[handles] Sanitize Handle and friends.

Bunch of cleanups to allow us to get rid of handles-inl.h at some
point (in the not so far future); but more importantly to sanitize uses
of handles and prepare for handle canonicalization support.

R=yangguo@chromium.org

Committed: https://crrev.com/3283195d0408333cce552cf4087577e6f41054e5
Cr-Commit-Position: refs/heads/master@{#28222}

Committed: https://crrev.com/d940c6d3bcc227b459cb4123d9a8332d9ed0d5f8
Cr-Commit-Position: refs/heads/master@{#29666}

Review URL: https://codereview.chromium.org/1128533002

Cr-Commit-Position: refs/heads/master@{#29675}

src/api.cc

@@ -3797,7 +3797,8 @@ MaybeLocal<String> v8::Object::ObjectProtoToString(Local<Context> context) {
                                  isolate, self, toStringTag).ToHandle(&tag);
     RETURN_ON_FAILED_EXECUTION(String);
     if (tag->IsString()) {
-      class_name = i::Handle<i::String>::cast(tag).EscapeFrom(&handle_scope);
+      class_name = Utils::OpenHandle(*handle_scope.Escape(
+          Utils::ToLocal(i::Handle<i::String>::cast(tag))));
     }
   }
   const char* prefix = "[object ";

src/api.h

@@ -308,17 +308,6 @@ OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)
 };
 
 
-template <class T>
-v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
-    v8::EscapableHandleScope* scope) {
-  v8::internal::Handle<T> handle;
-  if (!is_null()) {
-    handle = *this;
-  }
-  return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
-}
-
-
 template <class T>
 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
   return reinterpret_cast<T*>(obj.location());

src/handles-inl.h

@@ -1,7 +1,6 @@
 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-//
 
 #ifndef V8_HANDLES_INL_H_
 #define V8_HANDLES_INL_H_
@@ -14,72 +13,8 @@
 namespace v8 {
 namespace internal {
 
-template<typename T>
+HandleBase::HandleBase(Object* object, Isolate* isolate)
-Handle<T>::Handle(T* obj) {
+    : location_(HandleScope::CreateHandle(isolate, object)) {}
-  location_ = HandleScope::CreateHandle(obj->GetIsolate(), obj);
-}
-
-
-template<typename T>
-Handle<T>::Handle(T* obj, Isolate* isolate) {
-  location_ = HandleScope::CreateHandle(isolate, obj);
-}
-
-
-template <typename T>
-inline bool Handle<T>::is_identical_to(const Handle<T> o) const {
-  // Dereferencing deferred handles to check object equality is safe.
-  SLOW_DCHECK(
-      (location_ == NULL || IsDereferenceAllowed(NO_DEFERRED_CHECK)) &&
-      (o.location_ == NULL || o.IsDereferenceAllowed(NO_DEFERRED_CHECK)));
-  if (location_ == o.location_) return true;
-  if (location_ == NULL || o.location_ == NULL) return false;
-  return *location_ == *o.location_;
-}
-
-
-template <typename T>
-inline T* Handle<T>::operator*() const {
-  SLOW_DCHECK(IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK));
-  return *bit_cast<T**>(location_);
-}
-
-template <typename T>
-inline T** Handle<T>::location() const {
-  SLOW_DCHECK(location_ == NULL ||
-              IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK));
-  return location_;
-}
-
-#ifdef DEBUG
-template <typename T>
-bool Handle<T>::IsDereferenceAllowed(DereferenceCheckMode mode) const {
-  DCHECK(location_ != NULL);
-  Object* object = *bit_cast<T**>(location_);
-  if (object->IsSmi()) return true;
-  HeapObject* heap_object = HeapObject::cast(object);
-  Heap* heap = heap_object->GetHeap();
-  Object** handle = reinterpret_cast<Object**>(location_);
-  Object** roots_array_start = heap->roots_array_start();
-  if (roots_array_start <= handle &&
-      handle < roots_array_start + Heap::kStrongRootListLength &&
-      heap->RootCanBeTreatedAsConstant(
-        static_cast<Heap::RootListIndex>(handle - roots_array_start))) {
-    return true;
-  }
-  if (!AllowHandleDereference::IsAllowed()) return false;
-  if (mode == INCLUDE_DEFERRED_CHECK &&
-      !AllowDeferredHandleDereference::IsAllowed()) {
-    // Accessing cells, maps and internalized strings is safe.
-    if (heap_object->IsCell()) return true;
-    if (heap_object->IsMap()) return true;
-    if (heap_object->IsInternalizedString()) return true;
-    return !heap->isolate()->IsDeferredHandle(handle);
-  }
-  return true;
-}
-#endif
-
 
 
 HandleScope::HandleScope(Isolate* isolate) {
@@ -136,7 +71,7 @@ Handle<T> HandleScope::CloseAndEscape(Handle<T> handle_value) {
   CloseScope(isolate_, prev_next_, prev_limit_);
   // Allocate one handle in the parent scope.
   DCHECK(current->level > 0);
-  Handle<T> result(CreateHandle<T>(isolate_, value));
+  Handle<T> result(value, isolate_);
   // Reinitialize the current scope (so that it's ready
   // to be used or closed again).
   prev_next_ = current->next;
@@ -151,7 +86,7 @@ T** HandleScope::CreateHandle(Isolate* isolate, T* value) {
   DCHECK(AllowHandleAllocation::IsAllowed());
   HandleScopeData* current = isolate->handle_scope_data();
 
-  internal::Object** cur = current->next;
+  Object** cur = current->next;
   if (cur == current->limit) cur = Extend(isolate);
   // Update the current next field, set the value in the created
   // handle, and return the result.
@@ -190,6 +125,7 @@ inline SealHandleScope::~SealHandleScope() {
 
 #endif
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_HANDLES_INL_H_

src/handles.cc

@@ -9,6 +9,34 @@
 namespace v8 {
 namespace internal {
 
+#ifdef DEBUG
+bool HandleBase::IsDereferenceAllowed(DereferenceCheckMode mode) const {
+  DCHECK_NOT_NULL(location_);
+  Object* object = *location_;
+  if (object->IsSmi()) return true;
+  HeapObject* heap_object = HeapObject::cast(object);
+  Heap* heap = heap_object->GetHeap();
+  Object** roots_array_start = heap->roots_array_start();
+  if (roots_array_start <= location_ &&
+      location_ < roots_array_start + Heap::kStrongRootListLength &&
+      heap->RootCanBeTreatedAsConstant(
+          static_cast<Heap::RootListIndex>(location_ - roots_array_start))) {
+    return true;
+  }
+  if (!AllowHandleDereference::IsAllowed()) return false;
+  if (mode == INCLUDE_DEFERRED_CHECK &&
+      !AllowDeferredHandleDereference::IsAllowed()) {
+    // Accessing cells, maps and internalized strings is safe.
+    if (heap_object->IsCell()) return true;
+    if (heap_object->IsMap()) return true;
+    if (heap_object->IsInternalizedString()) return true;
+    return !heap->isolate()->IsDeferredHandle(location_);
+  }
+  return true;
+}
+#endif
+
+
 int HandleScope::NumberOfHandles(Isolate* isolate) {
   HandleScopeImplementer* impl = isolate->handle_scope_implementer();
   int n = impl->blocks()->length();
@@ -67,7 +95,7 @@ void HandleScope::DeleteExtensions(Isolate* isolate) {
 void HandleScope::ZapRange(Object** start, Object** end) {
   DCHECK(end - start <= kHandleBlockSize);
   for (Object** p = start; p != end; p++) {
-    *reinterpret_cast<Address*>(p) = v8::internal::kHandleZapValue;
+    *reinterpret_cast<Address*>(p) = kHandleZapValue;
   }
 }
 #endif

src/handles.h

@@ -10,52 +10,174 @@
 namespace v8 {
 namespace internal {
 
+// Forward declarations.
+class DeferredHandles;
+class HandleScopeImplementer;
+
+
+// ----------------------------------------------------------------------------
+// Base class for Handle instantiations.  Don't use directly.
+class HandleBase {
+ public:
+  V8_INLINE explicit HandleBase(Object** location) : location_(location) {}
+  V8_INLINE explicit HandleBase(Object* object, Isolate* isolate);
+
+  // Check if this handle refers to the exact same object as the other handle.
+  V8_INLINE bool is_identical_to(const HandleBase that) const {
+    // Dereferencing deferred handles to check object equality is safe.
+    SLOW_DCHECK((this->location_ == NULL ||
+                 this->IsDereferenceAllowed(NO_DEFERRED_CHECK)) &&
+                (that.location_ == NULL ||
+                 that.IsDereferenceAllowed(NO_DEFERRED_CHECK)));
+    if (this->location_ == that.location_) return true;
+    if (this->location_ == NULL || that.location_ == NULL) return false;
+    return *this->location_ == *that.location_;
+  }
+
+  V8_INLINE bool is_null() const { return location_ == nullptr; }
+
+ protected:
+  // Provides the C++ dereference operator.
+  V8_INLINE Object* operator*() const {
+    SLOW_DCHECK(IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK));
+    return *location_;
+  }
+
+  // Returns the address to where the raw pointer is stored.
+  V8_INLINE Object** location() const {
+    SLOW_DCHECK(location_ == NULL ||
+                IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK));
+    return location_;
+  }
+
+  enum DereferenceCheckMode { INCLUDE_DEFERRED_CHECK, NO_DEFERRED_CHECK };
+#ifdef DEBUG
+  bool IsDereferenceAllowed(DereferenceCheckMode mode) const;
+#else
+  V8_INLINE
+  bool IsDereferenceAllowed(DereferenceCheckMode mode) const { return true; }
+#endif  // DEBUG
+
+  Object** location_;
+};
+
+
+// ----------------------------------------------------------------------------
+// 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 <typename T>
+class Handle final : public HandleBase {
+ public:
+  V8_INLINE explicit Handle(T** location = nullptr)
+      : HandleBase(reinterpret_cast<Object**>(location)) {
+    Object* a = nullptr;
+    T* b = nullptr;
+    a = b;  // Fake assignment to enforce type checks.
+    USE(a);
+  }
+  V8_INLINE explicit Handle(T* object) : Handle(object, object->GetIsolate()) {}
+  V8_INLINE Handle(T* object, Isolate* isolate) : HandleBase(object, isolate) {}
+
+  // Constructor for handling automatic up casting.
+  // Ex. Handle<JSFunction> can be passed when Handle<Object> is expected.
+  template <typename S>
+  V8_INLINE Handle(Handle<S> handle)
+      : HandleBase(handle) {
+    T* a = nullptr;
+    S* b = nullptr;
+    a = b;  // Fake assignment to enforce type checks.
+    USE(a);
+  }
+
+  V8_INLINE T* operator->() const { return operator*(); }
+
+  // Provides the C++ dereference operator.
+  V8_INLINE T* operator*() const {
+    return reinterpret_cast<T*>(HandleBase::operator*());
+  }
+
+  // Returns the address to where the raw pointer is stored.
+  V8_INLINE T** location() const {
+    return reinterpret_cast<T**>(HandleBase::location());
+  }
+
+  template <typename S>
+  static const Handle<T> cast(Handle<S> that) {
+    T::cast(*reinterpret_cast<T**>(that.location_));
+    return Handle<T>(reinterpret_cast<T**>(that.location_));
+  }
+
+  // TODO(yangguo): Values that contain empty handles should be declared as
+  // MaybeHandle to force validation before being used as handles.
+  static const Handle<T> null() { return Handle<T>(); }
+
+ private:
+  // Handles of different classes are allowed to access each other's location_.
+  template <typename>
+  friend class Handle;
+  // MaybeHandle is allowed to access location_.
+  template <typename>
+  friend class MaybeHandle;
+};
+
+template <typename T>
+V8_INLINE Handle<T> handle(T* object, Isolate* isolate) {
+  return Handle<T>(object, isolate);
+}
+
+template <typename T>
+V8_INLINE Handle<T> handle(T* object) {
+  return Handle<T>(object);
+}
+
+
+// ----------------------------------------------------------------------------
 // A Handle can be converted into a MaybeHandle. Converting a MaybeHandle
 // into a Handle requires checking that it does not point to NULL.  This
 // ensures NULL checks before use.
 // Do not use MaybeHandle as argument type.
-
+template <typename T>
-template<typename T>
+class MaybeHandle final {
-class MaybeHandle {
  public:
-  INLINE(MaybeHandle()) : location_(NULL) { }
+  V8_INLINE MaybeHandle() {}
+  V8_INLINE ~MaybeHandle() {}
 
   // Constructor for handling automatic up casting from Handle.
   // Ex. Handle<JSArray> can be passed when MaybeHandle<Object> is expected.
-  template <class S> MaybeHandle(Handle<S> handle) {
+  template <typename S>
-#ifdef DEBUG
+  V8_INLINE MaybeHandle(Handle<S> handle)
-    T* a = NULL;
+      : location_(reinterpret_cast<T**>(handle.location_)) {
-    S* b = NULL;
+    T* a = nullptr;
+    S* b = nullptr;
     a = b;  // Fake assignment to enforce type checks.
     USE(a);
-#endif
-    this->location_ = reinterpret_cast<T**>(handle.location());
   }
 
   // Constructor for handling automatic up casting.
   // Ex. MaybeHandle<JSArray> can be passed when Handle<Object> is expected.
-  template <class S> MaybeHandle(MaybeHandle<S> maybe_handle) {
+  template <typename S>
-#ifdef DEBUG
+  V8_INLINE MaybeHandle(MaybeHandle<S> maybe_handle)
-    T* a = NULL;
+      : location_(reinterpret_cast<T**>(maybe_handle.location_)) {
-    S* b = NULL;
+    T* a = nullptr;
+    S* b = nullptr;
     a = b;  // Fake assignment to enforce type checks.
     USE(a);
-#endif
-    location_ = reinterpret_cast<T**>(maybe_handle.location_);
   }
 
-  INLINE(void Assert() const) { DCHECK(location_ != NULL); }
+  V8_INLINE void Assert() const { DCHECK_NOT_NULL(location_); }
-  INLINE(void Check() const) { CHECK(location_ != NULL); }
+  V8_INLINE void Check() const { CHECK_NOT_NULL(location_); }
 
-  INLINE(Handle<T> ToHandleChecked()) const {
+  V8_INLINE Handle<T> ToHandleChecked() const {
     Check();
     return Handle<T>(location_);
   }
 
   // Convert to a Handle with a type that can be upcasted to.
-  template <class S>
+  template <typename S>
   V8_INLINE bool ToHandle(Handle<S>* out) const {
-    if (location_ == NULL) {
+    if (location_ == nullptr) {
       *out = Handle<T>::null();
       return false;
     } else {
@@ -64,120 +186,37 @@ class MaybeHandle {
     }
   }
 
-  bool is_null() const { return location_ == NULL; }
+  bool is_null() const { return location_ == nullptr; }
 
   template <typename S>
-  bool operator==(MaybeHandle<S> that) const {
+  V8_INLINE bool operator==(MaybeHandle<S> that) const {
     return this->location_ == that.location_;
   }
   template <typename S>
-  bool operator!=(MaybeHandle<S> that) const {
+  V8_INLINE bool operator!=(MaybeHandle<S> that) const {
-    return !(*this == that);
+    return this->location_ != that.location_;
   }
 
-
  protected:
-  T** location_;
+  T** location_ = nullptr;
 
   // MaybeHandles of different classes are allowed to access each
   // other's location_.
-  template<class S> friend class MaybeHandle;
+  template <typename>
+  friend class MaybeHandle;
+  // Utility functions are allowed to access location_.
   template <typename S>
   friend size_t hash_value(MaybeHandle<S>);
 };
 
-template <typename S>
+template <typename T>
-inline size_t hash_value(MaybeHandle<S> maybe_handle) {
+V8_INLINE size_t hash_value(MaybeHandle<T> maybe_handle) {
-  return bit_cast<size_t>(maybe_handle.location_);
+  uintptr_t v = bit_cast<uintptr_t>(maybe_handle.location_);
+  DCHECK_EQ(0u, v & ((1u << kPointerSizeLog2) - 1));
+  return v >> kPointerSizeLog2;
 }
 
 
-// ----------------------------------------------------------------------------
-// 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<typename T>
-class Handle {
- public:
-  INLINE(explicit Handle(T** location)) { location_ = location; }
-  INLINE(explicit Handle(T* obj));
-  INLINE(Handle(T* obj, Isolate* isolate));
-
-  // TODO(yangguo): Values that contain empty handles should be declared as
-  // MaybeHandle to force validation before being used as handles.
-  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.
-  INLINE(bool is_identical_to(const Handle<T> other) const);
-
-  // Provides the C++ dereference operator.
-  INLINE(T* operator*() const);
-
-  // Returns the address to where the raw pointer is stored.
-  INLINE(T** location() const);
-
-  template <class S> static Handle<T> cast(Handle<S> that) {
-    T::cast(*reinterpret_cast<T**>(that.location_));
-    return Handle<T>(reinterpret_cast<T**>(that.location_));
-  }
-
-  // TODO(yangguo): Values that contain empty handles should be declared as
-  // MaybeHandle to force validation before being used as handles.
-  static Handle<T> null() { return Handle<T>(); }
-  bool is_null() const { return location_ == NULL; }
-
-  // Closes the given scope, but lets this handle escape. See
-  // implementation in api.h.
-  inline Handle<T> EscapeFrom(v8::EscapableHandleScope* scope);
-
-#ifdef DEBUG
-  enum DereferenceCheckMode { INCLUDE_DEFERRED_CHECK, NO_DEFERRED_CHECK };
-
-  bool IsDereferenceAllowed(DereferenceCheckMode mode) const;
-#endif  // DEBUG
-
- private:
-  T** location_;
-
-  // Handles of different classes are allowed to access each other's location_.
-  template<class S> friend class Handle;
-};
-
-
-// Convenience wrapper.
-template<class T>
-inline Handle<T> handle(T* t, Isolate* isolate) {
-  return Handle<T>(t, isolate);
-}
-
-
-// Convenience wrapper.
-template<class T>
-inline Handle<T> handle(T* t) {
-  return Handle<T>(t, t->GetIsolate());
-}
-
-
-class DeferredHandles;
-class HandleScopeImplementer;
-
-
 // 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
@@ -241,7 +280,7 @@ class HandleScope {
                                 Object** prev_limit);
 
   // Extend the handle scope making room for more handles.
-  static internal::Object** Extend(Isolate* isolate);
+  static Object** Extend(Isolate* isolate);
 
 #ifdef ENABLE_HANDLE_ZAPPING
   // Zaps the handles in the half-open interval [start, end).
@@ -249,16 +288,13 @@ class HandleScope {
 #endif
 
   friend class v8::HandleScope;
-  friend class v8::internal::DeferredHandles;
+  friend class DeferredHandles;
-  friend class v8::internal::HandleScopeImplementer;
+  friend class HandleScopeImplementer;
-  friend class v8::internal::Isolate;
+  friend class Isolate;
 };
 
 
-class DeferredHandles;
+class DeferredHandleScope final {
-
-
-class DeferredHandleScope {
  public:
   explicit DeferredHandleScope(Isolate* isolate);
   // The DeferredHandles object returned stores the Handles created
@@ -283,7 +319,7 @@ class DeferredHandleScope {
 
 // Seal off the current HandleScope so that new handles can only be created
 // if a new HandleScope is entered.
-class SealHandleScope BASE_EMBEDDED {
+class SealHandleScope final {
  public:
 #ifndef DEBUG
   explicit SealHandleScope(Isolate* isolate) {}
@@ -298,9 +334,10 @@ class SealHandleScope BASE_EMBEDDED {
 #endif
 };
 
-struct HandleScopeData {
+
-  internal::Object** next;
+struct HandleScopeData final {
-  internal::Object** limit;
+  Object** next;
+  Object** limit;
   int level;
 
   void Initialize() {
@@ -309,6 +346,7 @@ struct HandleScopeData {
   }
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_HANDLES_H_

test/cctest/test-api.cc

@@ -1965,7 +1965,7 @@ THREADED_TEST(UndefinedIsNotEnumerable) {
 
 
 v8::Handle<Script> call_recursively_script;
-static const int kTargetRecursionDepth = 200;  // near maximum
+static const int kTargetRecursionDepth = 150;  // near maximum
 
 
 static void CallScriptRecursivelyCall(

test/cctest/test-heap.cc

@@ -973,22 +973,6 @@ TEST(Iteration) {
 }
 
 
-TEST(EmptyHandleEscapeFrom) {
-  CcTest::InitializeVM();
-
-  v8::HandleScope scope(CcTest::isolate());
-  Handle<JSObject> runaway;
-
-  {
-      v8::EscapableHandleScope nested(CcTest::isolate());
-      Handle<JSObject> empty;
-      runaway = empty.EscapeFrom(&nested);
-  }
-
-  CHECK(runaway.is_null());
-}
-
-
 static int LenFromSize(int size) {
   return (size - FixedArray::kHeaderSize) / kPointerSize;
 }