[in-place weak refs] Force compacted WeakFixedArrays into old space.

This way the snapshot will contain only old space objects.

BUG=v8:7308

Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: Ib19642795b1e8c7cbeda5162be86909c1a777767
Reviewed-on: https://chromium-review.googlesource.com/1177384Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55186}

src/api.cc

@@ -766,7 +766,7 @@ StartupData SnapshotCreator::CreateBlob(
       i::GarbageCollectionReason::kSnapshotCreator);
   {
     i::HandleScope scope(isolate);
-    isolate->heap()->CompactWeakArrayLists();
+    isolate->heap()->CompactWeakArrayLists(internal::TENURED);
   }
 
   isolate->heap()->read_only_space()->ClearStringPaddingIfNeeded();

src/heap/heap.cc

@@ -5081,7 +5081,8 @@ void Heap::RemoveGCEpilogueCallback(v8::Isolate::GCCallbackWithData callback,
 
 namespace {
 Handle<WeakArrayList> CompactWeakArrayList(Heap* heap,
-                                           Handle<WeakArrayList> array) {
+                                           Handle<WeakArrayList> array,
+                                           PretenureFlag pretenure) {
   if (array->length() == 0) {
     return array;
   }
@@ -5093,7 +5094,7 @@ Handle<WeakArrayList> CompactWeakArrayList(Heap* heap,
   Handle<WeakArrayList> new_array = WeakArrayList::EnsureSpace(
       heap->isolate(),
       handle(ReadOnlyRoots(heap).empty_weak_array_list(), heap->isolate()),
-      new_length);
+      new_length, pretenure);
   // Allocation might have caused GC and turned some of the elements into
   // cleared weak heap objects. Count the number of live references again and
   // fill in the new array.
@@ -5109,7 +5110,7 @@ Handle<WeakArrayList> CompactWeakArrayList(Heap* heap,
 
 }  // anonymous namespace
 
-void Heap::CompactWeakArrayLists() {
+void Heap::CompactWeakArrayLists(PretenureFlag pretenure) {
   // Find known PrototypeUsers and compact them.
   std::vector<Handle<PrototypeInfo>> prototype_infos;
   {
@@ -5126,19 +5127,24 @@ void Heap::CompactWeakArrayLists() {
   for (auto& prototype_info : prototype_infos) {
     Handle<WeakArrayList> array(
         WeakArrayList::cast(prototype_info->prototype_users()), isolate());
+    DCHECK_IMPLIES(pretenure == TENURED,
+                   InOldSpace(*array) ||
+                       *array == ReadOnlyRoots(this).empty_weak_array_list());
     WeakArrayList* new_array = PrototypeUsers::Compact(
-        array, this, JSObject::PrototypeRegistryCompactionCallback);
+        array, this, JSObject::PrototypeRegistryCompactionCallback, pretenure);
     prototype_info->set_prototype_users(new_array);
   }
 
   // Find known WeakArrayLists and compact them.
   Handle<WeakArrayList> scripts(script_list(), isolate());
-  scripts = CompactWeakArrayList(this, scripts);
+  DCHECK_IMPLIES(pretenure == TENURED, InOldSpace(*scripts));
+  scripts = CompactWeakArrayList(this, scripts, pretenure);
   set_script_list(*scripts);
 
   Handle<WeakArrayList> no_script_list(noscript_shared_function_infos(),
                                        isolate());
-  no_script_list = CompactWeakArrayList(this, no_script_list);
+  DCHECK_IMPLIES(pretenure == TENURED, InOldSpace(*no_script_list));
+  no_script_list = CompactWeakArrayList(this, no_script_list, pretenure);
   set_noscript_shared_function_infos(*no_script_list);
 }
 

src/heap/heap.h

@@ -691,7 +691,7 @@ class Heap {
   void ProcessMovedExternalString(Page* old_page, Page* new_page,
                                   ExternalString* string);
 
-  void CompactWeakArrayLists();
+  void CompactWeakArrayLists(PretenureFlag pretenure);
 
   void AddRetainedMap(Handle<Map> map);
 

src/objects.cc

@@ -10463,13 +10463,15 @@ bool WeakArrayList::IsFull() { return length() == capacity(); }
 // static
 Handle<WeakArrayList> WeakArrayList::EnsureSpace(Isolate* isolate,
                                                  Handle<WeakArrayList> array,
-                                                 int length) {
+                                                 int length,
+                                                 PretenureFlag pretenure) {
   int capacity = array->capacity();
   if (capacity < length) {
     int new_capacity = length;
     new_capacity = new_capacity + Max(new_capacity / 2, 2);
     int grow_by = new_capacity - capacity;
-    array = isolate->factory()->CopyWeakArrayListAndGrow(array, grow_by);
+    array =
+        isolate->factory()->CopyWeakArrayListAndGrow(array, grow_by, pretenure);
   }
   return array;
 }
@@ -10550,7 +10552,8 @@ Handle<WeakArrayList> PrototypeUsers::Add(Isolate* isolate,
 }
 
 WeakArrayList* PrototypeUsers::Compact(Handle<WeakArrayList> array, Heap* heap,
-                                       CompactionCallback callback) {
+                                       CompactionCallback callback,
+                                       PretenureFlag pretenure) {
   if (array->length() == 0) {
     return *array;
   }
@@ -10562,7 +10565,7 @@ WeakArrayList* PrototypeUsers::Compact(Handle<WeakArrayList> array, Heap* heap,
   Handle<WeakArrayList> new_array = WeakArrayList::EnsureSpace(
       heap->isolate(),
       handle(ReadOnlyRoots(heap).empty_weak_array_list(), heap->isolate()),
-      new_length);
+      new_length, pretenure);
   // Allocation might have caused GC and turned some of the elements into
   // cleared weak heap objects. Count the number of live objects again.
   int copy_to = kFirstIndex;

src/objects/fixed-array.h

@@ -370,9 +370,9 @@ class WeakArrayList : public HeapObject {
   static const int kMaxCapacity =
       (FixedArray::kMaxSize - kHeaderSize) / kPointerSize;
 
-  static Handle<WeakArrayList> EnsureSpace(Isolate* isolate,
-                                           Handle<WeakArrayList> array,
-                                           int length);
+  static Handle<WeakArrayList> EnsureSpace(
+      Isolate* isolate, Handle<WeakArrayList> array, int length,
+      PretenureFlag pretenure = NOT_TENURED);
 
   // Returns the number of non-cleaned weak references in the array.
   int CountLiveWeakReferences() const;

src/objects/prototype-info.h

@@ -88,7 +88,8 @@ class PrototypeUsers : public WeakArrayList {
   typedef void (*CompactionCallback)(HeapObject* object, int from_index,
                                      int to_index);
   static WeakArrayList* Compact(Handle<WeakArrayList> array, Heap* heap,
-                                CompactionCallback callback);
+                                CompactionCallback callback,
+                                PretenureFlag pretenure = NOT_TENURED);
 
 #ifdef VERIFY_HEAP
   static void Verify(WeakArrayList* array);