1 files changed, 66 insertions, 29 deletions

diff --git a/chromium/v8/include/cppgc/persistent.h b/chromium/v8/include/cppgc/persistent.h
index fc6b0b9d92e..c2d8a7a5a64 100644
--- a/chromium/v8/include/cppgc/persistent.h
+++ b/chromium/v8/include/cppgc/persistent.h
@@ -15,14 +15,43 @@
 #include "v8config.h"  // NOLINT(build/include_directory)
 
 namespace cppgc {
+
+class Visitor;
+
 namespace internal {
 
+class PersistentBase {
+ protected:
+  PersistentBase() = default;
+  explicit PersistentBase(void* raw) : raw_(raw) {}
+
+  void* GetValue() const { return raw_; }
+  void SetValue(void* value) { raw_ = value; }
+
+  PersistentNode* GetNode() const { return node_; }
+  void SetNode(PersistentNode* node) { node_ = node; }
+
+  // Performs a shallow clear which assumes that internal persistent nodes are
+  // destroyed elsewhere.
+  void ClearFromGC() const {
+    raw_ = nullptr;
+    node_ = nullptr;
+  }
+
+ private:
+  mutable void* raw_ = nullptr;
+  mutable PersistentNode* node_ = nullptr;
+
+  friend class PersistentRegion;
+};
+
 // The basic class from which all Persistent classes are generated.
 template <typename T, typename WeaknessPolicy, typename LocationPolicy,
           typename CheckingPolicy>
-class BasicPersistent : public LocationPolicy,
-                        private WeaknessPolicy,
-                        private CheckingPolicy {
+class BasicPersistent final : public PersistentBase,
+                              public LocationPolicy,
+                              private WeaknessPolicy,
+                              private CheckingPolicy {
  public:
   using typename WeaknessPolicy::IsStrongPersistent;
   using PointeeType = T;
@@ -38,15 +67,15 @@ class BasicPersistent : public LocationPolicy,
 
   BasicPersistent(  // NOLINT
       SentinelPointer s, const SourceLocation& loc = SourceLocation::Current())
-      : LocationPolicy(loc), raw_(s) {}
+      : PersistentBase(s), LocationPolicy(loc) {}
 
-  // Raw value contstructors.
+  // Raw value constructors.
   BasicPersistent(T* raw,  // NOLINT
                   const SourceLocation& loc = SourceLocation::Current())
-      : LocationPolicy(loc), raw_(raw) {
+      : PersistentBase(raw), LocationPolicy(loc) {
     if (!IsValid()) return;
-    node_ = WeaknessPolicy::GetPersistentRegion(raw_).AllocateNode(
-        this, &BasicPersistent::Trace);
+    SetNode(WeaknessPolicy::GetPersistentRegion(GetValue())
+                .AllocateNode(this, &BasicPersistent::Trace));
     this->CheckPointer(Get());
   }
 
@@ -74,13 +103,11 @@ class BasicPersistent : public LocationPolicy,
   BasicPersistent(
       BasicPersistent&& other,
       const SourceLocation& loc = SourceLocation::Current()) noexcept
-      : LocationPolicy(std::move(other)),
-        raw_(std::move(other.raw_)),
-        node_(std::move(other.node_)) {
+      : PersistentBase(std::move(other)), LocationPolicy(std::move(other)) {
     if (!IsValid()) return;
-    node_->UpdateOwner(this);
-    other.raw_ = nullptr;
-    other.node_ = nullptr;
+    GetNode()->UpdateOwner(this);
+    other.SetValue(nullptr);
+    other.SetNode(nullptr);
     this->CheckPointer(Get());
   }
 
@@ -114,13 +141,12 @@ class BasicPersistent : public LocationPolicy,
   BasicPersistent& operator=(BasicPersistent&& other) {
     if (this == &other) return *this;
     Clear();
+    PersistentBase::operator=(std::move(other));
     LocationPolicy::operator=(std::move(other));
-    raw_ = std::move(other.raw_);
-    node_ = std::move(other.node_);
     if (!IsValid()) return *this;
-    node_->UpdateOwner(this);
-    other.raw_ = nullptr;
-    other.node_ = nullptr;
+    GetNode()->UpdateOwner(this);
+    other.SetValue(nullptr);
+    other.SetNode(nullptr);
     this->CheckPointer(Get());
     return *this;
   }
@@ -156,7 +182,12 @@ class BasicPersistent : public LocationPolicy,
   T* operator->() const { return Get(); }
   T& operator*() const { return *Get(); }
 
-  T* Get() const { return raw_; }
+  // CFI cast exemption to allow passing SentinelPointer through T* and support
+  // heterogeneous assignments between different Member and Persistent handles
+  // based on their actual types.
+  V8_CLANG_NO_SANITIZE("cfi-unrelated-cast") T* Get() const {
+    return static_cast<T*>(GetValue());
+  }
 
   void Clear() { Assign(nullptr); }
 
@@ -176,29 +207,35 @@ class BasicPersistent : public LocationPolicy,
     // Ideally, handling kSentinelPointer would be done by the embedder. On the
     // other hand, having Persistent aware of it is beneficial since no node
     // gets wasted.
-    return raw_ != nullptr && raw_ != kSentinelPointer;
+    return GetValue() != nullptr && GetValue() != kSentinelPointer;
   }
 
   void Assign(T* ptr) {
     if (IsValid()) {
       if (ptr && ptr != kSentinelPointer) {
         // Simply assign the pointer reusing the existing node.
-        raw_ = ptr;
+        SetValue(ptr);
         this->CheckPointer(ptr);
         return;
       }
-      WeaknessPolicy::GetPersistentRegion(raw_).FreeNode(node_);
-      node_ = nullptr;
+      WeaknessPolicy::GetPersistentRegion(GetValue()).FreeNode(GetNode());
+      SetNode(nullptr);
     }
-    raw_ = ptr;
+    SetValue(ptr);
     if (!IsValid()) return;
-    node_ = WeaknessPolicy::GetPersistentRegion(raw_).AllocateNode(
-        this, &BasicPersistent::Trace);
+    SetNode(WeaknessPolicy::GetPersistentRegion(GetValue())
+                .AllocateNode(this, &BasicPersistent::Trace));
     this->CheckPointer(Get());
   }
 
-  T* raw_ = nullptr;
-  PersistentNode* node_ = nullptr;
+  void ClearFromGC() const {
+    if (IsValid()) {
+      WeaknessPolicy::GetPersistentRegion(GetValue()).FreeNode(GetNode());
+      PersistentBase::ClearFromGC();
+    }
+  }
+
+  friend class cppgc::Visitor;
 };
 
 template <typename T1, typename WeaknessPolicy1, typename LocationPolicy1,