Incremental GCInfo descriptor table expansion.

Source/platform/heap/Visitor.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 824 matching lines @@
 template<typename T>
 struct TypenameStringTrait {
     static const String& get()
     {
         DEFINE_STATIC_LOCAL(String, typenameString, (WTF::extractTypeNameFromFunctionName(WTF::extractNameFunction<T>())));
         return typenameString;
     }
 };
 #endif
 
-// s_gcInfoTable is a map used to encode a GCInfo* into a 15 bit integer.
-const size_t gcInfoIndexMax = 1 << 15;
-extern PLATFORM_EXPORT int s_gcInfoIndex;
+// s_gcInfoTable holds the per-class GCInfo descriptors; each heap
+// object header keeps its index into this table.
 extern PLATFORM_EXPORT GCInfo const** s_gcInfoTable;
 
+class GCInfoTable {
+public:
+    PLATFORM_EXPORT static size_t allocateGCInfoSlot();
+
+    static void init();
+    static void shutdown();
+
+    // The (max + 1) GCInfo index supported.
+    static const size_t maxIndex = 1 << 15;
+
+private:
+    static void resize(size_t);
+
+    static int s_gcInfoIndex;
+    static size_t s_gcInfoTableSize;
+};
+
 // This macro should be used when returning a unique 15 bit integer
 // for a given gcInfo.
 #define RETURN_GCINFO_INDEX() \
-    static const size_t gcInfoIndex = atomicIncrement(&s_gcInfoIndex); \
+    static const size_t gcInfoIndex = GCInfoTable::allocateGCInfoSlot(); \
     ASSERT(gcInfoIndex >= 1); \
-    ASSERT(gcInfoIndex < gcInfoIndexMax); \
+    ASSERT(gcInfoIndex < GCInfoTable::maxIndex);  \
     ASSERT(s_gcInfoTable); \
     s_gcInfoTable[gcInfoIndex] = &gcInfo; \
     return gcInfoIndex;
 
 template<typename T>
 struct GCInfoAtBase {
     static size_t index()
     {
         static const GCInfo gcInfo = {
             TraceTrait<T>::trace,
@@ skipping 24 matching lines @@
 struct GCInfoTrait {
     static size_t index()
     {
         return GCInfoAtBase<typename GetGarbageCollectedBase<T>::type>::index();
     }
 };
 
 }
 
 #endif