[tracing] Adding class-wise memory statistics to blink gc memory dumps

Source/platform/heap/ThreadState.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 472 matching lines @@
     void visitStack(Visitor*);
 
     // Visit the asan fake stack frame corresponding to a slot on the
     // real machine stack if there is one.
     void visitAsanFakeStackForPointer(Visitor*, Address);
 
     // Visit all persistents allocated on this thread.
     void visitPersistents(Visitor*);
 
     struct GCSnapshotInfo {
+        // Map from gcInfoIndex to a snapshot class-ids (used as index below).

[haraken, 2015/06/27 07:27:40]

I'm wondering why you simply can't use gcInfoIndex as a tag. It is guaranteed
that gcInfoIndex returns an index in [0, # of classes actually used in this
execution).

+        using ClassTagMap = HashMap<size_t, size_t>;
+        ClassTagMap classTags;
+
+        // Map from class-id (index) to count/size.
+        Vector<int> liveCount;
+        Vector<int> deadCount;
+        Vector<size_t> liveSize;
+        Vector<size_t> deadSize;
+
         size_t currentHeapFreeSize;
         size_t currentHeapFreeCount;
+
+        size_t getClassTag(const size_t GCInfoIndex);
     };
 
 #if ENABLE(GC_PROFILING)
     const GCInfo* findGCInfo(Address);
     static const GCInfo* findGCInfoFromAllThreads(Address);
 
     struct SnapshotInfo {
         ThreadState* state;
 
         size_t freeSize;
@@ skipping 137 matching lines @@
     static bool isVectorHeapIndex(int heapIndex)
     {
         return Vector1HeapIndex <= heapIndex && heapIndex <= Vector4HeapIndex;
     }
     void allocationPointAdjusted(int heapIndex);
     void promptlyFreed(size_t gcInfoIndex);
 
 private:
     enum SnapshotType {
         HeapSnapshot,
-        FreelistSnapshot
+        FreelistSnapshot,
+        HeapSnapshotWithClasses
     };
 
     ThreadState();
     ~ThreadState();
 
     NO_SANITIZE_ADDRESS void copyStackUntilSafePointScope();
     void clearSafePointScopeMarker()
     {
         m_safePointStackCopy.clear();
         m_safePointScopeMarker = nullptr;
@@ skipping 122 matching lines @@
 };
 
 template<> class ThreadStateFor<AnyThread> {
 public:
     static ThreadState* state() { return ThreadState::current(); }
 };
 
 } // namespace blink
 
 #endif // ThreadState_h