Version 4.4.63.24 (cherry-pick)

src/snapshot/serialize.cc

Index: src/snapshot/serialize.cc
diff --git a/src/snapshot/serialize.cc b/src/snapshot/serialize.cc
index 55685be2785713ef97345842aa3b765e04869363..7f123a3fbed622040a5d7cc5fab7bd85a1560faa 100644
--- a/src/snapshot/serialize.cc
+++ b/src/snapshot/serialize.cc
@@ -516,10 +516,18 @@ void Deserializer::DecodeReservation(
 
 
 void Deserializer::FlushICacheForNewCodeObjects() {
-  PageIterator it(isolate_->heap()->code_space());
-  while (it.has_next()) {
-    Page* p = it.next();
-    CpuFeatures::FlushICache(p->area_start(), p->area_end() - p->area_start());
+  if (!deserializing_user_code_) {
+    // The entire isolate is newly deserialized. Simply flush all code pages.
+    PageIterator it(isolate_->heap()->code_space());
+    while (it.has_next()) {
+      Page* p = it.next();
+      CpuFeatures::FlushICache(p->area_start(),
+                               p->area_end() - p->area_start());
+    }
+  }
+  for (Code* code : new_code_objects_) {
+    CpuFeatures::FlushICache(code->instruction_start(),
+                             code->instruction_size());
   }
 }
 
@@ -556,10 +564,15 @@ void Deserializer::Deserialize(Isolate* isolate) {
   DCHECK_NULL(isolate_->thread_manager()->FirstThreadStateInUse());
   // No active handles.
   DCHECK(isolate_->handle_scope_implementer()->blocks()->is_empty());
-  isolate_->heap()->IterateSmiRoots(this);
-  isolate_->heap()->IterateStrongRoots(this, VISIT_ONLY_STRONG);
-  isolate_->heap()->RepairFreeListsAfterDeserialization();
-  isolate_->heap()->IterateWeakRoots(this, VISIT_ALL);
+
+  {
+    DisallowHeapAllocation no_gc;
+    isolate_->heap()->IterateSmiRoots(this);
+    isolate_->heap()->IterateStrongRoots(this, VISIT_ONLY_STRONG);
+    isolate_->heap()->RepairFreeListsAfterDeserialization();
+    isolate_->heap()->IterateWeakRoots(this, VISIT_ALL);
+    DeserializeDeferredObjects();
+  }
 
   isolate_->heap()->set_native_contexts_list(
       isolate_->heap()->undefined_value());
@@ -608,11 +621,12 @@ MaybeHandle<Object> Deserializer::DeserializePartial(
   Object* root;
   Object* outdated_contexts;
   VisitPointer(&root);
+  DeserializeDeferredObjects();
   VisitPointer(&outdated_contexts);
 
-  // There's no code deserialized here. If this assert fires
-  // then that's changed and logging should be added to notify
-  // the profiler et al of the new code.
+  // There's no code deserialized here. If this assert fires then that's
+  // changed and logging should be added to notify the profiler et al of the
+  // new code, which also has to be flushed from instruction cache.
   CHECK_EQ(start_address, code_space->top());
   CHECK(outdated_contexts->IsFixedArray());
   *outdated_contexts_out =
@@ -628,10 +642,17 @@ MaybeHandle<SharedFunctionInfo> Deserializer::DeserializeCode(
     return Handle<SharedFunctionInfo>();
   } else {
     deserializing_user_code_ = true;
-    DisallowHeapAllocation no_gc;
-    Object* root;
-    VisitPointer(&root);
-    return Handle<SharedFunctionInfo>(SharedFunctionInfo::cast(root));
+    HandleScope scope(isolate);
+    Handle<SharedFunctionInfo> result;
+    {
+      DisallowHeapAllocation no_gc;
+      Object* root;
+      VisitPointer(&root);
+      DeserializeDeferredObjects();
+      result = Handle<SharedFunctionInfo>(SharedFunctionInfo::cast(root));
+    }
+    CommitNewInternalizedStrings(isolate);
+    return scope.CloseAndEscape(result);
   }
 }
 
@@ -652,13 +673,21 @@ void Deserializer::VisitPointers(Object** start, Object** end) {
 }
 
 
-void Deserializer::RelinkAllocationSite(AllocationSite* site) {
-  if (isolate_->heap()->allocation_sites_list() == Smi::FromInt(0)) {
-    site->set_weak_next(isolate_->heap()->undefined_value());
-  } else {
-    site->set_weak_next(isolate_->heap()->allocation_sites_list());
+void Deserializer::DeserializeDeferredObjects() {
+  for (int code = source_.Get(); code != kSynchronize; code = source_.Get()) {
+    int space = code & kSpaceMask;
+    DCHECK(space <= kNumberOfSpaces);
+    DCHECK(code - space == kNewObject);
+    HeapObject* object = GetBackReferencedObject(space);
+    int size = source_.GetInt() << kPointerSizeLog2;
+    Address obj_address = object->address();
+    Object** start = reinterpret_cast<Object**>(obj_address + kPointerSize);
+    Object** end = reinterpret_cast<Object**>(obj_address + size);
+    bool filled = ReadData(start, end, space, obj_address);
+    CHECK(filled);
+    DCHECK(CanBeDeferred(object));
+    PostProcessNewObject(object, space);
   }
-  isolate_->heap()->set_allocation_sites_list(site);
 }
 
 
@@ -688,31 +717,76 @@ class StringTableInsertionKey : public HashTableKey {
     return handle(string_, isolate);
   }
 
+ private:
   String* string_;
   uint32_t hash_;
+  DisallowHeapAllocation no_gc;
 };
 
 
-HeapObject* Deserializer::ProcessNewObjectFromSerializedCode(HeapObject* obj) {
-  if (obj->IsString()) {
-    String* string = String::cast(obj);
-    // Uninitialize hash field as the hash seed may have changed.
-    string->set_hash_field(String::kEmptyHashField);
-    if (string->IsInternalizedString()) {
-      DisallowHeapAllocation no_gc;
-      HandleScope scope(isolate_);
-      StringTableInsertionKey key(string);
-      String* canonical = *StringTable::LookupKey(isolate_, &key);
-      string->SetForwardedInternalizedString(canonical);
-      return canonical;
+HeapObject* Deserializer::PostProcessNewObject(HeapObject* obj, int space) {
+  if (deserializing_user_code()) {
+    if (obj->IsString()) {
+      String* string = String::cast(obj);
+      // Uninitialize hash field as the hash seed may have changed.
+      string->set_hash_field(String::kEmptyHashField);
+      if (string->IsInternalizedString()) {
+        // Canonicalize the internalized string. If it already exists in the
+        // string table, set it to forward to the existing one.
+        StringTableInsertionKey key(string);
+        String* canonical = StringTable::LookupKeyIfExists(isolate_, &key);
+        if (canonical == NULL) {
+          new_internalized_strings_.Add(handle(string));
+          return string;
+        } else {
+          string->SetForwardedInternalizedString(canonical);
+          return canonical;
+        }
+      }
+    } else if (obj->IsScript()) {
+      // Assign a new script id to avoid collision.
+      Script::cast(obj)->set_id(isolate_->heap()->NextScriptId());
+    } else {
+      DCHECK(CanBeDeferred(obj));
+    }
+  }
+  if (obj->IsAllocationSite()) {
+    DCHECK(obj->IsAllocationSite());
+    // Allocation sites are present in the snapshot, and must be linked into
+    // a list at deserialization time.
+    AllocationSite* site = AllocationSite::cast(obj);
+    // TODO(mvstanton): consider treating the heap()->allocation_sites_list()
+    // as a (weak) root. If this root is relocated correctly, this becomes
+    // unnecessary.
+    if (isolate_->heap()->allocation_sites_list() == Smi::FromInt(0)) {
+      site->set_weak_next(isolate_->heap()->undefined_value());
+    } else {
+      site->set_weak_next(isolate_->heap()->allocation_sites_list());
+    }
+    isolate_->heap()->set_allocation_sites_list(site);
+  } else if (obj->IsCode()) {
+    // We flush all code pages after deserializing the startup snapshot. In that
+    // case, we only need to remember code objects in the large object space.
+    // When deserializing user code, remember each individual code object.
+    if (deserializing_user_code() || space == LO_SPACE) {
+      new_code_objects_.Add(Code::cast(obj));
     }
-  } else if (obj->IsScript()) {
-    Script::cast(obj)->set_id(isolate_->heap()->NextScriptId());
   }
   return obj;
 }
 
 
+void Deserializer::CommitNewInternalizedStrings(Isolate* isolate) {
+  StringTable::EnsureCapacityForDeserialization(
+      isolate, new_internalized_strings_.length());
+  for (Handle<String> string : new_internalized_strings_) {
+    StringTableInsertionKey key(*string);
+    DCHECK_NULL(StringTable::LookupKeyIfExists(isolate, &key));
+    StringTable::LookupKey(isolate, &key);
+  }
+}
+
+
 HeapObject* Deserializer::GetBackReferencedObject(int space) {
   HeapObject* obj;
   BackReference back_reference(source_.GetInt());
@@ -757,24 +831,17 @@ void Deserializer::ReadObject(int space_number, Object** write_back) {
   if (FLAG_log_snapshot_positions) {
     LOG(isolate_, SnapshotPositionEvent(address, source_.position()));
   }
-  ReadData(current, limit, space_number, address);
-
-  // TODO(mvstanton): consider treating the heap()->allocation_sites_list()
-  // as a (weak) root. If this root is relocated correctly,
-  // RelinkAllocationSite() isn't necessary.
-  if (obj->IsAllocationSite()) RelinkAllocationSite(AllocationSite::cast(obj));
 
-  // Fix up strings from serialized user code.
-  if (deserializing_user_code()) obj = ProcessNewObjectFromSerializedCode(obj);
+  if (ReadData(current, limit, space_number, address)) {
+    // Only post process if object content has not been deferred.
+    obj = PostProcessNewObject(obj, space_number);
+  }
 
   Object* write_back_obj = obj;
   UnalignedCopy(write_back, &write_back_obj);
 #ifdef DEBUG
   if (obj->IsCode()) {
     DCHECK(space_number == CODE_SPACE || space_number == LO_SPACE);
-#ifdef VERIFY_HEAP
-    obj->ObjectVerify();
-#endif  // VERIFY_HEAP
   } else {
     DCHECK(space_number != CODE_SPACE);
   }
@@ -818,7 +885,7 @@ Address Deserializer::Allocate(int space_index, int size) {
 }
 
 
-void Deserializer::ReadData(Object** current, Object** limit, int source_space,
+bool Deserializer::ReadData(Object** current, Object** limit, int source_space,
                             Address current_object_address) {
   Isolate* const isolate = isolate_;
   // Write barrier support costs around 1% in startup time.  In fact there
@@ -1075,6 +1142,18 @@ void Deserializer::ReadData(Object** current, Object** limit, int source_space,
         break;
       }
 
+      case kDeferred: {
+        // Deferred can only occur right after the heap object header.
+        DCHECK(current == reinterpret_cast<Object**>(current_object_address +
+                                                     kPointerSize));
+        HeapObject* obj = HeapObject::FromAddress(current_object_address);
+        // If the deferred object is a map, its instance type may be used
+        // during deserialization. Initialize it with a temporary value.
+        if (obj->IsMap()) Map::cast(obj)->set_instance_type(FILLER_TYPE);
+        current = limit;
+        return false;
+      }
+
       case kSynchronize:
         // If we get here then that indicates that you have a mismatch between
         // the number of GC roots when serializing and deserializing.
@@ -1181,6 +1260,7 @@ void Deserializer::ReadData(Object** current, Object** limit, int source_space,
     }
   }
   CHECK_EQ(limit, current);
+  return true;
 }
 
 
@@ -1189,6 +1269,7 @@ Serializer::Serializer(Isolate* isolate, SnapshotByteSink* sink)
       sink_(sink),
       external_reference_encoder_(isolate),
       root_index_map_(isolate),
+      recursion_depth_(0),
       code_address_map_(NULL),
       large_objects_total_size_(0),
       seen_large_objects_index_(0) {
@@ -1264,6 +1345,16 @@ void Serializer::OutputStatistics(const char* name) {
 }
 
 
+void Serializer::SerializeDeferredObjects() {
+  while (deferred_objects_.length() > 0) {
+    HeapObject* obj = deferred_objects_.RemoveLast();
+    ObjectSerializer obj_serializer(this, obj, sink_, kPlain, kStartOfObject);
+    obj_serializer.SerializeDeferred();
+  }
+  sink_->Put(kSynchronize, "Finished with deferred objects");
+}
+
+
 void StartupSerializer::SerializeStrongReferences() {
   Isolate* isolate = this->isolate();
   // No active threads.
@@ -1307,6 +1398,7 @@ void PartialSerializer::Serialize(Object** o) {
     back_reference_map()->AddGlobalProxy(context->global_proxy());
   }
   VisitPointer(o);
+  SerializeDeferredObjects();
   SerializeOutdatedContextsAsFixedArray();
   Pad();
 }
@@ -1331,10 +1423,10 @@ void PartialSerializer::SerializeOutdatedContextsAsFixedArray() {
       sink_->Put(reinterpret_cast<byte*>(&length_smi)[i], "Byte");
     }
     for (int i = 0; i < length; i++) {
-      BackReference back_ref = outdated_contexts_[i];
-      DCHECK(BackReferenceIsAlreadyAllocated(back_ref));
-      sink_->Put(kBackref + back_ref.space(), "BackRef");
-      sink_->PutInt(back_ref.reference(), "BackRefValue");
+      Context* context = outdated_contexts_[i];
+      BackReference back_reference = back_reference_map_.Lookup(context);
+      sink_->Put(kBackref + back_reference.space(), "BackRef");
+      PutBackReference(context, back_reference);
     }
   }
 }
@@ -1497,10 +1589,7 @@ bool Serializer::SerializeKnownObject(HeapObject* obj, HowToCode how_to_code,
                    "BackRefWithSkip");
         sink_->PutInt(skip, "BackRefSkipDistance");
       }
-      DCHECK(BackReferenceIsAlreadyAllocated(back_reference));
-      sink_->PutInt(back_reference.reference(), "BackRefValue");
-
-      hot_objects_.Add(obj);
+      PutBackReference(obj, back_reference);
     }
     return true;
   }
@@ -1536,7 +1625,7 @@ void StartupSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
 }
 
 
-void StartupSerializer::SerializeWeakReferences() {
+void StartupSerializer::SerializeWeakReferencesAndDeferred() {
   // This phase comes right after the serialization (of the snapshot).
   // After we have done the partial serialization the partial snapshot cache
   // will contain some references needed to decode the partial snapshot.  We
@@ -1545,6 +1634,7 @@ void StartupSerializer::SerializeWeakReferences() {
   Object* undefined = isolate()->heap()->undefined_value();
   VisitPointer(&undefined);
   isolate()->heap()->IterateWeakRoots(this, VISIT_ALL);
+  SerializeDeferredObjects();
   Pad();
 }
 
@@ -1577,6 +1667,13 @@ void Serializer::PutRoot(int root_index,
 }
 
 
+void Serializer::PutBackReference(HeapObject* object, BackReference reference) {
+  DCHECK(BackReferenceIsAlreadyAllocated(reference));
+  sink_->PutInt(reference.reference(), "BackRefValue");
+  hot_objects_.Add(object);
+}
+
+
 void PartialSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
                                         WhereToPoint where_to_point, int skip) {
   if (obj->IsMap()) {
@@ -1630,9 +1727,7 @@ void PartialSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
       Context::cast(obj)->global_object() == global_object_) {
     // Context refers to the current global object. This reference will
     // become outdated after deserialization.
-    BackReference back_reference = back_reference_map_.Lookup(obj);
-    DCHECK(back_reference.is_valid());
-    outdated_contexts_.Add(back_reference);
+    outdated_contexts_.Add(Context::cast(obj));
   }
 }
 
@@ -1753,6 +1848,9 @@ void Serializer::ObjectSerializer::Serialize() {
   // We cannot serialize typed array objects correctly.
   DCHECK(!object_->IsJSTypedArray());
 
+  // We don't expect fillers.
+  DCHECK(!object_->IsFiller());
+
   if (object_->IsPrototypeInfo()) {
     Object* prototype_users = PrototypeInfo::cast(object_)->prototype_users();
     if (prototype_users->IsWeakFixedArray()) {
@@ -1790,6 +1888,39 @@ void Serializer::ObjectSerializer::Serialize() {
   CHECK_EQ(0, bytes_processed_so_far_);
   bytes_processed_so_far_ = kPointerSize;
 
+  RecursionScope recursion(serializer_);
+  // Objects that are immediately post processed during deserialization
+  // cannot be deferred, since post processing requires the object content.
+  if (recursion.ExceedsMaximum() && CanBeDeferred(object_)) {
+    serializer_->QueueDeferredObject(object_);
+    sink_->Put(kDeferred, "Deferring object content");
+    return;
+  }
+
+  object_->IterateBody(map->instance_type(), size, this);
+  OutputRawData(object_->address() + size);
+}
+
+
+void Serializer::ObjectSerializer::SerializeDeferred() {
+  if (FLAG_trace_serializer) {
+    PrintF(" Encoding deferred heap object: ");
+    object_->ShortPrint();
+    PrintF("\n");
+  }
+
+  int size = object_->Size();
+  Map* map = object_->map();
+  BackReference reference = serializer_->back_reference_map()->Lookup(object_);
+
+  // Serialize the rest of the object.
+  CHECK_EQ(0, bytes_processed_so_far_);
+  bytes_processed_so_far_ = kPointerSize;
+
+  sink_->Put(kNewObject + reference.space(), "deferred object");
+  serializer_->PutBackReference(object_, reference);
+  sink_->PutInt(size >> kPointerSizeLog2, "deferred object size");
+
   object_->IterateBody(map->instance_type(), size, this);
   OutputRawData(object_->address() + size);
 }
@@ -2114,6 +2245,7 @@ ScriptData* CodeSerializer::Serialize(Isolate* isolate,
   DisallowHeapAllocation no_gc;
   Object** location = Handle<Object>::cast(info).location();
   cs.VisitPointer(location);
+  cs.SerializeDeferredObjects();
   cs.Pad();
 
   SerializedCodeData data(sink.data(), cs);
@@ -2192,8 +2324,6 @@ void CodeSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
 void CodeSerializer::SerializeGeneric(HeapObject* heap_object,
                                       HowToCode how_to_code,
                                       WhereToPoint where_to_point) {
-  if (heap_object->IsInternalizedString()) num_internalized_strings_++;
-
   // Object has not yet been serialized.  Serialize it here.
   ObjectSerializer serializer(this, heap_object, sink_, how_to_code,
                               where_to_point);
@@ -2305,10 +2435,6 @@ MaybeHandle<SharedFunctionInfo> CodeSerializer::Deserialize(
     return MaybeHandle<SharedFunctionInfo>();
   }
 
-  // Eagerly expand string table to avoid allocations during deserialization.
-  StringTable::EnsureCapacityForDeserialization(isolate,
-                                                scd->NumInternalizedStrings());
-
   // Prepare and register list of attached objects.
   Vector<const uint32_t> code_stub_keys = scd->CodeStubKeys();
   Vector<Handle<Object> > attached_objects = Vector<Handle<Object> >::New(
@@ -2472,7 +2598,6 @@ SerializedCodeData::SerializedCodeData(const List<byte>& payload,
   SetHeaderValue(kCpuFeaturesOffset,
                  static_cast<uint32_t>(CpuFeatures::SupportedFeatures()));
   SetHeaderValue(kFlagHashOffset, FlagList::Hash());
-  SetHeaderValue(kNumInternalizedStringsOffset, cs.num_internalized_strings());
   SetHeaderValue(kNumReservationsOffset, reservations.length());
   SetHeaderValue(kNumCodeStubKeysOffset, num_stub_keys);
   SetHeaderValue(kPayloadLengthOffset, payload.length());
@@ -2550,10 +2675,6 @@ Vector<const byte> SerializedCodeData::Payload() const {
 }
 
 
-int SerializedCodeData::NumInternalizedStrings() const {
-  return GetHeaderValue(kNumInternalizedStringsOffset);
-}
-
 Vector<const uint32_t> SerializedCodeData::CodeStubKeys() const {
   int reservations_size = GetHeaderValue(kNumReservationsOffset) * kInt32Size;
   const byte* start = data_ + kHeaderSize + reservations_size;