cppgc: young-gen: Schedule Minor GCs

The CL runs Oilpan minor GCs after each Scavenger cycle.

Bug: chromium:1029379
Change-Id: Ic67cf4dc9158759207f0209640f1720bf188cc1d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3472500Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79440}

src/heap/cppgc-js/cpp-heap.cc

@@ -642,6 +642,28 @@ void CppHeap::TraceEpilogue() {
   sweeper().NotifyDoneIfNeeded();
 }
 
+void CppHeap::RunMinorGC() {
+#if defined(CPPGC_YOUNG_GENERATION)
+  if (in_no_gc_scope()) return;
+  // Minor GC does not support nesting in full GCs.
+  if (IsMarking()) return;
+  // Finish sweeping in case it is still running.
+  sweeper().FinishIfRunning();
+
+  SetStackEndOfCurrentGC(v8::base::Stack::GetCurrentStackPosition());
+
+  // Perform an atomic GC, with starting incremental/concurrent marking and
+  // immediately finalizing the garbage collection.
+  InitializeTracing(
+      cppgc::internal::GarbageCollector::Config::CollectionType::kMinor,
+      GarbageCollectionFlagValues::kForced);
+  StartTracing();
+  EnterFinalPause(cppgc::EmbedderStackState::kMayContainHeapPointers);
+  AdvanceTracing(std::numeric_limits<double>::infinity());
+  TraceEpilogue();
+#endif  // defined(CPPGC_YOUNG_GENERATION)
+}
+
 void CppHeap::AllocatedObjectSizeIncreased(size_t bytes) {
   buffered_allocated_bytes_ += static_cast<int64_t>(bytes);
   ReportBufferedAllocationSizeIfPossible();

src/heap/cppgc-js/cpp-heap.h

@@ -129,6 +129,8 @@ class V8_EXPORT_PRIVATE CppHeap final
   void TraceEpilogue();
   void EnterFinalPause(cppgc::EmbedderStackState stack_state);
 
+  void RunMinorGC();
+
   // StatsCollector::AllocationObserver interface.
   void AllocatedObjectSizeIncreased(size_t) final;
   void AllocatedObjectSizeDecreased(size_t) final;

src/heap/heap.cc

@@ -2327,6 +2327,10 @@ size_t Heap::PerformGarbageCollection(
     local_embedder_heap_tracer()->TraceEpilogue();
   }
 
+  if (collector == GarbageCollector::SCAVENGER && cpp_heap()) {
+    CppHeap::From(cpp_heap())->RunMinorGC();
+  }
+
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     // We don't really perform a GC here but need this scope for the nested