[heap] Scavenger: Cache pretenuring feedback locally

Bug: chromium:738865
Change-Id: Icb92b649ecd3d4ab4c60f35ffe0649a35fe8b3f6
Reviewed-on: https://chromium-review.googlesource.com/565285Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46530}

src/heap/heap.cc

@@ -1782,6 +1782,8 @@ void Heap::Scavenge() {
       &root_scavenge_visitor);
   scavenger.Process();
 
+  scavenger.Finalize();
+
   UpdateNewSpaceReferencesInExternalStringTable(
       &UpdateNewSpaceReferenceInExternalStringTableEntry);
 

src/heap/scavenger-inl.h

@@ -245,8 +245,8 @@ void Scavenger::ScavengeObject(HeapObject** p, HeapObject* object) {
     return;
   }
 
-  heap()->UpdateAllocationSite<Heap::kGlobal>(
-      object, heap()->global_pretenuring_feedback_);
+  heap()->UpdateAllocationSite<Heap::kCached>(object,
+                                              &local_pretenuring_feedback_);
 
   // AllocationMementos are unrooted and shouldn't survive a scavenge
   DCHECK_NE(heap()->allocation_memento_map(), object->map());

src/heap/scavenger.cc

@@ -132,6 +132,10 @@ void Scavenger::RecordCopiedObject(HeapObject* obj) {
   }
 }
 
+void Scavenger::Finalize() {
+  heap()->MergeAllocationSitePretenuringFeedback(local_pretenuring_feedback_);
+}
+
 void RootScavengeVisitor::VisitRootPointer(Root root, Object** p) {
   ScavengePointer(p);
 }

src/heap/scavenger.h

@@ -73,6 +73,7 @@ class Scavenger {
       : heap_(heap),
         promotion_list_(promotion_list, task_id),
         copied_list_(copied_list, task_id),
+        local_pretenuring_feedback_(kInitialLocalPretenuringFeedbackCapacity),
         is_logging_(is_logging),
         is_incremental_marking_(is_incremental_marking) {}
 
@@ -89,7 +90,12 @@ class Scavenger {
   // manually scavenged using ScavengeObject or CheckAndScavengeObject.
   void Process();
 
+  // Finalize the Scavenger. Needs to be called from the main thread.
+  void Finalize();
+
  private:
+  static const int kInitialLocalPretenuringFeedbackCapacity = 256;
+
   inline Heap* heap() { return heap_; }
 
   V8_INLINE HeapObject* MigrateObject(HeapObject* source, HeapObject* target,
@@ -125,6 +131,7 @@ class Scavenger {
   Heap* const heap_;
   PromotionList::View promotion_list_;
   CopiedRangesList copied_list_;
+  base::HashMap local_pretenuring_feedback_;
   bool is_logging_;
   bool is_incremental_marking_;
 };