1 files changed, 81 insertions, 48 deletions

diff --git a/deps/v8/include/v8-local-handle.h b/deps/v8/include/v8-local-handle.h
index cbf87f949d..0dbbfdbc9f 100644
--- a/deps/v8/include/v8-local-handle.h
+++ b/deps/v8/include/v8-local-handle.h
@@ -50,9 +50,14 @@ class TracedReference;
 class TracedReferenceBase;
 class Utils;
 
+namespace debug {
+class ConsoleCallArguments;
+}
+
 namespace internal {
 template <typename T>
 class CustomArguments;
+class SamplingHeapProfiler;
 }  // namespace internal
 
 namespace api_internal {
@@ -92,6 +97,9 @@ class V8_EXPORT V8_NODISCARD HandleScope {
   HandleScope(const HandleScope&) = delete;
   void operator=(const HandleScope&) = delete;
 
+  static internal::Address* CreateHandleForCurrentIsolate(
+      internal::Address value);
+
  protected:
   V8_INLINE HandleScope() = default;
 
@@ -122,6 +130,33 @@ class V8_EXPORT V8_NODISCARD HandleScope {
   friend class Context;
 };
 
+namespace internal {
+
+/**
+ * Helper functions about handles.
+ */
+class HandleHelper final {
+ public:
+  /**
+   * Checks whether two handles are equal.
+   * They are equal iff they are both empty or they are both non-empty and the
+   * objects to which they refer are physically equal.
+   *
+   * If both handles refer to JS objects, this is the same as strict equality.
+   * For primitives, such as numbers or strings, a `false` return value does not
+   * indicate that the values aren't equal in the JavaScript sense.
+   * Use `Value::StrictEquals()` to check primitives for equality.
+   */
+  template <typename T1, typename T2>
+  V8_INLINE static bool EqualHandles(const T1& lhs, const T2& rhs) {
+    if (lhs.IsEmpty()) return rhs.IsEmpty();
+    if (rhs.IsEmpty()) return false;
+    return lhs.address() == rhs.address();
+  }
+};
+
+}  // namespace internal
+
 /**
  * An object reference managed by the v8 garbage collector.
  *
@@ -154,7 +189,8 @@ class V8_EXPORT V8_NODISCARD HandleScope {
 template <class T>
 class Local {
  public:
-  V8_INLINE Local() : val_(nullptr) {}
+  V8_INLINE Local() : val_(internal::ValueHelper::EmptyValue<T>()) {}
+
   template <class S>
   V8_INLINE Local(Local<S> that) : val_(reinterpret_cast<T*>(*that)) {
     /**
@@ -168,55 +204,40 @@ class Local {
   /**
    * Returns true if the handle is empty.
    */
-  V8_INLINE bool IsEmpty() const { return val_ == nullptr; }
+  V8_INLINE bool IsEmpty() const {
+    return val_ == internal::ValueHelper::EmptyValue<T>();
+  }
 
   /**
    * Sets the handle to be empty. IsEmpty() will then return true.
    */
-  V8_INLINE void Clear() { val_ = nullptr; }
+  V8_INLINE void Clear() { val_ = internal::ValueHelper::EmptyValue<T>(); }
 
   V8_INLINE T* operator->() const { return val_; }
 
   V8_INLINE T* operator*() const { return val_; }
 
   /**
-   * Checks whether two handles are the same.
-   * Returns true if both are empty, or if the objects to which they refer
-   * are identical.
+   * Checks whether two handles are equal or different.
+   * They are equal iff they are both empty or they are both non-empty and the
+   * objects to which they refer are physically equal.
    *
-   * If both handles refer to JS objects, this is the same as strict equality.
-   * For primitives, such as numbers or strings, a `false` return value does not
-   * indicate that the values aren't equal in the JavaScript sense.
-   * Use `Value::StrictEquals()` to check primitives for equality.
+   * If both handles refer to JS objects, this is the same as strict
+   * non-equality. For primitives, such as numbers or strings, a `true` return
+   * value does not indicate that the values aren't equal in the JavaScript
+   * sense. Use `Value::StrictEquals()` to check primitives for equality.
    */
+
   template <class S>
   V8_INLINE bool operator==(const Local<S>& that) const {
-    internal::Address* a = reinterpret_cast<internal::Address*>(this->val_);
-    internal::Address* b = reinterpret_cast<internal::Address*>(that.val_);
-    if (a == nullptr) return b == nullptr;
-    if (b == nullptr) return false;
-    return *a == *b;
+    return internal::HandleHelper::EqualHandles(*this, that);
   }
 
   template <class S>
   V8_INLINE bool operator==(const PersistentBase<S>& that) const {
-    internal::Address* a = reinterpret_cast<internal::Address*>(this->val_);
-    internal::Address* b = reinterpret_cast<internal::Address*>(that.val_);
-    if (a == nullptr) return b == nullptr;
-    if (b == nullptr) return false;
-    return *a == *b;
+    return internal::HandleHelper::EqualHandles(*this, that);
   }
 
-  /**
-   * Checks whether two handles are different.
-   * Returns true if only one of the handles is empty, or if
-   * the objects to which they refer are different.
-   *
-   * If both handles refer to JS objects, this is the same as strict
-   * non-equality. For primitives, such as numbers or strings, a `true` return
-   * value does not indicate that the values aren't equal in the JavaScript
-   * sense. Use `Value::StrictEquals()` to check primitives for equality.
-   */
   template <class S>
   V8_INLINE bool operator!=(const Local<S>& that) const {
     return !operator==(that);
@@ -263,12 +284,12 @@ class Local {
 
   V8_INLINE static Local<T> New(Isolate* isolate,
                                 const PersistentBase<T>& that) {
-    return New(isolate, that.val_);
+    return New(isolate, internal::ValueHelper::SlotAsValue<T>(that.val_));
   }
 
   V8_INLINE static Local<T> New(Isolate* isolate,
                                 const BasicTracedReference<T>& that) {
-    return New(isolate, *that);
+    return New(isolate, internal::ValueHelper::SlotAsValue<T>(*that));
   }
 
  private:
@@ -277,12 +298,6 @@ class Local {
   template <class F>
   friend class Eternal;
   template <class F>
-  friend class PersistentBase;
-  template <class F, class M>
-  friend class Persistent;
-  template <class F>
-  friend class Local;
-  template <class F>
   friend class MaybeLocal;
   template <class F>
   friend class FunctionCallbackInfo;
@@ -309,19 +324,31 @@ class Local {
   friend class ReturnValue;
   template <class F>
   friend class Traced;
-  template <class F>
-  friend class BasicTracedReference;
-  template <class F>
-  friend class TracedReference;
+  friend class internal::SamplingHeapProfiler;
+  friend class internal::HandleHelper;
+  friend class debug::ConsoleCallArguments;
 
   explicit V8_INLINE Local(T* that) : val_(that) {}
+
+  V8_INLINE internal::Address address() const {
+    return internal::ValueHelper::ValueAsAddress(val_);
+  }
+
+  V8_INLINE static Local<T> FromSlot(internal::Address* slot) {
+    return Local<T>(internal::ValueHelper::SlotAsValue<T>(slot));
+  }
+
   V8_INLINE static Local<T> New(Isolate* isolate, T* that) {
+#ifdef V8_ENABLE_CONSERVATIVE_STACK_SCANNING
+    return Local<T>(that);
+#else
     if (that == nullptr) return Local<T>();
-    T* that_ptr = that;
-    internal::Address* p = reinterpret_cast<internal::Address*>(that_ptr);
+    internal::Address* p = reinterpret_cast<internal::Address*>(that);
     return Local<T>(reinterpret_cast<T*>(HandleScope::CreateHandle(
         reinterpret_cast<internal::Isolate*>(isolate), *p)));
+#endif
   }
+
   T* val_;
 };
 
@@ -344,13 +371,15 @@ using Handle = Local<T>;
 template <class T>
 class MaybeLocal {
  public:
-  V8_INLINE MaybeLocal() : val_(nullptr) {}
+  V8_INLINE MaybeLocal() : val_(internal::ValueHelper::EmptyValue<T>()) {}
   template <class S>
   V8_INLINE MaybeLocal(Local<S> that) : val_(reinterpret_cast<T*>(*that)) {
     static_assert(std::is_base_of<T, S>::value, "type check");
   }
 
-  V8_INLINE bool IsEmpty() const { return val_ == nullptr; }
+  V8_INLINE bool IsEmpty() const {
+    return val_ == internal::ValueHelper::EmptyValue<T>();
+  }
 
   /**
    * Converts this MaybeLocal<> to a Local<>. If this MaybeLocal<> is empty,
@@ -358,7 +387,7 @@ class MaybeLocal {
    */
   template <class S>
   V8_WARN_UNUSED_RESULT V8_INLINE bool ToLocal(Local<S>* out) const {
-    out->val_ = IsEmpty() ? nullptr : this->val_;
+    out->val_ = IsEmpty() ? internal::ValueHelper::EmptyValue<T>() : this->val_;
     return !IsEmpty();
   }
 
@@ -367,7 +396,7 @@ class MaybeLocal {
    * V8 will crash the process.
    */
   V8_INLINE Local<T> ToLocalChecked() {
-    if (V8_UNLIKELY(val_ == nullptr)) api_internal::ToLocalEmpty();
+    if (V8_UNLIKELY(IsEmpty())) api_internal::ToLocalEmpty();
     return Local<T>(val_);
   }
 
@@ -399,9 +428,13 @@ class V8_EXPORT V8_NODISCARD EscapableHandleScope : public HandleScope {
    */
   template <class T>
   V8_INLINE Local<T> Escape(Local<T> value) {
+#ifdef V8_ENABLE_CONSERVATIVE_STACK_SCANNING
+    return value;
+#else
     internal::Address* slot =
         Escape(reinterpret_cast<internal::Address*>(*value));
     return Local<T>(reinterpret_cast<T*>(slot));
+#endif
   }
 
   template <class T>