[serializer] add synchronize codes to detect mismatch.

src/snapshot/serialize.cc

 // Copyright 2012 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/serialize.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/platform/platform.h"
 #include "src/bootstrapper.h"
@@ skipping 625 matching lines @@
 
 
 // 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) {
   // 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());
+}
 
 void Deserializer::DeserializeDeferredObjects() {
   for (int code = source_.Get(); code != kSynchronize; code = source_.Get()) {
     switch (code) {
       case kAlignmentPrefix:
       case kAlignmentPrefix + 1:
       case kAlignmentPrefix + 2:
         SetAlignment(code);
         break;
       default: {
@@ skipping 1080 matching lines @@
   VisitPointer(&undefined);
   isolate()->heap()->IterateWeakRoots(this, VISIT_ALL);
   SerializeDeferredObjects();
   Pad();
 }
 
 void StartupSerializer::Synchronize(VisitorSynchronization::SyncTag tag) {
   // We expect the builtins tag after builtins have been serialized.
   DCHECK(!serializing_builtins_ || tag == VisitorSynchronization::kBuiltins);
   serializing_builtins_ = (tag == VisitorSynchronization::kHandleScope);
+  sink_->Put(kSynchronize, "Synchronize");
 }
 
 void Serializer::PutRoot(int root_index,
                          HeapObject* object,
                          SerializerDeserializer::HowToCode how_to_code,
                          SerializerDeserializer::WhereToPoint where_to_point,
                          int skip) {
   if (FLAG_trace_serializer) {
     PrintF(" Encoding root %d:", root_index);
     object->ShortPrint();
@@ skipping 1075 matching lines @@
   SerializedCodeData* scd = new SerializedCodeData(cached_data);
   SanityCheckResult r = scd->SanityCheck(isolate, source);
   if (r == CHECK_SUCCESS) return scd;
   cached_data->Reject();
   source->GetIsolate()->counters()->code_cache_reject_reason()->AddSample(r);
   delete scd;
   return NULL;
 }
 }  // namespace internal
 }  // namespace v8