Decouple root visitors from object visitors.

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 126 matching lines @@
   }
 
   AddAttachedObject(global_proxy);
 
   DisallowHeapAllocation no_gc;
   // Keep track of the code space start and end pointers in case new
   // code objects were unserialized
   OldSpace* code_space = isolate_->heap()->code_space();
   Address start_address = code_space->top();
   Object* root;
-  VisitPointer(&root);
+  VisitRootPointer(Root::kPartialSnapshotCache, &root);
   DeserializeDeferredObjects();
   DeserializeEmbedderFields(embedder_fields_deserializer);
 
   isolate->heap()->RegisterReservationsForBlackAllocation(reservations_);
 
   // 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());
   return Handle<Object>(root, isolate);
 }
 
 MaybeHandle<HeapObject> Deserializer::DeserializeObject(Isolate* isolate) {
   Initialize(isolate);
   if (!ReserveSpace()) {
     return MaybeHandle<HeapObject>();
   } else {
     deserializing_user_code_ = true;
     HandleScope scope(isolate);
     Handle<HeapObject> result;
     {
       DisallowHeapAllocation no_gc;
       Object* root;
-      VisitPointer(&root);
+      VisitRootPointer(Root::kPartialSnapshotCache, &root);
       DeserializeDeferredObjects();
       FlushICacheForNewCodeObjectsAndRecordEmbeddedObjects();
       result = Handle<HeapObject>(HeapObject::cast(root));
       isolate->heap()->RegisterReservationsForBlackAllocation(reservations_);
     }
     CommitPostProcessedObjects(isolate);
     return scope.CloseAndEscape(result);
   }
 }
 
 Deserializer::~Deserializer() {
 #ifdef DEBUG
   // Do not perform checks if we aborted deserialization.
   if (source_.position() == 0) return;
   // Check that we only have padding bytes remaining.
   while (source_.HasMore()) CHECK_EQ(kNop, source_.Get());
   for (int space = 0; space < kNumberOfPreallocatedSpaces; space++) {
     int chunk_index = current_chunk_[space];
     CHECK_EQ(reservations_[space].length(), chunk_index + 1);
     CHECK_EQ(reservations_[space][chunk_index].end, high_water_[space]);
   }
   CHECK_EQ(allocated_maps_.length(), next_map_index_);
 #endif  // DEBUG
 }
 
 // This is called on the roots.  It is the driver of the deserialization
 // process.  It is also called on the body of each function.
-void Deserializer::VisitPointers(Object** start, Object** end) {
+void Deserializer::VisitRootPointers(Root root, Object** start, Object** end) {
   // The space must be new space.  Any other space would cause ReadChunk to try
   // to update the remembered using NULL as the address.
   ReadData(start, end, NEW_SPACE, NULL);
 }
 
 void Deserializer::Synchronize(VisitorSynchronization::SyncTag tag) {
   static const byte expected = kSynchronize;
   CHECK_EQ(expected, source_.Get());
 }
 
@@ skipping 700 matching lines @@
 
       default:
         CHECK(false);
     }
   }
   CHECK_EQ(limit, current);
   return true;
 }
 }  // namespace internal
 }  // namespace v8