root/src/execution.cc

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DEFINITIONS

This source file includes following definitions.
  1. set_interrupt_limits
  2. reset_limits
  3. Invoke
  4. Call
  5. New
  6. TryCall
  7. GetFunctionDelegate
  8. TryGetFunctionDelegate
  9. GetConstructorDelegate
  10. TryGetConstructorDelegate
  11. IsStackOverflow
  12. EnableInterrupts
  13. SetStackLimit
  14. DisableInterrupts
  15. ShouldPostponeInterrupts
  16. IsInterrupted
  17. Interrupt
  18. IsPreempted
  19. Preempt
  20. IsTerminateExecution
  21. TerminateExecution
  22. IsRuntimeProfilerTick
  23. RequestRuntimeProfilerTick
  24. IsGCRequest
  25. RequestGC
  26. IsDebugBreak
  27. DebugBreak
  28. IsDebugCommand
  29. DebugCommand
  30. Continue
  31. ArchiveStackGuard
  32. RestoreStackGuard
  33. FreeThreadResources
  34. Clear
  35. Initialize
  36. ClearThread
  37. InitThread
  38. ToBoolean
  39. ToNumber
  40. ToString
  41. ToDetailString
  42. ToObject
  43. ToInteger
  44. ToUint32
  45. ToInt32
  46. NewDate
  47. NewJSRegExp
  48. CharAt
  49. InstantiateFunction
  50. InstantiateObject
  51. ConfigureInstance
  52. GetStackTraceLine
  53. RuntimePreempt
  54. DebugBreakHelper
  55. ProcessDebugMessages
  56. HandleStackGuardInterrupt

// 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 "api.h"
#include "bootstrapper.h"
#include "codegen.h"
#include "debug.h"
#include "isolate-inl.h"
#include "runtime-profiler.h"
#include "simulator.h"
#include "v8threads.h"
#include "vm-state-inl.h"

namespace v8 {
namespace internal {


StackGuard::StackGuard()
    : isolate_(NULL) {
}


void StackGuard::set_interrupt_limits(const ExecutionAccess& lock) {
  ASSERT(isolate_ != NULL);
  // Ignore attempts to interrupt when interrupts are postponed.
  if (should_postpone_interrupts(lock)) return;
  thread_local_.jslimit_ = kInterruptLimit;
  thread_local_.climit_ = kInterruptLimit;
  isolate_->heap()->SetStackLimits();
}


void StackGuard::reset_limits(const ExecutionAccess& lock) {
  ASSERT(isolate_ != NULL);
  thread_local_.jslimit_ = thread_local_.real_jslimit_;
  thread_local_.climit_ = thread_local_.real_climit_;
  isolate_->heap()->SetStackLimits();
}


static Handle<Object> Invoke(bool is_construct,
                             Handle<JSFunction> function,
                             Handle<Object> receiver,
                             int argc,
                             Handle<Object> args[],
                             bool* has_pending_exception) {
  Isolate* isolate = function->GetIsolate();

  // Entering JavaScript.
  VMState state(isolate, JS);

  // Placeholder for return value.
  MaybeObject* value = reinterpret_cast<Object*>(kZapValue);

  typedef Object* (*JSEntryFunction)(byte* entry,
                                     Object* function,
                                     Object* receiver,
                                     int argc,
                                     Object*** args);

  Handle<Code> code = is_construct
      ? isolate->factory()->js_construct_entry_code()
      : isolate->factory()->js_entry_code();

  // Convert calls on global objects to be calls on the global
  // receiver instead to avoid having a 'this' pointer which refers
  // directly to a global object.
  if (receiver->IsGlobalObject()) {
    Handle<GlobalObject> global = Handle<GlobalObject>::cast(receiver);
    receiver = Handle<JSObject>(global->global_receiver());
  }

  // Make sure that the global object of the context we're about to
  // make the current one is indeed a global object.
  ASSERT(function->context()->global()->IsGlobalObject());

  {
    // Save and restore context around invocation and block the
    // allocation of handles without explicit handle scopes.
    SaveContext save(isolate);
    NoHandleAllocation na;
    JSEntryFunction stub_entry = FUNCTION_CAST<JSEntryFunction>(code->entry());

    // Call the function through the right JS entry stub.
    byte* function_entry = function->code()->entry();
    JSFunction* func = *function;
    Object* recv = *receiver;
    Object*** argv = reinterpret_cast<Object***>(args);
    value =
        CALL_GENERATED_CODE(stub_entry, function_entry, func, recv, argc, argv);
  }

#ifdef DEBUG
  value->Verify();
#endif

  // Update the pending exception flag and return the value.
  *has_pending_exception = value->IsException();
  ASSERT(*has_pending_exception == Isolate::Current()->has_pending_exception());
  if (*has_pending_exception) {
    isolate->ReportPendingMessages();
    if (isolate->pending_exception() == Failure::OutOfMemoryException()) {
      if (!isolate->ignore_out_of_memory()) {
        V8::FatalProcessOutOfMemory("JS", true);
      }
    }
#ifdef ENABLE_DEBUGGER_SUPPORT
    // Reset stepping state when script exits with uncaught exception.
    if (isolate->debugger()->IsDebuggerActive()) {
      isolate->debug()->ClearStepping();
    }
#endif  // ENABLE_DEBUGGER_SUPPORT
    return Handle<Object>();
  } else {
    isolate->clear_pending_message();
  }

  return Handle<Object>(value->ToObjectUnchecked(), isolate);
}


Handle<Object> Execution::Call(Handle<Object> callable,
                               Handle<Object> receiver,
                               int argc,
                               Handle<Object> argv[],
                               bool* pending_exception,
                               bool convert_receiver) {
  *pending_exception = false;

  if (!callable->IsJSFunction()) {
    callable = TryGetFunctionDelegate(callable, pending_exception);
    if (*pending_exception) return callable;
  }
  Handle<JSFunction> func = Handle<JSFunction>::cast(callable);

  // In non-strict mode, convert receiver.
  if (convert_receiver && !receiver->IsJSReceiver() &&
      !func->shared()->native() && func->shared()->is_classic_mode()) {
    if (receiver->IsUndefined() || receiver->IsNull()) {
      Object* global = func->context()->global()->global_receiver();
      // Under some circumstances, 'global' can be the JSBuiltinsObject
      // In that case, don't rewrite.
      // (FWIW, the same holds for GetIsolate()->global()->global_receiver().)
      if (!global->IsJSBuiltinsObject()) receiver = Handle<Object>(global);
    } else {
      receiver = ToObject(receiver, pending_exception);
    }
    if (*pending_exception) return callable;
  }

  return Invoke(false, func, receiver, argc, argv, pending_exception);
}


Handle<Object> Execution::New(Handle<JSFunction> func,
                              int argc,
                              Handle<Object> argv[],
                              bool* pending_exception) {
  return Invoke(true, func, Isolate::Current()->global(), argc, argv,
                pending_exception);
}


Handle<Object> Execution::TryCall(Handle<JSFunction> func,
                                  Handle<Object> receiver,
                                  int argc,
                                  Handle<Object> args[],
                                  bool* caught_exception) {
  // Enter a try-block while executing the JavaScript code. To avoid
  // duplicate error printing it must be non-verbose.  Also, to avoid
  // creating message objects during stack overflow we shouldn't
  // capture messages.
  v8::TryCatch catcher;
  catcher.SetVerbose(false);
  catcher.SetCaptureMessage(false);
  *caught_exception = false;

  Handle<Object> result = Invoke(false, func, receiver, argc, args,
                                 caught_exception);

  if (*caught_exception) {
    ASSERT(catcher.HasCaught());
    Isolate* isolate = Isolate::Current();
    ASSERT(isolate->has_pending_exception());
    ASSERT(isolate->external_caught_exception());
    if (isolate->pending_exception() ==
        isolate->heap()->termination_exception()) {
      result = isolate->factory()->termination_exception();
    } else {
      result = v8::Utils::OpenHandle(*catcher.Exception());
    }
    isolate->OptionalRescheduleException(true);
  }

  ASSERT(!Isolate::Current()->has_pending_exception());
  ASSERT(!Isolate::Current()->external_caught_exception());
  return result;
}


Handle<Object> Execution::GetFunctionDelegate(Handle<Object> object) {
  ASSERT(!object->IsJSFunction());
  Isolate* isolate = Isolate::Current();
  Factory* factory = isolate->factory();

  // If you return a function from here, it will be called when an
  // attempt is made to call the given object as a function.

  // If object is a function proxy, get its handler. Iterate if necessary.
  Object* fun = *object;
  while (fun->IsJSFunctionProxy()) {
    fun = JSFunctionProxy::cast(fun)->call_trap();
  }
  if (fun->IsJSFunction()) return Handle<Object>(fun);

  // Objects created through the API can have an instance-call handler
  // that should be used when calling the object as a function.
  if (fun->IsHeapObject() &&
      HeapObject::cast(fun)->map()->has_instance_call_handler()) {
    return Handle<JSFunction>(
        isolate->global_context()->call_as_function_delegate());
  }

  return factory->undefined_value();
}


Handle<Object> Execution::TryGetFunctionDelegate(Handle<Object> object,
                                                 bool* has_pending_exception) {
  ASSERT(!object->IsJSFunction());
  Isolate* isolate = Isolate::Current();

  // If object is a function proxy, get its handler. Iterate if necessary.
  Object* fun = *object;
  while (fun->IsJSFunctionProxy()) {
    fun = JSFunctionProxy::cast(fun)->call_trap();
  }
  if (fun->IsJSFunction()) return Handle<Object>(fun);

  // Objects created through the API can have an instance-call handler
  // that should be used when calling the object as a function.
  if (fun->IsHeapObject() &&
      HeapObject::cast(fun)->map()->has_instance_call_handler()) {
    return Handle<JSFunction>(
        isolate->global_context()->call_as_function_delegate());
  }

  // If the Object doesn't have an instance-call handler we should
  // throw a non-callable exception.
  i::Handle<i::Object> error_obj = isolate->factory()->NewTypeError(
      "called_non_callable", i::HandleVector<i::Object>(&object, 1));
  isolate->Throw(*error_obj);
  *has_pending_exception = true;

  return isolate->factory()->undefined_value();
}


Handle<Object> Execution::GetConstructorDelegate(Handle<Object> object) {
  ASSERT(!object->IsJSFunction());
  Isolate* isolate = Isolate::Current();

  // If you return a function from here, it will be called when an
  // attempt is made to call the given object as a constructor.

  // If object is a function proxies, get its handler. Iterate if necessary.
  Object* fun = *object;
  while (fun->IsJSFunctionProxy()) {
    fun = JSFunctionProxy::cast(fun)->call_trap();
  }
  if (fun->IsJSFunction()) return Handle<Object>(fun);

  // Objects created through the API can have an instance-call handler
  // that should be used when calling the object as a function.
  if (fun->IsHeapObject() &&
      HeapObject::cast(fun)->map()->has_instance_call_handler()) {
    return Handle<JSFunction>(
        isolate->global_context()->call_as_constructor_delegate());
  }

  return isolate->factory()->undefined_value();
}


Handle<Object> Execution::TryGetConstructorDelegate(
    Handle<Object> object,
    bool* has_pending_exception) {
  ASSERT(!object->IsJSFunction());
  Isolate* isolate = Isolate::Current();

  // If you return a function from here, it will be called when an
  // attempt is made to call the given object as a constructor.

  // If object is a function proxies, get its handler. Iterate if necessary.
  Object* fun = *object;
  while (fun->IsJSFunctionProxy()) {
    fun = JSFunctionProxy::cast(fun)->call_trap();
  }
  if (fun->IsJSFunction()) return Handle<Object>(fun);

  // Objects created through the API can have an instance-call handler
  // that should be used when calling the object as a function.
  if (fun->IsHeapObject() &&
      HeapObject::cast(fun)->map()->has_instance_call_handler()) {
    return Handle<JSFunction>(
        isolate->global_context()->call_as_constructor_delegate());
  }

  // If the Object doesn't have an instance-call handler we should
  // throw a non-callable exception.
  i::Handle<i::Object> error_obj = isolate->factory()->NewTypeError(
      "called_non_callable", i::HandleVector<i::Object>(&object, 1));
  isolate->Throw(*error_obj);
  *has_pending_exception = true;

  return isolate->factory()->undefined_value();
}


bool StackGuard::IsStackOverflow() {
  ExecutionAccess access(isolate_);
  return (thread_local_.jslimit_ != kInterruptLimit &&
          thread_local_.climit_ != kInterruptLimit);
}


void StackGuard::EnableInterrupts() {
  ExecutionAccess access(isolate_);
  if (has_pending_interrupts(access)) {
    set_interrupt_limits(access);
  }
}


void StackGuard::SetStackLimit(uintptr_t limit) {
  ExecutionAccess access(isolate_);
  // If the current limits are special (e.g. due to a pending interrupt) then
  // leave them alone.
  uintptr_t jslimit = SimulatorStack::JsLimitFromCLimit(isolate_, limit);
  if (thread_local_.jslimit_ == thread_local_.real_jslimit_) {
    thread_local_.jslimit_ = jslimit;
  }
  if (thread_local_.climit_ == thread_local_.real_climit_) {
    thread_local_.climit_ = limit;
  }
  thread_local_.real_climit_ = limit;
  thread_local_.real_jslimit_ = jslimit;
}


void StackGuard::DisableInterrupts() {
  ExecutionAccess access(isolate_);
  reset_limits(access);
}


bool StackGuard::ShouldPostponeInterrupts() {
  ExecutionAccess access(isolate_);
  return should_postpone_interrupts(access);
}


bool StackGuard::IsInterrupted() {
  ExecutionAccess access(isolate_);
  return (thread_local_.interrupt_flags_ & INTERRUPT) != 0;
}


void StackGuard::Interrupt() {
  ExecutionAccess access(isolate_);
  thread_local_.interrupt_flags_ |= INTERRUPT;
  set_interrupt_limits(access);
}


bool StackGuard::IsPreempted() {
  ExecutionAccess access(isolate_);
  return thread_local_.interrupt_flags_ & PREEMPT;
}


void StackGuard::Preempt() {
  ExecutionAccess access(isolate_);
  thread_local_.interrupt_flags_ |= PREEMPT;
  set_interrupt_limits(access);
}


bool StackGuard::IsTerminateExecution() {
  ExecutionAccess access(isolate_);
  return (thread_local_.interrupt_flags_ & TERMINATE) != 0;
}


void StackGuard::TerminateExecution() {
  ExecutionAccess access(isolate_);
  thread_local_.interrupt_flags_ |= TERMINATE;
  set_interrupt_limits(access);
}


bool StackGuard::IsRuntimeProfilerTick() {
  ExecutionAccess access(isolate_);
  return (thread_local_.interrupt_flags_ & RUNTIME_PROFILER_TICK) != 0;
}


void StackGuard::RequestRuntimeProfilerTick() {
  // Ignore calls if we're not optimizing or if we can't get the lock.
  if (FLAG_opt && ExecutionAccess::TryLock(isolate_)) {
    thread_local_.interrupt_flags_ |= RUNTIME_PROFILER_TICK;
    if (thread_local_.postpone_interrupts_nesting_ == 0) {
      thread_local_.jslimit_ = thread_local_.climit_ = kInterruptLimit;
      isolate_->heap()->SetStackLimits();
    }
    ExecutionAccess::Unlock(isolate_);
  }
}


bool StackGuard::IsGCRequest() {
  ExecutionAccess access(isolate_);
  return (thread_local_.interrupt_flags_ & GC_REQUEST) != 0;
}


void StackGuard::RequestGC() {
  ExecutionAccess access(isolate_);
  thread_local_.interrupt_flags_ |= GC_REQUEST;
  if (thread_local_.postpone_interrupts_nesting_ == 0) {
    thread_local_.jslimit_ = thread_local_.climit_ = kInterruptLimit;
    isolate_->heap()->SetStackLimits();
  }
}


#ifdef ENABLE_DEBUGGER_SUPPORT
bool StackGuard::IsDebugBreak() {
  ExecutionAccess access(isolate_);
  return thread_local_.interrupt_flags_ & DEBUGBREAK;
}


void StackGuard::DebugBreak() {
  ExecutionAccess access(isolate_);
  thread_local_.interrupt_flags_ |= DEBUGBREAK;
  set_interrupt_limits(access);
}


bool StackGuard::IsDebugCommand() {
  ExecutionAccess access(isolate_);
  return thread_local_.interrupt_flags_ & DEBUGCOMMAND;
}


void StackGuard::DebugCommand() {
  if (FLAG_debugger_auto_break) {
    ExecutionAccess access(isolate_);
    thread_local_.interrupt_flags_ |= DEBUGCOMMAND;
    set_interrupt_limits(access);
  }
}
#endif

void StackGuard::Continue(InterruptFlag after_what) {
  ExecutionAccess access(isolate_);
  thread_local_.interrupt_flags_ &= ~static_cast<int>(after_what);
  if (!should_postpone_interrupts(access) && !has_pending_interrupts(access)) {
    reset_limits(access);
  }
}


char* StackGuard::ArchiveStackGuard(char* to) {
  ExecutionAccess access(isolate_);
  memcpy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
  ThreadLocal blank;

  // Set the stack limits using the old thread_local_.
  // TODO(isolates): This was the old semantics of constructing a ThreadLocal
  //                 (as the ctor called SetStackLimits, which looked at the
  //                 current thread_local_ from StackGuard)-- but is this
  //                 really what was intended?
  isolate_->heap()->SetStackLimits();
  thread_local_ = blank;

  return to + sizeof(ThreadLocal);
}


char* StackGuard::RestoreStackGuard(char* from) {
  ExecutionAccess access(isolate_);
  memcpy(reinterpret_cast<char*>(&thread_local_), from, sizeof(ThreadLocal));
  isolate_->heap()->SetStackLimits();
  return from + sizeof(ThreadLocal);
}


void StackGuard::FreeThreadResources() {
  Isolate::PerIsolateThreadData* per_thread =
      isolate_->FindOrAllocatePerThreadDataForThisThread();
  per_thread->set_stack_limit(thread_local_.real_climit_);
}


void StackGuard::ThreadLocal::Clear() {
  real_jslimit_ = kIllegalLimit;
  jslimit_ = kIllegalLimit;
  real_climit_ = kIllegalLimit;
  climit_ = kIllegalLimit;
  nesting_ = 0;
  postpone_interrupts_nesting_ = 0;
  interrupt_flags_ = 0;
}


bool StackGuard::ThreadLocal::Initialize(Isolate* isolate) {
  bool should_set_stack_limits = false;
  if (real_climit_ == kIllegalLimit) {
    // Takes the address of the limit variable in order to find out where
    // the top of stack is right now.
    const uintptr_t kLimitSize = FLAG_stack_size * KB;
    uintptr_t limit = reinterpret_cast<uintptr_t>(&limit) - kLimitSize;
    ASSERT(reinterpret_cast<uintptr_t>(&limit) > kLimitSize);
    real_jslimit_ = SimulatorStack::JsLimitFromCLimit(isolate, limit);
    jslimit_ = SimulatorStack::JsLimitFromCLimit(isolate, limit);
    real_climit_ = limit;
    climit_ = limit;
    should_set_stack_limits = true;
  }
  nesting_ = 0;
  postpone_interrupts_nesting_ = 0;
  interrupt_flags_ = 0;
  return should_set_stack_limits;
}


void StackGuard::ClearThread(const ExecutionAccess& lock) {
  thread_local_.Clear();
  isolate_->heap()->SetStackLimits();
}


void StackGuard::InitThread(const ExecutionAccess& lock) {
  if (thread_local_.Initialize(isolate_)) isolate_->heap()->SetStackLimits();
  Isolate::PerIsolateThreadData* per_thread =
      isolate_->FindOrAllocatePerThreadDataForThisThread();
  uintptr_t stored_limit = per_thread->stack_limit();
  // You should hold the ExecutionAccess lock when you call this.
  if (stored_limit != 0) {
    SetStackLimit(stored_limit);
  }
}


// --- C a l l s   t o   n a t i v e s ---

#define RETURN_NATIVE_CALL(name, args, has_pending_exception)           \
  do {                                                                  \
    Isolate* isolate = Isolate::Current();                              \
    Handle<Object> argv[] = args;                                       \
    ASSERT(has_pending_exception != NULL);                              \
    return Call(isolate->name##_fun(),                                  \
                isolate->js_builtins_object(),                          \
                ARRAY_SIZE(argv), argv,                                 \
                has_pending_exception);                                 \
  } while (false)


Handle<Object> Execution::ToBoolean(Handle<Object> obj) {
  // See the similar code in runtime.js:ToBoolean.
  if (obj->IsBoolean()) return obj;
  bool result = true;
  if (obj->IsString()) {
    result = Handle<String>::cast(obj)->length() != 0;
  } else if (obj->IsNull() || obj->IsUndefined()) {
    result = false;
  } else if (obj->IsNumber()) {
    double value = obj->Number();
    result = !((value == 0) || isnan(value));
  }
  return Handle<Object>(HEAP->ToBoolean(result));
}


Handle<Object> Execution::ToNumber(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_number, { obj }, exc);
}


Handle<Object> Execution::ToString(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_string, { obj }, exc);
}


Handle<Object> Execution::ToDetailString(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_detail_string, { obj }, exc);
}


Handle<Object> Execution::ToObject(Handle<Object> obj, bool* exc) {
  if (obj->IsSpecObject()) return obj;
  RETURN_NATIVE_CALL(to_object, { obj }, exc);
}


Handle<Object> Execution::ToInteger(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_integer, { obj }, exc);
}


Handle<Object> Execution::ToUint32(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_uint32, { obj }, exc);
}


Handle<Object> Execution::ToInt32(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_int32, { obj }, exc);
}


Handle<Object> Execution::NewDate(double time, bool* exc) {
  Handle<Object> time_obj = FACTORY->NewNumber(time);
  RETURN_NATIVE_CALL(create_date, { time_obj }, exc);
}


#undef RETURN_NATIVE_CALL


Handle<JSRegExp> Execution::NewJSRegExp(Handle<String> pattern,
                                        Handle<String> flags,
                                        bool* exc) {
  Handle<JSFunction> function = Handle<JSFunction>(
      pattern->GetIsolate()->global_context()->regexp_function());
  Handle<Object> re_obj = RegExpImpl::CreateRegExpLiteral(
      function, pattern, flags, exc);
  if (*exc) return Handle<JSRegExp>();
  return Handle<JSRegExp>::cast(re_obj);
}


Handle<Object> Execution::CharAt(Handle<String> string, uint32_t index) {
  Isolate* isolate = string->GetIsolate();
  Factory* factory = isolate->factory();

  int int_index = static_cast<int>(index);
  if (int_index < 0 || int_index >= string->length()) {
    return factory->undefined_value();
  }

  Handle<Object> char_at =
      GetProperty(isolate->js_builtins_object(),
                  factory->char_at_symbol());
  if (!char_at->IsJSFunction()) {
    return factory->undefined_value();
  }

  bool caught_exception;
  Handle<Object> index_object = factory->NewNumberFromInt(int_index);
  Handle<Object> index_arg[] = { index_object };
  Handle<Object> result = TryCall(Handle<JSFunction>::cast(char_at),
                                  string,
                                  ARRAY_SIZE(index_arg),
                                  index_arg,
                                  &caught_exception);
  if (caught_exception) {
    return factory->undefined_value();
  }
  return result;
}


Handle<JSFunction> Execution::InstantiateFunction(
    Handle<FunctionTemplateInfo> data,
    bool* exc) {
  Isolate* isolate = data->GetIsolate();
  // Fast case: see if the function has already been instantiated
  int serial_number = Smi::cast(data->serial_number())->value();
  Object* elm =
      isolate->global_context()->function_cache()->
          GetElementNoExceptionThrown(serial_number);
  if (elm->IsJSFunction()) return Handle<JSFunction>(JSFunction::cast(elm));
  // The function has not yet been instantiated in this context; do it.
  Handle<Object> args[] = { data };
  Handle<Object> result = Call(isolate->instantiate_fun(),
                               isolate->js_builtins_object(),
                               ARRAY_SIZE(args),
                               args,
                               exc);
  if (*exc) return Handle<JSFunction>::null();
  return Handle<JSFunction>::cast(result);
}


Handle<JSObject> Execution::InstantiateObject(Handle<ObjectTemplateInfo> data,
                                              bool* exc) {
  Isolate* isolate = data->GetIsolate();
  if (data->property_list()->IsUndefined() &&
      !data->constructor()->IsUndefined()) {
    // Initialization to make gcc happy.
    Object* result = NULL;
    {
      HandleScope scope(isolate);
      Handle<FunctionTemplateInfo> cons_template =
          Handle<FunctionTemplateInfo>(
              FunctionTemplateInfo::cast(data->constructor()));
      Handle<JSFunction> cons = InstantiateFunction(cons_template, exc);
      if (*exc) return Handle<JSObject>::null();
      Handle<Object> value = New(cons, 0, NULL, exc);
      if (*exc) return Handle<JSObject>::null();
      result = *value;
    }
    ASSERT(!*exc);
    return Handle<JSObject>(JSObject::cast(result));
  } else {
    Handle<Object> args[] = { data };
    Handle<Object> result = Call(isolate->instantiate_fun(),
                                 isolate->js_builtins_object(),
                                 ARRAY_SIZE(args),
                                 args,
                                 exc);
    if (*exc) return Handle<JSObject>::null();
    return Handle<JSObject>::cast(result);
  }
}


void Execution::ConfigureInstance(Handle<Object> instance,
                                  Handle<Object> instance_template,
                                  bool* exc) {
  Isolate* isolate = Isolate::Current();
  Handle<Object> args[] = { instance, instance_template };
  Execution::Call(isolate->configure_instance_fun(),
                  isolate->js_builtins_object(),
                  ARRAY_SIZE(args),
                  args,
                  exc);
}


Handle<String> Execution::GetStackTraceLine(Handle<Object> recv,
                                            Handle<JSFunction> fun,
                                            Handle<Object> pos,
                                            Handle<Object> is_global) {
  Isolate* isolate = fun->GetIsolate();
  Handle<Object> args[] = { recv, fun, pos, is_global };
  bool caught_exception;
  Handle<Object> result = TryCall(isolate->get_stack_trace_line_fun(),
                                  isolate->js_builtins_object(),
                                  ARRAY_SIZE(args),
                                  args,
                                  &caught_exception);
  if (caught_exception || !result->IsString()) {
      return isolate->factory()->empty_symbol();
  }

  return Handle<String>::cast(result);
}


static Object* RuntimePreempt() {
  Isolate* isolate = Isolate::Current();

  // Clear the preempt request flag.
  isolate->stack_guard()->Continue(PREEMPT);

  ContextSwitcher::PreemptionReceived();

#ifdef ENABLE_DEBUGGER_SUPPORT
  if (isolate->debug()->InDebugger()) {
    // If currently in the debugger don't do any actual preemption but record
    // that preemption occoured while in the debugger.
    isolate->debug()->PreemptionWhileInDebugger();
  } else {
    // Perform preemption.
    v8::Unlocker unlocker(reinterpret_cast<v8::Isolate*>(isolate));
    Thread::YieldCPU();
  }
#else
  { // NOLINT
    // Perform preemption.
    v8::Unlocker unlocker(reinterpret_cast<v8::Isolate*>(isolate));
    Thread::YieldCPU();
  }
#endif

  return isolate->heap()->undefined_value();
}


#ifdef ENABLE_DEBUGGER_SUPPORT
Object* Execution::DebugBreakHelper() {
  Isolate* isolate = Isolate::Current();

  // Just continue if breaks are disabled.
  if (isolate->debug()->disable_break()) {
    return isolate->heap()->undefined_value();
  }

  // Ignore debug break during bootstrapping.
  if (isolate->bootstrapper()->IsActive()) {
    return isolate->heap()->undefined_value();
  }

  // Ignore debug break if debugger is not active.
  if (!isolate->debugger()->IsDebuggerActive()) {
    return isolate->heap()->undefined_value();
  }

  StackLimitCheck check(isolate);
  if (check.HasOverflowed()) {
    return isolate->heap()->undefined_value();
  }

  {
    JavaScriptFrameIterator it(isolate);
    ASSERT(!it.done());
    Object* fun = it.frame()->function();
    if (fun && fun->IsJSFunction()) {
      // Don't stop in builtin functions.
      if (JSFunction::cast(fun)->IsBuiltin()) {
        return isolate->heap()->undefined_value();
      }
      GlobalObject* global = JSFunction::cast(fun)->context()->global();
      // Don't stop in debugger functions.
      if (isolate->debug()->IsDebugGlobal(global)) {
        return isolate->heap()->undefined_value();
      }
    }
  }

  // Collect the break state before clearing the flags.
  bool debug_command_only =
      isolate->stack_guard()->IsDebugCommand() &&
      !isolate->stack_guard()->IsDebugBreak();

  // Clear the debug break request flag.
  isolate->stack_guard()->Continue(DEBUGBREAK);

  ProcessDebugMessages(debug_command_only);

  // Return to continue execution.
  return isolate->heap()->undefined_value();
}

void Execution::ProcessDebugMessages(bool debug_command_only) {
  Isolate* isolate = Isolate::Current();
  // Clear the debug command request flag.
  isolate->stack_guard()->Continue(DEBUGCOMMAND);

  StackLimitCheck check(isolate);
  if (check.HasOverflowed()) {
    return;
  }

  HandleScope scope(isolate);
  // Enter the debugger. Just continue if we fail to enter the debugger.
  EnterDebugger debugger;
  if (debugger.FailedToEnter()) {
    return;
  }

  // Notify the debug event listeners. Indicate auto continue if the break was
  // a debug command break.
  isolate->debugger()->OnDebugBreak(isolate->factory()->undefined_value(),
                                    debug_command_only);
}


#endif

MaybeObject* Execution::HandleStackGuardInterrupt(Isolate* isolate) {
  StackGuard* stack_guard = isolate->stack_guard();
  if (stack_guard->ShouldPostponeInterrupts()) {
    return isolate->heap()->undefined_value();
  }

  if (stack_guard->IsGCRequest()) {
    isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                       "StackGuard GC request");
    stack_guard->Continue(GC_REQUEST);
  }

  isolate->counters()->stack_interrupts()->Increment();
  // If FLAG_count_based_interrupts, every interrupt is a profiler interrupt.
  if (FLAG_count_based_interrupts ||
      stack_guard->IsRuntimeProfilerTick()) {
    isolate->counters()->runtime_profiler_ticks()->Increment();
    stack_guard->Continue(RUNTIME_PROFILER_TICK);
    isolate->runtime_profiler()->OptimizeNow();
  }
#ifdef ENABLE_DEBUGGER_SUPPORT
  if (stack_guard->IsDebugBreak() || stack_guard->IsDebugCommand()) {
    DebugBreakHelper();
  }
#endif
  if (stack_guard->IsPreempted()) RuntimePreempt();
  if (stack_guard->IsTerminateExecution()) {
    stack_guard->Continue(TERMINATE);
    return isolate->TerminateExecution();
  }
  if (stack_guard->IsInterrupted()) {
    stack_guard->Continue(INTERRUPT);
    return isolate->StackOverflow();
  }
  return isolate->heap()->undefined_value();
}


} }  // namespace v8::internal

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