Oilpan: Remove GC_INFO_{DEFINE,DECLARE} macros

Source/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 118 matching lines @@
 // of the object. The FinalizerTrait can be specialized if the default
 // behavior is not desired.
 template<typename T>
 struct FinalizerTrait {
     static const bool nonTrivialFinalizer = IsGarbageCollectedFinalized<T>::value;
     static void finalize(void* obj) { FinalizerTraitImpl<T, nonTrivialFinalizer>::finalize(obj); }
 };
 
 // Macros to declare and define GCInfo structures for objects
 // allocated in the Blink garbage-collected heap.
-#define DECLARE_GC_INFO                                                       \
-public:                                                                       \
-    static const GCInfo s_gcInfo;                                             \
-    template<typename Any> friend struct FinalizerTrait;                      \

[Mads Ager (chromium), 2014/02/17 07:22:07]

Here we are losing a friend declaration. Maybe that is not needed on trunk yes
but it is on the branch. That might make this less ideal since we would then
have to sometimes add a friend declaration and sometimes not. It might be easier
to just have the rule that you always have DECLARE_GC_INFO?

[kouhei (in TOK), 2014/02/17 08:35:53]

This friend stmt is for calling |finalize()| method declared private. However,
there is only a few places where finalize() is declared, so I think it is better
to have friend declaration at there. I'll write a follow up patch for this.

[wibling-chromium, 2014/02/17 08:44:15]

Can't we add the friend declaration to GarbageCollectedFinalized instead? Or are
you talking about the case where it is overriden by the specific classes?

[kouhei (in TOK), 2014/02/17 08:48:19]

Yes. I think we can add the friend decl to GarbageCollectedFinalized and other
specific classes where finalized() is manually overriden.

-private:                                                                      \
-
-#define DEFINE_GC_INFO(Type)                                                  \
-const GCInfo Type::s_gcInfo = {                                               \
-    #Type,                                                                    \
-    TraceTrait<Type>::trace,                                                  \
-    FinalizerTrait<Type>::finalize,                                           \
-    FinalizerTrait<Type>::nonTrivialFinalizer,                                \
-};                                                                            \
+#define DECLARE_GC_INFO
+#define DEFINE_GC_INFO(Type)
 
 // Trait to get the GCInfo structure for types that have their
 // instances allocated in the Blink garbage-collected heap.
-template<typename T>
-struct GCInfoTrait {
-    static const GCInfo* get()
-    {
-        return &T::s_gcInfo;
-    }
-};
+template<typename T> struct GCInfoTrait;
 
 template<typename T>
 const char* getTypeMarker()
 {
     return GCInfoTrait<T>::get()->m_typeMarker;
 }
 
 // The TraceTrait is used to specify how to mark an object pointer and
 // how to trace all of the pointers in the object.
 //
@@ skipping 368 matching lines @@
 
 template<typename T> bool ObjectAliveTrait<T>::isAlive(Visitor* visitor, T obj)
 {
     return visitor->isMarked(obj);
 }
 template<typename T> bool ObjectAliveTrait<Member<T> >::isAlive(Visitor* visitor, const Member<T>& obj)
 {
     return visitor->isMarked(obj.get());
 }
 
+template<typename T>
+struct GCInfoKeep
+{
+    static const GCInfo* get()
+    {
+        static char foo = 'a'; // FIXME: use extractNameFromFunctionName()
+        static const GCInfo gcInfo = {

[Mads Ager (chromium), 2014/02/17 07:22:07]

The other difference with this is that these structures are now local statics
and therefore setup on first call to the get method instead of at startup. That
could be a good thing.

[kouhei (in TOK), 2014/02/17 08:35:53]

There is no difference in generated code.
I tested this on g++, but this don't setup on first call, but the struct is
statically embedded to the binary ".rodata" section.

+            &foo,
+            TraceTrait<T>::trace,
+            FinalizerTrait<T>::finalize,
+            FinalizerTrait<T>::nonTrivialFinalizer,
+        };
+        return &gcInfo;
+    }
+};
+
+template<typename T>
+struct GCInfoTrait
+{
+    static const GCInfo* get()
+    {
+        return GCInfoKeep<typename T::GarbageCollectedBase>::get();
+    }
+};
+
 }
 
 #endif