cppgc-js: Deprecate explicit write barrier API

Write barriers are automatically emitted by v8::TracedReference.

Bug: v8:12165
Change-Id: I6ee9b95e9d25fe9606ce1b11b21b3905d47ee8cb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3253343Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77642}

include/v8-cppgc.h

@@ -195,9 +195,11 @@ class V8_EXPORT JSHeapConsistency final {
    * \returns whether a write barrier is needed and which barrier to invoke.
    */
   template <typename HeapHandleCallback>
+  V8_DEPRECATE_SOON("Write barriers automatically emitted by TracedReference.")
   static V8_INLINE WriteBarrierType
-  GetWriteBarrierType(const TracedReferenceBase& ref,
-                      WriteBarrierParams& params, HeapHandleCallback callback) {
+      GetWriteBarrierType(const TracedReferenceBase& ref,
+                          WriteBarrierParams& params,
+                          HeapHandleCallback callback) {
     if (ref.IsEmpty()) return WriteBarrierType::kNone;
 
     if (V8_LIKELY(!cppgc::internal::WriteBarrier::
@@ -251,6 +253,7 @@ class V8_EXPORT JSHeapConsistency final {
    * \param params The parameters retrieved from `GetWriteBarrierType()`.
    * \param ref The reference being written to.
    */
+  V8_DEPRECATE_SOON("Write barriers automatically emitted by TracedReference.")
   static V8_INLINE void DijkstraMarkingBarrier(const WriteBarrierParams& params,
                                                cppgc::HeapHandle& heap_handle,
                                                const TracedReferenceBase& ref) {
@@ -280,6 +283,7 @@ class V8_EXPORT JSHeapConsistency final {
    * \param params The parameters retrieved from `GetWriteBarrierType()`.
    * \param ref The reference being written to.
    */
+  V8_DEPRECATE_SOON("Write barriers automatically emitted by TracedReference.")
   static V8_INLINE void GenerationalBarrier(const WriteBarrierParams& params,
                                             const TracedReferenceBase& ref) {}
 

test/unittests/heap/unified-heap-unittest.cc

@@ -104,6 +104,9 @@ TEST_F(UnifiedHeapTest, WriteBarrierV8ToCppReference) {
 }
 
 TEST_F(UnifiedHeapTest, WriteBarrierCppToV8Reference) {
+// TODO(v8:12165): Remove test when fully removing the deprecated API.
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
   if (!FLAG_incremental_marking) return;
   v8::HandleScope scope(v8_isolate());
   v8::Local<v8::Context> context = v8::Context::New(v8_isolate());
@@ -125,6 +128,7 @@ TEST_F(UnifiedHeapTest, WriteBarrierCppToV8Reference) {
     api_object->SetAlignedPointerInInternalField(1, kMagicAddress);
     wrappable->SetWrapper(v8_isolate(), api_object);
     JSHeapConsistency::WriteBarrierParams params;
+
     auto barrier_type = JSHeapConsistency::GetWriteBarrierType(
         wrappable->wrapper(), params,
         [this]() -> cppgc::HeapHandle& { return cpp_heap().GetHeapHandle(); });
@@ -136,6 +140,7 @@ TEST_F(UnifiedHeapTest, WriteBarrierCppToV8Reference) {
   EXPECT_EQ(0u, Wrappable::destructor_callcount);
   EXPECT_EQ(kMagicAddress,
             wrappable->wrapper()->GetAlignedPointerFromInternalField(1));
+#pragma GCC diagnostic pop
 }
 
 #if DEBUG