Isolates cleanup: move top.cc to isolate.cc.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 48717021d7f75e8b5eb304ab2eaa14c39ae9e692..9fac06a9f2fb650671e2776e93e95e3036b4b2ab 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -40,6 +40,7 @@
 #include "isolate.h"
 #include "lithium-allocator.h"
 #include "log.h"
+#include "messages.h"
 #include "regexp-stack.h"
 #include "runtime-profiler.h"
 #include "scanner.h"
@@ -49,6 +50,7 @@
 #include "spaces.h"
 #include "stub-cache.h"
 #include "version.h"
+#include "vm-state-inl.h"
 
 
 namespace v8 {
@@ -61,6 +63,7 @@ int ThreadId::AllocateThreadId() {
   return new_id;
 }
 
+
 int ThreadId::GetCurrentThreadId() {
   int thread_id = Thread::GetThreadLocalInt(Isolate::thread_id_key_);
   if (thread_id == 0) {
@@ -70,6 +73,53 @@ int ThreadId::GetCurrentThreadId() {
   return thread_id;
 }
 
+
+ThreadLocalTop::ThreadLocalTop() {
+  InitializeInternal();
+}
+
+
+void ThreadLocalTop::InitializeInternal() {
+  c_entry_fp_ = 0;
+  handler_ = 0;
+#ifdef USE_SIMULATOR
+  simulator_ = NULL;
+#endif
+#ifdef ENABLE_LOGGING_AND_PROFILING
+  js_entry_sp_ = NULL;
+  external_callback_ = NULL;
+#endif
+#ifdef ENABLE_VMSTATE_TRACKING
+  current_vm_state_ = EXTERNAL;
+#endif
+  try_catch_handler_address_ = NULL;
+  context_ = NULL;
+  thread_id_ = ThreadId::Invalid();
+  external_caught_exception_ = false;
+  failed_access_check_callback_ = NULL;
+  save_context_ = NULL;
+  catcher_ = NULL;
+}
+
+
+void ThreadLocalTop::Initialize() {
+  InitializeInternal();
+#ifdef USE_SIMULATOR
+#ifdef V8_TARGET_ARCH_ARM
+  simulator_ = Simulator::current(isolate_);
+#elif V8_TARGET_ARCH_MIPS
+  simulator_ = Simulator::current(isolate_);
+#endif
+#endif
+  thread_id_ = ThreadId::Current();
+}
+
+
+v8::TryCatch* ThreadLocalTop::TryCatchHandler() {
+  return TRY_CATCH_FROM_ADDRESS(try_catch_handler_address());
+}
+
+
 // Create a dummy thread that will wait forever on a semaphore. The only
 // purpose for this thread is to have some stack area to save essential data
 // into for use by a stacks only core dump (aka minidump).
@@ -372,6 +422,890 @@ Isolate* Isolate::GetDefaultIsolateForLocking() {
 }
 
 
+Address Isolate::get_address_from_id(Isolate::AddressId id) {
+  return isolate_addresses_[id];
+}
+
+
+char* Isolate::Iterate(ObjectVisitor* v, char* thread_storage) {
+  ThreadLocalTop* thread = reinterpret_cast<ThreadLocalTop*>(thread_storage);
+  Iterate(v, thread);
+  return thread_storage + sizeof(ThreadLocalTop);
+}
+
+
+void Isolate::IterateThread(ThreadVisitor* v) {
+  v->VisitThread(this, thread_local_top());
+}
+
+
+void Isolate::IterateThread(ThreadVisitor* v, char* t) {
+  ThreadLocalTop* thread = reinterpret_cast<ThreadLocalTop*>(t);
+  v->VisitThread(this, thread);
+}
+
+
+void Isolate::Iterate(ObjectVisitor* v, ThreadLocalTop* thread) {
+  // Visit the roots from the top for a given thread.
+  Object* pending;
+  // The pending exception can sometimes be a failure.  We can't show
+  // that to the GC, which only understands objects.
+  if (thread->pending_exception_->ToObject(&pending)) {
+    v->VisitPointer(&pending);
+    thread->pending_exception_ = pending;  // In case GC updated it.
+  }
+  v->VisitPointer(&(thread->pending_message_obj_));
+  v->VisitPointer(BitCast<Object**>(&(thread->pending_message_script_)));
+  v->VisitPointer(BitCast<Object**>(&(thread->context_)));
+  Object* scheduled;
+  if (thread->scheduled_exception_->ToObject(&scheduled)) {
+    v->VisitPointer(&scheduled);
+    thread->scheduled_exception_ = scheduled;
+  }
+
+  for (v8::TryCatch* block = thread->TryCatchHandler();
+       block != NULL;
+       block = TRY_CATCH_FROM_ADDRESS(block->next_)) {
+    v->VisitPointer(BitCast<Object**>(&(block->exception_)));
+    v->VisitPointer(BitCast<Object**>(&(block->message_)));
+  }
+
+  // Iterate over pointers on native execution stack.
+  for (StackFrameIterator it(this, thread); !it.done(); it.Advance()) {
+    it.frame()->Iterate(v);
+  }
+}
+
+
+void Isolate::Iterate(ObjectVisitor* v) {
+  ThreadLocalTop* current_t = thread_local_top();
+  Iterate(v, current_t);
+}
+
+
+void Isolate::RegisterTryCatchHandler(v8::TryCatch* that) {
+  // The ARM simulator has a separate JS stack.  We therefore register
+  // the C++ try catch handler with the simulator and get back an
+  // address that can be used for comparisons with addresses into the
+  // JS stack.  When running without the simulator, the address
+  // returned will be the address of the C++ try catch handler itself.
+  Address address = reinterpret_cast<Address>(
+      SimulatorStack::RegisterCTryCatch(reinterpret_cast<uintptr_t>(that)));
+  thread_local_top()->set_try_catch_handler_address(address);
+}
+
+
+void Isolate::UnregisterTryCatchHandler(v8::TryCatch* that) {
+  ASSERT(thread_local_top()->TryCatchHandler() == that);
+  thread_local_top()->set_try_catch_handler_address(
+      reinterpret_cast<Address>(that->next_));
+  thread_local_top()->catcher_ = NULL;
+  SimulatorStack::UnregisterCTryCatch();
+}
+
+
+Handle<String> Isolate::StackTraceString() {
+  if (stack_trace_nesting_level_ == 0) {
+    stack_trace_nesting_level_++;
+    HeapStringAllocator allocator;
+    StringStream::ClearMentionedObjectCache();
+    StringStream accumulator(&allocator);
+    incomplete_message_ = &accumulator;
+    PrintStack(&accumulator);
+    Handle<String> stack_trace = accumulator.ToString();
+    incomplete_message_ = NULL;
+    stack_trace_nesting_level_ = 0;
+    return stack_trace;
+  } else if (stack_trace_nesting_level_ == 1) {
+    stack_trace_nesting_level_++;
+    OS::PrintError(
+      "\n\nAttempt to print stack while printing stack (double fault)\n");
+    OS::PrintError(
+      "If you are lucky you may find a partial stack dump on stdout.\n\n");
+    incomplete_message_->OutputToStdOut();
+    return factory()->empty_symbol();
+  } else {
+    OS::Abort();
+    // Unreachable
+    return factory()->empty_symbol();
+  }
+}
+
+
+Handle<JSArray> Isolate::CaptureCurrentStackTrace(
+    int frame_limit, StackTrace::StackTraceOptions options) {
+  // Ensure no negative values.
+  int limit = Max(frame_limit, 0);
+  Handle<JSArray> stack_trace = factory()->NewJSArray(frame_limit);
+
+  Handle<String> column_key = factory()->LookupAsciiSymbol("column");
+  Handle<String> line_key = factory()->LookupAsciiSymbol("lineNumber");
+  Handle<String> script_key = factory()->LookupAsciiSymbol("scriptName");
+  Handle<String> name_or_source_url_key =
+      factory()->LookupAsciiSymbol("nameOrSourceURL");
+  Handle<String> script_name_or_source_url_key =
+      factory()->LookupAsciiSymbol("scriptNameOrSourceURL");
+  Handle<String> function_key = factory()->LookupAsciiSymbol("functionName");
+  Handle<String> eval_key = factory()->LookupAsciiSymbol("isEval");
+  Handle<String> constructor_key =
+      factory()->LookupAsciiSymbol("isConstructor");
+
+  StackTraceFrameIterator it(this);
+  int frames_seen = 0;
+  while (!it.done() && (frames_seen < limit)) {
+    JavaScriptFrame* frame = it.frame();
+    // Set initial size to the maximum inlining level + 1 for the outermost
+    // function.
+    List<FrameSummary> frames(Compiler::kMaxInliningLevels + 1);
+    frame->Summarize(&frames);
+    for (int i = frames.length() - 1; i >= 0 && frames_seen < limit; i--) {
+      // Create a JSObject to hold the information for the StackFrame.
+      Handle<JSObject> stackFrame = factory()->NewJSObject(object_function());
+
+      Handle<JSFunction> fun = frames[i].function();
+      Handle<Script> script(Script::cast(fun->shared()->script()));
+
+      if (options & StackTrace::kLineNumber) {
+        int script_line_offset = script->line_offset()->value();
+        int position = frames[i].code()->SourcePosition(frames[i].pc());
+        int line_number = GetScriptLineNumber(script, position);
+        // line_number is already shifted by the script_line_offset.
+        int relative_line_number = line_number - script_line_offset;
+        if (options & StackTrace::kColumnOffset && relative_line_number >= 0) {
+          Handle<FixedArray> line_ends(FixedArray::cast(script->line_ends()));
+          int start = (relative_line_number == 0) ? 0 :
+              Smi::cast(line_ends->get(relative_line_number - 1))->value() + 1;
+          int column_offset = position - start;
+          if (relative_line_number == 0) {
+            // For the case where the code is on the same line as the script
+            // tag.
+            column_offset += script->column_offset()->value();
+          }
+          SetLocalPropertyNoThrow(stackFrame, column_key,
+                                  Handle<Smi>(Smi::FromInt(column_offset + 1)));
+        }
+        SetLocalPropertyNoThrow(stackFrame, line_key,
+                                Handle<Smi>(Smi::FromInt(line_number + 1)));
+      }
+
+      if (options & StackTrace::kScriptName) {
+        Handle<Object> script_name(script->name(), this);
+        SetLocalPropertyNoThrow(stackFrame, script_key, script_name);
+      }
+
+      if (options & StackTrace::kScriptNameOrSourceURL) {
+        Handle<Object> script_name(script->name(), this);
+        Handle<JSValue> script_wrapper = GetScriptWrapper(script);
+        Handle<Object> property = GetProperty(script_wrapper,
+                                              name_or_source_url_key);
+        ASSERT(property->IsJSFunction());
+        Handle<JSFunction> method = Handle<JSFunction>::cast(property);
+        bool caught_exception;
+        Handle<Object> result = Execution::TryCall(method, script_wrapper, 0,
+                                                   NULL, &caught_exception);
+        if (caught_exception) {
+          result = factory()->undefined_value();
+        }
+        SetLocalPropertyNoThrow(stackFrame, script_name_or_source_url_key,
+                                result);
+      }
+
+      if (options & StackTrace::kFunctionName) {
+        Handle<Object> fun_name(fun->shared()->name(), this);
+        if (fun_name->ToBoolean()->IsFalse()) {
+          fun_name = Handle<Object>(fun->shared()->inferred_name(), this);
+        }
+        SetLocalPropertyNoThrow(stackFrame, function_key, fun_name);
+      }
+
+      if (options & StackTrace::kIsEval) {
+        int type = Smi::cast(script->compilation_type())->value();
+        Handle<Object> is_eval = (type == Script::COMPILATION_TYPE_EVAL) ?
+            factory()->true_value() : factory()->false_value();
+        SetLocalPropertyNoThrow(stackFrame, eval_key, is_eval);
+      }
+
+      if (options & StackTrace::kIsConstructor) {
+        Handle<Object> is_constructor = (frames[i].is_constructor()) ?
+            factory()->true_value() : factory()->false_value();
+        SetLocalPropertyNoThrow(stackFrame, constructor_key, is_constructor);
+      }
+
+      FixedArray::cast(stack_trace->elements())->set(frames_seen, *stackFrame);
+      frames_seen++;
+    }
+    it.Advance();
+  }
+
+  stack_trace->set_length(Smi::FromInt(frames_seen));
+  return stack_trace;
+}
+
+
+void Isolate::PrintStack() {
+  if (stack_trace_nesting_level_ == 0) {
+    stack_trace_nesting_level_++;
+
+    StringAllocator* allocator;
+    if (preallocated_message_space_ == NULL) {
+      allocator = new HeapStringAllocator();
+    } else {
+      allocator = preallocated_message_space_;
+    }
+
+    StringStream::ClearMentionedObjectCache();
+    StringStream accumulator(allocator);
+    incomplete_message_ = &accumulator;
+    PrintStack(&accumulator);
+    accumulator.OutputToStdOut();
+    accumulator.Log();
+    incomplete_message_ = NULL;
+    stack_trace_nesting_level_ = 0;
+    if (preallocated_message_space_ == NULL) {
+      // Remove the HeapStringAllocator created above.
+      delete allocator;
+    }
+  } else if (stack_trace_nesting_level_ == 1) {
+    stack_trace_nesting_level_++;
+    OS::PrintError(
+      "\n\nAttempt to print stack while printing stack (double fault)\n");
+    OS::PrintError(
+      "If you are lucky you may find a partial stack dump on stdout.\n\n");
+    incomplete_message_->OutputToStdOut();
+  }
+}
+
+
+static void PrintFrames(StringStream* accumulator,
+                        StackFrame::PrintMode mode) {
+  StackFrameIterator it;
+  for (int i = 0; !it.done(); it.Advance()) {
+    it.frame()->Print(accumulator, mode, i++);
+  }
+}
+
+
+void Isolate::PrintStack(StringStream* accumulator) {
+  if (!IsInitialized()) {
+    accumulator->Add(
+        "\n==== Stack trace is not available ==========================\n\n");
+    accumulator->Add(
+        "\n==== Isolate for the thread is not initialized =============\n\n");
+    return;
+  }
+  // The MentionedObjectCache is not GC-proof at the moment.
+  AssertNoAllocation nogc;
+  ASSERT(StringStream::IsMentionedObjectCacheClear());
+
+  // Avoid printing anything if there are no frames.
+  if (c_entry_fp(thread_local_top()) == 0) return;
+
+  accumulator->Add(
+      "\n==== Stack trace ============================================\n\n");
+  PrintFrames(accumulator, StackFrame::OVERVIEW);
+
+  accumulator->Add(
+      "\n==== Details ================================================\n\n");
+  PrintFrames(accumulator, StackFrame::DETAILS);
+
+  accumulator->PrintMentionedObjectCache();
+  accumulator->Add("=====================\n\n");
+}
+
+
+void Isolate::SetFailedAccessCheckCallback(
+    v8::FailedAccessCheckCallback callback) {
+  thread_local_top()->failed_access_check_callback_ = callback;
+}
+
+
+void Isolate::ReportFailedAccessCheck(JSObject* receiver, v8::AccessType type) {
+  if (!thread_local_top()->failed_access_check_callback_) return;
+
+  ASSERT(receiver->IsAccessCheckNeeded());
+  ASSERT(context());
+
+  // Get the data object from access check info.
+  JSFunction* constructor = JSFunction::cast(receiver->map()->constructor());
+  if (!constructor->shared()->IsApiFunction()) return;
+  Object* data_obj =
+      constructor->shared()->get_api_func_data()->access_check_info();
+  if (data_obj == heap_.undefined_value()) return;
+
+  HandleScope scope;
+  Handle<JSObject> receiver_handle(receiver);
+  Handle<Object> data(AccessCheckInfo::cast(data_obj)->data());
+  thread_local_top()->failed_access_check_callback_(
+    v8::Utils::ToLocal(receiver_handle),
+    type,
+    v8::Utils::ToLocal(data));
+}
+
+
+enum MayAccessDecision {
+  YES, NO, UNKNOWN
+};
+
+
+static MayAccessDecision MayAccessPreCheck(Isolate* isolate,
+                                           JSObject* receiver,
+                                           v8::AccessType type) {
+  // During bootstrapping, callback functions are not enabled yet.
+  if (isolate->bootstrapper()->IsActive()) return YES;
+
+  if (receiver->IsJSGlobalProxy()) {
+    Object* receiver_context = JSGlobalProxy::cast(receiver)->context();
+    if (!receiver_context->IsContext()) return NO;
+
+    // Get the global context of current top context.
+    // avoid using Isolate::global_context() because it uses Handle.
+    Context* global_context = isolate->context()->global()->global_context();
+    if (receiver_context == global_context) return YES;
+
+    if (Context::cast(receiver_context)->security_token() ==
+        global_context->security_token())
+      return YES;
+  }
+
+  return UNKNOWN;
+}
+
+
+bool Isolate::MayNamedAccess(JSObject* receiver, Object* key,
+                             v8::AccessType type) {
+  ASSERT(receiver->IsAccessCheckNeeded());
+
+  // The callers of this method are not expecting a GC.
+  AssertNoAllocation no_gc;
+
+  // Skip checks for hidden properties access.  Note, we do not
+  // require existence of a context in this case.
+  if (key == heap_.hidden_symbol()) return true;
+
+  // Check for compatibility between the security tokens in the
+  // current lexical context and the accessed object.
+  ASSERT(context());
+
+  MayAccessDecision decision = MayAccessPreCheck(this, receiver, type);
+  if (decision != UNKNOWN) return decision == YES;
+
+  // Get named access check callback
+  JSFunction* constructor = JSFunction::cast(receiver->map()->constructor());
+  if (!constructor->shared()->IsApiFunction()) return false;
+
+  Object* data_obj =
+     constructor->shared()->get_api_func_data()->access_check_info();
+  if (data_obj == heap_.undefined_value()) return false;
+
+  Object* fun_obj = AccessCheckInfo::cast(data_obj)->named_callback();
+  v8::NamedSecurityCallback callback =
+      v8::ToCData<v8::NamedSecurityCallback>(fun_obj);
+
+  if (!callback) return false;
+
+  HandleScope scope(this);
+  Handle<JSObject> receiver_handle(receiver, this);
+  Handle<Object> key_handle(key, this);
+  Handle<Object> data(AccessCheckInfo::cast(data_obj)->data(), this);
+  LOG(this, ApiNamedSecurityCheck(key));
+  bool result = false;
+  {
+    // Leaving JavaScript.
+    VMState state(this, EXTERNAL);
+    result = callback(v8::Utils::ToLocal(receiver_handle),
+                      v8::Utils::ToLocal(key_handle),
+                      type,
+                      v8::Utils::ToLocal(data));
+  }
+  return result;
+}
+
+
+bool Isolate::MayIndexedAccess(JSObject* receiver,
+                               uint32_t index,
+                               v8::AccessType type) {
+  ASSERT(receiver->IsAccessCheckNeeded());
+  // Check for compatibility between the security tokens in the
+  // current lexical context and the accessed object.
+  ASSERT(context());
+
+  MayAccessDecision decision = MayAccessPreCheck(this, receiver, type);
+  if (decision != UNKNOWN) return decision == YES;
+
+  // Get indexed access check callback
+  JSFunction* constructor = JSFunction::cast(receiver->map()->constructor());
+  if (!constructor->shared()->IsApiFunction()) return false;
+
+  Object* data_obj =
+      constructor->shared()->get_api_func_data()->access_check_info();
+  if (data_obj == heap_.undefined_value()) return false;
+
+  Object* fun_obj = AccessCheckInfo::cast(data_obj)->indexed_callback();
+  v8::IndexedSecurityCallback callback =
+      v8::ToCData<v8::IndexedSecurityCallback>(fun_obj);
+
+  if (!callback) return false;
+
+  HandleScope scope(this);
+  Handle<JSObject> receiver_handle(receiver, this);
+  Handle<Object> data(AccessCheckInfo::cast(data_obj)->data(), this);
+  LOG(this, ApiIndexedSecurityCheck(index));
+  bool result = false;
+  {
+    // Leaving JavaScript.
+    VMState state(this, EXTERNAL);
+    result = callback(v8::Utils::ToLocal(receiver_handle),
+                      index,
+                      type,
+                      v8::Utils::ToLocal(data));
+  }
+  return result;
+}
+
+
+const char* const Isolate::kStackOverflowMessage =
+  "Uncaught RangeError: Maximum call stack size exceeded";
+
+
+Failure* Isolate::StackOverflow() {
+  HandleScope scope;
+  Handle<String> key = factory()->stack_overflow_symbol();
+  Handle<JSObject> boilerplate =
+      Handle<JSObject>::cast(GetProperty(js_builtins_object(), key));
+  Handle<Object> exception = Copy(boilerplate);
+  // TODO(1240995): To avoid having to call JavaScript code to compute
+  // the message for stack overflow exceptions which is very likely to
+  // double fault with another stack overflow exception, we use a
+  // precomputed message.
+  DoThrow(*exception, NULL);
+  return Failure::Exception();
+}
+
+
+Failure* Isolate::TerminateExecution() {
+  DoThrow(heap_.termination_exception(), NULL);
+  return Failure::Exception();
+}
+
+
+Failure* Isolate::Throw(Object* exception, MessageLocation* location) {
+  DoThrow(exception, location);
+  return Failure::Exception();
+}
+
+
+Failure* Isolate::ReThrow(MaybeObject* exception, MessageLocation* location) {
+  bool can_be_caught_externally = false;
+  ShouldReportException(&can_be_caught_externally,
+                        is_catchable_by_javascript(exception));
+  thread_local_top()->catcher_ = can_be_caught_externally ?
+      try_catch_handler() : NULL;
+
+  // Set the exception being re-thrown.
+  set_pending_exception(exception);
+  return Failure::Exception();
+}
+
+
+Failure* Isolate::ThrowIllegalOperation() {
+  return Throw(heap_.illegal_access_symbol());
+}
+
+
+void Isolate::ScheduleThrow(Object* exception) {
+  // When scheduling a throw we first throw the exception to get the
+  // error reporting if it is uncaught before rescheduling it.
+  Throw(exception);
+  thread_local_top()->scheduled_exception_ = pending_exception();
+  thread_local_top()->external_caught_exception_ = false;
+  clear_pending_exception();
+}
+
+
+Failure* Isolate::PromoteScheduledException() {
+  MaybeObject* thrown = scheduled_exception();
+  clear_scheduled_exception();
+  // Re-throw the exception to avoid getting repeated error reporting.
+  return ReThrow(thrown);
+}
+
+
+void Isolate::PrintCurrentStackTrace(FILE* out) {
+  StackTraceFrameIterator it(this);
+  while (!it.done()) {
+    HandleScope scope;
+    // Find code position if recorded in relocation info.
+    JavaScriptFrame* frame = it.frame();
+    int pos = frame->LookupCode()->SourcePosition(frame->pc());
+    Handle<Object> pos_obj(Smi::FromInt(pos));
+    // Fetch function and receiver.
+    Handle<JSFunction> fun(JSFunction::cast(frame->function()));
+    Handle<Object> recv(frame->receiver());
+    // Advance to the next JavaScript frame and determine if the
+    // current frame is the top-level frame.
+    it.Advance();
+    Handle<Object> is_top_level = it.done()
+        ? factory()->true_value()
+        : factory()->false_value();
+    // Generate and print stack trace line.
+    Handle<String> line =
+        Execution::GetStackTraceLine(recv, fun, pos_obj, is_top_level);
+    if (line->length() > 0) {
+      line->PrintOn(out);
+      fprintf(out, "\n");
+    }
+  }
+}
+
+
+void Isolate::ComputeLocation(MessageLocation* target) {
+  *target = MessageLocation(Handle<Script>(heap_.empty_script()), -1, -1);
+  StackTraceFrameIterator it(this);
+  if (!it.done()) {
+    JavaScriptFrame* frame = it.frame();
+    JSFunction* fun = JSFunction::cast(frame->function());
+    Object* script = fun->shared()->script();
+    if (script->IsScript() &&
+        !(Script::cast(script)->source()->IsUndefined())) {
+      int pos = frame->LookupCode()->SourcePosition(frame->pc());
+      // Compute the location from the function and the reloc info.
+      Handle<Script> casted_script(Script::cast(script));
+      *target = MessageLocation(casted_script, pos, pos + 1);
+    }
+  }
+}
+
+
+bool Isolate::ShouldReportException(bool* can_be_caught_externally,
+                                    bool catchable_by_javascript) {
+  // Find the top-most try-catch handler.
+  StackHandler* handler =
+      StackHandler::FromAddress(Isolate::handler(thread_local_top()));
+  while (handler != NULL && !handler->is_try_catch()) {
+    handler = handler->next();
+  }
+
+  // Get the address of the external handler so we can compare the address to
+  // determine which one is closer to the top of the stack.
+  Address external_handler_address =
+      thread_local_top()->try_catch_handler_address();
+
+  // The exception has been externally caught if and only if there is
+  // an external handler which is on top of the top-most try-catch
+  // handler.
+  *can_be_caught_externally = external_handler_address != NULL &&
+      (handler == NULL || handler->address() > external_handler_address ||
+       !catchable_by_javascript);
+
+  if (*can_be_caught_externally) {
+    // Only report the exception if the external handler is verbose.
+    return try_catch_handler()->is_verbose_;
+  } else {
+    // Report the exception if it isn't caught by JavaScript code.
+    return handler == NULL;
+  }
+}
+
+
+void Isolate::DoThrow(MaybeObject* exception, MessageLocation* location) {
+  ASSERT(!has_pending_exception());
+
+  HandleScope scope;
+  Object* exception_object = Smi::FromInt(0);
+  bool is_object = exception->ToObject(&exception_object);
+  Handle<Object> exception_handle(exception_object);
+
+  // Determine reporting and whether the exception is caught externally.
+  bool catchable_by_javascript = is_catchable_by_javascript(exception);
+  // Only real objects can be caught by JS.
+  ASSERT(!catchable_by_javascript || is_object);
+  bool can_be_caught_externally = false;
+  bool should_report_exception =
+      ShouldReportException(&can_be_caught_externally, catchable_by_javascript);
+  bool report_exception = catchable_by_javascript && should_report_exception;
+
+#ifdef ENABLE_DEBUGGER_SUPPORT
+  // Notify debugger of exception.
+  if (catchable_by_javascript) {
+    debugger_->OnException(exception_handle, report_exception);
+  }
+#endif
+
+  // Generate the message.
+  Handle<Object> message_obj;
+  MessageLocation potential_computed_location;
+  bool try_catch_needs_message =
+      can_be_caught_externally &&
+      try_catch_handler()->capture_message_;
+  if (report_exception || try_catch_needs_message) {
+    if (location == NULL) {
+      // If no location was specified we use a computed one instead
+      ComputeLocation(&potential_computed_location);
+      location = &potential_computed_location;
+    }
+    if (!bootstrapper()->IsActive()) {
+      // It's not safe to try to make message objects or collect stack
+      // traces while the bootstrapper is active since the infrastructure
+      // may not have been properly initialized.
+      Handle<String> stack_trace;
+      if (FLAG_trace_exception) stack_trace = StackTraceString();
+      Handle<JSArray> stack_trace_object;
+      if (report_exception && capture_stack_trace_for_uncaught_exceptions_) {
+          stack_trace_object = CaptureCurrentStackTrace(
+              stack_trace_for_uncaught_exceptions_frame_limit_,
+              stack_trace_for_uncaught_exceptions_options_);
+      }
+      ASSERT(is_object);  // Can't use the handle unless there's a real object.
+      message_obj = MessageHandler::MakeMessageObject("uncaught_exception",
+          location, HandleVector<Object>(&exception_handle, 1), stack_trace,
+          stack_trace_object);
+    }
+  }
+
+  // Save the message for reporting if the the exception remains uncaught.
+  thread_local_top()->has_pending_message_ = report_exception;
+  if (!message_obj.is_null()) {
+    thread_local_top()->pending_message_obj_ = *message_obj;
+    if (location != NULL) {
+      thread_local_top()->pending_message_script_ = *location->script();
+      thread_local_top()->pending_message_start_pos_ = location->start_pos();
+      thread_local_top()->pending_message_end_pos_ = location->end_pos();
+    }
+  }
+
+  // Do not forget to clean catcher_ if currently thrown exception cannot
+  // be caught.  If necessary, ReThrow will update the catcher.
+  thread_local_top()->catcher_ = can_be_caught_externally ?
+      try_catch_handler() : NULL;
+
+  // NOTE: Notifying the debugger or generating the message
+  // may have caused new exceptions. For now, we just ignore
+  // that and set the pending exception to the original one.
+  if (is_object) {
+    set_pending_exception(*exception_handle);
+  } else {
+    // Failures are not on the heap so they neither need nor work with handles.
+    ASSERT(exception_handle->IsFailure());
+    set_pending_exception(exception);
+  }
+}
+
+
+bool Isolate::IsExternallyCaught() {
+  ASSERT(has_pending_exception());
+
+  if ((thread_local_top()->catcher_ == NULL) ||
+      (try_catch_handler() != thread_local_top()->catcher_)) {
+    // When throwing the exception, we found no v8::TryCatch
+    // which should care about this exception.
+    return false;
+  }
+
+  if (!is_catchable_by_javascript(pending_exception())) {
+    return true;
+  }
+
+  // Get the address of the external handler so we can compare the address to
+  // determine which one is closer to the top of the stack.
+  Address external_handler_address =
+      thread_local_top()->try_catch_handler_address();
+  ASSERT(external_handler_address != NULL);
+
+  // The exception has been externally caught if and only if there is
+  // an external handler which is on top of the top-most try-finally
+  // handler.
+  // There should be no try-catch blocks as they would prohibit us from
+  // finding external catcher in the first place (see catcher_ check above).
+  //
+  // Note, that finally clause would rethrow an exception unless it's
+  // aborted by jumps in control flow like return, break, etc. and we'll
+  // have another chances to set proper v8::TryCatch.
+  StackHandler* handler =
+      StackHandler::FromAddress(Isolate::handler(thread_local_top()));
+  while (handler != NULL && handler->address() < external_handler_address) {
+    ASSERT(!handler->is_try_catch());
+    if (handler->is_try_finally()) return false;
+
+    handler = handler->next();
+  }
+
+  return true;
+}
+
+
+void Isolate::ReportPendingMessages() {
+  ASSERT(has_pending_exception());
+  PropagatePendingExceptionToExternalTryCatch();
+
+  // If the pending exception is OutOfMemoryException set out_of_memory in
+  // the global context.  Note: We have to mark the global context here
+  // since the GenerateThrowOutOfMemory stub cannot make a RuntimeCall to
+  // set it.
+  HandleScope scope;
+  if (thread_local_top_.pending_exception_ == Failure::OutOfMemoryException()) {
+    context()->mark_out_of_memory();
+  } else if (thread_local_top_.pending_exception_ ==
+             heap()->termination_exception()) {
+    // Do nothing: if needed, the exception has been already propagated to
+    // v8::TryCatch.
+  } else {
+    if (thread_local_top_.has_pending_message_) {
+      thread_local_top_.has_pending_message_ = false;
+      if (!thread_local_top_.pending_message_obj_->IsTheHole()) {
+        HandleScope scope;
+        Handle<Object> message_obj(thread_local_top_.pending_message_obj_);
+        if (thread_local_top_.pending_message_script_ != NULL) {
+          Handle<Script> script(thread_local_top_.pending_message_script_);
+          int start_pos = thread_local_top_.pending_message_start_pos_;
+          int end_pos = thread_local_top_.pending_message_end_pos_;
+          MessageLocation location(script, start_pos, end_pos);
+          MessageHandler::ReportMessage(this, &location, message_obj);
+        } else {
+          MessageHandler::ReportMessage(this, NULL, message_obj);
+        }
+      }
+    }
+  }
+  clear_pending_message();
+}
+
+
+void Isolate::TraceException(bool flag) {
+  FLAG_trace_exception = flag;  // TODO(isolates): This is an unfortunate use.
+}
+
+
+bool Isolate::OptionalRescheduleException(bool is_bottom_call) {
+  ASSERT(has_pending_exception());
+  PropagatePendingExceptionToExternalTryCatch();
+
+  // Allways reschedule out of memory exceptions.
+  if (!is_out_of_memory()) {
+    bool is_termination_exception =
+        pending_exception() == heap_.termination_exception();
+
+    // Do not reschedule the exception if this is the bottom call.
+    bool clear_exception = is_bottom_call;
+
+    if (is_termination_exception) {
+      if (is_bottom_call) {
+        thread_local_top()->external_caught_exception_ = false;
+        clear_pending_exception();
+        return false;
+      }
+    } else if (thread_local_top()->external_caught_exception_) {
+      // If the exception is externally caught, clear it if there are no
+      // JavaScript frames on the way to the C++ frame that has the
+      // external handler.
+      ASSERT(thread_local_top()->try_catch_handler_address() != NULL);
+      Address external_handler_address =
+          thread_local_top()->try_catch_handler_address();
+      JavaScriptFrameIterator it;
+      if (it.done() || (it.frame()->sp() > external_handler_address)) {
+        clear_exception = true;
+      }
+    }
+
+    // Clear the exception if needed.
+    if (clear_exception) {
+      thread_local_top()->external_caught_exception_ = false;
+      clear_pending_exception();
+      return false;
+    }
+  }
+
+  // Reschedule the exception.
+  thread_local_top()->scheduled_exception_ = pending_exception();
+  clear_pending_exception();
+  return true;
+}
+
+
+void Isolate::SetCaptureStackTraceForUncaughtExceptions(
+      bool capture,
+      int frame_limit,
+      StackTrace::StackTraceOptions options) {
+  capture_stack_trace_for_uncaught_exceptions_ = capture;
+  stack_trace_for_uncaught_exceptions_frame_limit_ = frame_limit;
+  stack_trace_for_uncaught_exceptions_options_ = options;
+}
+
+
+bool Isolate::is_out_of_memory() {
+  if (has_pending_exception()) {
+    MaybeObject* e = pending_exception();
+    if (e->IsFailure() && Failure::cast(e)->IsOutOfMemoryException()) {
+      return true;
+    }
+  }
+  if (has_scheduled_exception()) {
+    MaybeObject* e = scheduled_exception();
+    if (e->IsFailure() && Failure::cast(e)->IsOutOfMemoryException()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+
+Handle<Context> Isolate::global_context() {
+  GlobalObject* global = thread_local_top()->context_->global();
+  return Handle<Context>(global->global_context());
+}
+
+
+Handle<Context> Isolate::GetCallingGlobalContext() {
+  JavaScriptFrameIterator it;
+#ifdef ENABLE_DEBUGGER_SUPPORT
+  if (debug_->InDebugger()) {
+    while (!it.done()) {
+      JavaScriptFrame* frame = it.frame();
+      Context* context = Context::cast(frame->context());
+      if (context->global_context() == *debug_->debug_context()) {
+        it.Advance();
+      } else {
+        break;
+      }
+    }
+  }
+#endif  // ENABLE_DEBUGGER_SUPPORT
+  if (it.done()) return Handle<Context>::null();
+  JavaScriptFrame* frame = it.frame();
+  Context* context = Context::cast(frame->context());
+  return Handle<Context>(context->global_context());
+}
+
+
+char* Isolate::ArchiveThread(char* to) {
+  if (RuntimeProfiler::IsEnabled() && current_vm_state() == JS) {
+    RuntimeProfiler::IsolateExitedJS(this);
+  }
+  memcpy(to, reinterpret_cast<char*>(thread_local_top()),
+         sizeof(ThreadLocalTop));
+  InitializeThreadLocal();
+  return to + sizeof(ThreadLocalTop);
+}
+
+
+char* Isolate::RestoreThread(char* from) {
+  memcpy(reinterpret_cast<char*>(thread_local_top()), from,
+         sizeof(ThreadLocalTop));
+  // This might be just paranoia, but it seems to be needed in case a
+  // thread_local_top_ is restored on a separate OS thread.
+#ifdef USE_SIMULATOR
+#ifdef V8_TARGET_ARCH_ARM
+  thread_local_top()->simulator_ = Simulator::current(this);
+#elif V8_TARGET_ARCH_MIPS
+  thread_local_top()->simulator_ = Simulator::current(this);
+#endif
+#endif
+  if (RuntimeProfiler::IsEnabled() && current_vm_state() == JS) {
+    RuntimeProfiler::IsolateEnteredJS(this);
+  }
+  return from + sizeof(ThreadLocalTop);
+}
+
+
 Isolate::ThreadDataTable::ThreadDataTable()
     : list_(NULL) {
 }