Extend locking of GCInfo table to include slot allocation.

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 845 matching lines @@
     }
 };
 #endif
 
 // 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();
+    PLATFORM_EXPORT static bool allocateGCInfoSlot(size_t&);
 
     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 void resize();
 
     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 = GCInfoTable::allocateGCInfoSlot(); \
-    ASSERT(gcInfoIndex >= 1); \
-    ASSERT(gcInfoIndex < GCInfoTable::maxIndex);  \
-    ASSERT(s_gcInfoTable); \
-    s_gcInfoTable[gcInfoIndex] = &gcInfo; \
+#define RETURN_GCINFO_INDEX()                          \
+    static size_t gcInfoIndex = 0;                     \
+    ASSERT(s_gcInfoTable);                             \
+    if (!gcInfoIndex && GCInfoTable::allocateGCInfoSlot(gcInfoIndex)) \
+        s_gcInfoTable[gcInfoIndex] = &gcInfo;          \

[haraken, 2015/01/10 08:37:24]

Can we do this assignment in allocateGCInfoSlot? Probably we can rename it to
ensureGCInfoIndex or something.

[sof, 2015/01/10 08:42:46]

I suppose, but I don't see the overall benefit.

[haraken, 2015/01/10 08:48:45]

up to you :)

[sof, 2015/01/10 08:54:23]

Done.

+    ASSERT(gcInfoIndex >= 1);                          \
+    ASSERT(gcInfoIndex < GCInfoTable::maxIndex);       \
     return gcInfoIndex;
 
 template<typename T>
 struct GCInfoAtBase {
     static size_t index()
     {
         static const GCInfo gcInfo = {
             TraceTrait<T>::trace,
             FinalizerTrait<T>::finalize,
             FinalizerTrait<T>::nonTrivialFinalizer,
@@ skipping 22 matching lines @@
 struct GCInfoTrait {
     static size_t index()
     {
         return GCInfoAtBase<typename GetGarbageCollectedBase<T>::type>::index();
     }
 };
 
 }
 
 #endif