[deserializer] Make large object deserialization GC safe

src/snapshot/deserializer.cc

 // Copyright 2016 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/snapshot/deserializer.h"
 
 #include "src/api.h"
 #include "src/assembler-inl.h"
 #include "src/bootstrapper.h"
 #include "src/deoptimizer.h"
@@ skipping 36 matching lines @@
   for (Code* code : new_code_objects_) {
     // Record all references to embedded objects in the new code object.
     isolate_->heap()->RecordWritesIntoCode(code);
 
     if (FLAG_serialize_age_code) code->PreAge(isolate_);
     Assembler::FlushICache(isolate_, code->instruction_start(),
                            code->instruction_size());
   }
 }
 
+void Deserializer::RecordWritesForLargeObjects() {
+  Heap* heap = isolate_->heap();
+  if (!heap->incremental_marking()->black_allocation()) return;
+  for (HeapObject* object : deserialized_large_objects_) {
+    heap->incremental_marking()->IterateBlackObject(object);
+  }
+}
+
 bool Deserializer::ReserveSpace() {
 #ifdef DEBUG
   for (int i = NEW_SPACE; i < kNumberOfSpaces; ++i) {
     CHECK(reservations_[i].size() > 0);
   }
 #endif  // DEBUG
   DCHECK(allocated_maps_.is_empty());
   if (!isolate_->heap()->ReserveSpace(reservations_, &allocated_maps_))
     return false;
   for (int i = 0; i < kNumberOfPreallocatedSpaces; i++) {
@@ skipping 97 matching lines @@
   } else {
     deserializing_user_code_ = true;
     HandleScope scope(isolate);
     Handle<HeapObject> result;
     {
       DisallowHeapAllocation no_gc;
       Object* root;
       VisitRootPointer(Root::kPartialSnapshotCache, &root);
       DeserializeDeferredObjects();
       FlushICacheForNewCodeObjectsAndRecordEmbeddedObjects();
+      RecordWritesForLargeObjects();

[Hannes Payer (out of office), 2017/05/09 21:19:51]

Ideally, we would move this one into RegisterReservationsForBlackAllocation and
rename RegisterReservationsForBlackAllocation to something more generic like
RegisterDeserializedObjectsForBlackAllocation.

[Jakob Kummerow, 2017/05/10 11:09:07]

Done.

       result = Handle<HeapObject>(HeapObject::cast(root));
       isolate->heap()->RegisterReservationsForBlackAllocation(reservations_);

[Hannes Payer (out of office), 2017/05/09 21:19:51]

I guess that means we never have reservations for LO? Whenever we iterate
reservations we go to LO space.

[Jakob Kummerow, 2017/05/10 11:09:07]

Correct; LO space doesn't use reservations (because it can't -- there's no way
to batch allocations for several large objects).

     }
     CommitPostProcessedObjects(isolate);
     return scope.CloseAndEscape(result);
   }
 }
 
 Deserializer::~Deserializer() {
 #ifdef DEBUG
   // Do not perform checks if we aborted deserialization.
   if (source_.position() == 0) return;
@@ skipping 724 matching lines @@
 
       default:
         CHECK(false);
     }
   }
   CHECK_EQ(limit, current);
   return true;
 }
 }  // namespace internal
 }  // namespace v8