Patch for allowing several V8 instances in process:...

src/top.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 20 matching lines @@
 #include "bootstrapper.h"
 #include "debug.h"
 #include "execution.h"
 #include "platform.h"
 #include "simulator.h"
 #include "string-stream.h"
 
 namespace v8 {
 namespace internal {
 
-ThreadLocalTop Top::thread_local_;
-Mutex* Top::break_access_ = OS::CreateMutex();
-
-NoAllocationStringAllocator* preallocated_message_space = NULL;
-
-Address top_addresses[] = {
-#define C(name) reinterpret_cast<Address>(Top::name()),
-    TOP_ADDRESS_LIST(C)
-    TOP_ADDRESS_LIST_PROF(C)
-#undef C
-    NULL
-};
-
-
-v8::TryCatch* ThreadLocalTop::TryCatchHandler() {
-  return TRY_CATCH_FROM_ADDRESS(try_catch_handler_address());
-}
-
-
-void ThreadLocalTop::Initialize() {
-  c_entry_fp_ = 0;
-  handler_ = 0;
-#ifdef ENABLE_LOGGING_AND_PROFILING
-  js_entry_sp_ = 0;
-#endif
-  stack_is_cooked_ = false;
-  try_catch_handler_address_ = NULL;
-  context_ = NULL;
-  int id = ThreadManager::CurrentId();
-  thread_id_ = (id == 0) ? ThreadManager::kInvalidId : id;
-  external_caught_exception_ = false;
-  failed_access_check_callback_ = NULL;
-  save_context_ = NULL;
-  catcher_ = NULL;
-}
-
-
-Address Top::get_address_from_id(Top::AddressId id) {
-  return top_addresses[id];
-}
-
-
-char* Top::Iterate(ObjectVisitor* v, char* thread_storage) {
-  ThreadLocalTop* thread = reinterpret_cast<ThreadLocalTop*>(thread_storage);
-  Iterate(v, thread);
-  return thread_storage + sizeof(ThreadLocalTop);
-}
-
-
-void Top::Iterate(ObjectVisitor* v, ThreadLocalTop* thread) {
-  v->VisitPointer(&(thread->pending_exception_));
-  v->VisitPointer(&(thread->pending_message_obj_));
-  v->VisitPointer(
-      bit_cast<Object**, Script**>(&(thread->pending_message_script_)));
-  v->VisitPointer(bit_cast<Object**, Context**>(&(thread->context_)));
-  v->VisitPointer(&(thread->scheduled_exception_));
-
-  for (v8::TryCatch* block = thread->TryCatchHandler();
-       block != NULL;
-       block = TRY_CATCH_FROM_ADDRESS(block->next_)) {
-    v->VisitPointer(bit_cast<Object**, void**>(&(block->exception_)));
-    v->VisitPointer(bit_cast<Object**, void**>(&(block->message_)));
-  }
-
-  // Iterate over pointers on native execution stack.
-  for (StackFrameIterator it(thread); !it.done(); it.Advance()) {
-    it.frame()->Iterate(v);
-  }
-}
-
-
-void Top::Iterate(ObjectVisitor* v) {
-  ThreadLocalTop* current_t = &thread_local_;
-  Iterate(v, current_t);
-}
-
-
-void Top::InitializeThreadLocal() {
-  thread_local_.Initialize();
-  clear_pending_exception();
-  clear_pending_message();
-  clear_scheduled_exception();
-}
-
-
 // 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).
 class PreallocatedMemoryThread: public Thread {
  public:
-  PreallocatedMemoryThread() : keep_running_(true) {
-    wait_for_ever_semaphore_ = OS::CreateSemaphore(0);
-    data_ready_semaphore_ = OS::CreateSemaphore(0);
+  PreallocatedMemoryThread() : keep_running_(true),
+    wait_for_ever_semaphore_(OS::CreateSemaphore(0)),
+    data_ready_semaphore_(OS::CreateSemaphore(0)),
+    data_(NULL), length_(0) {
   }
 
   // When the thread starts running it will allocate a fixed number of bytes
   // on the stack and publish the location of this memory for others to use.
   void Run() {
     EmbeddedVector<char, 15 * 1024> local_buffer;
 
     // Initialize the buffer with a known good value.
     OS::StrNCpy(local_buffer, "Trace data was not generated.\n",
                 local_buffer.length());
 
     // Publish the local buffer and signal its availability.
     data_ = local_buffer.start();
     length_ = local_buffer.length();
     data_ready_semaphore_->Signal();
 
     while (keep_running_) {
       // This thread will wait here until the end of time.
       wait_for_ever_semaphore_->Wait();
     }
 
     // Make sure we access the buffer after the wait to remove all possibility
     // of it being optimized away.
     OS::StrNCpy(local_buffer, "PreallocatedMemoryThread shutting down.\n",
                 local_buffer.length());
   }
 
-  static char* data() {
+  char* data() {
     if (data_ready_semaphore_ != NULL) {
       // Initial access is guarded until the data has been published.
       data_ready_semaphore_->Wait();
       delete data_ready_semaphore_;
       data_ready_semaphore_ = NULL;
     }
     return data_;
   }
 
-  static unsigned length() {
+  unsigned length() {
     if (data_ready_semaphore_ != NULL) {
       // Initial access is guarded until the data has been published.
       data_ready_semaphore_->Wait();
       delete data_ready_semaphore_;
       data_ready_semaphore_ = NULL;
     }
     return length_;
   }
 
-  static void StartThread() {
-    if (the_thread_ != NULL) return;
-
-    the_thread_ = new PreallocatedMemoryThread();
-    the_thread_->Start();
-  }
-
   // Stop the PreallocatedMemoryThread and release its resources.
-  static void StopThread() {
-    if (the_thread_ == NULL) return;
-
-    the_thread_->keep_running_ = false;
+  void RequestEnd() {
+    keep_running_ = false;
     wait_for_ever_semaphore_->Signal();
 
     // Wait for the thread to terminate.
-    the_thread_->Join();
+    Join();
 
     if (data_ready_semaphore_ != NULL) {
       delete data_ready_semaphore_;
       data_ready_semaphore_ = NULL;
     }
 
     delete wait_for_ever_semaphore_;
     wait_for_ever_semaphore_ = NULL;
+  }
+
+ private:
+  // Used to make sure that the thread keeps looping even for spurious wakeups.
+  bool keep_running_;
+
+  // This semaphore is used by the PreallocatedMemoryThread to wait for ever.
+  Semaphore* wait_for_ever_semaphore_;
+  // Semaphore to signal that the data has been initialized.
+  Semaphore* data_ready_semaphore_;
+
+  // Location and size of the preallocated memory block.
+  char* data_;
+  unsigned length_;
+
+  DISALLOW_COPY_AND_ASSIGN(PreallocatedMemoryThread);
+};
+
+class TopPrivateData {
+ public:
+  NoAllocationStringAllocator* preallocated_message_space;
+  Address top_addresses[Top::k_top_address_count];
+
+  // The preallocated memory thread singleton.
+  PreallocatedMemoryThread* the_thread_;
+  int stack_trace_nesting_level;
+  StringStream* incomplete_message;
+  bool initialized;
+
+  TopPrivateData()
+    :initialized(false), preallocated_message_space(NULL),
+    incomplete_message(NULL), stack_trace_nesting_level(NULL),
+    the_thread_(NULL) {
+    Address _top_addresses[] = {
+    #define C(name) reinterpret_cast<Address>(Top::name()),
+        TOP_ADDRESS_LIST(C)
+        TOP_ADDRESS_LIST_PROF(C)
+    #undef C
+        NULL
+    };
+    for (int i = 0; i < Top::k_top_address_count; ++i)
+      top_addresses[i] = _top_addresses[i];
+  }
+
+  void StartThread() {
+    if (the_thread_ != NULL) return;
+
+    the_thread_ = new PreallocatedMemoryThread();
+    the_thread_->Start();
+  }
+
+  // Stop the PreallocatedMemoryThread and release its resources.
+  void StopThread() {
+    if (the_thread_ == NULL) return;
+    the_thread_->RequestEnd();
 
     // Done with the thread entirely.
     delete the_thread_;
     the_thread_ = NULL;
   }
-
- private:
-  // Used to make sure that the thread keeps looping even for spurious wakeups.
-  bool keep_running_;
-
-  // The preallocated memory thread singleton.
-  static PreallocatedMemoryThread* the_thread_;
-  // This semaphore is used by the PreallocatedMemoryThread to wait for ever.
-  static Semaphore* wait_for_ever_semaphore_;
-  // Semaphore to signal that the data has been initialized.
-  static Semaphore* data_ready_semaphore_;
-
-  // Location and size of the preallocated memory block.
-  static char* data_;
-  static unsigned length_;
-
-  DISALLOW_COPY_AND_ASSIGN(PreallocatedMemoryThread);
 };
 
-PreallocatedMemoryThread* PreallocatedMemoryThread::the_thread_ = NULL;
-Semaphore* PreallocatedMemoryThread::wait_for_ever_semaphore_ = NULL;
-Semaphore* PreallocatedMemoryThread::data_ready_semaphore_ = NULL;
-char* PreallocatedMemoryThread::data_ = NULL;
-unsigned PreallocatedMemoryThread::length_ = 0;
-
-static bool initialized = false;
+TopData::TopData()
+  :break_access_(OS::CreateMutex()),
+  thread_local_(),
+  top_private_data_(NULL) {
+}
+
+void Top::PostConstruct() {
+  v8_context()->top_data_.top_private_data_ = new TopPrivateData();
+}
+
+void Top::PreDestroy() {
+  delete v8_context()->top_data_.top_private_data_;
+}
+
+ThreadLocalTop::ThreadLocalTop()
+  :context_(NULL),
+  has_pending_message_(false),
+  external_caught_exception_(false),
+  formal_count_(0),
+  stack_is_cooked_(false),
+  #ifdef ENABLE_LOGGING_AND_PROFILING
+  js_entry_sp_(NULL),
+  #endif
+  handler_(NULL),
+  c_entry_fp_(NULL),
+  catcher_(NULL),
+  save_context_(NULL),
+  scheduled_exception_(NULL),
+  pending_message_end_pos_(0),
+  pending_message_start_pos_(0),
+  pending_message_script_(0),
+  pending_message_obj_(NULL),
+  pending_message_(NULL),
+  pending_exception_(false),
+  thread_id_(0),
+  failed_access_check_callback_(NULL),
+  try_catch_handler_address_(NULL) {
+}
+
+v8::TryCatch* ThreadLocalTop::TryCatchHandler() {
+  return TRY_CATCH_FROM_ADDRESS(try_catch_handler_address());
+}
+
+
+void ThreadLocalTop::Initialize() {
+  c_entry_fp_ = 0;
+  handler_ = 0;
+#ifdef ENABLE_LOGGING_AND_PROFILING
+  js_entry_sp_ = 0;
+#endif
+  stack_is_cooked_ = false;
+  try_catch_handler_address_ = NULL;
+  context_ = NULL;
+  int id = ThreadManager::CurrentId();
+  thread_id_ = (id == 0) ? ThreadManager::kInvalidId : id;
+  external_caught_exception_ = false;
+  failed_access_check_callback_ = NULL;
+  save_context_ = NULL;
+  catcher_ = NULL;
+}
+
+
+Address Top::get_address_from_id(Top::AddressId id) {
+  return v8_context()->top_data_.top_private_data_->top_addresses[id];
+}
+
+
+char* Top::Iterate(ObjectVisitor* v, char* thread_storage) {
+  ThreadLocalTop* thread = reinterpret_cast<ThreadLocalTop*>(thread_storage);
+  Iterate(v, thread);
+  return thread_storage + sizeof(ThreadLocalTop);
+}
+
+
+void Top::Iterate(ObjectVisitor* v, ThreadLocalTop* thread) {
+  v->VisitPointer(&(thread->pending_exception_));
+  v->VisitPointer(&(thread->pending_message_obj_));
+  v->VisitPointer(
+      bit_cast<Object**, Script**>(&(thread->pending_message_script_)));
+  v->VisitPointer(bit_cast<Object**, Context**>(&(thread->context_)));
+  v->VisitPointer(&(thread->scheduled_exception_));
+
+  for (v8::TryCatch* block = thread->TryCatchHandler();
+       block != NULL;
+       block = TRY_CATCH_FROM_ADDRESS(block->next_)) {
+    v->VisitPointer(bit_cast<Object**, void**>(&(block->exception_)));
+    v->VisitPointer(bit_cast<Object**, void**>(&(block->message_)));
+  }
+
+  // Iterate over pointers on native execution stack.
+  for (StackFrameIterator it(thread); !it.done(); it.Advance()) {
+    it.frame()->Iterate(v);
+  }
+}
+
+
+void Top::Iterate(ObjectVisitor* v) {
+  ThreadLocalTop* current_t = &v8_context()->top_data_.thread_local_;
+  Iterate(v, current_t);
+}
+
+
+void Top::InitializeThreadLocal() {
+  v8_context()->top_data_.thread_local_.Initialize();
+  clear_pending_exception();
+  clear_pending_message();
+  clear_scheduled_exception();
+}
 
 void Top::Initialize() {
-  CHECK(!initialized);
+  TopPrivateData* top_private_data = v8_context()->top_data_.top_private_data_;
+  CHECK(!top_private_data->initialized);
 
   InitializeThreadLocal();
 
   // Only preallocate on the first initialization.
-  if (FLAG_preallocate_message_memory && (preallocated_message_space == NULL)) {
+  if (FLAG_preallocate_message_memory &&
+      (top_private_data->preallocated_message_space == NULL)) {
     // Start the thread which will set aside some memory.
-    PreallocatedMemoryThread::StartThread();
-    preallocated_message_space =
-        new NoAllocationStringAllocator(PreallocatedMemoryThread::data(),
-                                        PreallocatedMemoryThread::length());
-    PreallocatedStorage::Init(PreallocatedMemoryThread::length() / 4);
-  }
-  initialized = true;
+    top_private_data->StartThread();
+    top_private_data->preallocated_message_space =
+        new NoAllocationStringAllocator(
+          top_private_data->the_thread_->data(),
+          top_private_data->the_thread_->length());
+    PreallocatedStorage::Init(top_private_data->the_thread_->length() / 4);
+  }
+  top_private_data->initialized = true;
 }
 
 
 void Top::TearDown() {
-  if (initialized) {
+  TopPrivateData* top_private_data = v8_context()->top_data_.top_private_data_;
+  if (top_private_data->initialized) {
     // Remove the external reference to the preallocated stack memory.
-    if (preallocated_message_space != NULL) {
-      delete preallocated_message_space;
-      preallocated_message_space = NULL;
+    if (top_private_data->preallocated_message_space != NULL) {
+      delete top_private_data->preallocated_message_space;
+      top_private_data->preallocated_message_space = NULL;
     }
 
-    PreallocatedMemoryThread::StopThread();
-    initialized = false;
-  }
-}
-
+    top_private_data->StopThread();
+    top_private_data->initialized = false;
+  }
+}
+
 
 void Top::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_.set_try_catch_handler_address(address);
+  v8_context()->top_data_.thread_local_.set_try_catch_handler_address(address);
 }
 
 
 void Top::UnregisterTryCatchHandler(v8::TryCatch* that) {
-  ASSERT(thread_local_.TryCatchHandler() == that);
-  thread_local_.set_try_catch_handler_address(
+  ThreadLocalTop& thread_local = v8_context()->top_data_.thread_local_;
+  ASSERT(thread_local.TryCatchHandler() == that);
+  thread_local.set_try_catch_handler_address(
       reinterpret_cast<Address>(that->next_));
-  thread_local_.catcher_ = NULL;
+  thread_local.catcher_ = NULL;
   SimulatorStack::UnregisterCTryCatch();
 }
 
 
 void Top::MarkCompactPrologue(bool is_compacting) {
-  MarkCompactPrologue(is_compacting, &thread_local_);
+  MarkCompactPrologue(is_compacting, &v8_context()->top_data_.thread_local_);
 }
 
 
 void Top::MarkCompactPrologue(bool is_compacting, char* data) {
   MarkCompactPrologue(is_compacting, reinterpret_cast<ThreadLocalTop*>(data));
 }
 
 
 void Top::MarkCompactPrologue(bool is_compacting, ThreadLocalTop* thread) {
   if (is_compacting) {
     StackFrame::CookFramesForThread(thread);
   }
 }
 
 
 void Top::MarkCompactEpilogue(bool is_compacting, char* data) {
   MarkCompactEpilogue(is_compacting, reinterpret_cast<ThreadLocalTop*>(data));
 }
 
 
 void Top::MarkCompactEpilogue(bool is_compacting) {
-  MarkCompactEpilogue(is_compacting, &thread_local_);
+  MarkCompactEpilogue(is_compacting, &v8_context()->top_data_.thread_local_);
 }
 
 
 void Top::MarkCompactEpilogue(bool is_compacting, ThreadLocalTop* thread) {
   if (is_compacting) {
     StackFrame::UncookFramesForThread(thread);
   }
 }
 
-
-static int stack_trace_nesting_level = 0;
-static StringStream* incomplete_message = NULL;
-
-
 Handle<String> Top::StackTrace() {
-  if (stack_trace_nesting_level == 0) {
-    stack_trace_nesting_level++;
+  TopPrivateData* top_private_data = v8_context()->top_data_.top_private_data_;
+  if (top_private_data->stack_trace_nesting_level == 0) {
+    top_private_data->stack_trace_nesting_level++;
     HeapStringAllocator allocator;
     StringStream::ClearMentionedObjectCache();
     StringStream accumulator(&allocator);
-    incomplete_message = &accumulator;
+    top_private_data->incomplete_message = &accumulator;
+
     PrintStack(&accumulator);
     Handle<String> stack_trace = accumulator.ToString();
-    incomplete_message = NULL;
-    stack_trace_nesting_level = 0;
+    top_private_data->incomplete_message = NULL;
+    top_private_data->stack_trace_nesting_level = 0;
     return stack_trace;
-  } else if (stack_trace_nesting_level == 1) {
-    stack_trace_nesting_level++;
+  } else if (top_private_data->stack_trace_nesting_level == 1) {
+    top_private_data->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();
+    top_private_data->incomplete_message->OutputToStdOut();
     return Factory::empty_symbol();
   } else {
     OS::Abort();
     // Unreachable
     return Factory::empty_symbol();
   }
 }
 
 
 void Top::PrintStack() {
-  if (stack_trace_nesting_level == 0) {
-    stack_trace_nesting_level++;
+  TopPrivateData* top_private_data = v8_context()->top_data_.top_private_data_;
+  if (top_private_data->stack_trace_nesting_level == 0) {
+    top_private_data->stack_trace_nesting_level++;
 
     StringAllocator* allocator;
-    if (preallocated_message_space == NULL) {
+    if (top_private_data->preallocated_message_space == NULL) {
       allocator = new HeapStringAllocator();
     } else {
-      allocator = preallocated_message_space;
+      allocator = top_private_data->preallocated_message_space;
     }
 
     NativeAllocationChecker allocation_checker(
       !FLAG_preallocate_message_memory ?
       NativeAllocationChecker::ALLOW :
       NativeAllocationChecker::DISALLOW);
 
     StringStream::ClearMentionedObjectCache();
     StringStream accumulator(allocator);
-    incomplete_message = &accumulator;
+    top_private_data->incomplete_message = &accumulator;
     PrintStack(&accumulator);
     accumulator.OutputToStdOut();
     accumulator.Log();
-    incomplete_message = NULL;
-    stack_trace_nesting_level = 0;
-    if (preallocated_message_space == NULL) {
+    top_private_data->incomplete_message = NULL;
+    top_private_data->stack_trace_nesting_level = 0;
+    if (top_private_data->preallocated_message_space == NULL) {
       // Remove the HeapStringAllocator created above.
       delete allocator;
     }
-  } else if (stack_trace_nesting_level == 1) {
-    stack_trace_nesting_level++;
+  } else if (top_private_data->stack_trace_nesting_level == 1) {
+    top_private_data->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();
+    top_private_data->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++);
   }
@@ skipping 15 matching lines @@
   accumulator->Add(
       "\n==== Details ================================================\n\n");
   PrintFrames(accumulator, StackFrame::DETAILS);
 
   accumulator->PrintMentionedObjectCache();
   accumulator->Add("=====================\n\n");
 }
 
 
 void Top::SetFailedAccessCheckCallback(v8::FailedAccessCheckCallback callback) {
-  ASSERT(thread_local_.failed_access_check_callback_ == NULL);
-  thread_local_.failed_access_check_callback_ = callback;
+  ThreadLocalTop& thread_local = v8_context()->top_data_.thread_local_;
+  ASSERT(thread_local.failed_access_check_callback_ == NULL);
+  thread_local.failed_access_check_callback_ = callback;
 }
 
 
 void Top::ReportFailedAccessCheck(JSObject* receiver, v8::AccessType type) {
-  if (!thread_local_.failed_access_check_callback_) return;
+  ThreadLocalTop& thread_local = v8_context()->top_data_.thread_local_;
+  if (!thread_local.failed_access_check_callback_) return;
 
   ASSERT(receiver->IsAccessCheckNeeded());
   ASSERT(Top::context());
   // The callers of this method are not expecting a GC.
   AssertNoAllocation no_gc;
 
   // Get the data object from access check info.
   JSFunction* constructor = JSFunction::cast(receiver->map()->constructor());
   Object* info = constructor->shared()->function_data();
   if (info == Heap::undefined_value()) return;
 
   Object* data_obj = FunctionTemplateInfo::cast(info)->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_.failed_access_check_callback_(
+  thread_local.failed_access_check_callback_(
     v8::Utils::ToLocal(receiver_handle),
     type,
     v8::Utils::ToLocal(data));
 }
 
 
 enum MayAccessDecision {
   YES, NO, UNKNOWN
 };
 
@@ skipping 157 matching lines @@
 
 Failure* Top::ThrowIllegalOperation() {
   return Throw(Heap::illegal_access_symbol());
 }
 
 
 void Top::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_.scheduled_exception_ = pending_exception();
-  thread_local_.external_caught_exception_ = false;
+  ThreadLocalTop& thread_local = v8_context()->top_data_.thread_local_;
+  thread_local.scheduled_exception_ = pending_exception();
+  thread_local.external_caught_exception_ = false;
   clear_pending_exception();
 }
 
 
 Object* Top::PromoteScheduledException() {
   Object* thrown = scheduled_exception();
   clear_scheduled_exception();
   // Re-throw the exception to avoid getting repeated error reporting.
   return ReThrow(thrown);
 }
@@ skipping 66 matching lines @@
 
 bool Top::ShouldReturnException(bool* is_caught_externally,
                                 bool catchable_by_javascript) {
   // Find the top-most try-catch handler.
   StackHandler* handler =
       StackHandler::FromAddress(Top::handler(Top::GetCurrentThread()));
   while (handler != NULL && !handler->is_try_catch()) {
     handler = handler->next();
   }
 
+  ThreadLocalTop& thread_local = v8_context()->top_data_.thread_local_;
   // 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_.try_catch_handler_address();
+  Address external_handler_address = thread_local.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.
   *is_caught_externally = external_handler_address != NULL &&
       (handler == NULL || handler->address() > external_handler_address ||
        !catchable_by_javascript);
 
   if (*is_caught_externally) {
     // Only report the exception if the external handler is verbose.
-    return thread_local_.TryCatchHandler()->is_verbose_;
+    return thread_local.TryCatchHandler()->is_verbose_;
   } else {
     // Report the exception if it isn't caught by JavaScript code.
     return handler == NULL;
   }
 }
 
 
 void Top::DoThrow(Object* exception,
                   MessageLocation* location,
                   const char* message) {
   ASSERT(!has_pending_exception());
 
   HandleScope scope;
   Handle<Object> exception_handle(exception);
+  ThreadLocalTop& thread_local = v8_context()->top_data_.thread_local_;
 
   // Determine reporting and whether the exception is caught externally.
   bool is_caught_externally = false;
   bool is_out_of_memory = exception == Failure::OutOfMemoryException();
   bool is_termination_exception = exception == Heap::termination_exception();
   bool catchable_by_javascript = !is_termination_exception && !is_out_of_memory;
   bool should_return_exception =
       ShouldReturnException(&is_caught_externally, catchable_by_javascript);
   bool report_exception = catchable_by_javascript && should_return_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 =
       is_caught_externally &&
-      thread_local_.TryCatchHandler()->capture_message_;
+      thread_local.TryCatchHandler()->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 = StackTrace();
       message_obj = MessageHandler::MakeMessageObject("uncaught_exception",
           location, HandleVector<Object>(&exception_handle, 1), stack_trace);
     }
   }
 
   // Save the message for reporting if the the exception remains uncaught.
-  thread_local_.has_pending_message_ = report_exception;
-  thread_local_.pending_message_ = message;
+  thread_local.has_pending_message_ = report_exception;
+  thread_local.pending_message_ = message;
   if (!message_obj.is_null()) {
-    thread_local_.pending_message_obj_ = *message_obj;
+    thread_local.pending_message_obj_ = *message_obj;
     if (location != NULL) {
-      thread_local_.pending_message_script_ = *location->script();
-      thread_local_.pending_message_start_pos_ = location->start_pos();
-      thread_local_.pending_message_end_pos_ = location->end_pos();
+      thread_local.pending_message_script_ = *location->script();
+      thread_local.pending_message_start_pos_ = location->start_pos();
+      thread_local.pending_message_end_pos_ = location->end_pos();
     }
   }
 
   if (is_caught_externally) {
-    thread_local_.catcher_ = thread_local_.TryCatchHandler();
+    thread_local.catcher_ = thread_local.TryCatchHandler();
   }
 
   // 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.
   set_pending_exception(*exception_handle);
 }
 
 
 void Top::ReportPendingMessages() {
   ASSERT(has_pending_exception());
   setup_external_caught();
+  ThreadLocalTop& thread_local = v8_context()->top_data_.thread_local_;
   // 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.
-  bool external_caught = thread_local_.external_caught_exception_;
+  bool external_caught = thread_local.external_caught_exception_;
   HandleScope scope;
-  if (thread_local_.pending_exception_ == Failure::OutOfMemoryException()) {
+  if (thread_local.pending_exception_ == Failure::OutOfMemoryException()) {
     context()->mark_out_of_memory();
-  } else if (thread_local_.pending_exception_ ==
+  } else if (thread_local.pending_exception_ ==
              Heap::termination_exception()) {
     if (external_caught) {
-      thread_local_.TryCatchHandler()->can_continue_ = false;
-      thread_local_.TryCatchHandler()->exception_ = Heap::null_value();
+      thread_local.TryCatchHandler()->can_continue_ = false;
+      thread_local.TryCatchHandler()->exception_ = Heap::null_value();
     }
   } else {
     Handle<Object> exception(pending_exception());
-    thread_local_.external_caught_exception_ = false;
+    thread_local.external_caught_exception_ = false;
     if (external_caught) {
-      thread_local_.TryCatchHandler()->can_continue_ = true;
-      thread_local_.TryCatchHandler()->exception_ =
-        thread_local_.pending_exception_;
-      if (!thread_local_.pending_message_obj_->IsTheHole()) {
-        try_catch_handler()->message_ = thread_local_.pending_message_obj_;
+      thread_local.TryCatchHandler()->can_continue_ = true;
+      thread_local.TryCatchHandler()->exception_ =
+        thread_local.pending_exception_;
+      if (!thread_local.pending_message_obj_->IsTheHole()) {
+        try_catch_handler()->message_ = thread_local.pending_message_obj_;
       }
     }
-    if (thread_local_.has_pending_message_) {
-      thread_local_.has_pending_message_ = false;
-      if (thread_local_.pending_message_ != NULL) {
-        MessageHandler::ReportMessage(thread_local_.pending_message_);
-      } else if (!thread_local_.pending_message_obj_->IsTheHole()) {
-        Handle<Object> message_obj(thread_local_.pending_message_obj_);
-        if (thread_local_.pending_message_script_ != NULL) {
-          Handle<Script> script(thread_local_.pending_message_script_);
-          int start_pos = thread_local_.pending_message_start_pos_;
-          int end_pos = thread_local_.pending_message_end_pos_;
+    if (thread_local.has_pending_message_) {
+      thread_local.has_pending_message_ = false;
+      if (thread_local.pending_message_ != NULL) {
+        MessageHandler::ReportMessage(thread_local.pending_message_);
+      } else if (!thread_local.pending_message_obj_->IsTheHole()) {
+        Handle<Object> message_obj(thread_local.pending_message_obj_);
+        if (thread_local.pending_message_script_ != NULL) {
+          Handle<Script> script(thread_local.pending_message_script_);
+          int start_pos = thread_local.pending_message_start_pos_;
+          int end_pos = thread_local.pending_message_end_pos_;
           MessageLocation location(script, start_pos, end_pos);
           MessageHandler::ReportMessage(&location, message_obj);
         } else {
           MessageHandler::ReportMessage(NULL, message_obj);
         }
       }
     }
-    thread_local_.external_caught_exception_ = external_caught;
+    thread_local.external_caught_exception_ = external_caught;
     set_pending_exception(*exception);
   }
   clear_pending_message();
 }
 
 
 void Top::TraceException(bool flag) {
   FLAG_trace_exception = flag;
 }
 
 
 bool Top::OptionalRescheduleException(bool is_bottom_call) {
+  ThreadLocalTop& thread_local = v8_context()->top_data_.thread_local_;
   // 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_.external_caught_exception_ = false;
+        thread_local.external_caught_exception_ = false;
         clear_pending_exception();
         return false;
       }
-    } else if (thread_local_.external_caught_exception_) {
+    } else if (thread_local.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_.try_catch_handler_address() != NULL);
+      ASSERT(thread_local.try_catch_handler_address() != NULL);
       Address external_handler_address =
-          thread_local_.try_catch_handler_address();
+          thread_local.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_.external_caught_exception_ = false;
+      thread_local.external_caught_exception_ = false;
       clear_pending_exception();
       return false;
     }
   }
 
   // Reschedule the exception.
-  thread_local_.scheduled_exception_ = pending_exception();
+  thread_local.scheduled_exception_ = pending_exception();
   clear_pending_exception();
   return true;
 }
 
 
 bool Top::is_out_of_memory() {
   if (has_pending_exception()) {
     Object* e = pending_exception();
     if (e->IsFailure() && Failure::cast(e)->IsOutOfMemoryException()) {
       return true;
     }
   }
   if (has_scheduled_exception()) {
     Object* e = scheduled_exception();
     if (e->IsFailure() && Failure::cast(e)->IsOutOfMemoryException()) {
       return true;
     }
   }
   return false;
 }
 
 
 Handle<Context> Top::global_context() {
-  GlobalObject* global = thread_local_.context_->global();
+  GlobalObject* global = v8_context()->top_data_.thread_local_.context_->
+    global();
   return Handle<Context>(global->global_context());
 }
 
 
 Handle<Context> Top::GetCallingGlobalContext() {
   JavaScriptFrameIterator it;
 #ifdef ENABLE_DEBUGGER_SUPPORT
   if (Debug::InDebugger()) {
     while (!it.done()) {
       JavaScriptFrame* frame = it.frame();
@@ skipping 23 matching lines @@
           (function == table->get(index+1))) {
         return table->get(index+2);
       }
     }
   }
   return Heap::undefined_value();
 }
 
 
 char* Top::ArchiveThread(char* to) {
-  memcpy(to, reinterpret_cast<char*>(&thread_local_), sizeof(thread_local_));
+  memcpy(
+    to,
+    reinterpret_cast<char*>(&v8_context()->top_data_.thread_local_),
+    sizeof(ThreadLocalTop));
   InitializeThreadLocal();
-  return to + sizeof(thread_local_);
+  return to + sizeof(ThreadLocalTop);
 }
 
 
 char* Top::RestoreThread(char* from) {
-  memcpy(reinterpret_cast<char*>(&thread_local_), from, sizeof(thread_local_));
-  return from + sizeof(thread_local_);
+  memcpy(
+    reinterpret_cast<char*>(&v8_context()->top_data_.thread_local_),
+    from,
+    sizeof(ThreadLocalTop));
+  return from + sizeof(ThreadLocalTop);
 }
 
 
 ExecutionAccess::ExecutionAccess() {
-  Top::break_access_->Lock();
+  v8_context()->top_data_.break_access_->Lock();
 }
 
 
 ExecutionAccess::~ExecutionAccess() {
-  Top::break_access_->Unlock();
+  v8_context()->top_data_.break_access_->Unlock();
 }
 
 
 } }  // namespace v8::internal