Move map retaining to finalization of incremental marking.

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 5293 matching lines @@
 DependentCode* Heap::LookupWeakObjectToCodeDependency(Handle<HeapObject> obj) {
   Object* dep = weak_object_to_code_table()->Lookup(obj);
   if (dep->IsDependentCode()) return DependentCode::cast(dep);
   return DependentCode::cast(empty_fixed_array());
 }
 
 
 void Heap::AddRetainedMap(Handle<Map> map) {
   Handle<WeakCell> cell = Map::WeakCellForMap(map);
   Handle<ArrayList> array(retained_maps(), isolate());
+  if (array->IsFull()) {
+    CompactRetainedMaps(*array);
+  }
   array = ArrayList::Add(
       array, cell, handle(Smi::FromInt(FLAG_retain_maps_for_n_gc), isolate()),
       ArrayList::kReloadLengthAfterAllocation);
   if (*array != retained_maps()) {
     set_retained_maps(*array);
   }
 }
 
 
+void Heap::CompactRetainedMaps(ArrayList* retained_maps) {
+  DCHECK_EQ(retained_maps, this->retained_maps());
+  int length = retained_maps->Length();
+  int new_length = 0;
+  int new_number_of_disposed_maps = 0;
+  // This loop compacts the array by removing cleared weak cells.
+  for (int i = 0; i < length; i += 2) {
+    DCHECK(retained_maps->Get(i)->IsWeakCell());
+    WeakCell* cell = WeakCell::cast(retained_maps->Get(i));
+    Object* age = retained_maps->Get(i + 1);
+    if (cell->cleared()) continue;
+    if (i != new_length) {
+      retained_maps->Set(new_length, cell);
+      retained_maps->Set(new_length + 1, age);
+    }
+    if (i < number_of_disposed_maps_) {
+      new_number_of_disposed_maps += 2;
+    }
+    new_length += 2;
+  }
+  number_of_disposed_maps_ = new_number_of_disposed_maps;
+  Object* undefined = undefined_value();
+  for (int i = new_length; i < length; i++) {
+    retained_maps->Clear(i, undefined);
+  }
+  if (new_length != length) retained_maps->SetLength(new_length);
+}
+
+
 void Heap::FatalProcessOutOfMemory(const char* location, bool take_snapshot) {
   v8::internal::V8::FatalProcessOutOfMemory(location, take_snapshot);
 }
 
 #ifdef DEBUG
 
 class PrintHandleVisitor : public ObjectVisitor {
  public:
   void VisitPointers(Object** start, Object** end) override {
     for (Object** p = start; p < end; p++)
@@ skipping 770 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8