CSE2410 Fall 2014 Bounce

// 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.

#ifndef V8_HANDLES_H_

#define V8_HANDLES_H_

#include "apiutils.h"

namespace v8 { namespace internal {

// ----------------------------------------------------------------------------

// A Handle provides a reference to an object that survives relocation by

// the garbage collector.

// Handles are only valid within a HandleScope.

// When a handle is created for an object a cell is allocated in the heap.

template<class T>

class Handle {

 public:

  INLINE(Handle(T** location))  { location_ = location; }

  INLINE(explicit Handle(T* obj));

  INLINE(Handle()) : location_(NULL) {}

  // Constructor for handling automatic up casting.

  // Ex. Handle<JSFunction> can be passed when Handle<Object> is expected.

  template <class S> Handle(Handle<S> handle) {

#ifdef DEBUG

    T* a = NULL;

    S* b = NULL;

    a = b;  // Fake assignment to enforce type checks.

    USE(a);

#endif

    location_ = reinterpret_cast<T**>(handle.location());

  }

  INLINE(T* operator ->() const)  { return operator*(); }

  // Check if this handle refers to the exact same object as the other handle.

  bool is_identical_to(const Handle<T> other) const {

    return operator*() == *other;

  }

  // Provides the C++ dereference operator.

  INLINE(T* operator*() const);

  // Returns the address to where the raw pointer is stored.

  T** location() const {

    ASSERT(location_ == NULL ||

           reinterpret_cast<Address>(*location_) != kZapValue);

    return location_;

  }

  template <class S> static Handle<T> cast(Handle<S> that) {

    T::cast(*that);

    return Handle<T>(reinterpret_cast<T**>(that.location()));

  }

  static Handle<T> null() { return Handle<T>(); }

  bool is_null() {return location_ == NULL; }

  // Closes the given scope, but lets this handle escape. See

  // implementation in api.h.

  inline Handle<T> EscapeFrom(v8::HandleScope* scope);

 private:

  T** location_;

};

// A stack-allocated class that governs a number of local handles.

// After a handle scope has been created, all local handles will be

// allocated within that handle scope until either the handle scope is

// deleted or another handle scope is created.  If there is already a

// handle scope and a new one is created, all allocations will take

// place in the new handle scope until it is deleted.  After that,

// new handles will again be allocated in the original handle scope.

//

// After the handle scope of a local handle has been deleted the

// garbage collector will no longer track the object stored in the

// handle and may deallocate it.  The behavior of accessing a handle

// for which the handle scope has been deleted is undefined.

class HandleScope {

 public:

  HandleScope() : previous_(current_) {

    current_.extensions = 0;

  }

  ~HandleScope() {

    Leave(&previous_);

  }

  // Counts the number of allocated handles.

  static int NumberOfHandles();

  // Creates a new handle with the given value.

  static inline void** CreateHandle(void* value) {

    void** result = current_.next;

    if (result == current_.limit) result = Extend();

    // Update the current next field, set the value in the created

    // handle, and return the result.

    ASSERT(result < current_.limit);

    current_.next = result + 1;

    *result = value;

    return result;

  }

 private:

  // Prevent heap allocation or illegal handle scopes.

  HandleScope(const HandleScope&);

  void operator=(const HandleScope&);

  void* operator new(size_t size);

  void operator delete(void* size_t);

  static v8::ImplementationUtilities::HandleScopeData current_;

  const v8::ImplementationUtilities::HandleScopeData previous_;

  // Pushes a fresh handle scope to be used when allocating new handles.

  static void Enter(

      v8::ImplementationUtilities::HandleScopeData* previous) {

    *previous = current_;

    current_.extensions = 0;

  }

  // Re-establishes the previous scope state. Should be called only

  // once, and only for the current scope.

  static void Leave(

      const v8::ImplementationUtilities::HandleScopeData* previous) {

    if (current_.extensions > 0) {

      DeleteExtensions();

    }

    current_ = *previous;

#ifdef DEBUG

    ZapRange(current_.next, current_.limit);

#endif

  }

  // Extend the handle scope making room for more handles.

  static void** Extend();

  // Deallocates any extensions used by the current scope.

  static void DeleteExtensions();

  // Zaps the handles in the half-open interval [start, end).

  static void ZapRange(void** start, void** end);

  friend class v8::HandleScope;

  friend class v8::ImplementationUtilities;

};

// ----------------------------------------------------------------------------

// Handle operations.

// They might invoke garbage collection. The result is an handle to

// an object of expected type, or the handle is an error if running out

// of space or encountering an internal error.

void NormalizeProperties(Handle<JSObject> object,

                         PropertyNormalizationMode mode);

void NormalizeElements(Handle<JSObject> object);

void TransformToFastProperties(Handle<JSObject> object,

                               int unused_property_fields);

void FlattenString(Handle<String> str);

Handle<Object> SetProperty(Handle<JSObject> object,

                           Handle<String> key,

                           Handle<Object> value,

                           PropertyAttributes attributes);

Handle<Object> SetProperty(Handle<Object> object,

                           Handle<Object> key,

                           Handle<Object> value,

                           PropertyAttributes attributes);

Handle<Object> IgnoreAttributesAndSetLocalProperty(Handle<JSObject> object,

                                                   Handle<String> key,

                                                   Handle<Object> value,

    PropertyAttributes attributes);

Handle<Object> SetPropertyWithInterceptor(Handle<JSObject> object,

                                          Handle<String> key,

                                          Handle<Object> value,

                                          PropertyAttributes attributes);

Handle<Object> SetElement(Handle<JSObject> object,

                          uint32_t index,

                          Handle<Object> value);

Handle<Object> GetProperty(Handle<JSObject> obj,

                           const char* name);

Handle<Object> GetProperty(Handle<Object> obj,

                           Handle<Object> key);

Handle<Object> GetPropertyWithInterceptor(Handle<JSObject> receiver,

                                          Handle<JSObject> holder,

                                          Handle<String> name,

                                          PropertyAttributes* attributes);

Handle<Object> GetPrototype(Handle<Object> obj);

Handle<Object> GetHiddenProperties(Handle<JSObject> obj, bool create_if_needed);

Handle<Object> DeleteElement(Handle<JSObject> obj, uint32_t index);

Handle<Object> DeleteProperty(Handle<JSObject> obj, Handle<String> prop);

Handle<Object> LookupSingleCharacterStringFromCode(uint32_t index);

Handle<JSObject> Copy(Handle<JSObject> obj);

Handle<FixedArray> AddKeysFromJSArray(Handle<FixedArray>,

                                      Handle<JSArray> array);

// Get the JS object corresponding to the given script; create it

// if none exists.

Handle<JSValue> GetScriptWrapper(Handle<Script> script);

// Script line number computations.

void InitScriptLineEnds(Handle<Script> script);

int GetScriptLineNumber(Handle<Script> script, int code_position);

// Computes the enumerable keys from interceptors. Used for debug mirrors and

// by GetKeysInFixedArrayFor below.

v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSObject> receiver,

                                                 Handle<JSObject> object);

v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSObject> receiver,

                                                   Handle<JSObject> object);

// Computes the enumerable keys for a JSObject. Used for implementing

// "for (n in object) { }".

Handle<FixedArray> GetKeysInFixedArrayFor(Handle<JSObject> object);

Handle<JSArray> GetKeysFor(Handle<JSObject> object);

Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object);

// Computes the union of keys and return the result.

// Used for implementing "for (n in object) { }"

Handle<FixedArray> UnionOfKeys(Handle<FixedArray> first,

                               Handle<FixedArray> second);

Handle<String> SubString(Handle<String> str, int start, int end);

// Sets the expected number of properties for the function's instances.

void SetExpectedNofProperties(Handle<JSFunction> func, int nof);

// Sets the prototype property for a function instance.

void SetPrototypeProperty(Handle<JSFunction> func, Handle<JSObject> value);

// Sets the expected number of properties based on estimate from compiler.

void SetExpectedNofPropertiesFromEstimate(Handle<SharedFunctionInfo> shared,

                                          int estimate);

void SetExpectedNofPropertiesFromEstimate(Handle<JSFunction> func,

                                          int estimate);

Handle<JSGlobalProxy> ReinitializeJSGlobalProxy(

    Handle<JSFunction> constructor,

    Handle<JSGlobalProxy> global);

Handle<Object> SetPrototype(Handle<JSFunction> function,

                            Handle<Object> prototype);

// Do lazy compilation of the given function. Returns true on success

// and false if the compilation resulted in a stack overflow.

enum ClearExceptionFlag { KEEP_EXCEPTION, CLEAR_EXCEPTION };

bool CompileLazyShared(Handle<SharedFunctionInfo> shared,

                       ClearExceptionFlag flag,

                       int loop_nesting);

bool CompileLazy(Handle<JSFunction> function, ClearExceptionFlag flag);

bool CompileLazyInLoop(Handle<JSFunction> function, ClearExceptionFlag flag);

// These deal with lazily loaded properties.

void SetupLazy(Handle<JSFunction> fun,

               int index,

               Handle<Context> compile_context,

               Handle<Context> function_context);

void LoadLazy(Handle<JSFunction> fun, bool* pending_exception);

class NoHandleAllocation BASE_EMBEDDED {

 public:

#ifndef DEBUG

  NoHandleAllocation() {}

  ~NoHandleAllocation() {}

#else

  inline NoHandleAllocation();

  inline ~NoHandleAllocation();

 private:

  int extensions_;

#endif

};

// ----------------------------------------------------------------------------

// Stack allocated wrapper call for optimizing adding multiple

// properties to an object.

class OptimizedObjectForAddingMultipleProperties BASE_EMBEDDED {

 public:

  OptimizedObjectForAddingMultipleProperties(Handle<JSObject> object,

                                             bool condition = true);

  ~OptimizedObjectForAddingMultipleProperties();

 private:

  bool has_been_transformed_;  // Tells whether the object has been transformed.

  int unused_property_fields_;  // Captures the unused number of field.

  Handle<JSObject> object_;    // The object being optimized.

};

} }  // namespace v8::internal

#endif  // V8_HANDLES_H_