text: // Copyright 2012 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
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #include <stdlib.h>
  
  #include "v8.h"
  
  #include "ast.h"
  #include "bootstrapper.h"
  #include "codegen.h"
  #include "compilation-cache.h"
  #include "debug.h"
  #include "deoptimizer.h"
  #include "heap-profiler.h"
  #include "hydrogen.h"
  #include "isolate.h"
  #include "lithium-allocator.h"
  #include "log.h"
  #include "messages.h"
  #include "platform.h"
  #include "regexp-stack.h"
  #include "runtime-profiler.h"
  #include "scopeinfo.h"
  #include "serialize.h"
  #include "simulator.h"
  #include "spaces.h"
  #include "stub-cache.h"
  #include "version.h"
  #include "vm-state-inl.h"
  
  
  namespace v8 {
  namespace internal {
  
  Atomic32 ThreadId::highest_thread_id_ = 0;
  
  int ThreadId::AllocateThreadId() {
    int new_id = NoBarrier_AtomicIncrement(&highest_thread_id_, 1);
    return new_id;
  }
  
  
  int ThreadId::GetCurrentThreadId() {
    int thread_id = Thread::GetThreadLocalInt(Isolate::thread_id_key_);
    if (thread_id == 0) {
      thread_id = AllocateThreadId();
      Thread::SetThreadLocalInt(Isolate::thread_id_key_, thread_id);
    }
    return thread_id;
  }
  
  
  ThreadLocalTop::ThreadLocalTop() {
    InitializeInternal();
    // This flag may be set using v8::V8::IgnoreOutOfMemoryException()
    // before an isolate is initialized. The initialize methods below do
    // not touch it to preserve its value.
    ignore_out_of_memory_ = false;
  }
  
  
  void ThreadLocalTop::InitializeInternal() {
    c_entry_fp_ = 0;
    handler_ = 0;
  #ifdef USE_SIMULATOR
    simulator_ = NULL;
  #endif
    js_entry_sp_ = NULL;
    external_callback_ = NULL;
    current_vm_state_ = EXTERNAL;
    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;
    top_lookup_result_ = NULL;
  
    // These members are re-initialized later after deserialization
    // is complete.
    pending_exception_ = NULL;
    has_pending_message_ = false;
    pending_message_obj_ = NULL;
    pending_message_script_ = NULL;
    scheduled_exception_ = 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).
  class PreallocatedMemoryThread: public Thread {
   public:
    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_;
    }
  
    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_;
    }
  
    // Stop the PreallocatedMemoryThread and release its resources.
    void StopThread() {
      keep_running_ = false;
      wait_for_ever_semaphore_->Signal();
  
      // Wait for the thread to terminate.
      Join();
  
      if (data_ready_semaphore_ != NULL) {
        delete data_ready_semaphore_;
        data_ready_semaphore_ = NULL;
      }
  
      delete wait_for_ever_semaphore_;
      wait_for_ever_semaphore_ = NULL;
    }
  
   protected:
    // 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());
    }
  
  
   private:
    PreallocatedMemoryThread()
        : Thread("v8:PreallocMem"),
          keep_running_(true),
          wait_for_ever_semaphore_(OS::CreateSemaphore(0)),
          data_ready_semaphore_(OS::CreateSemaphore(0)),
          data_(NULL),
          length_(0) {
    }
  
    // 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_;
  
    friend class Isolate;
  
    DISALLOW_COPY_AND_ASSIGN(PreallocatedMemoryThread);
  };
  
  
  void Isolate::PreallocatedMemoryThreadStart() {
    if (preallocated_memory_thread_ != NULL) return;
    preallocated_memory_thread_ = new PreallocatedMemoryThread();
    preallocated_memory_thread_->Start();
  }
  
  
  void Isolate::PreallocatedMemoryThreadStop() {
    if (preallocated_memory_thread_ == NULL) return;
    preallocated_memory_thread_->StopThread();
    // Done with the thread entirely.
    delete preallocated_memory_thread_;
    preallocated_memory_thread_ = NULL;
  }
  
  
  void Isolate::PreallocatedStorageInit(size_t size) {
    ASSERT(free_list_.next_ == &free_list_);
    ASSERT(free_list_.previous_ == &free_list_);
    PreallocatedStorage* free_chunk =
        reinterpret_cast<PreallocatedStorage*>(new char[size]);
    free_list_.next_ = free_list_.previous_ = free_chunk;
    free_chunk->next_ = free_chunk->previous_ = &free_list_;
    free_chunk->size_ = size - sizeof(PreallocatedStorage);
    preallocated_storage_preallocated_ = true;
  }
  
  
  void* Isolate::PreallocatedStorageNew(size_t size) {
    if (!preallocated_storage_preallocated_) {
      return FreeStoreAllocationPolicy().New(size);
    }
    ASSERT(free_list_.next_ != &free_list_);
    ASSERT(free_list_.previous_ != &free_list_);
  
    size = (size + kPointerSize - 1) & ~(kPointerSize - 1);
    // Search for exact fit.
    for (PreallocatedStorage* storage = free_list_.next_;
         storage != &free_list_;
         storage = storage->next_) {
      if (storage->size_ == size) {
        storage->Unlink();
        storage->LinkTo(&in_use_list_);
        return reinterpret_cast<void*>(storage + 1);
      }
    }
    // Search for first fit.
    for (PreallocatedStorage* storage = free_list_.next_;
         storage != &free_list_;
         storage = storage->next_) {
      if (storage->size_ >= size + sizeof(PreallocatedStorage)) {
        storage->Unlink();
        storage->LinkTo(&in_use_list_);
        PreallocatedStorage* left_over =
            reinterpret_cast<PreallocatedStorage*>(
                reinterpret_cast<char*>(storage + 1) + size);
        left_over->size_ = storage->size_ - size - sizeof(PreallocatedStorage);
        ASSERT(size + left_over->size_ + sizeof(PreallocatedStorage) ==
               storage->size_);
        storage->size_ = size;
        left_over->LinkTo(&free_list_);
        return reinterpret_cast<void*>(storage + 1);
      }
    }
    // Allocation failure.
    ASSERT(false);
    return NULL;
  }
  
  
  // We don't attempt to coalesce.
  void Isolate::PreallocatedStorageDelete(void* p) {
    if (p == NULL) {
      return;
    }
    if (!preallocated_storage_preallocated_) {
      FreeStoreAllocationPolicy::Delete(p);
      return;
    }
    PreallocatedStorage* storage = reinterpret_cast<PreallocatedStorage*>(p) - 1;
    ASSERT(storage->next_->previous_ == storage);
    ASSERT(storage->previous_->next_ == storage);
    storage->Unlink();
    storage->LinkTo(&free_list_);
  }
  
  Isolate* Isolate::default_isolate_ = NULL;
  Thread::LocalStorageKey Isolate::isolate_key_;
  Thread::LocalStorageKey Isolate::thread_id_key_;
  Thread::LocalStorageKey Isolate::per_isolate_thread_data_key_;
  Mutex* Isolate::process_wide_mutex_ = OS::CreateMutex();
  Isolate::ThreadDataTable* Isolate::thread_data_table_ = NULL;
  
  
  Isolate::PerIsolateThreadData* Isolate::AllocatePerIsolateThreadData(
      ThreadId thread_id) {
    ASSERT(!thread_id.Equals(ThreadId::Invalid()));
    PerIsolateThreadData* per_thread = new PerIsolateThreadData(this, thread_id);
    {
      ScopedLock lock(process_wide_mutex_);
      ASSERT(thread_data_table_->Lookup(this, thread_id) == NULL);
      thread_data_table_->Insert(per_thread);
      ASSERT(thread_data_table_->Lookup(this, thread_id) == per_thread);
    }
    return per_thread;
  }
  
  
  Isolate::PerIsolateThreadData*
      Isolate::FindOrAllocatePerThreadDataForThisThread() {
    ThreadId thread_id = ThreadId::Current();
    PerIsolateThreadData* per_thread = NULL;
    {
      ScopedLock lock(process_wide_mutex_);
      per_thread = thread_data_table_->Lookup(this, thread_id);
      if (per_thread == NULL) {
        per_thread = AllocatePerIsolateThreadData(thread_id);
      }
    }
    return per_thread;
  }
  
  
  Isolate::PerIsolateThreadData* Isolate::FindPerThreadDataForThisThread() {
    ThreadId thread_id = ThreadId::Current();
    PerIsolateThreadData* per_thread = NULL;
    {
      ScopedLock lock(process_wide_mutex_);
      per_thread = thread_data_table_->Lookup(this, thread_id);
    }
    return per_thread;
  }
  
  
  void Isolate::EnsureDefaultIsolate() {
    ScopedLock lock(process_wide_mutex_);
    if (default_isolate_ == NULL) {
      isolate_key_ = Thread::CreateThreadLocalKey();
      thread_id_key_ = Thread::CreateThreadLocalKey();
      per_isolate_thread_data_key_ = Thread::CreateThreadLocalKey();
      thread_data_table_ = new Isolate::ThreadDataTable();
      default_isolate_ = new Isolate();
    }
    // Can't use SetIsolateThreadLocals(default_isolate_, NULL) here
    // because a non-null thread data may be already set.
    if (Thread::GetThreadLocal(isolate_key_) == NULL) {
      Thread::SetThreadLocal(isolate_key_, default_isolate_);
    }
  }
  
  struct StaticInitializer {
    StaticInitializer() {
      Isolate::EnsureDefaultIsolate();
    }
  } static_initializer;
  
  #ifdef ENABLE_DEBUGGER_SUPPORT
  Debugger* Isolate::GetDefaultIsolateDebugger() {
    EnsureDefaultIsolate();
    return default_isolate_->debugger();
  }
  #endif
  
  
  StackGuard* Isolate::GetDefaultIsolateStackGuard() {
    EnsureDefaultIsolate();
    return default_isolate_->stack_guard();
  }
  
  
  void Isolate::EnterDefaultIsolate() {
    EnsureDefaultIsolate();
    ASSERT(default_isolate_ != NULL);
  
    PerIsolateThreadData* data = CurrentPerIsolateThreadData();
    // If not yet in default isolate - enter it.
    if (data == NULL || data->isolate() != default_isolate_) {
      default_isolate_->Enter();
    }
  }
  
  
  Isolate* Isolate::GetDefaultIsolateForLocking() {
    EnsureDefaultIsolate();
    return default_isolate_;
  }
  
  
  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);
    }
  
    // Iterate pointers in live lookup results.
    thread->top_lookup_result_->Iterate(v);
  }
  
  
  void Isolate::Iterate(ObjectVisitor* v) {
    ThreadLocalTop* current_t = thread_local_top();
    Iterate(v, current_t);
  }
  
  void Isolate::IterateDeferredHandles(ObjectVisitor* visitor) {
    for (DeferredHandles* deferred = deferred_handles_head_;
         deferred != NULL;
         deferred = deferred->next_) {
      deferred->Iterate(visitor);
    }
  }
  
  
  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();
    }
  }
  
  
  void Isolate::PushStackTraceAndDie(unsigned int magic,
                                     Object* object,
                                     Map* map,
                                     unsigned int magic2) {
    const int kMaxStackTraceSize = 8192;
    Handle<String> trace = StackTraceString();
    char buffer[kMaxStackTraceSize];
    int length = Min(kMaxStackTraceSize - 1, trace->length());
    String::WriteToFlat(*trace, buffer, 0, length);
    buffer[length] = '\0';
    OS::PrintError("Stacktrace (%x-%x) %p %p: %s\n",
                   magic, magic2,
                   static_cast<void*>(object), static_cast<void*>(map),
                   buffer);
    OS::Abort();
  }
  
  
  void Isolate::CaptureAndSetCurrentStackTraceFor(Handle<JSObject> error_object) {
    if (capture_stack_trace_for_uncaught_exceptions_) {
      // Capture stack trace for a detailed exception message.
      Handle<String> key = factory()->hidden_stack_trace_symbol();
      Handle<JSArray> stack_trace = CaptureCurrentStackTrace(
          stack_trace_for_uncaught_exceptions_frame_limit_,
          stack_trace_for_uncaught_exceptions_options_);
      JSObject::SetHiddenProperty(error_object, key, stack_trace);
    }
  }
  
  
  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> stack_frame = 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();
            }
            CHECK_NOT_EMPTY_HANDLE(
                this,
                JSObject::SetLocalPropertyIgnoreAttributes(
                    stack_frame, column_key,
                    Handle<Smi>(Smi::FromInt(column_offset + 1)), NONE));
          }
          CHECK_NOT_EMPTY_HANDLE(
              this,
              JSObject::SetLocalPropertyIgnoreAttributes(
                  stack_frame, line_key,
                  Handle<Smi>(Smi::FromInt(line_number + 1)), NONE));
        }
  
        if (options & StackTrace::kScriptName) {
          Handle<Object> script_name(script->name(), this);
          CHECK_NOT_EMPTY_HANDLE(this,
                                 JSObject::SetLocalPropertyIgnoreAttributes(
                                     stack_frame, script_key, script_name, NONE));
        }
  
        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();
          }
          CHECK_NOT_EMPTY_HANDLE(this,
                                 JSObject::SetLocalPropertyIgnoreAttributes(
                                     stack_frame, script_name_or_source_url_key,
                                     result, NONE));
        }
  
        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);
          }
          CHECK_NOT_EMPTY_HANDLE(this,
                                 JSObject::SetLocalPropertyIgnoreAttributes(
                                     stack_frame, function_key, fun_name, NONE));
        }
  
        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();
          CHECK_NOT_EMPTY_HANDLE(this,
                                 JSObject::SetLocalPropertyIgnoreAttributes(
                                     stack_frame, eval_key, is_eval, NONE));
        }
  
        if (options & StackTrace::kIsConstructor) {
          Handle<Object> is_constructor = (frames[i].is_constructor()) ?
              factory()->true_value() : factory()->false_value();
          CHECK_NOT_EMPTY_HANDLE(this,
                                 JSObject::SetLocalPropertyIgnoreAttributes(
                                     stack_frame, constructor_key,
                                     is_constructor, NONE));
        }
  
        FixedArray::cast(stack_trace->elements())->set(frames_seen, *stack_frame);
        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();
      InitializeLoggingAndCounters();
      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());
    { VMState state(this, EXTERNAL);
      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) {
    bool can_be_caught_externally = false;
    bool catchable_by_javascript = is_catchable_by_javascript(exception);
    ShouldReportException(&can_be_caught_externally, catchable_by_javascript);
  
    thread_local_top()->catcher_ = can_be_caught_externally ?
        try_catch_handler() : NULL;
  
    // Set the exception being re-thrown.
    set_pending_exception(exception);
    if (exception->IsFailure()) return exception->ToFailureUnchecked();
    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_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;
    }
  }
  
  
  bool Isolate::IsErrorObject(Handle<Object> obj) {
    if (!obj->IsJSObject()) return false;
  
    String* error_key = *(factory()->LookupAsciiSymbol("$Error"));
    Object* error_constructor =
        js_builtins_object()->GetPropertyNoExceptionThrown(error_key);
  
    for (Object* prototype = *obj; !prototype->IsNull();
         prototype = prototype->GetPrototype()) {
      if (!prototype->IsJSObject()) return false;
      if (JSObject::cast(prototype)->map()->constructor() == error_constructor) {
        return true;
      }
    }
    return false;
  }
  
  
  void Isolate::DoThrow(Object* exception, MessageLocation* location) {
    ASSERT(!has_pending_exception());
  
    HandleScope scope;
    Handle<Object> exception_handle(exception);
  
    // Determine reporting and whether the exception is caught externally.
    bool catchable_by_javascript = is_catchable_by_javascript(exception);
    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;
    bool try_catch_needs_message =
        can_be_caught_externally && try_catch_handler()->capture_message_;
    bool bootstrapping = bootstrapper()->IsActive();
  
  #ifdef ENABLE_DEBUGGER_SUPPORT
    // Notify debugger of exception.
    if (catchable_by_javascript) {
      debugger_->OnException(exception_handle, report_exception);
    }
  #endif
  
    // Generate the message if required.
    if (report_exception || try_catch_needs_message) {
      MessageLocation potential_computed_location;
      if (location == NULL) {
        // If no location was specified we use a computed one instead.
        ComputeLocation(&potential_computed_location);
        location = &potential_computed_location;
      }
      // 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.
      if (!bootstrapping) {
        Handle<String> stack_trace;
        if (FLAG_trace_exception) stack_trace = StackTraceString();
        Handle<JSArray> stack_trace_object;
        if (capture_stack_trace_for_uncaught_exceptions_) {
          if (IsErrorObject(exception_handle)) {
            // We fetch the stack trace that corresponds to this error object.
            String* key = heap()->hidden_stack_trace_symbol();
            Object* stack_property =
                JSObject::cast(*exception_handle)->GetHiddenProperty(key);
            // Property lookup may have failed.  In this case it's probably not
            // a valid Error object.
            if (stack_property->IsJSArray()) {
              stack_trace_object = Handle<JSArray>(JSArray::cast(stack_property));
            }
          }
          if (stack_trace_object.is_null()) {
            // Not an error object, we capture at throw site.
            stack_trace_object = CaptureCurrentStackTrace(
                stack_trace_for_uncaught_exceptions_frame_limit_,
                stack_trace_for_uncaught_exceptions_options_);
          }
        }
        Handle<Object> message_obj = MessageHandler::MakeMessageObject(
            "uncaught_exception",
            location,
            HandleVector<Object>(&exception_handle, 1),
            stack_trace,
            stack_trace_object);
        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();
        }
      } else if (location != NULL && !location->script().is_null()) {
        // We are bootstrapping and caught an error where the location is set
        // and we have a script for the location.
        // In this case we could have an extension (or an internal error
        // somewhere) and we print out the line number at which the error occured
        // to the console for easier debugging.
        int line_number = GetScriptLineNumberSafe(location->script(),
                                                  location->start_pos());
        if (exception->IsString()) {
          OS::PrintError(
              "Extension or internal compilation error: %s in %s at line %d.\n",
              *String::cast(exception)->ToCString(),
              *String::cast(location->script()->name())->ToCString(),
              line_number + 1);
        } else {
          OS::PrintError(
              "Extension or internal compilation error in %s at line %d.\n",
              *String::cast(location->script()->name())->ToCString(),
              line_number + 1);
        }
      }
    }
  
    // Save the message for reporting if the the exception remains uncaught.
    thread_local_top()->has_pending_message_ = report_exception;
  
    // 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;
  
    set_pending_exception(*exception_handle);
  }
  
  
  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_catch());
      if (handler->is_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();
  
    // Always 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();
    clear_pending_exception();
    clear_pending_message();
    clear_scheduled_exception();
    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);
    }
    ASSERT(context() == NULL || context()->IsContext());
    return from + sizeof(ThreadLocalTop);
  }
  
  
  Isolate::ThreadDataTable::ThreadDataTable()
      : list_(NULL) {
  }
  
  
  Isolate::PerIsolateThreadData*
      Isolate::ThreadDataTable::Lookup(Isolate* isolate,
                                       ThreadId thread_id) {
    for (PerIsolateThreadData* data = list_; data != NULL; data = data->next_) {
      if (data->Matches(isolate, thread_id)) return data;
    }
    return NULL;
  }
  
  
  void Isolate::ThreadDataTable::Insert(Isolate::PerIsolateThreadData* data) {
    if (list_ != NULL) list_->prev_ = data;
    data->next_ = list_;
    list_ = data;
  }
  
  
  void Isolate::ThreadDataTable::Remove(PerIsolateThreadData* data) {
    if (list_ == data) list_ = data->next_;
    if (data->next_ != NULL) data->next_->prev_ = data->prev_;
    if (data->prev_ != NULL) data->prev_->next_ = data->next_;
    delete data;
  }
  
  
  void Isolate::ThreadDataTable::Remove(Isolate* isolate,
                                        ThreadId thread_id) {
    PerIsolateThreadData* data = Lookup(isolate, thread_id);
    if (data != NULL) {
      Remove(data);
    }
  }
  
  
  void Isolate::ThreadDataTable::RemoveAllThreads(Isolate* isolate) {
    PerIsolateThreadData* data = list_;
    while (data != NULL) {
      PerIsolateThreadData* next = data->next_;
      if (data->isolate() == isolate) Remove(data);
      data = next;
    }
  }
  
  
  #ifdef DEBUG
  #define TRACE_ISOLATE(tag)                                              \
    do {                                                                  \
      if (FLAG_trace_isolates) {                                          \
        PrintF("Isolate %p " #tag "\n", reinterpret_cast<void*>(this));   \
      }                                                                   \
    } while (false)
  #else
  #define TRACE_ISOLATE(tag)
  #endif
  
  
  Isolate::Isolate()
      : state_(UNINITIALIZED),
        embedder_data_(NULL),
        entry_stack_(NULL),
        stack_trace_nesting_level_(0),
        incomplete_message_(NULL),
        preallocated_memory_thread_(NULL),
        preallocated_message_space_(NULL),
        bootstrapper_(NULL),
        runtime_profiler_(NULL),
        compilation_cache_(NULL),
        counters_(NULL),
        code_range_(NULL),
        // Must be initialized early to allow v8::SetResourceConstraints calls.
        break_access_(OS::CreateMutex()),
        debugger_initialized_(false),
        // Must be initialized early to allow v8::Debug calls.
        debugger_access_(OS::CreateMutex()),
        logger_(NULL),
        stats_table_(NULL),
        stub_cache_(NULL),
        deoptimizer_data_(NULL),
        capture_stack_trace_for_uncaught_exceptions_(false),
        stack_trace_for_uncaught_exceptions_frame_limit_(0),
        stack_trace_for_uncaught_exceptions_options_(StackTrace::kOverview),
        transcendental_cache_(NULL),
        memory_allocator_(NULL),
        keyed_lookup_cache_(NULL),
        context_slot_cache_(NULL),
        descriptor_lookup_cache_(NULL),
        handle_scope_implementer_(NULL),
        unicode_cache_(NULL),
        runtime_zone_(this),
        in_use_list_(0),
        free_list_(0),
        preallocated_storage_preallocated_(false),
        inner_pointer_to_code_cache_(NULL),
        write_input_buffer_(NULL),
        global_handles_(NULL),
        context_switcher_(NULL),
        thread_manager_(NULL),
        fp_stubs_generated_(false),
        has_installed_extensions_(false),
        string_tracker_(NULL),
        regexp_stack_(NULL),
        date_cache_(NULL),
        context_exit_happened_(false),
        deferred_handles_head_(NULL),
        optimizing_compiler_thread_(this) {
    TRACE_ISOLATE(constructor);
  
    memset(isolate_addresses_, 0,
        sizeof(isolate_addresses_[0]) * (kIsolateAddressCount + 1));
  
    heap_.isolate_ = this;
    stack_guard_.isolate_ = this;
  
    // ThreadManager is initialized early to support locking an isolate
    // before it is entered.
    thread_manager_ = new ThreadManager();
    thread_manager_->isolate_ = this;
  
  #if defined(V8_TARGET_ARCH_ARM) && !defined(__arm__) || \
      defined(V8_TARGET_ARCH_MIPS) && !defined(__mips__)
    simulator_initialized_ = false;
    simulator_i_cache_ = NULL;
    simulator_redirection_ = NULL;
  #endif
  
  #ifdef DEBUG
    // heap_histograms_ initializes itself.
    memset(&js_spill_information_, 0, sizeof(js_spill_information_));
    memset(code_kind_statistics_, 0,
           sizeof(code_kind_statistics_[0]) * Code::NUMBER_OF_KINDS);
  #endif
  
  #ifdef ENABLE_DEBUGGER_SUPPORT
    debug_ = NULL;
    debugger_ = NULL;
  #endif
  
    handle_scope_data_.Initialize();
  
  #define ISOLATE_INIT_EXECUTE(type, name, initial_value)                        \
    name##_ = (initial_value);
    ISOLATE_INIT_LIST(ISOLATE_INIT_EXECUTE)
  #undef ISOLATE_INIT_EXECUTE
  
  #define ISOLATE_INIT_ARRAY_EXECUTE(type, name, length)                         \
    memset(name##_, 0, sizeof(type) * length);
    ISOLATE_INIT_ARRAY_LIST(ISOLATE_INIT_ARRAY_EXECUTE)
  #undef ISOLATE_INIT_ARRAY_EXECUTE
  }
  
  void Isolate::TearDown() {
    TRACE_ISOLATE(tear_down);
  
    // Temporarily set this isolate as current so that various parts of
    // the isolate can access it in their destructors without having a
    // direct pointer. We don't use Enter/Exit here to avoid
    // initializing the thread data.
    PerIsolateThreadData* saved_data = CurrentPerIsolateThreadData();
    Isolate* saved_isolate = UncheckedCurrent();
    SetIsolateThreadLocals(this, NULL);
  
    Deinit();
  
    { ScopedLock lock(process_wide_mutex_);
      thread_data_table_->RemoveAllThreads(this);
    }
  
    if (serialize_partial_snapshot_cache_ != NULL) {
      delete[] serialize_partial_snapshot_cache_;
      serialize_partial_snapshot_cache_ = NULL;
    }
  
    if (!IsDefaultIsolate()) {
      delete this;
    }
  
    // Restore the previous current isolate.
    SetIsolateThreadLocals(saved_isolate, saved_data);
  }
  
  
  void Isolate::Deinit() {
    if (state_ == INITIALIZED) {
      TRACE_ISOLATE(deinit);
  
      if (FLAG_parallel_recompilation) optimizing_compiler_thread_.Stop();
  
      if (FLAG_hydrogen_stats) HStatistics::Instance()->Print();
  
      // We must stop the logger before we tear down other components.
      logger_->EnsureTickerStopped();
  
      delete deoptimizer_data_;
      deoptimizer_data_ = NULL;
      if (FLAG_preemption) {
        v8::Locker locker;
        v8::Locker::StopPreemption();
      }
      builtins_.TearDown();
      bootstrapper_->TearDown();
  
      // Remove the external reference to the preallocated stack memory.
      delete preallocated_message_space_;
      preallocated_message_space_ = NULL;
      PreallocatedMemoryThreadStop();
  
      HeapProfiler::TearDown();
      CpuProfiler::TearDown();
      if (runtime_profiler_ != NULL) {
        runtime_profiler_->TearDown();
        delete runtime_profiler_;
        runtime_profiler_ = NULL;
      }
      heap_.TearDown();
      logger_->TearDown();
  
      // The default isolate is re-initializable due to legacy API.
      state_ = UNINITIALIZED;
    }
  }
  
  
  void Isolate::PushToPartialSnapshotCache(Object* obj) {
    int length = serialize_partial_snapshot_cache_length();
    int capacity = serialize_partial_snapshot_cache_capacity();
  
    if (length >= capacity) {
      int new_capacity = static_cast<int>((capacity + 10) * 1.2);
      Object** new_array = new Object*[new_capacity];
      for (int i = 0; i < length; i++) {
        new_array[i] = serialize_partial_snapshot_cache()[i];
      }
      if (capacity != 0) delete[] serialize_partial_snapshot_cache();
      set_serialize_partial_snapshot_cache(new_array);
      set_serialize_partial_snapshot_cache_capacity(new_capacity);
    }
  
    serialize_partial_snapshot_cache()[length] = obj;
    set_serialize_partial_snapshot_cache_length(length + 1);
  }
  
  
  void Isolate::SetIsolateThreadLocals(Isolate* isolate,
                                       PerIsolateThreadData* data) {
    Thread::SetThreadLocal(isolate_key_, isolate);
    Thread::SetThreadLocal(per_isolate_thread_data_key_, data);
  }
  
  
  Isolate::~Isolate() {
    TRACE_ISOLATE(destructor);
  
    // Has to be called while counters_ are still alive.
    runtime_zone_.DeleteKeptSegment();
  
    delete[] assembler_spare_buffer_;
    assembler_spare_buffer_ = NULL;
  
    delete unicode_cache_;
    unicode_cache_ = NULL;
  
    delete date_cache_;
    date_cache_ = NULL;
  
    delete regexp_stack_;
    regexp_stack_ = NULL;
  
    delete descriptor_lookup_cache_;
    descriptor_lookup_cache_ = NULL;
    delete context_slot_cache_;
    context_slot_cache_ = NULL;
    delete keyed_lookup_cache_;
    keyed_lookup_cache_ = NULL;
  
    delete transcendental_cache_;
    transcendental_cache_ = NULL;
    delete stub_cache_;
    stub_cache_ = NULL;
    delete stats_table_;
    stats_table_ = NULL;
  
    delete logger_;
    logger_ = NULL;
  
    delete counters_;
    counters_ = NULL;
  
    delete handle_scope_implementer_;
    handle_scope_implementer_ = NULL;
    delete break_access_;
    break_access_ = NULL;
    delete debugger_access_;
    debugger_access_ = NULL;
  
    delete compilation_cache_;
    compilation_cache_ = NULL;
    delete bootstrapper_;
    bootstrapper_ = NULL;
    delete inner_pointer_to_code_cache_;
    inner_pointer_to_code_cache_ = NULL;
    delete write_input_buffer_;
    write_input_buffer_ = NULL;
  
    delete context_switcher_;
    context_switcher_ = NULL;
    delete thread_manager_;
    thread_manager_ = NULL;
  
    delete string_tracker_;
    string_tracker_ = NULL;
  
    delete memory_allocator_;
    memory_allocator_ = NULL;
    delete code_range_;
    code_range_ = NULL;
    delete global_handles_;
    global_handles_ = NULL;
  
    delete external_reference_table_;
    external_reference_table_ = NULL;
  
  #ifdef ENABLE_DEBUGGER_SUPPORT
    delete debugger_;
    debugger_ = NULL;
    delete debug_;
    debug_ = NULL;
  #endif
  }
  
  
  void Isolate::InitializeThreadLocal() {
    thread_local_top_.isolate_ = this;
    thread_local_top_.Initialize();
  }
  
  
  void Isolate::PropagatePendingExceptionToExternalTryCatch() {
    ASSERT(has_pending_exception());
  
    bool external_caught = IsExternallyCaught();
    thread_local_top_.external_caught_exception_ = external_caught;
  
    if (!external_caught) return;
  
    if (thread_local_top_.pending_exception_ == Failure::OutOfMemoryException()) {
      // Do not propagate OOM exception: we should kill VM asap.
    } else if (thread_local_top_.pending_exception_ ==
               heap()->termination_exception()) {
      try_catch_handler()->can_continue_ = false;
      try_catch_handler()->exception_ = heap()->null_value();
    } else {
      // At this point all non-object (failure) exceptions have
      // been dealt with so this shouldn't fail.
      ASSERT(!pending_exception()->IsFailure());
      try_catch_handler()->can_continue_ = true;
      try_catch_handler()->exception_ = pending_exception();
      if (!thread_local_top_.pending_message_obj_->IsTheHole()) {
        try_catch_handler()->message_ = thread_local_top_.pending_message_obj_;
      }
    }
  }
  
  
  void Isolate::InitializeLoggingAndCounters() {
    if (logger_ == NULL) {
      logger_ = new Logger;
    }
    if (counters_ == NULL) {
      counters_ = new Counters;
    }
  }
  
  
  void Isolate::InitializeDebugger() {
  #ifdef ENABLE_DEBUGGER_SUPPORT
    ScopedLock lock(debugger_access_);
    if (NoBarrier_Load(&debugger_initialized_)) return;
    InitializeLoggingAndCounters();
    debug_ = new Debug(this);
    debugger_ = new Debugger(this);
    Release_Store(&debugger_initialized_, true);
  #endif
  }
  
  
  bool Isolate::Init(Deserializer* des) {
    ASSERT(state_ != INITIALIZED);
    ASSERT(Isolate::Current() == this);
    TRACE_ISOLATE(init);
  
    // The initialization process does not handle memory exhaustion.
    DisallowAllocationFailure disallow_allocation_failure;
  
    InitializeLoggingAndCounters();
  
    InitializeDebugger();
  
    memory_allocator_ = new MemoryAllocator(this);
    code_range_ = new CodeRange(this);
  
    // Safe after setting Heap::isolate_, initializing StackGuard and
    // ensuring that Isolate::Current() == this.
    heap_.SetStackLimits();
  
  #define ASSIGN_ELEMENT(CamelName, hacker_name)                  \
    isolate_addresses_[Isolate::k##CamelName##Address] =          \
        reinterpret_cast<Address>(hacker_name##_address());
    FOR_EACH_ISOLATE_ADDRESS_NAME(ASSIGN_ELEMENT)
  #undef C
  
    string_tracker_ = new StringTracker();
    string_tracker_->isolate_ = this;
    compilation_cache_ = new CompilationCache(this);
    transcendental_cache_ = new TranscendentalCache();
    keyed_lookup_cache_ = new KeyedLookupCache();
    context_slot_cache_ = new ContextSlotCache();
    descriptor_lookup_cache_ = new DescriptorLookupCache();
    unicode_cache_ = new UnicodeCache();
    inner_pointer_to_code_cache_ = new InnerPointerToCodeCache(this);
    write_input_buffer_ = new StringInputBuffer();
    global_handles_ = new GlobalHandles(this);
    bootstrapper_ = new Bootstrapper();
    handle_scope_implementer_ = new HandleScopeImplementer(this);
    stub_cache_ = new StubCache(this, runtime_zone());
    regexp_stack_ = new RegExpStack();
    regexp_stack_->isolate_ = this;
    date_cache_ = new DateCache();
  
    // Enable logging before setting up the heap
    logger_->SetUp();
  
    CpuProfiler::SetUp();
    HeapProfiler::SetUp();
  
    // Initialize other runtime facilities
  #if defined(USE_SIMULATOR)
  #if defined(V8_TARGET_ARCH_ARM) || defined(V8_TARGET_ARCH_MIPS)
    Simulator::Initialize(this);
  #endif
  #endif
  
    { // NOLINT
      // Ensure that the thread has a valid stack guard.  The v8::Locker object
      // will ensure this too, but we don't have to use lockers if we are only
      // using one thread.
      ExecutionAccess lock(this);
      stack_guard_.InitThread(lock);
    }
  
    // SetUp the object heap.
    const bool create_heap_objects = (des == NULL);
    ASSERT(!heap_.HasBeenSetUp());
    if (!heap_.SetUp(create_heap_objects)) {
      V8::SetFatalError();
      return false;
    }
  
    if (create_heap_objects) {
      // Terminate the cache array with the sentinel so we can iterate.
      PushToPartialSnapshotCache(heap_.undefined_value());
    }
  
    InitializeThreadLocal();
  
    bootstrapper_->Initialize(create_heap_objects);
    builtins_.SetUp(create_heap_objects);
  
    // Only preallocate on the first initialization.
    if (FLAG_preallocate_message_memory && preallocated_message_space_ == NULL) {
      // Start the thread which will set aside some memory.
      PreallocatedMemoryThreadStart();
      preallocated_message_space_ =
          new NoAllocationStringAllocator(
              preallocated_memory_thread_->data(),
              preallocated_memory_thread_->length());
      PreallocatedStorageInit(preallocated_memory_thread_->length() / 4);
    }
  
    if (FLAG_preemption) {
      v8::Locker locker;
      v8::Locker::StartPreemption(100);
    }
  
  #ifdef ENABLE_DEBUGGER_SUPPORT
    debug_->SetUp(create_heap_objects);
  #endif
  
    // If we are deserializing, read the state into the now-empty heap.
    if (!create_heap_objects) {
      des->Deserialize();
    }
    stub_cache_->Initialize();
  
    // Finish initialization of ThreadLocal after deserialization is done.
    clear_pending_exception();
    clear_pending_message();
    clear_scheduled_exception();
  
    // Deserializing may put strange things in the root array's copy of the
    // stack guard.
    heap_.SetStackLimits();
  
    // Quiet the heap NaN if needed on target platform.
    if (!create_heap_objects) Assembler::QuietNaN(heap_.nan_value());
  
    deoptimizer_data_ = new DeoptimizerData;
    runtime_profiler_ = new RuntimeProfiler(this);
    runtime_profiler_->SetUp();
  
    // If we are deserializing, log non-function code objects and compiled
    // functions found in the snapshot.
    if (create_heap_objects && (FLAG_log_code || FLAG_ll_prof)) {
      HandleScope scope;
      LOG(this, LogCodeObjects());
      LOG(this, LogCompiledFunctions());
    }
  
    CHECK_EQ(static_cast<int>(OFFSET_OF(Isolate, state_)),
             Internals::kIsolateStateOffset);
    CHECK_EQ(static_cast<int>(OFFSET_OF(Isolate, embedder_data_)),
             Internals::kIsolateEmbedderDataOffset);
    CHECK_EQ(static_cast<int>(OFFSET_OF(Isolate, heap_.roots_)),
             Internals::kIsolateRootsOffset);
  
    state_ = INITIALIZED;
    time_millis_at_init_ = OS::TimeCurrentMillis();
    if (FLAG_parallel_recompilation) optimizing_compiler_thread_.Start();
    return true;
  }
  
  
  // Initialized lazily to allow early
  // v8::V8::SetAddHistogramSampleFunction calls.
  StatsTable* Isolate::stats_table() {
    if (stats_table_ == NULL) {
      stats_table_ = new StatsTable;
    }
    return stats_table_;
  }
  
  
  void Isolate::Enter() {
    Isolate* current_isolate = NULL;
    PerIsolateThreadData* current_data = CurrentPerIsolateThreadData();
    if (current_data != NULL) {
      current_isolate = current_data->isolate_;
      ASSERT(current_isolate != NULL);
      if (current_isolate == this) {
        ASSERT(Current() == this);
        ASSERT(entry_stack_ != NULL);
        ASSERT(entry_stack_->previous_thread_data == NULL ||
               entry_stack_->previous_thread_data->thread_id().Equals(
                   ThreadId::Current()));
        // Same thread re-enters the isolate, no need to re-init anything.
        entry_stack_->entry_count++;
        return;
      }
    }
  
    // Threads can have default isolate set into TLS as Current but not yet have
    // PerIsolateThreadData for it, as it requires more advanced phase of the
    // initialization. For example, a thread might be the one that system used for
    // static initializers - in this case the default isolate is set in TLS but
    // the thread did not yet Enter the isolate. If PerisolateThreadData is not
    // there, use the isolate set in TLS.
    if (current_isolate == NULL) {
      current_isolate = Isolate::UncheckedCurrent();
    }
  
    PerIsolateThreadData* data = FindOrAllocatePerThreadDataForThisThread();
    ASSERT(data != NULL);
    ASSERT(data->isolate_ == this);
  
    EntryStackItem* item = new EntryStackItem(current_data,
                                              current_isolate,
                                              entry_stack_);
    entry_stack_ = item;
  
    SetIsolateThreadLocals(this, data);
  
    // In case it's the first time some thread enters the isolate.
    set_thread_id(data->thread_id());
  }
  
  
  void Isolate::Exit() {
    ASSERT(entry_stack_ != NULL);
    ASSERT(entry_stack_->previous_thread_data == NULL ||
           entry_stack_->previous_thread_data->thread_id().Equals(
               ThreadId::Current()));
  
    if (--entry_stack_->entry_count > 0) return;
  
    ASSERT(CurrentPerIsolateThreadData() != NULL);
    ASSERT(CurrentPerIsolateThreadData()->isolate_ == this);
  
    // Pop the stack.
    EntryStackItem* item = entry_stack_;
    entry_stack_ = item->previous_item;
  
    PerIsolateThreadData* previous_thread_data = item->previous_thread_data;
    Isolate* previous_isolate = item->previous_isolate;
  
    delete item;
  
    // Reinit the current thread for the isolate it was running before this one.
    SetIsolateThreadLocals(previous_isolate, previous_thread_data);
  }
  
  
  void Isolate::LinkDeferredHandles(DeferredHandles* deferred) {
    deferred->next_ = deferred_handles_head_;
    if (deferred_handles_head_ != NULL) {
      deferred_handles_head_->previous_ = deferred;
    }
    deferred_handles_head_ = deferred;
  }
  
  
  void Isolate::UnlinkDeferredHandles(DeferredHandles* deferred) {
  #ifdef DEBUG
    // In debug mode assert that the linked list is well-formed.
    DeferredHandles* deferred_iterator = deferred;
    while (deferred_iterator->previous_ != NULL) {
      deferred_iterator = deferred_iterator->previous_;
    }
    ASSERT(deferred_handles_head_ == deferred_iterator);
  #endif
    if (deferred_handles_head_ == deferred) {
      deferred_handles_head_ = deferred_handles_head_->next_;
    }
    if (deferred->next_ != NULL) {
      deferred->next_->previous_ = deferred->previous_;
    }
    if (deferred->previous_ != NULL) {
      deferred->previous_->next_ = deferred->next_;
    }
  }
  
  
  #ifdef DEBUG
  #define ISOLATE_FIELD_OFFSET(type, name, ignored)                       \
  const intptr_t Isolate::name##_debug_offset_ = OFFSET_OF(Isolate, name##_);
  ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
  ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
  #undef ISOLATE_FIELD_OFFSET
  #endif
  
  } }  // namespace v8::internal
  