Revert of Prevent stack overflow in the serializer/deserializer.

src/snapshot/serialize.cc

Index: src/snapshot/serialize.cc
diff --git a/src/snapshot/serialize.cc b/src/snapshot/serialize.cc
index b19e4388af07e3076f4978c083849c5401bc78dd..dbe92a6accb129520b22838e09ea8a7f3ee485a1 100644
--- a/src/snapshot/serialize.cc
+++ b/src/snapshot/serialize.cc
@@ -560,7 +560,6 @@
   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());
@@ -610,7 +609,6 @@
   Object* outdated_contexts;
   VisitPointer(&root);
   VisitPointer(&outdated_contexts);
-  DeserializeDeferredObjects();
 
   // There's no code deserialized here. If this assert fires
   // then that's changed and logging should be added to notify
@@ -633,7 +631,6 @@
     DisallowHeapAllocation no_gc;
     Object* root;
     VisitPointer(&root);
-    DeserializeDeferredObjects();
     return Handle<SharedFunctionInfo>(SharedFunctionInfo::cast(root));
   }
 }
@@ -655,22 +652,13 @@
 }
 
 
-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);
-    if (object->IsAllocationSite()) {
-      RelinkAllocationSite(AllocationSite::cast(object));
-    }
-  }
+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());
+  }
+  isolate_->heap()->set_allocation_sites_list(site);
 }
 
 
@@ -705,8 +693,7 @@
 };
 
 
-HeapObject* Deserializer::PostProcessNewObject(HeapObject* obj) {
-  DCHECK(deserializing_user_code());
+HeapObject* Deserializer::ProcessNewObjectFromSerializedCode(HeapObject* obj) {
   if (obj->IsString()) {
     String* string = String::cast(obj);
     // Uninitialize hash field as the hash seed may have changed.
@@ -721,27 +708,8 @@
     }
   } else if (obj->IsScript()) {
     Script::cast(obj)->set_id(isolate_->heap()->NextScriptId());
-  } else {
-    DCHECK(CanBeDeferred(obj));
   }
   return obj;
-}
-
-
-void Deserializer::RelinkAllocationSite(AllocationSite* obj) {
-  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,
-  // RelinkAllocationSite() isn't necessary.
-  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);
 }
 
 
@@ -800,21 +768,24 @@
   if (FLAG_log_snapshot_positions) {
     LOG(isolate_, SnapshotPositionEvent(address, source_.position()));
   }
-
-  if (ReadData(current, limit, space_number, address)) {
-    // Only post process if object content has not been deferred.
-    if (obj->IsAllocationSite()) {
-      RelinkAllocationSite(AllocationSite::cast(obj));
-    }
-  }
-
-  if (deserializing_user_code()) obj = PostProcessNewObject(obj);
+  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);
 
   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);
   }
@@ -858,7 +829,7 @@
 }
 
 
-bool Deserializer::ReadData(Object** current, Object** limit, int source_space,
+void 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
@@ -1115,14 +1086,6 @@
         break;
       }
 
-      case kDeferred: {
-        // Deferred can only occur right after the heap object header.
-        DCHECK(current == reinterpret_cast<Object**>(current_object_address +
-                                                     kPointerSize));
-        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.
@@ -1229,7 +1192,6 @@
     }
   }
   CHECK_EQ(limit, current);
-  return true;
 }
 
 
@@ -1238,7 +1200,6 @@
       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) {
@@ -1311,16 +1272,6 @@
 #undef PRINT_INSTANCE_TYPE
   PrintF("\n");
 #endif  // OBJECT_PRINT
-}
-
-
-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");
 }
 
 
@@ -1368,7 +1319,6 @@
   }
   VisitPointer(o);
   SerializeOutdatedContextsAsFixedArray();
-  SerializeDeferredObjects();
   Pad();
 }
 
@@ -1392,10 +1342,10 @@
       sink_->Put(reinterpret_cast<byte*>(&length_smi)[i], "Byte");
     }
     for (int i = 0; i < length; i++) {
-      Context* context = outdated_contexts_[i];
-      BackReference back_reference = back_reference_map_.Lookup(context);
-      sink_->Put(kBackref + back_reference.space(), "BackRef");
-      PutBackReference(context, back_reference);
+      BackReference back_ref = outdated_contexts_[i];
+      DCHECK(BackReferenceIsAlreadyAllocated(back_ref));
+      sink_->Put(kBackref + back_ref.space(), "BackRef");
+      sink_->PutInt(back_ref.reference(), "BackRefValue");
     }
   }
 }
@@ -1558,7 +1508,10 @@
                    "BackRefWithSkip");
         sink_->PutInt(skip, "BackRefSkipDistance");
       }
-      PutBackReference(obj, back_reference);
+      DCHECK(BackReferenceIsAlreadyAllocated(back_reference));
+      sink_->PutInt(back_reference.reference(), "BackRefValue");
+
+      hot_objects_.Add(obj);
     }
     return true;
   }
@@ -1594,7 +1547,7 @@
 }
 
 
-void StartupSerializer::SerializeWeakReferencesAndDeferred() {
+void StartupSerializer::SerializeWeakReferences() {
   // 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
@@ -1603,7 +1556,6 @@
   Object* undefined = isolate()->heap()->undefined_value();
   VisitPointer(&undefined);
   isolate()->heap()->IterateWeakRoots(this, VISIT_ALL);
-  SerializeDeferredObjects();
   Pad();
 }
 
@@ -1636,13 +1588,6 @@
 }
 
 
-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()) {
@@ -1696,7 +1641,9 @@
       Context::cast(obj)->global_object() == global_object_) {
     // Context refers to the current global object. This reference will
     // become outdated after deserialization.
-    outdated_contexts_.Add(Context::cast(obj));
+    BackReference back_reference = back_reference_map_.Lookup(obj);
+    DCHECK(back_reference.is_valid());
+    outdated_contexts_.Add(back_reference);
   }
 }
 
@@ -1863,39 +1810,6 @@
   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);
 }
@@ -2220,7 +2134,6 @@
   DisallowHeapAllocation no_gc;
   Object** location = Handle<Object>::cast(info).location();
   cs.VisitPointer(location);
-  cs.SerializeDeferredObjects();
   cs.Pad();
 
   SerializedCodeData data(sink.data(), cs);