retrieving debug info failed.
-    return true;
-  }
-
-  Handle<DebugInfo> debug_info(shared->GetDebugInfo());
-  // Source positions starts with zero.
-  DCHECK(*source_position >= 0);
-
-  // Find the break point and change it.
-  BreakLocation location = BreakLocation::FromPosition(
-      debug_info, ALL_BREAK_LOCATIONS, *source_position, STATEMENT_ALIGNED);
-  *source_position = location.statement_position();
-  location.SetBreakPoint(break_point_object);
-
-  // At least one active break point now.
-  return debug_info->GetBreakPointCount() > 0;
-}
-
-
-bool Debug::SetBreakPointForScript(Handle<Script> script,
-                                   Handle<Object> break_point_object,
-                                   int* source_position,
-                                   BreakPositionAlignment alignment) {
-  HandleScope scope(isolate_);
-
-  // Obtain shared function info for the function.
-  Handle<Object> result =
-      FindSharedFunctionInfoInScript(script, *source_position);
-  if (result->IsUndefined()) return false;
-
-  // Make sure the function has set up the debug info.
-  Handle<SharedFunctionInfo> shared = Handle<SharedFunctionInfo>::cast(result);
-  if (!EnsureDebugInfo(shared, Handle<JSFunction>::null())) {
-    // Return if retrieving debug info failed.
-    return false;
-  }
-
-  // Find position within function. The script position might be before the
-  // source position of the first function.
-  int position;
-  if (shared->start_position() > *source_position) {
-    position = 0;
-  } else {
-    position = *source_position - shared->start_position();
-  }
-
-  Handle<DebugInfo> debug_info(shared->GetDebugInfo());
-  // Source positions starts with zero.
-  DCHECK(position >= 0);
-
-  // Find the break point and change it.
-  BreakLocation location = BreakLocation::FromPosition(
-      debug_info, ALL_BREAK_LOCATIONS, position, alignment);
-  location.SetBreakPoint(break_point_object);
-
-  position = (alignment == STATEMENT_ALIGNED) ? location.statement_position()
-                                              : location.position();
-
-  *source_position = position + shared->start_position();
-
-  // At least one active break point now.
-  DCHECK(debug_info->GetBreakPointCount() > 0);
-  return true;
-}
-
-
-void Debug::ClearBreakPoint(Handle<Object> break_point_object) {
-  HandleScope scope(isolate_);
-
-  DebugInfoListNode* node = debug_info_list_;
-  while (node != NULL) {
-    Handle<Object> result =
-        DebugInfo::FindBreakPointInfo(node->debug_info(), break_point_object);
-    if (!result->IsUndefined()) {
-      // Get information in the break point.
-      Handle<BreakPointInfo> break_point_info =
-          Handle<BreakPointInfo>::cast(result);
-      Handle<DebugInfo> debug_info = node->debug_info();
-
-      // Find the break point and clear it.
-      Address pc = debug_info->code()->entry() +
-                   break_point_info->code_position()->value();
-
-      BreakLocation location =
-          BreakLocation::FromAddress(debug_info, ALL_BREAK_LOCATIONS, pc);
-      location.ClearBreakPoint(break_point_object);
-
-      // If there are no more break points left remove the debug info for this
-      // function.
-      if (debug_info->GetBreakPointCount() == 0) {
-        RemoveDebugInfoAndClearFromShared(debug_info);
-      }
-
-      return;
-    }
-    node = node->next();
-  }
-}
-
-
-// Clear out all the debug break code. This is ONLY supposed to be used when
-// shutting down the debugger as it will leave the break point information in
-// DebugInfo even though the code is patched back to the non break point state.
-void Debug::ClearAllBreakPoints() {
-  for (DebugInfoListNode* node = debug_info_list_; node != NULL;
-       node = node->next()) {
-    for (BreakLocation::Iterator it(node->debug_info(), ALL_BREAK_LOCATIONS);
-         !it.Done(); it.Next()) {
-      it.GetBreakLocation().ClearDebugBreak();
-    }
-  }
-  // Remove all debug info.
-  while (debug_info_list_ != NULL) {
-    RemoveDebugInfoAndClearFromShared(debug_info_list_->debug_info());
-  }
-}
-
-
-void Debug::FloodWithOneShot(Handle<JSFunction> function,
-                             BreakLocatorType type) {
-  // Make sure the function is compiled and has set up the debug info.
-  Handle<SharedFunctionInfo> shared(function->shared());
-  if (!EnsureDebugInfo(shared, function)) {
-    // Return if we failed to retrieve the debug info.
-    return;
-  }
-
-  // Flood the function with break points.
-  Handle<DebugInfo> debug_info(shared->GetDebugInfo());
-  for (BreakLocation::Iterator it(debug_info, type); !it.Done(); it.Next()) {
-    it.GetBreakLocation().SetOneShot();
-  }
-}
-
-
-void Debug::FloodBoundFunctionWithOneShot(Handle<JSFunction> function) {
-  Handle<FixedArray> new_bindings(function->function_bindings());
-  Handle<Object> bindee(new_bindings->get(JSFunction::kBoundFunctionIndex),
-                        isolate_);
-
-  if (!bindee.is_null() && bindee->IsJSFunction()) {
-    Handle<JSFunction> bindee_function(JSFunction::cast(*bindee));
-    FloodWithOneShotGeneric(bindee_function);
-  }
-}
-
-
-void Debug::FloodDefaultConstructorWithOneShot(Handle<JSFunction> function) {
-  DCHECK(function->shared()->is_default_constructor());
-  // Instead of stepping into the function we directly step into the super class
-  // constructor.
-  Isolate* isolate = function->GetIsolate();
-  PrototypeIterator iter(isolate, function);
-  Handle<Object> proto = PrototypeIterator::GetCurrent(iter);
-  if (!proto->IsJSFunction()) return;  // Object.prototype
-  Handle<JSFunction> function_proto = Handle<JSFunction>::cast(proto);
-  FloodWithOneShotGeneric(function_proto);
-}
-
-
-void Debug::FloodWithOneShotGeneric(Handle<JSFunction> function,
-                                    Handle<Object> holder) {
-  if (function->shared()->bound()) {
-    FloodBoundFunctionWithOneShot(function);
-  } else if (function->shared()->is_default_constructor()) {
-    FloodDefaultConstructorWithOneShot(function);
-  } else {
-    Isolate* isolate = function->GetIsolate();
-    // Don't allow step into functions in the native context.
-    if (function->shared()->code() ==
-            isolate->builtins()->builtin(Builtins::kFunctionApply) ||
-        function->shared()->code() ==
-            isolate->builtins()->builtin(Builtins::kFunctionCall)) {
-      // Handle function.apply and function.call separately to flood the
-      // function to be called and not the code for Builtins::FunctionApply or
-      // Builtins::FunctionCall. The receiver of call/apply is the target
-      // function.
-      if (!holder.is_null() && holder->IsJSFunction()) {
-        Handle<JSFunction> js_function = Handle<JSFunction>::cast(holder);
-        FloodWithOneShotGeneric(js_function);
-      }
-    } else {
-      FloodWithOneShot(function);
-    }
-  }
-}
-
-
-void Debug::FloodHandlerWithOneShot() {
-  // Iterate through the JavaScript stack looking for handlers.
-  StackFrame::Id id = break_frame_id();
-  if (id == StackFrame::NO_ID) {
-    // If there is no JavaScript stack don't do anything.
-    return;
-  }
-  for (JavaScriptFrameIterator it(isolate_, id); !it.done(); it.Advance()) {
-    JavaScriptFrame* frame = it.frame();
-    int stack_slots = 0;  // The computed stack slot count is not used.
-    if (frame->LookupExceptionHandlerInTable(&stack_slots, NULL) > 0) {
-      // Flood the function with the catch/finally block with break points.
-      FloodWithOneShot(Handle<JSFunction>(frame->function()));
-      return;
-    }
-  }
-}
-
-
-void Debug::ChangeBreakOnException(ExceptionBreakType type, bool enable) {
-  if (type == BreakUncaughtException) {
-    break_on_uncaught_exception_ = enable;
-  } else {
-    break_on_exception_ = enable;
-  }
-}
-
-
-bool Debug::IsBreakOnException(ExceptionBreakType type) {
-  if (type == BreakUncaughtException) {
-    return break_on_uncaught_exception_;
-  } else {
-    return break_on_exception_;
-  }
-}
-
-
-FrameSummary GetFirstFrameSummary(JavaScriptFrame* frame) {
-  List<FrameSummary> frames(FLAG_max_inlining_levels + 1);
-  frame->Summarize(&frames);
-  return frames.first();
-}
-
-
-void Debug::PrepareStep(StepAction step_action,
-                        int step_count,
-                        StackFrame::Id frame_id) {
-  HandleScope scope(isolate_);
-
-  DCHECK(in_debug_scope());
-
-  // Remember this step action and count.
-  thread_local_.last_step_action_ = step_action;
-  if (step_action == StepOut) {
-    // For step out target frame will be found on the stack so there is no need
-    // to set step counter for it. It's expected to always be 0 for StepOut.
-    thread_local_.step_count_ = 0;
-  } else {
-    thread_local_.step_count_ = step_count;
-  }
-
-  // Get the frame where the execution has stopped and skip the debug frame if
-  // any. The debug frame will only be present if execution was stopped due to
-  // hitting a break point. In other situations (e.g. unhandled exception) the
-  // debug frame is not present.
-  StackFrame::Id id = break_frame_id();
-  if (id == StackFrame::NO_ID) {
-    // If there is no JavaScript stack don't do anything.
-    return;
-  }
-  if (frame_id != StackFrame::NO_ID) {
-    id = frame_id;
-  }
-  JavaScriptFrameIterator frames_it(isolate_, id);
-  JavaScriptFrame* frame = frames_it.frame();
-
-  // First of all ensure there is one-shot break points in the top handler
-  // if any.
-  FloodHandlerWithOneShot();
-
-  // If the function on the top frame is unresolved perform step out. This will
-  // be the case when calling unknown function and having the debugger stopped
-  // in an unhandled exception.
-  if (!frame->function()->IsJSFunction()) {
-    // Step out: Find the calling JavaScript frame and flood it with
-    // breakpoints.
-    frames_it.Advance();
-    // Fill the function to return to with one-shot break points.
-    JSFunction* function = frames_it.frame()->function();
-    FloodWithOneShot(Handle<JSFunction>(function));
-    return;
-  }
-
-  // Get the debug info (create it if it does not exist).
-  FrameSummary summary = GetFirstFrameSummary(frame);
-  Handle<JSFunction> function(summary.function());
-  Handle<SharedFunctionInfo> shared(function->shared());
-  if (!EnsureDebugInfo(shared, function)) {
-    // Return if ensuring debug info failed.
-    return;
-  }
-
-  Handle<DebugInfo> debug_info(shared->GetDebugInfo());
-  // Refresh frame summary if the code has been recompiled for debugging.
-  if (shared->code() != *summary.code()) summary = GetFirstFrameSummary(frame);
-
-  // PC points to the instruction after the current one, possibly a break
-  // location as well. So the "- 1" to exclude it from the search.
-  Address call_pc = summary.pc() - 1;
-  BreakLocation location =
-      BreakLocation::FromAddress(debug_info, ALL_BREAK_LOCATIONS, call_pc);
-
-  // If this is the last break code target step out is the only possibility.
-  if (location.IsReturn() || step_action == StepOut) {
-    if (step_action == StepOut) {
-      // Skip step_count frames starting with the current one.
-      while (step_count-- > 0 && !frames_it.done()) {
-        frames_it.Advance();
-      }
-    } else {
-      DCHECK(location.IsReturn());
-      frames_it.Advance();
-    }
-    // Skip native and extension functions on the stack.
-    while (!frames_it.done() &&
-           !frames_it.frame()->function()->IsSubjectToDebugging()) {
-      frames_it.Advance();
-    }
-    // Step out: If there is a JavaScript caller frame, we need to
-    // flood it with breakpoints.
-    if (!frames_it.done()) {
-      // Fill the function to return to with one-shot break points.
-      JSFunction* function = frames_it.frame()->function();
-      FloodWithOneShot(Handle<JSFunction>(function));
-      // Set target frame pointer.
-      ActivateStepOut(frames_it.frame());
-    }
-    return;
-  }
-
-  if (step_action != StepNext && step_action != StepMin) {
-    // If there's restarter frame on top of the stack, just get the pointer
-    // to function which is going to be restarted.
-    if (thread_local_.restarter_frame_function_pointer_ != NULL) {
-      Handle<JSFunction> restarted_function(
-          JSFunction::cast(*thread_local_.restarter_frame_function_pointer_));
-      FloodWithOneShot(restarted_function);
-    } else if (location.IsCall()) {
-      // Find target function on the expression stack.
-      // Expression stack looks like this (top to bottom):
-      // argN
-      // ...
-      // arg0
-      // Receiver
-      // Function to call
-      int num_expressions_without_args =
-          frame->ComputeExpressionsCount() - location.CallArgumentsCount();
-      DCHECK(num_expressions_without_args >= 2);
-      Object* fun = frame->GetExpression(num_expressions_without_args - 2);
-
-      // Flood the actual target of call/apply.
-      if (fun->IsJSFunction()) {
-        Isolate* isolate = JSFunction::cast(fun)->GetIsolate();
-        Code* apply = isolate->builtins()->builtin(Builtins::kFunctionApply);
-        Code* call = isolate->builtins()->builtin(Builtins::kFunctionCall);
-        // Find target function on the expression stack for expression like
-        // Function.call.call...apply(...)
-        int i = 1;
-        while (fun->IsJSFunction()) {
-          Code* code = JSFunction::cast(fun)->shared()->code();
-          if (code != apply && code != call) break;
-          DCHECK(num_expressions_without_args >= i);
-          fun = frame->GetExpression(num_expressions_without_args - i);
-          i--;
-        }
-      }
-
-      if (fun->IsJSFunction()) {
-        Handle<JSFunction> js_function(JSFunction::cast(fun));
-        FloodWithOneShotGeneric(js_function);
-      }
-    }
-
-    ActivateStepIn(frame);
-  }
-
-  // Fill the current function with one-shot break points even for step in on
-  // a call target as the function called might be a native function for
-  // which step in will not stop. It also prepares for stepping in
-  // getters/setters.
-  // If we are stepping into another frame, only fill calls and returns.
-  FloodWithOneShot(function, step_action == StepFrame ? CALLS_AND_RETURNS
-                                                      : ALL_BREAK_LOCATIONS);
-
-  // Remember source position and frame to handle step next.
-  thread_local_.last_statement_position_ =
-      debug_info->code()->SourceStatementPosition(summary.pc());
-  thread_local_.last_fp_ = frame->UnpaddedFP();
-}
-
-
-// Check whether the current debug break should be reported to the debugger. It
-// is used to have step next and step in only report break back to the debugger
-// if on a different frame or in a different statement. In some situations
-// there will be several break points in the same statement when the code is
-// flooded with one-shot break points. This function helps to perform several
-// steps before reporting break back to the debugger.
-bool Debug::StepNextContinue(BreakLocation* break_location,
-                             JavaScriptFrame* frame) {
-  // StepNext and StepOut shouldn't bring us deeper in code, so last frame
-  // shouldn't be a parent of current frame.
-  StepAction step_action = thread_local_.last_step_action_;
-
-  if (step_action == StepNext || step_action == StepOut) {
-    if (frame->fp() < thread_local_.last_fp_) return true;
-  }
-
-  // We stepped into a new frame if the frame pointer changed.
-  if (step_action == StepFrame) {
-    return frame->UnpaddedFP() == thread_local_.last_fp_;
-  }
-
-  // If the step last action was step next or step in make sure that a new
-  // statement is hit.
-  if (step_action == StepNext || step_action == StepIn) {
-    // Never continue if returning from function.
-    if (break_location->IsReturn()) return false;
-
-    // Continue if we are still on the same frame and in the same statement.
-    int current_statement_position =
-        break_location->code()->SourceStatementPosition(frame->pc());
-    return thread_local_.last_fp_ == frame->UnpaddedFP() &&
-        thread_local_.last_statement_position_ == current_statement_position;
-  }
-
-  // No step next action - don't continue.
-  return false;
-}
-
-
-// Check whether the code object at the specified address is a debug break code
-// object.
-bool Debug::IsDebugBreak(Address addr) {
-  Code* code = Code::GetCodeFromTargetAddress(addr);
-  return code->is_debug_stub();
-}
-
-
-// Simple function for returning the source positions for active break points.
-Handle<Object> Debug::GetSourceBreakLocations(
-    Handle<SharedFunctionInfo> shared,
-    BreakPositionAlignment position_alignment) {
-  Isolate* isolate = shared->GetIsolate();
-  Heap* heap = isolate->heap();
-  if (!shared->HasDebugInfo()) {
-    return Handle<Object>(heap->undefined_value(), isolate);
-  }
-  Handle<DebugInfo> debug_info(shared->GetDebugInfo());
-  if (debug_info->GetBreakPointCount() == 0) {
-    return Handle<Object>(heap->undefined_value(), isolate);
-  }
-  Handle<FixedArray> locations =
-      isolate->factory()->NewFixedArray(debug_info->GetBreakPointCount());
-  int count = 0;
-  for (int i = 0; i < debug_info->break_points()->length(); ++i) {
-    if (!debug_info->break_points()->get(i)->IsUndefined()) {
-      BreakPointInfo* break_point_info =
-          BreakPointInfo::cast(debug_info->break_points()->get(i));
-      int break_points = break_point_info->GetBreakPointCount();
-      if (break_points == 0) continue;
-      Smi* position = NULL;
-      switch (position_alignment) {
-        case STATEMENT_ALIGNED:
-          position = break_point_info->statement_position();
-          break;
-        case BREAK_POSITION_ALIGNED:
-          position = break_point_info->source_position();
-          break;
-      }
-      for (int j = 0; j < break_points; ++j) locations->set(count++, position);
-    }
-  }
-  return locations;
-}
-
-
-// Handle stepping into a function.
-void Debug::HandleStepIn(Handle<Object> function_obj, bool is_constructor) {
-  // Flood getter/setter if we either step in or step to another frame.
-  bool step_frame = thread_local_.last_step_action_ == StepFrame;
-  if (!StepInActive() && !step_frame) return;
-  if (!function_obj->IsJSFunction()) return;
-  Handle<JSFunction> function = Handle<JSFunction>::cast(function_obj);
-  Isolate* isolate = function->GetIsolate();
-
-  StackFrameIterator it(isolate);
-  it.Advance();
-  // For constructor functions skip another frame.
-  if (is_constructor) {
-    DCHECK(it.frame()->is_construct());
-    it.Advance();
-  }
-  Address fp = it.frame()->fp();
-
-  // Flood the function with one-shot break points if it is called from where
-  // step into was requested, or when stepping into a new frame.
-  if (fp == thread_local_.step_into_fp_ || step_frame) {
-    FloodWithOneShotGeneric(function, Handle<Object>());
-  }
-}
-
-
-void Debug::ClearStepping() {
-  // Clear the various stepping setup.
-  ClearOneShot();
-  ClearStepIn();
-  ClearStepOut();
-  ClearStepNext();
-
-  // Clear multiple step counter.
-  thread_local_.step_count_ = 0;
-}
-
-
-// Clears all the one-shot break points that are currently set. Normally this
-// function is called each time a break point is hit as one shot break points
-// are used to support stepping.
-void Debug::ClearOneShot() {
-  // The current implementation just runs through all the breakpoints. When the
-  // last break point for a function is removed that function is automatically
-  // removed from the list.
-  for (DebugInfoListNode* node = debug_info_list_; node != NULL;
-       node = node->next()) {
-    for (BreakLocation::Iterator it(node->debug_info(), ALL_BREAK_LOCATIONS);
-         !it.Done(); it.Next()) {
-      it.GetBreakLocation().ClearOneShot();
-    }
-  }
-}
-
-
-void Debug::ActivateStepIn(StackFrame* frame) {
-  DCHECK(!StepOutActive());
-  thread_local_.step_into_fp_ = frame->UnpaddedFP();
-}
-
-
-void Debug::ClearStepIn() {
-  thread_local_.step_into_fp_ = 0;
-}
-
-
-void Debug::ActivateStepOut(StackFrame* frame) {
-  DCHECK(!StepInActive());
-  thread_local_.step_out_fp_ = frame->UnpaddedFP();
-}
-
-
-void Debug::ClearStepOut() {
-  thread_local_.step_out_fp_ = 0;
-}
-
-
-void Debug::ClearStepNext() {
-  thread_local_.last_step_action_ = StepNone;
-  thread_local_.last_statement_position_ = RelocInfo::kNoPosition;
-  thread_local_.last_fp_ = 0;
-}
-
-
-bool MatchingCodeTargets(Code* target1, Code* target2) {
-  if (target1 == target2) return true;
-  if (target1->kind() != target2->kind()) return false;
-  return target1->is_handler() || target1->is_inline_cache_stub();
-}
-
-
-// Count the number of calls before the current frame PC to find the
-// corresponding PC in the newly recompiled code.
-static Address ComputeNewPcForRedirect(Code* new_code, Code* old_code,
-                                       Address old_pc) {
-  DCHECK_EQ(old_code->kind(), Code::FUNCTION);
-  DCHECK_EQ(new_code->kind(), Code::FUNCTION);
-  DCHECK(new_code->has_debug_break_slots());
-  static const int mask = RelocInfo::kCodeTargetMask;
-
-  // Find the target of the current call.
-  Code* target = NULL;
-  intptr_t delta = 0;
-  for (RelocIterator it(old_code, mask); !it.done(); it.next()) {
-    RelocInfo* rinfo = it.rinfo();
-    Address current_pc = rinfo->pc();
-    // The frame PC is behind the call instruction by the call instruction size.
-    if (current_pc > old_pc) break;
-    delta = old_pc - current_pc;
-    target = Code::GetCodeFromTargetAddress(rinfo->target_address());
-  }
-
-  // Count the number of calls to the same target before the current call.
-  int index = 0;
-  for (RelocIterator it(old_code, mask); !it.done(); it.next()) {
-    RelocInfo* rinfo = it.rinfo();
-    Address current_pc = rinfo->pc();
-    if (current_pc > old_pc) break;
-    Code* current = Code::GetCodeFromTargetAddress(rinfo->target_address());
-    if (MatchingCodeTargets(target, current)) index++;
-  }
-
-  DCHECK(index > 0);
-
-  // Repeat the count on the new code to find corresponding call.
-  for (RelocIterator it(new_code, mask); !it.done(); it.next()) {
-    RelocInfo* rinfo = it.rinfo();
-    Code* current = Code::GetCodeFromTargetAddress(rinfo->target_address());
-    if (MatchingCodeTargets(target, current)) index--;
-    if (index == 0) return rinfo->pc() + delta;
-  }
-
-  UNREACHABLE();
-  return NULL;
-}
-
-
-// Count the number of continuations at which the current pc offset is at.
-static int ComputeContinuationIndexFromPcOffset(Code* code, int pc_offset) {
-  DCHECK_EQ(code->kind(), Code::FUNCTION);
-  Address pc = code->instruction_start() + pc_offset;
-  int mask = RelocInfo::ModeMask(RelocInfo::GENERATOR_CONTINUATION);
-  int index = 0;
-  for (RelocIterator it(code, mask); !it.done(); it.next()) {
-    index++;
-    RelocInfo* rinfo = it.rinfo();
-    Address current_pc = rinfo->pc();
-    if (current_pc == pc) break;
-    DCHECK(current_pc < pc);
-  }
-  return index;
-}
-
-
-// Find the pc offset for the given continuation index.
-static int ComputePcOffsetFromContinuationIndex(Code* code, int index) {
-  DCHECK_EQ(code->kind(), Code::FUNCTION);
-  DCHECK(code->has_debug_break_slots());
-  int mask = RelocInfo::ModeMask(RelocInfo::GENERATOR_CONTINUATION);
-  RelocIterator it(code, mask);
-  for (int i = 1; i < index; i++) it.next();
-  return static_cast<int>(it.rinfo()->pc() - code->instruction_start());
-}
-
-
-class RedirectActiveFunctions : public ThreadVisitor {
- public:
-  explicit RedirectActiveFunctions(SharedFunctionInfo* shared)
-      : shared_(shared) {
-    DCHECK(shared->HasDebugCode());
-  }
-
-  void VisitThread(Isolate* isolate, ThreadLocalTop* top) {
-    for (JavaScriptFrameIterator it(isolate, top); !it.done(); it.Advance()) {
-      JavaScriptFrame* frame = it.frame();
-      JSFunction* function = frame->function();
-      if (frame->is_optimized()) continue;
-      if (!function->Inlines(shared_)) continue;
-
-      Code* frame_code = frame->LookupCode();
-      DCHECK(frame_code->kind() == Code::FUNCTION);
-      if (frame_code->has_debug_break_slots()) continue;
-
-      Code* new_code = function->shared()->code();
-      Address old_pc = frame->pc();
-      Address new_pc = ComputeNewPcForRedirect(new_code, frame_code, old_pc);
-
-      if (FLAG_trace_deopt) {
-        PrintF("Replacing pc for debugging: %08" V8PRIxPTR " => %08" V8PRIxPTR
-               "\n",
-               reinterpret_cast<intptr_t>(old_pc),
-               reinterpret_cast<intptr_t>(new_pc));
-      }
-
-      if (FLAG_enable_embedded_constant_pool) {
-        // Update constant pool pointer for new code.
-        frame->set_constant_pool(new_code->constant_pool());
-      }
-
-      // Patch the return address to return into the code with
-      // debug break slots.
-      frame->set_pc(new_pc);
-    }
-  }
-
- private:
-  SharedFunctionInfo* shared_;
-  DisallowHeapAllocation no_gc_;
-};
-
-
-bool Debug::PrepareFunctionForBreakPoints(Handle<SharedFunctionInfo> shared) {
-  DCHECK(shared->is_compiled());
-
-  if (isolate_->concurrent_recompilation_enabled()) {
-    isolate_->optimizing_compile_dispatcher()->Flush();
-  }
-
-  List<Handle<JSFunction> > functions;
-  List<Handle<JSGeneratorObject> > suspended_generators;
-
-  if (!shared->optimized_code_map()->IsSmi()) {
-    shared->ClearOptimizedCodeMap();
-  }
-
-  // Make sure we abort incremental marking.
-  isolate_->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask,
-                                      "prepare for break points");
-
-  {
-    HeapIterator iterator(isolate_->heap());
-    HeapObject* obj;
-    bool include_generators = shared->is_generator();
-
-    while ((obj = iterator.next())) {
-      if (obj->IsJSFunction()) {
-        JSFunction* function = JSFunction::cast(obj);
-        if (!function->Inlines(*shared)) continue;
-        if (function->code()->kind() == Code::OPTIMIZED_FUNCTION) {
-          Deoptimizer::DeoptimizeFunction(function);
-        }
-        if (function->shared() == *shared) functions.Add(handle(function));
-      } else if (include_generators && obj->IsJSGeneratorObject()) {
-        JSGeneratorObject* generator_obj = JSGeneratorObject::cast(obj);
-        if (!generator_obj->is_suspended()) continue;
-        JSFunction* function = generator_obj->function();
-        if (!function->Inlines(*shared)) continue;
-        int pc_offset = generator_obj->continuation();
-        int index =
-            ComputeContinuationIndexFromPcOffset(function->code(), pc_offset);
-        generator_obj->set_continuation(index);
-        suspended_generators.Add(handle(generator_obj));
-      }
-    }
-  }
-
-  if (!shared->HasDebugCode()) {
-    DCHECK(functions.length() > 0);
-    if (!Compiler::CompileDebugCode(functions.first())) return false;
-  }
-
-  for (Handle<JSFunction> const function : functions) {
-    function->ReplaceCode(shared->code());
-  }
-
-  for (Handle<JSGeneratorObject> const generator_obj : suspended_generators) {
-    int index = generator_obj->continuation();
-    int pc_offset = ComputePcOffsetFromContinuationIndex(shared->code(), index);
-    generator_obj->set_continuation(pc_offset);
-  }
-
-  // Update PCs on the stack to point to recompiled code.
-  RedirectActiveFunctions redirect_visitor(*shared);
-  redirect_visitor.VisitThread(isolate_, isolate_->thread_local_top());
-  isolate_->thread_manager()->IterateArchivedThreads(&redirect_visitor);
-
-  return true;
-}
-
-
-class SharedFunctionInfoFinder {
- public:
-  explicit SharedFunctionInfoFinder(int target_position)
-      : current_candidate_(NULL),
-        current_candidate_closure_(NULL),
-        current_start_position_(RelocInfo::kNoPosition),
-        target_position_(target_position) {}
-
-  void NewCandidate(SharedFunctionInfo* shared, JSFunction* closure = NULL) {
-    int start_position = shared->function_token_position();
-    if (start_position == RelocInfo::kNoPosition) {
-      start_position = shared->start_position();
-    }
-
-    if (start_position > target_position_) return;
-    if (target_position_ > shared->end_position()) return;
-
-    if (current_candidate_ != NULL) {
-      if (current_start_position_ == start_position &&
-          shared->end_position() == current_candidate_->end_position()) {
-        // If a top-level function contains only one function
-        // declaration the source for the top-level and the function
-        // is the same. In that case prefer the non top-level function.
-        if (shared->is_toplevel()) return;
-      } else if (start_position < current_start_position_ ||
-                 current_candidate_->end_position() < shared->end_position()) {
-        return;
-      }
-    }
-
-    current_start_position_ = start_position;
-    current_candidate_ = shared;
-    current_candidate_closure_ = closure;
-  }
-
-  SharedFunctionInfo* Result() { return current_candidate_; }
-
-  JSFunction* ResultClosure() { return current_candidate_closure_; }
-
- private:
-  SharedFunctionInfo* current_candidate_;
-  JSFunction* current_candidate_closure_;
-  int current_start_position_;
-  int target_position_;
-  DisallowHeapAllocation no_gc_;
-};
-
-
-// We need to find a SFI for a literal that may not yet have been compiled yet,
-// and there may not be a JSFunction referencing it. Find the SFI closest to
-// the given position, compile it to reveal possible inner SFIs and repeat.
-// While we are at this, also ensure code with debug break slots so that we do
-// not have to compile a SFI without JSFunction, which is paifu for those that
-// cannot be compiled without context (need to find outer compilable SFI etc.)
-Handle<Object> Debug::FindSharedFunctionInfoInScript(Handle<Script> script,
-                                                     int position) {
-  while (true) {
-    // Go through all shared function infos associated with this script to
-    // find the inner most function containing this position.
-    if (!script->shared_function_infos()->IsWeakFixedArray()) break;
-    WeakFixedArray* array =
-        WeakFixedArray::cast(script->shared_function_infos());
-
-    SharedFunctionInfo* shared;
-    {
-      SharedFunctionInfoFinder finder(position);
-      for (int i = 0; i < array->Length(); i++) {
-        Object* item = array->Get(i);
-        if (!item->IsSharedFunctionInfo()) continue;
-        finder.NewCandidate(SharedFunctionInfo::cast(item));
-      }
-      shared = finder.Result();
-      if (shared == NULL) break;
-      // We found it if it's already compiled and has debug code.
-      if (shared->HasDebugCode()) return handle(shared);
-    }
-    // If not, compile to reveal inner functions, if possible.
-    if (shared->allows_lazy_compilation_without_context()) {
-      HandleScope scope(isolate_);
-      if (!Compiler::CompileDebugCode(handle(shared))) break;
-      continue;
-    }
-
-    // If not possible, comb the heap for the best suitable compile target.
-    JSFunction* closure;
-    {
-      HeapIterator it(isolate_->heap());
-      SharedFunctionInfoFinder finder(position);
-      while (HeapObject* object = it.next()) {
-        JSFunction* candidate_closure = NULL;
-        SharedFunctionInfo* candidate = NULL;
-        if (object->IsJSFunction()) {
-          candidate_closure = JSFunction::cast(object);
-          candidate = candidate_closure->shared();
-        } else if (object->IsSharedFunctionInfo()) {
-          candidate = SharedFunctionInfo::cast(object);
-          if (!candidate->allows_lazy_compilation_without_context()) continue;
-        } else {
-          continue;
-        }
-        if (candidate->script() == *script) {
-          finder.NewCandidate(candidate, candidate_closure);
-        }
-      }
-      closure = finder.ResultClosure();
-      shared = finder.Result();
-    }
-    HandleScope scope(isolate_);
-    if (closure == NULL) {
-      if (!Compiler::CompileDebugCode(handle(shared))) break;
-    } else {
-      if (!Compiler::CompileDebugCode(handle(closure))) break;
-    }
-  }
-  return isolate_->factory()->undefined_value();
-}
-
-
-// Ensures the debug information is present for shared.
-bool Debug::EnsureDebugInfo(Handle<SharedFunctionInfo> shared,
-                            Handle<JSFunction> function) {
-  if (!shared->IsSubjectToDebugging()) return false;
-
-  // Return if we already have the debug info for shared.
-  if (shared->HasDebugInfo()) return true;
-
-  if (function.is_null()) {
-    DCHECK(shared->HasDebugCode());
-  } else if (!Compiler::EnsureCompiled(function, CLEAR_EXCEPTION)) {
-    return false;
-  }
-
-  if (!PrepareFunctionForBreakPoints(shared)) return false;
-
-  // Make sure IC state is clean. This is so that we correctly flood
-  // accessor pairs when stepping in.
-  shared->code()->ClearInlineCaches();
-  shared->feedback_vector()->ClearICSlots(*shared);
-
-  // Create the debug info object.
-  DCHECK(shared->HasDebugCode());
-  Handle<DebugInfo> debug_info = isolate_->factory()->NewDebugInfo(shared);
-
-  // Add debug info to the list.
-  DebugInfoListNode* node = new DebugInfoListNode(*debug_info);
-  node->set_next(debug_info_list_);
-  debug_info_list_ = node;
-
-  return true;
-}
-
-
-void Debug::RemoveDebugInfoAndClearFromShared(Handle<DebugInfo> debug_info) {
-  HandleScope scope(isolate_);
-  Handle<SharedFunctionInfo> shared(debug_info->shared());
-
-  DCHECK_NOT_NULL(debug_info_list_);
-  // Run through the debug info objects to find this one and remove it.
-  DebugInfoListNode* prev = NULL;
-  DebugInfoListNode* current = debug_info_list_;
-  while (current != NULL) {
-    if (current->debug_info().is_identical_to(debug_info)) {
-      // Unlink from list. If prev is NULL we are looking at the first element.
-      if (prev == NULL) {
-        debug_info_list_ = current->next();
-      } else {
-        prev->set_next(current->next());
-      }
-      delete current;
-      shared->set_debug_info(isolate_->heap()->undefined_value());
-      return;
-    }
-    // Move to next in list.
-    prev = current;
-    current = current->next();
-  }
-
-  UNREACHABLE();
-}
-
-
-void Debug::SetAfterBreakTarget(JavaScriptFrame* frame) {
-  after_break_target_ = NULL;
-
-  if (LiveEdit::SetAfterBreakTarget(this)) return;  // LiveEdit did the job.
-
-  // Continue just after the slot.
-  after_break_target_ = frame->pc();
-}
-
-
-bool Debug::IsBreakAtReturn(JavaScriptFrame* frame) {
-  HandleScope scope(isolate_);
-
-  // Get the executing function in which the debug break occurred.
-  Handle<JSFunction> function(JSFunction::cast(frame->function()));
-  Handle<SharedFunctionInfo> shared(function->shared());
-
-  // With no debug info there are no break points, so we can't be at a return.
-  if (!shared->HasDebugInfo()) return false;
-  Handle<DebugInfo> debug_info(shared->GetDebugInfo());
-  Handle<Code> code(debug_info->code());
-#ifdef DEBUG
-  // Get the code which is actually executing.
-  Handle<Code> frame_code(frame->LookupCode());
-  DCHECK(frame_code.is_identical_to(code));
-#endif
-
-  // Find the reloc info matching the start of the debug break slot.
-  Address slot_pc = frame->pc() - Assembler::kDebugBreakSlotLength;
-  int mask = RelocInfo::ModeMask(RelocInfo::DEBUG_BREAK_SLOT_AT_RETURN);
-  for (RelocIterator it(*code, mask); !it.done(); it.next()) {
-    if (it.rinfo()->pc() == slot_pc) return true;
-  }
-  return false;
-}
-
-
-void Debug::FramesHaveBeenDropped(StackFrame::Id new_break_frame_id,
-                                  LiveEdit::FrameDropMode mode,
-                                  Object** restarter_frame_function_pointer) {
-  if (mode != LiveEdit::CURRENTLY_SET_MODE) {
-    thread_local_.frame_drop_mode_ = mode;
-  }
-  thread_local_.break_frame_id_ = new_break_frame_id;
-  thread_local_.restarter_frame_function_pointer_ =
-      restarter_frame_function_pointer;
-}
-
-
-bool Debug::IsDebugGlobal(GlobalObject* global) {
-  return is_loaded() && global == debug_context()->global_object();
-}
-
-
-void Debug::ClearMirrorCache() {
-  PostponeInterruptsScope postpone(isolate_);
-  HandleScope scope(isolate_);
-  AssertDebugContext();
-  Factory* factory = isolate_->factory();
-  Handle<GlobalObject> global(isolate_->global_object());
-  JSObject::SetProperty(global,
-                        factory->NewStringFromAsciiChecked("next_handle_"),
-                        handle(Smi::FromInt(0), isolate_), SLOPPY).Check();
-  JSObject::SetProperty(global,
-                        factory->NewStringFromAsciiChecked("mirror_cache_"),
-                        factory->NewJSArray(0, FAST_ELEMENTS), SLOPPY).Check();
-}
-
-
-Handle<FixedArray> Debug::GetLoadedScripts() {
-  // Create and fill the script cache when the loaded scripts is requested for
-  // the first time.
-  if (script_cache_ == NULL) script_cache_ = new ScriptCache(isolate_);
-
-  // Perform GC to get unreferenced scripts evicted from the cache before
-  // returning the content.
-  isolate_->heap()->CollectAllGarbage(Heap::kNoGCFlags,
-                                      "Debug::GetLoadedScripts");
-
-  // Get the scripts from the cache.
-  return script_cache_->GetScripts();
-}
-
-
-void Debug::GetStepinPositions(JavaScriptFrame* frame, StackFrame::Id frame_id,
-                               List<int>* results_out) {
-  FrameSummary summary = GetFirstFrameSummary(frame);
-
-  Handle<JSFunction> fun = Handle<JSFunction>(summary.function());
-  Handle<SharedFunctionInfo> shared = Handle<SharedFunctionInfo>(fun->shared());
-
-  if (!EnsureDebugInfo(shared, fun)) return;
-
-  Handle<DebugInfo> debug_info(shared->GetDebugInfo());
-  // Refresh frame summary if the code has been recompiled for debugging.
-  if (shared->code() != *summary.code()) summary = GetFirstFrameSummary(frame);
-
-  // Find range of break points starting from the break point where execution
-  // has stopped.
-  Address call_pc = summary.pc() - 1;
-  List<BreakLocation> locations;
-  BreakLocation::FromAddressSameStatement(debug_info, ALL_BREAK_LOCATIONS,
-                                          call_pc, &locations);
-
-  for (BreakLocation location : locations) {
-    if (location.pc() <= summary.pc()) {
-      // The break point is near our pc. Could be a step-in possibility,
-      // that is currently taken by active debugger call.
-      if (break_frame_id() == StackFrame::NO_ID) {
-        continue;  // We are not stepping.
-      } else {
-        JavaScriptFrameIterator frame_it(isolate_, break_frame_id());
-        // If our frame is a top frame and we are stepping, we can do step-in
-        // at this place.
-        if (frame_it.frame()->id() != frame_id) continue;
-      }
-    }
-    if (location.IsStepInLocation()) results_out->Add(location.position());
-  }
-}
-
-
-void Debug::RecordEvalCaller(Handle<Script> script) {
-  script->set_compilation_type(Script::COMPILATION_TYPE_EVAL);
-  // For eval scripts add information on the function from which eval was
-  // called.
-  StackTraceFrameIterator it(script->GetIsolate());
-  if (!it.done()) {
-    script->set_eval_from_shared(it.frame()->function()->shared());
-    Code* code = it.frame()->LookupCode();
-    int offset = static_cast<int>(
-        it.frame()->pc() - code->instruction_start());
-    script->set_eval_from_instructions_offset(Smi::FromInt(offset));
-  }
-}
-
-
-MaybeHandle<Object> Debug::MakeJSObject(const char* constructor_name,
-                                        int argc,
-                                        Handle<Object> argv[]) {
-  AssertDebugContext();
-  // Create the execution state object.
-  Handle<GlobalObject> global(isolate_->global_object());
-  Handle<Object> constructor = Object::GetProperty(
-      isolate_, global, constructor_name).ToHandleChecked();
-  DCHECK(constructor->IsJSFunction());
-  if (!constructor->IsJSFunction()) return MaybeHandle<Object>();
-  // We do not handle interrupts here.  In particular, termination interrupts.
-  PostponeInterruptsScope no_interrupts(isolate_);
-  return Execution::TryCall(Handle<JSFunction>::cast(constructor),
-                            handle(debug_context()->global_proxy()),
-                            argc,
-                            argv);
-}
-
-
-MaybeHandle<Object> Debug::MakeExecutionState() {
-  // Create the execution state object.
-  Handle<Object> argv[] = { isolate_->factory()->NewNumberFromInt(break_id()) };
-  return MakeJSObject("MakeExecutionState", arraysize(argv), argv);
-}
-
-
-MaybeHandle<Object> Debug::MakeBreakEvent(Handle<Object> break_points_hit) {
-  // Create the new break event object.
-  Handle<Object> argv[] = { isolate_->factory()->NewNumberFromInt(break_id()),
-                            break_points_hit };
-  return MakeJSObject("MakeBreakEvent", arraysize(argv), argv);
-}
-
-
-MaybeHandle<Object> Debug::MakeExceptionEvent(Handle<Object> exception,
-                                              bool uncaught,
-                                              Handle<Object> promise) {
-  // Create the new exception event object.
-  Handle<Object> argv[] = { isolate_->factory()->NewNumberFromInt(break_id()),
-                            exception,
-                            isolate_->factory()->ToBoolean(uncaught),
-                            promise };
-  return MakeJSObject("MakeExceptionEvent", arraysize(argv), argv);
-}
-
-
-MaybeHandle<Object> Debug::MakeCompileEvent(Handle<Script> script,
-                                            v8::DebugEvent type) {
-  // Create the compile event object.
-  Handle<Object> script_wrapper = Script::GetWrapper(script);
-  Handle<Object> argv[] = { script_wrapper,
-                            isolate_->factory()->NewNumberFromInt(type) };
-  return MakeJSObject("MakeCompileEvent", arraysize(argv), argv);
-}
-
-
-MaybeHandle<Object> Debug::MakePromiseEvent(Handle<JSObject> event_data) {
-  // Create the promise event object.
-  Handle<Object> argv[] = { event_data };
-  return MakeJSObject("MakePromiseEvent", arraysize(argv), argv);
-}
-
-
-MaybeHandle<Object> Debug::MakeAsyncTaskEvent(Handle<JSObject> task_event) {
-  // Create the async task event object.
-  Handle<Object> argv[] = { task_event };
-  return MakeJSObject("MakeAsyncTaskEvent", arraysize(argv), argv);
-}
-
-
-void Debug::OnThrow(Handle<Object> exception) {
-  if (in_debug_scope() || ignore_events()) return;
-  // Temporarily clear any scheduled_exception to allow evaluating
-  // JavaScript from the debug event handler.
-  HandleScope scope(isolate_);
-  Handle<Object> scheduled_exception;
-  if (isolate_->has_scheduled_exception()) {
-    scheduled_exception = handle(isolate_->scheduled_exception(), isolate_);
-    isolate_->clear_scheduled_exception();
-  }
-  OnException(exception, isolate_->GetPromiseOnStackOnThrow());
-  if (!scheduled_exception.is_null()) {
-    isolate_->thread_local_top()->scheduled_exception_ = *scheduled_exception;
-  }
-}
-
-
-void Debug::OnPromiseReject(Handle<JSObject> promise, Handle<Object> value) {
-  if (in_debug_scope() || ignore_events()) return;
-  HandleScope scope(isolate_);
-  // Check whether the promise has been marked as having triggered a message.
-  Handle<Symbol> key = isolate_->factory()->promise_debug_marker_symbol();
-  if (JSReceiver::GetDataProperty(promise, key)->IsUndefined()) {
-    OnException(value, promise);
-  }
-}
-
-
-MaybeHandle<Object> Debug::PromiseHasUserDefinedRejectHandler(
-    Handle<JSObject> promise) {
-  Handle<JSFunction> fun = Handle<JSFunction>::cast(
-      JSReceiver::GetDataProperty(isolate_->js_builtins_object(),
-                                  isolate_->factory()->NewStringFromStaticChars(
-                                      "$promiseHasUserDefinedRejectHandler")));
-  return Execution::Call(isolate_, fun, promise, 0, NULL);
-}
-
-
-void Debug::OnException(Handle<Object> exception, Handle<Object> promise) {
-  // In our prediction, try-finally is not considered to catch.
-  Isolate::CatchType catch_type = isolate_->PredictExceptionCatcher();
-  bool uncaught = (catch_type == Isolate::NOT_CAUGHT);
-  if (promise->IsJSObject()) {
-    Handle<JSObject> jspromise = Handle<JSObject>::cast(promise);
-    // Mark the promise as already having triggered a message.
-    Handle<Symbol> key = isolate_->factory()->promise_debug_marker_symbol();
-    JSObject::SetProperty(jspromise, key, key, STRICT).Assert();
-    // Check whether the promise reject is considered an uncaught exception.
-    Handle<Object> has_reject_handler;
-    ASSIGN_RETURN_ON_EXCEPTION_VALUE(
-        isolate_, has_reject_handler,
-        PromiseHasUserDefinedRejectHandler(jspromise), /* void */);
-    uncaught = has_reject_handler->IsFalse();
-  }
-  // Bail out if exception breaks are not active
-  if (uncaught) {
-    // Uncaught exceptions are reported by either flags.
-    if (!(break_on_uncaught_exception_ || break_on_exception_)) return;
-  } else {
-    // Caught exceptions are reported is activated.
-    if (!break_on_exception_) return;
-  }
-
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return;
-
-  // Clear all current stepping setup.
-  ClearStepping();
-
-  // Create the event data object.
-  Handle<Object> event_data;
-  // Bail out and don't call debugger if exception.
-  if (!MakeExceptionEvent(
-          exception, uncaught, promise).ToHandle(&event_data)) {
-    return;
-  }
-
-  // Process debug event.
-  ProcessDebugEvent(v8::Exception, Handle<JSObject>::cast(event_data), false);
-  // Return to continue execution from where the exception was thrown.
-}
-
-
-void Debug::OnCompileError(Handle<Script> script) {
-  if (ignore_events()) return;
-
-  if (in_debug_scope()) {
-    ProcessCompileEventInDebugScope(v8::CompileError, script);
-    return;
-  }
-
-  HandleScope scope(isolate_);
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return;
-
-  // Create the compile state object.
-  Handle<Object> event_data;
-  // Bail out and don't call debugger if exception.
-  if (!MakeCompileEvent(script, v8::CompileError).ToHandle(&event_data)) return;
-
-  // Process debug event.
-  ProcessDebugEvent(v8::CompileError, Handle<JSObject>::cast(event_data), true);
-}
-
-
-void Debug::OnDebugBreak(Handle<Object> break_points_hit,
-                            bool auto_continue) {
-  // The caller provided for DebugScope.
-  AssertDebugContext();
-  // Bail out if there is no listener for this event
-  if (ignore_events()) return;
-
-  HandleScope scope(isolate_);
-  // Create the event data object.
-  Handle<Object> event_data;
-  // Bail out and don't call debugger if exception.
-  if (!MakeBreakEvent(break_points_hit).ToHandle(&event_data)) return;
-
-  // Process debug event.
-  ProcessDebugEvent(v8::Break,
-                    Handle<JSObject>::cast(event_data),
-                    auto_continue);
-}
-
-
-void Debug::OnBeforeCompile(Handle<Script> script) {
-  if (in_debug_scope() || ignore_events()) return;
-
-  HandleScope scope(isolate_);
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return;
-
-  // Create the event data object.
-  Handle<Object> event_data;
-  // Bail out and don't call debugger if exception.
-  if (!MakeCompileEvent(script, v8::BeforeCompile).ToHandle(&event_data))
-    return;
-
-  // Process debug event.
-  ProcessDebugEvent(v8::BeforeCompile,
-                    Handle<JSObject>::cast(event_data),
-                    true);
-}
-
-
-// Handle debugger actions when a new script is compiled.
-void Debug::OnAfterCompile(Handle<Script> script) {
-  // Add the newly compiled script to the script cache.
-  if (script_cache_ != NULL) script_cache_->Add(script);
-
-  if (ignore_events()) return;
-
-  if (in_debug_scope()) {
-    ProcessCompileEventInDebugScope(v8::AfterCompile, script);
-    return;
-  }
-
-  HandleScope scope(isolate_);
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return;
-
-  // If debugging there might be script break points registered for this
-  // script. Make sure that these break points are set.
-
-  // Get the function UpdateScriptBreakPoints (defined in debug-debugger.js).
-  Handle<String> update_script_break_points_string =
-      isolate_->factory()->InternalizeOneByteString(
-          STATIC_CHAR_VECTOR("UpdateScriptBreakPoints"));
-  Handle<GlobalObject> debug_global(debug_context()->global_object());
-  Handle<Object> update_script_break_points =
-      Object::GetProperty(
-          debug_global, update_script_break_points_string).ToHandleChecked();
-  if (!update_script_break_points->IsJSFunction()) {
-    return;
-  }
-  DCHECK(update_script_break_points->IsJSFunction());
-
-  // Wrap the script object in a proper JS object before passing it
-  // to JavaScript.
-  Handle<Object> wrapper = Script::GetWrapper(script);
-
-  // Call UpdateScriptBreakPoints expect no exceptions.
-  Handle<Object> argv[] = { wrapper };
-  if (Execution::TryCall(Handle<JSFunction>::cast(update_script_break_points),
-                         isolate_->js_builtins_object(),
-                         arraysize(argv),
-                         argv).is_null()) {
-    return;
-  }
-
-  // Create the compile state object.
-  Handle<Object> event_data;
-  // Bail out and don't call debugger if exception.
-  if (!MakeCompileEvent(script, v8::AfterCompile).ToHandle(&event_data)) return;
-
-  // Process debug event.
-  ProcessDebugEvent(v8::AfterCompile, Handle<JSObject>::cast(event_data), true);
-}
-
-
-void Debug::OnPromiseEvent(Handle<JSObject> data) {
-  if (in_debug_scope() || ignore_events()) return;
-
-  HandleScope scope(isolate_);
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return;
-
-  // Create the script collected state object.
-  Handle<Object> event_data;
-  // Bail out and don't call debugger if exception.
-  if (!MakePromiseEvent(data).ToHandle(&event_data)) return;
-
-  // Process debug event.
-  ProcessDebugEvent(v8::PromiseEvent,
-                    Handle<JSObject>::cast(event_data),
-                    true);
-}
-
-
-void Debug::OnAsyncTaskEvent(Handle<JSObject> data) {
-  if (in_debug_scope() || ignore_events()) return;
-
-  HandleScope scope(isolate_);
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return;
-
-  // Create the script collected state object.
-  Handle<Object> event_data;
-  // Bail out and don't call debugger if exception.
-  if (!MakeAsyncTaskEvent(data).ToHandle(&event_data)) return;
-
-  // Process debug event.
-  ProcessDebugEvent(v8::AsyncTaskEvent,
-                    Handle<JSObject>::cast(event_data),
-                    true);
-}
-
-
-void Debug::ProcessDebugEvent(v8::DebugEvent event,
-                              Handle<JSObject> event_data,
-                              bool auto_continue) {
-  HandleScope scope(isolate_);
-
-  // Create the execution state.
-  Handle<Object> exec_state;
-  // Bail out and don't call debugger if exception.
-  if (!MakeExecutionState().ToHandle(&exec_state)) return;
-
-  // First notify the message handler if any.
-  if (message_handler_ != NULL) {
-    NotifyMessageHandler(event,
-                         Handle<JSObject>::cast(exec_state),
-                         event_data,
-                         auto_continue);
-  }
-  // Notify registered debug event listener. This can be either a C or
-  // a JavaScript function. Don't call event listener for v8::Break
-  // here, if it's only a debug command -- they will be processed later.
-  if ((event != v8::Break || !auto_continue) && !event_listener_.is_null()) {
-    CallEventCallback(event, exec_state, event_data, NULL);
-  }
-}
-
-
-void Debug::CallEventCallback(v8::DebugEvent event,
-                              Handle<Object> exec_state,
-                              Handle<Object> event_data,
-                              v8::Debug::ClientData* client_data) {
-  bool previous = in_debug_event_listener_;
-  in_debug_event_listener_ = true;
-  if (event_listener_->IsForeign()) {
-    // Invoke the C debug event listener.
-    v8::Debug::EventCallback callback =
-        FUNCTION_CAST<v8::Debug::EventCallback>(
-            Handle<Foreign>::cast(event_listener_)->foreign_address());
-    EventDetailsImpl event_details(event,
-                                   Handle<JSObject>::cast(exec_state),
-                                   Handle<JSObject>::cast(event_data),
-                                   event_listener_data_,
-                                   client_data);
-    callback(event_details);
-    DCHECK(!isolate_->has_scheduled_exception());
-  } else {
-    // Invoke the JavaScript debug event listener.
-    DCHECK(event_listener_->IsJSFunction());
-    Handle<Object> argv[] = { Handle<Object>(Smi::FromInt(event), isolate_),
-                              exec_state,
-                              event_data,
-                              event_listener_data_ };
-    Handle<JSReceiver> global(isolate_->global_proxy());
-    Execution::TryCall(Handle<JSFunction>::cast(event_listener_),
-                       global, arraysize(argv), argv);
-  }
-  in_debug_event_listener_ = previous;
-}
-
-
-void Debug::ProcessCompileEventInDebugScope(v8::DebugEvent event,
-                                            Handle<Script> script) {
-  if (event_listener_.is_null()) return;
-
-  SuppressDebug while_processing(this);
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return;
-
-  Handle<Object> event_data;
-  // Bail out and don't call debugger if exception.
-  if (!MakeCompileEvent(script, event).ToHandle(&event_data)) return;
-
-  // Create the execution state.
-  Handle<Object> exec_state;
-  // Bail out and don't call debugger if exception.
-  if (!MakeExecutionState().ToHandle(&exec_state)) return;
-
-  CallEventCallback(event, exec_state, event_data, NULL);
-}
-
-
-Handle<Context> Debug::GetDebugContext() {
-  if (!is_loaded()) return Handle<Context>();
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return Handle<Context>();
-  // The global handle may be destroyed soon after.  Return it reboxed.
-  return handle(*debug_context(), isolate_);
-}
-
-
-void Debug::NotifyMessageHandler(v8::DebugEvent event,
-                                 Handle<JSObject> exec_state,
-                                 Handle<JSObject> event_data,
-                                 bool auto_continue) {
-  // Prevent other interrupts from triggering, for example API callbacks,
-  // while dispatching message handler callbacks.
-  PostponeInterruptsScope no_interrupts(isolate_);
-  DCHECK(is_active_);
-  HandleScope scope(isolate_);
-  // Process the individual events.
-  bool sendEventMessage = false;
-  switch (event) {
-    case v8::Break:
-      sendEventMessage = !auto_continue;
-      break;
-    case v8::NewFunction:
-    case v8::BeforeCompile:
-    case v8::CompileError:
-    case v8::PromiseEvent:
-    case v8::AsyncTaskEvent:
-      break;
-    case v8::Exception:
-    case v8::AfterCompile:
-      sendEventMessage = true;
-      break;
-  }
-
-  // The debug command interrupt flag might have been set when the command was
-  // added. It should be enough to clear the flag only once while we are in the
-  // debugger.
-  DCHECK(in_debug_scope());
-  isolate_->stack_guard()->ClearDebugCommand();
-
-  // Notify the debugger that a debug event has occurred unless auto continue is
-  // active in which case no event is send.
-  if (sendEventMessage) {
-    MessageImpl message = MessageImpl::NewEvent(
-        event,
-        auto_continue,
-        Handle<JSObject>::cast(exec_state),
-        Handle<JSObject>::cast(event_data));
-    InvokeMessageHandler(message);
-  }
-
-  // If auto continue don't make the event cause a break, but process messages
-  // in the queue if any. For script collected events don't even process
-  // messages in the queue as the execution state might not be what is expected
-  // by the client.
-  if (auto_continue && !has_commands()) return;
-
-  // DebugCommandProcessor goes here.
-  bool running = auto_continue;
-
-  Handle<Object> cmd_processor_ctor = Object::GetProperty(
-      isolate_, exec_state, "debugCommandProcessor").ToHandleChecked();
-  Handle<Object> ctor_args[] = { isolate_->factory()->ToBoolean(running) };
-  Handle<Object> cmd_processor = Execution::Call(
-      isolate_, cmd_processor_ctor, exec_state, 1, ctor_args).ToHandleChecked();
-  Handle<JSFunction> process_debug_request = Handle<JSFunction>::cast(
-      Object::GetProperty(
-          isolate_, cmd_processor, "processDebugRequest").ToHandleChecked());
-  Handle<Object> is_running = Object::GetProperty(
-      isolate_, cmd_processor, "isRunning").ToHandleChecked();
-
-  // Process requests from the debugger.
-  do {
-    // Wait for new command in the queue.
-    command_received_.Wait();
-
-    // Get the command from the queue.
-    CommandMessage command = command_queue_.Get();
-    isolate_->logger()->DebugTag(
-        "Got request from command queue, in interactive loop.");
-    if (!is_active()) {
-      // Delete command text and user data.
-      command.Dispose();
-      return;
-    }
-
-    Vector<const uc16> command_text(
-        const_cast<const uc16*>(command.text().start()),
-        command.text().length());
-    Handle<String> request_text = isolate_->factory()->NewStringFromTwoByte(
-        command_text).ToHandleChecked();
-    Handle<Object> request_args[] = { request_text };
-    Handle<Object> answer_value;
-    Handle<String> answer;
-    MaybeHandle<Object> maybe_exception;
-    MaybeHandle<Object> maybe_result =
-        Execution::TryCall(process_debug_request, cmd_processor, 1,
-                           request_args, &maybe_exception);
-
-    if (maybe_result.ToHandle(&answer_value)) {
-      if (answer_value->IsUndefined()) {
-        answer = isolate_->factory()->empty_string();
-      } else {
-        answer = Handle<String>::cast(answer_value);
-      }
-
-      // Log the JSON request/response.
-      if (FLAG_trace_debug_json) {
-        PrintF("%s\n", request_text->ToCString().get());
-        PrintF("%s\n", answer->ToCString().get());
-      }
-
-      Handle<Object> is_running_args[] = { answer };
-      maybe_result = Execution::Call(
-          isolate_, is_running, cmd_processor, 1, is_running_args);
-      Handle<Object> result;
-      if (!maybe_result.ToHandle(&result)) break;
-      running = result->IsTrue();
-    } else {
-      Handle<Object> exception;
-      if (!maybe_exception.ToHandle(&exception)) break;
-      Handle<Object> result;
-      if (!Execution::ToString(isolate_, exception).ToHandle(&result)) break;
-      answer = Handle<String>::cast(result);
-    }
-
-    // Return the result.
-    MessageImpl message = MessageImpl::NewResponse(
-        event, running, exec_state, event_data, answer, command.client_data());
-    InvokeMessageHandler(message);
-    command.Dispose();
-
-    // Return from debug event processing if either the VM is put into the
-    // running state (through a continue command) or auto continue is active
-    // and there are no more commands queued.
-  } while (!running || has_commands());
-  command_queue_.Clear();
-}
-
-
-void Debug::SetEventListener(Handle<Object> callback,
-                             Handle<Object> data) {
-  GlobalHandles* global_handles = isolate_->global_handles();
-
-  // Remove existing entry.
-  GlobalHandles::Destroy(event_listener_.location());
-  event_listener_ = Handle<Object>();
-  GlobalHandles::Destroy(event_listener_data_.location());
-  event_listener_data_ = Handle<Object>();
-
-  // Set new entry.
-  if (!callback->IsUndefined() && !callback->IsNull()) {
-    event_listener_ = global_handles->Create(*callback);
-    if (data.is_null()) data = isolate_->factory()->undefined_value();
-    event_listener_data_ = global_handles->Create(*data);
-  }
-
-  UpdateState();
-}
-
-
-void Debug::SetMessageHandler(v8::Debug::MessageHandler handler) {
-  message_handler_ = handler;
-  UpdateState();
-  if (handler == NULL && in_debug_scope()) {
-    // Send an empty command to the debugger if in a break to make JavaScript
-    // run again if the debugger is closed.
-    EnqueueCommandMessage(Vector<const uint16_t>::empty());
-  }
-}
-
-
-
-void Debug::UpdateState() {
-  bool is_active = message_handler_ != NULL || !event_listener_.is_null();
-  if (is_active || in_debug_scope()) {
-    // Note that the debug context could have already been loaded to
-    // bootstrap test cases.
-    isolate_->compilation_cache()->Disable();
-    is_active = Load();
-  } else if (is_loaded()) {
-    isolate_->compilation_cache()->Enable();
-    Unload();
-  }
-  is_active_ = is_active;
-}
-
-
-// Calls the registered debug message handler. This callback is part of the
-// public API.
-void Debug::InvokeMessageHandler(MessageImpl message) {
-  if (message_handler_ != NULL) message_handler_(message);
-}
-
-
-// Puts a command coming from the public API on the queue.  Creates
-// a copy of the command string managed by the debugger.  Up to this
-// point, the command data was managed by the API client.  Called
-// by the API client thread.
-void Debug::EnqueueCommandMessage(Vector<const uint16_t> command,
-                                  v8::Debug::ClientData* client_data) {
-  // Need to cast away const.
-  CommandMessage message = CommandMessage::New(
-      Vector<uint16_t>(const_cast<uint16_t*>(command.start()),
-                       command.length()),
-      client_data);
-  isolate_->logger()->DebugTag("Put command on command_queue.");
-  command_queue_.Put(message);
-  command_received_.Signal();
-
-  // Set the debug command break flag to have the command processed.
-  if (!in_debug_scope()) isolate_->stack_guard()->RequestDebugCommand();
-}
-
-
-MaybeHandle<Object> Debug::Call(Handle<JSFunction> fun, Handle<Object> data) {
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return isolate_->factory()->undefined_value();
-
-  // Create the execution state.
-  Handle<Object> exec_state;
-  if (!MakeExecutionState().ToHandle(&exec_state)) {
-    return isolate_->factory()->undefined_value();
-  }
-
-  Handle<Object> argv[] = { exec_state, data };
-  return Execution::Call(
-      isolate_,
-      fun,
-      Handle<Object>(debug_context()->global_proxy(), isolate_),
-      arraysize(argv),
-      argv);
-}
-
-
-void Debug::HandleDebugBreak() {
-  // Ignore debug break during bootstrapping.
-  if (isolate_->bootstrapper()->IsActive()) return;
-  // Just continue if breaks are disabled.
-  if (break_disabled()) return;
-  // Ignore debug break if debugger is not active.
-  if (!is_active()) return;
-
-  StackLimitCheck check(isolate_);
-  if (check.HasOverflowed()) return;
-
-  { JavaScriptFrameIterator it(isolate_);
-    DCHECK(!it.done());
-    Object* fun = it.frame()->function();
-    if (fun && fun->IsJSFunction()) {
-      // Don't stop in builtin functions.
-      if (JSFunction::cast(fun)->IsBuiltin()) return;
-      GlobalObject* global = JSFunction::cast(fun)->context()->global_object();
-      // Don't stop in debugger functions.
-      if (IsDebugGlobal(global)) return;
-    }
-  }
-
-  // Collect the break state before clearing the flags.
-  bool debug_command_only = isolate_->stack_guard()->CheckDebugCommand() &&
-                            !isolate_->stack_guard()->CheckDebugBreak();
-
-  isolate_->stack_guard()->ClearDebugBreak();
-
-  ProcessDebugMessages(debug_command_only);
-}
-
-
-void Debug::ProcessDebugMessages(bool debug_command_only) {
-  isolate_->stack_guard()->ClearDebugCommand();
-
-  StackLimitCheck check(isolate_);
-  if (check.HasOverflowed()) return;
-
-  HandleScope scope(isolate_);
-  DebugScope debug_scope(this);
-  if (debug_scope.failed()) return;
-
-  // Notify the debug event listeners. Indicate auto continue if the break was
-  // a debug command break.
-  OnDebugBreak(isolate_->factory()->undefined_value(), debug_command_only);
-}
-
-
-DebugScope::DebugScope(Debug* debug)
-    : debug_(debug),
-      prev_(debug->debugger_entry()),
-      save_(debug_->isolate_),
-      no_termination_exceptons_(debug_->isolate_,
-                                StackGuard::TERMINATE_EXECUTION) {
-  // Link recursive debugger entry.
-  base::NoBarrier_Store(&debug_->thread_local_.current_debug_scope_,
-                        reinterpret_cast<base::AtomicWord>(this));
-
-  // Store the previous break id and frame id.
-  break_id_ = debug_->break_id();
-  break_frame_id_ = debug_->break_frame_id();
-
-  // Create the new break info. If there is no JavaScript frames there is no
-  // break frame id.
-  JavaScriptFrameIterator it(isolate());
-  bool has_js_frames = !it.done();
-  debug_->thread_local_.break_frame_id_ = has_js_frames ? it.frame()->id()
-                                                        : StackFrame::NO_ID;
-  debug_->SetNextBreakId();
-
-  debug_->UpdateState();
-  // Make sure that debugger is loaded and enter the debugger context.
-  // The previous context is kept in save_.
-  failed_ = !debug_->is_loaded();
-  if (!failed_) isolate()->set_context(*debug->debug_context());
-}
-
-
-
-DebugScope::~DebugScope() {
-  if (!failed_ && prev_ == NULL) {
-    // Clear mirror cache when leaving the debugger. Skip this if there is a
-    // pending exception as clearing the mirror cache calls back into
-    // JavaScript. This can happen if the v8::Debug::Call is used in which
-    // case the exception should end up in the calling code.
-    if (!isolate()->has_pending_exception()) debug_->ClearMirrorCache();
-
-    // If there are commands in the queue when leaving the debugger request
-    // that these commands are processed.
-    if (debug_->has_commands()) isolate()->stack_guard()->RequestDebugCommand();
-  }
-
-  // Leaving this debugger entry.
-  base::NoBarrier_Store(&debug_->thread_local_.current_debug_scope_,
-                        reinterpret_cast<base::AtomicWord>(prev_));
-
-  // Restore to the previous break state.
-  debug_->thread_local_.break_frame_id_ = break_frame_id_;
-  debug_->thread_local_.break_id_ = break_id_;
-
-  debug_->UpdateState();
-}
-
-
-MessageImpl MessageImpl::NewEvent(DebugEvent event,
-                                  bool running,
-                                  Handle<JSObject> exec_state,
-                                  Handle<JSObject> event_data) {
-  MessageImpl message(true, event, running,
-                      exec_state, event_data, Handle<String>(), NULL);
-  return message;
-}
-
-
-MessageImpl MessageImpl::NewResponse(DebugEvent event,
-                                     bool running,
-                                     Handle<JSObject> exec_state,
-                                     Handle<JSObject> event_data,
-                                     Handle<String> response_json,
-                                     v8::Debug::ClientData* client_data) {
-  MessageImpl message(false, event, running,
-                      exec_state, event_data, response_json, client_data);
-  return message;
-}
-
-
-MessageImpl::MessageImpl(bool is_event,
-                         DebugEvent event,
-                         bool running,
-                         Handle<JSObject> exec_state,
-                         Handle<JSObject> event_data,
-                         Handle<String> response_json,
-                         v8::Debug::ClientData* client_data)
-    : is_event_(is_event),
-      event_(event),
-      running_(running),
-      exec_state_(exec_state),
-      event_data_(event_data),
-      response_json_(response_json),
-      client_data_(client_data) {}
-
-
-bool MessageImpl::IsEvent() const {
-  return is_event_;
-}
-
-
-bool MessageImpl::IsResponse() const {
-  return !is_event_;
-}
-
-
-DebugEvent MessageImpl::GetEvent() const {
-  return event_;
-}
-
-
-bool MessageImpl::WillStartRunning() const {
-  return running_;
-}
-
-
-v8::Local<v8::Object> MessageImpl::GetExecutionState() const {
-  return v8::Utils::ToLocal(exec_state_);
-}
-
-
-v8::Isolate* MessageImpl::GetIsolate() const {
-  return reinterpret_cast<v8::Isolate*>(exec_state_->GetIsolate());
-}
-
-
-v8::Local<v8::Object> MessageImpl::GetEventData() const {
-  return v8::Utils::ToLocal(event_data_);
-}
-
-
-v8::Local<v8::String> MessageImpl::GetJSON() const {
-  Isolate* isolate = event_data_->GetIsolate();
-  v8::EscapableHandleScope scope(reinterpret_cast<v8::Isolate*>(isolate));
-
-  if (IsEvent()) {
-    // Call toJSONProtocol on the debug event object.
-    Handle<Object> fun = Object::GetProperty(
-        isolate, event_data_, "toJSONProtocol").ToHandleChecked();
-    if (!fun->IsJSFunction()) {
-      return v8::Local<v8::String>();
-    }
-
-    MaybeHandle<Object> maybe_json =
-        Execution::TryCall(Handle<JSFunction>::cast(fun), event_data_, 0, NULL);
-    Handle<Object> json;
-    if (!maybe_json.ToHandle(&json) || !json->IsString()) {
-      return v8::Local<v8::String>();
-    }
-    return scope.Escape(v8::Utils::ToLocal(Handle<String>::cast(json)));
-  } else {
-    return v8::Utils::ToLocal(response_json_);
-  }
-}
-
-
-v8::Local<v8::Context> MessageImpl::GetEventContext() const {
-  Isolate* isolate = event_data_->GetIsolate();
-  v8::Local<v8::Context> context = GetDebugEventContext(isolate);
-  // Isolate::context() may be NULL when "script collected" event occurs.
-  DCHECK(!context.IsEmpty());
-  return context;
-}
-
-
-v8::Debug::ClientData* MessageImpl::GetClientData() const {
-  return client_data_;
-}
-
-
-EventDetailsImpl::EventDetailsImpl(DebugEvent event,
-                                   Handle<JSObject> exec_state,
-                                   Handle<JSObject> event_data,
-                                   Handle<Object> callback_data,
-                                   v8::Debug::ClientData* client_data)
-    : event_(event),
-      exec_state_(exec_state),
-      event_data_(event_data),
-      callback_data_(callback_data),
-      client_data_(client_data) {}
-
-
-DebugEvent EventDetailsImpl::GetEvent() const {
-  return event_;
-}
-
-
-v8::Local<v8::Object> EventDetailsImpl::GetExecutionState() const {
-  return v8::Utils::ToLocal(exec_state_);
-}
-
-
-v8::Local<v8::Object> EventDetailsImpl::GetEventData() const {
-  return v8::Utils::ToLocal(event_data_);
-}
-
-
-v8::Local<v8::Context> EventDetailsImpl::GetEventContext() const {
-  return GetDebugEventContext(exec_state_->GetIsolate());
-}
-
-
-v8::Local<v8::Value> EventDetailsImpl::GetCallbackData() const {
-  return v8::Utils::ToLocal(callback_data_);
-}
-
-
-v8::Debug::ClientData* EventDetailsImpl::GetClientData() const {
-  return client_data_;
-}
-
-
-CommandMessage::CommandMessage() : text_(Vector<uint16_t>::empty()),
-                                   client_data_(NULL) {
-}
-
-
-CommandMessage::CommandMessage(const Vector<uint16_t>& text,
-                               v8::Debug::ClientData* data)
-    : text_(text),
-      client_data_(data) {
-}
-
-
-void CommandMessage::Dispose() {
-  text_.Dispose();
-  delete client_data_;
-  client_data_ = NULL;
-}
-
-
-CommandMessage CommandMessage::New(const Vector<uint16_t>& command,
-                                   v8::Debug::ClientData* data) {
-  return CommandMessage(command.Clone(), data);
-}
-
-
-CommandMessageQueue::CommandMessageQueue(int size) : start_(0), end_(0),
-                                                     size_(size) {
-  messages_ = NewArray<CommandMessage>(size);
-}
-
-
-CommandMessageQueue::~CommandMessageQueue() {
-  while (!IsEmpty()) Get().Dispose();
-  DeleteArray(messages_);
-}
-
-
-CommandMessage CommandMessageQueue::Get() {
-  DCHECK(!IsEmpty());
-  int result = start_;
-  start_ = (start_ + 1) % size_;
-  return messages_[result];
-}
-
-
-void CommandMessageQueue::Put(const CommandMessage& message) {
-  if ((end_ + 1) % size_ == start_) {
-    Expand();
-  }
-  messages_[end_] = message;
-  end_ = (end_ + 1) % size_;
-}
-
-
-void CommandMessageQueue::Expand() {
-  CommandMessageQueue new_queue(size_ * 2);
-  while (!IsEmpty()) {
-    new_queue.Put(Get());
-  }
-  CommandMessage* array_to_free = messages_;
-  *this = new_queue;
-  new_queue.messages_ = array_to_free;
-  // Make the new_queue empty so that it doesn't call Dispose on any messages.
-  new_queue.start_ = new_queue.end_;
-  // Automatic destructor called on new_queue, freeing array_to_free.
-}
-
-
-LockingCommandMessageQueue::LockingCommandMessageQueue(Logger* logger, int size)
-    : logger_(logger), queue_(size) {}
-
-
-bool LockingCommandMessageQueue::IsEmpty() const {
-  base::LockGuard<base::Mutex> lock_guard(&mutex_);
-  return queue_.IsEmpty();
-}
-
-
-CommandMessage LockingCommandMessageQueue::Get() {
-  base::LockGuard<base::Mutex> lock_guard(&mutex_);
-  CommandMessage result = queue_.Get();
-  logger_->DebugEvent("Get", result.text());
-  return result;
-}
-
-
-void LockingCommandMessageQueue::Put(const CommandMessage& message) {
-  base::LockGuard<base::Mutex> lock_guard(&mutex_);
-  queue_.Put(message);
-  logger_->DebugEvent("Put", message.text());
-}
-
-
-void LockingCommandMessageQueue::Clear() {
-  base::LockGuard<base::Mutex> lock_guard(&mutex_);
-  queue_.Clear();
-}
-
-}  // namespace internal
-}  // namespace v8