VM: Reland Inline instance object hash code into object header on 64bit.

runtime/vm/clustered_snapshot.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/clustered_snapshot.h"
 
 #include "platform/assert.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
@@ skipping 22 matching lines @@
   return reinterpret_cast<RawObject*>(address + kHeapObjectTag);
 }
 
 
 void Deserializer::InitializeHeader(RawObject* raw,
                                     intptr_t class_id,
                                     intptr_t size,
                                     bool is_vm_isolate,
                                     bool is_canonical) {
   ASSERT(Utils::IsAligned(size, kObjectAlignment));
-  uword tags = 0;
+  uint32_t tags = 0;
   tags = RawObject::ClassIdTag::update(class_id, tags);
   tags = RawObject::SizeTag::update(size, tags);
   tags = RawObject::VMHeapObjectTag::update(is_vm_isolate, tags);
   tags = RawObject::CanonicalObjectTag::update(is_canonical, tags);
   raw->ptr()->tags_ = tags;
+#if defined(HASH_IN_OBJECT_HEADER)
+  raw->ptr()->hash_ = 0;
+#endif
 }
 
 
 #if !defined(DART_PRECOMPILED_RUNTIME)
 class ClassSerializationCluster : public SerializationCluster {
  public:
   explicit ClassSerializationCluster(intptr_t num_cids)
       : predefined_(kNumPredefinedCids), objects_(num_cids) {}
   virtual ~ClassSerializationCluster() {}
 
@@ skipping 5580 matching lines @@
     thread_->isolate()->SetupImagePage(data_buffer_,
                                        /* is_executable */ false);
   }
 
   deserializer.ReadIsolateSnapshot(thread_->isolate()->object_store());
 
   return ApiError::null();
 }
 
 }  // namespace dart