src/execution.cc

// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       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 "codegen-inl.h"

#ifdef ARM
#include "arm/simulator-arm.h"
#else  // ia32
#include "ia32/simulator-ia32.h"
#endif

#include "debug.h"
#include "v8threads.h"

namespace v8 { namespace internal {


static Handle<Object> Invoke(bool construct,
                             Handle<JSFunction> func,
                             Handle<Object> receiver,
                             int argc,
                             Object*** args,
                             bool* has_pending_exception) {
  // Make sure we have a real function, not a boilerplate function.
  ASSERT(!func->IsBoilerplate());

  // Entering JavaScript.
  VMState state(JS);

  // Guard the stack against too much recursion.
  StackGuard guard;

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

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

  Handle<Code> code;
  if (construct) {
    JSConstructEntryStub stub;
    code = stub.GetCode();
  } else {
    JSEntryStub stub;
    code = stub.GetCode();
  }

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

    // Call the function through the right JS entry stub.
    value = CALL_GENERATED_CODE(entry, func->code()->entry(), *func,
                                *receiver, argc, args);
  }

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

  // Update the pending exception flag and return the value.
  *has_pending_exception = value->IsException();
  ASSERT(*has_pending_exception == Top::has_pending_exception());
  if (*has_pending_exception) {
    Top::ReportPendingMessages();
    return Handle<Object>();
  } else {
    Top::clear_pending_message();
  }

  return Handle<Object>(value);
}


Handle<Object> Execution::Call(Handle<JSFunction> func,
                               Handle<Object> receiver,
                               int argc,
                               Object*** args,
                               bool* pending_exception) {
  return Invoke(false, func, receiver, argc, args, pending_exception);
}


Handle<Object> Execution::New(Handle<JSFunction> func, int argc,
                              Object*** args, bool* pending_exception) {
  return Invoke(true, func, Top::global(), argc, args, pending_exception);
}


Handle<Object> Execution::TryCall(Handle<JSFunction> func,
                                  Handle<Object> receiver,
                                  int argc,
                                  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);

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

  if (*caught_exception) {
    ASSERT(catcher.HasCaught());
    ASSERT(Top::has_pending_exception());
    ASSERT(Top::external_caught_exception());
    Top::optional_reschedule_exception(true);
    result = v8::Utils::OpenHandle(*catcher.Exception());
  }

  ASSERT(!Top::has_pending_exception());
  ASSERT(!Top::external_caught_exception());
  return result;
}


Handle<Object> Execution::GetFunctionDelegate(Handle<Object> object) {
  ASSERT(!object->IsJSFunction());

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

  // The regular expression code here is really meant more as an
  // example than anything else. KJS does not support calling regular
  // expressions as functions, but SpiderMonkey does.
  if (FLAG_call_regexp) {
    bool is_regexp =
        object->IsHeapObject() &&
        (HeapObject::cast(*object)->map()->constructor() ==
         *Top::regexp_function());

    if (is_regexp) {
      Handle<String> exec = Factory::exec_symbol();
      return Handle<Object>(object->GetProperty(*exec));
    }
  }

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

  return Factory::undefined_value();
}


// Static state for stack guards.
StackGuard::ThreadLocal StackGuard::thread_local_;


StackGuard::StackGuard() {
  // NOTE: Overall the StackGuard code assumes that the stack grows towards
  // lower addresses.
  ExecutionAccess access;
  if (thread_local_.nesting_++ == 0) {
    // Initial StackGuard is being set. We will set the stack limits based on
    // the current stack pointer allowing the stack to grow kLimitSize from
    // here.

    // Ensure that either the stack limits are unset (kIllegalLimit) or that
    // they indicate a pending interruption. The interrupt limit will be
    // temporarily reset through the code below and reestablished if the
    // interrupt flags indicate that an interrupt is pending.
    ASSERT(thread_local_.jslimit_ == kIllegalLimit ||
           (thread_local_.jslimit_ == kInterruptLimit &&
            thread_local_.interrupt_flags_ != 0));
    ASSERT(thread_local_.climit_ == kIllegalLimit ||
           (thread_local_.climit_ == kInterruptLimit &&
            thread_local_.interrupt_flags_ != 0));

    thread_local_.initial_jslimit_ = thread_local_.jslimit_ =
        GENERATED_CODE_STACK_LIMIT(kLimitSize);
    // NOTE: The check for overflow is not safe as there is no guarantee that
    // the running thread has its stack in all memory up to address 0x00000000.
    thread_local_.initial_climit_ = thread_local_.climit_ =
        reinterpret_cast<uintptr_t>(this) >= kLimitSize ?
            reinterpret_cast<uintptr_t>(this) - kLimitSize : 0;

    if (thread_local_.interrupt_flags_ != 0) {
      set_limits(kInterruptLimit, access);
    }
  }
  // Ensure that proper limits have been set.
  ASSERT(thread_local_.jslimit_ != kIllegalLimit &&
         thread_local_.climit_ != kIllegalLimit);
  ASSERT(thread_local_.initial_jslimit_ != kIllegalLimit &&
         thread_local_.initial_climit_ != kIllegalLimit);
}


StackGuard::~StackGuard() {
  ExecutionAccess access;
  if (--thread_local_.nesting_ == 0) {
    set_limits(kIllegalLimit, access);
  }
}


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


void StackGuard::EnableInterrupts() {
  ExecutionAccess access;
  if (IsSet(access)) {
    set_limits(kInterruptLimit, access);
  }
}


void StackGuard::SetStackLimit(uintptr_t limit) {
  ExecutionAccess access;
  // If the current limits are special (eg due to a pending interrupt) then
  // leave them alone.
  if (thread_local_.jslimit_ == thread_local_.initial_jslimit_) {
    thread_local_.jslimit_ = limit;
  }
  if (thread_local_.climit_ == thread_local_.initial_climit_) {
    thread_local_.climit_ = limit;
  }
  thread_local_.initial_climit_ = limit;
  thread_local_.initial_jslimit_ = limit;
}


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


bool StackGuard::IsSet(const ExecutionAccess& lock) {
  return thread_local_.interrupt_flags_ != 0;
}


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


void StackGuard::Interrupt() {
  ExecutionAccess access;
  thread_local_.interrupt_flags_ |= INTERRUPT;
  set_limits(kInterruptLimit, access);
}


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


void StackGuard::Preempt() {
  ExecutionAccess access;
  thread_local_.interrupt_flags_ |= PREEMPT;
  set_limits(kInterruptLimit, access);
}


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


void StackGuard::DebugBreak() {
  ExecutionAccess access;
  thread_local_.interrupt_flags_ |= DEBUGBREAK;
  set_limits(kInterruptLimit, access);
}


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


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

void StackGuard::Continue(InterruptFlag after_what) {
  ExecutionAccess access;
  thread_local_.interrupt_flags_ &= ~static_cast<int>(after_what);
  if (thread_local_.interrupt_flags_ == 0) {
    reset_limits(access);
  }
}


int StackGuard::ArchiveSpacePerThread() {
  return sizeof(ThreadLocal);
}


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


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


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

#define RETURN_NATIVE_CALL(name, argc, argv, has_pending_exception) \
  do {                                                              \
    Object** args[argc] = argv;                                     \
    ASSERT(has_pending_exception != NULL);                          \
    return Call(Top::name##_fun(), Top::builtins(), argc, args,     \
                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, 1, { obj.location() }, exc);
}


Handle<Object> Execution::ToString(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_string, 1, { obj.location() }, exc);
}


Handle<Object> Execution::ToDetailString(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_detail_string, 1, { obj.location() }, exc);
}


Handle<Object> Execution::ToObject(Handle<Object> obj, bool* exc) {
  if (obj->IsJSObject()) return obj;
  RETURN_NATIVE_CALL(to_object, 1, { obj.location() }, exc);
}


Handle<Object> Execution::ToInteger(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_integer, 1, { obj.location() }, exc);
}


Handle<Object> Execution::ToUint32(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_uint32, 1, { obj.location() }, exc);
}


Handle<Object> Execution::ToInt32(Handle<Object> obj, bool* exc) {
  RETURN_NATIVE_CALL(to_int32, 1, { obj.location() }, exc);
}


Handle<Object> Execution::NewDate(double time, bool* exc) {
  Handle<Object> time_obj = Factory::NewNumber(time);
  RETURN_NATIVE_CALL(create_date, 1, { time_obj.location() }, exc);
}


#undef RETURN_NATIVE_CALL


Handle<Object> Execution::CharAt(Handle<String> string, uint32_t index) {
  int int_index = static_cast<int>(index);
  if (int_index < 0 || int_index >= string->length()) {
    return Factory::undefined_value();
  }

  Handle<Object> char_at =
      GetProperty(Top::builtins(), Factory::char_at_symbol());
  if (!char_at->IsJSFunction()) {
    return Factory::undefined_value();
  }

  bool caught_exception;
  Handle<Object> index_object = Factory::NewNumberFromInt(int_index);
  Object** index_arg[] = { index_object.location() };
  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) {
  // Fast case: see if the function has already been instantiated
  int serial_number = Smi::cast(data->serial_number())->value();
  Object* elm =
      Top::global_context()->function_cache()->GetElement(serial_number);
  if (elm->IsJSFunction()) return Handle<JSFunction>(JSFunction::cast(elm));
  // The function has not yet been instantiated in this context; do it.
  Object** args[1] = { Handle<Object>::cast(data).location() };
  Handle<Object> result =
      Call(Top::instantiate_fun(), Top::builtins(), 1, args, exc);
  if (*exc) return Handle<JSFunction>::null();
  return Handle<JSFunction>::cast(result);
}


Handle<JSObject> Execution::InstantiateObject(Handle<ObjectTemplateInfo> data,
                                              bool* exc) {
  if (data->property_list()->IsUndefined() &&
      !data->constructor()->IsUndefined()) {
    // Initialization to make gcc happy.
    Object* result = NULL;
    {
      HandleScope scope;
      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 {
    Object** args[1] = { Handle<Object>::cast(data).location() };
    Handle<Object> result =
        Call(Top::instantiate_fun(), Top::builtins(), 1, 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) {
  Object** args[2] = { instance.location(), instance_template.location() };
  Execution::Call(Top::configure_instance_fun(), Top::builtins(), 2, args, exc);
}


Handle<String> Execution::GetStackTraceLine(Handle<Object> recv,
                                            Handle<JSFunction> fun,
                                            Handle<Object> pos,
                                            Handle<Object> is_global) {
  const int argc = 4;
  Object** args[argc] = { recv.location(),
                          Handle<Object>::cast(fun).location(),
                          pos.location(),
                          is_global.location() };
  bool caught_exception = false;
  Handle<Object> result = TryCall(Top::get_stack_trace_line_fun(),
                                  Top::builtins(), argc, args,
                                  &caught_exception);
  if (caught_exception || !result->IsString()) return Factory::empty_symbol();
  return Handle<String>::cast(result);
}


static Object* RuntimePreempt() {
  // Clear the preempt request flag.
  StackGuard::Continue(PREEMPT);

  ContextSwitcher::PreemptionReceived();

#ifdef ENABLE_DEBUGGER_SUPPORT
  if (Debug::InDebugger()) {
    // If currently in the debugger don't do any actual preemption but record
    // that preemption occoured while in the debugger.
    Debug::PreemptionWhileInDebugger();
  } else {
    // Perform preemption.
    v8::Unlocker unlocker;
    Thread::YieldCPU();
  }
#else
  // Perform preemption.
  v8::Unlocker unlocker;
  Thread::YieldCPU();
#endif

  return Heap::undefined_value();
}


#ifdef ENABLE_DEBUGGER_SUPPORT
Object* Execution::DebugBreakHelper() {
  // Just continue if breaks are disabled.
  if (Debug::disable_break()) {
    return Heap::undefined_value();
  }

  // Don't break in system functions. If the current function is
  // either in the builtins object of some context or is in the debug
  // context just return with the debug break stack guard active.
  JavaScriptFrameIterator it;
  JavaScriptFrame* frame = it.frame();
  Object* fun = frame->function();
  if (fun->IsJSFunction()) {
    GlobalObject* global = JSFunction::cast(fun)->context()->global();
    if (global->IsJSBuiltinsObject() || Debug::IsDebugGlobal(global)) {
      return Heap::undefined_value();
    }
  }

  // Check for debug command break only.
  bool debug_command_only =
      StackGuard::IsDebugCommand() && !StackGuard::IsDebugBreak();

  // Clear the debug request flags.
  StackGuard::Continue(DEBUGBREAK);
  StackGuard::Continue(DEBUGCOMMAND);

  // If debug command only and already in debugger ignore it.
  if (debug_command_only && Debug::InDebugger()) {
    return Heap::undefined_value();
  }

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

  // Notify the debug event listeners.
  Debugger::OnDebugBreak(Factory::undefined_value(), debug_command_only);

  // Return to continue execution.
  return Heap::undefined_value();
}
#endif

Object* Execution::HandleStackGuardInterrupt() {
#ifdef ENABLE_DEBUGGER_SUPPORT
  if (StackGuard::IsDebugBreak() || StackGuard::IsDebugCommand()) {
    DebugBreakHelper();
  }
#endif
  if (StackGuard::IsPreempted()) RuntimePreempt();
  if (StackGuard::IsInterrupted()) {
    // interrupt
    StackGuard::Continue(INTERRUPT);
    return Top::StackOverflow();
  }
  return Heap::undefined_value();
}

// --- G C   E x t e n s i o n ---

const char* GCExtension::kSource = "native function gc();";


v8::Handle<v8::FunctionTemplate> GCExtension::GetNativeFunction(
    v8::Handle<v8::String> str) {
  return v8::FunctionTemplate::New(GCExtension::GC);
}


v8::Handle<v8::Value> GCExtension::GC(const v8::Arguments& args) {
  // All allocation spaces other than NEW_SPACE have the same effect.
  Heap::CollectAllGarbage();
  return v8::Undefined();
}


static GCExtension kGCExtension;
v8::DeclareExtension kGCExtensionDeclaration(&kGCExtension);

} }  // namespace v8::internal