Serializer: fix false negative in hashmap lookups.

src/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/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/platform/platform.h"
 #include "src/bootstrapper.h"
@@ skipping 462 matching lines @@
   for (int type = kFirstTypeCode; type < kTypeCodeCount; ++type) {
     DeleteArray(encodings_[type]);
   }
   DeleteArray(encodings_);
 }
 
 
 RootIndexMap::RootIndexMap(Isolate* isolate) {
   map_ = new HashMap(HashMap::PointersMatch);
   Object** root_array = isolate->heap()->roots_array_start();
-  for (int i = 0; i < Heap::kStrongRootListLength; i++) {
+  for (uint32_t i = 0; i < Heap::kStrongRootListLength; i++) {
     Object* root = root_array[i];
     if (root->IsHeapObject() && !isolate->heap()->InNewSpace(root)) {
       HeapObject* heap_object = HeapObject::cast(root);
-      if (LookupEntry(map_, heap_object, false) != NULL) {
-        // Some root values are initialized to the empty FixedArray();
-        // Do not add them to the map.
-        // TODO(yangguo): This assert is not true. Some roots like
-        // instanceof_cache_answer can be e.g. null.
-        // DCHECK_EQ(isolate->heap()->empty_fixed_array(), heap_object);
+      HashMap::Entry* entry = LookupEntry(map_, heap_object, false);
+      if (entry != NULL) {
+        // Some are initialized to a previous value in the root list.
+        DCHECK_LT(GetValue(entry), i);
       } else {
         SetValue(LookupEntry(map_, heap_object, true), i);
       }
     }
   }
 }
 
 
 class CodeAddressMap: public CodeEventLogger {
  public:
@@ skipping 2149 matching lines @@
   DisallowHeapAllocation no_gc;
   SerializedCodeData* scd = new SerializedCodeData(cached_data);
   SanityCheckResult r = scd->SanityCheck(source);
   if (r == CHECK_SUCCESS) return scd;
   cached_data->Reject();
   source->GetIsolate()->counters()->code_cache_reject_reason()->AddSample(r);
   delete scd;
   return NULL;
 }
 } }  // namespace v8::internal