[Oilpan] Add use-after-free detector in Member<>

third_party/WebKit/Source/platform/heap/Heap.h

Index: third_party/WebKit/Source/platform/heap/Heap.h
diff --git a/third_party/WebKit/Source/platform/heap/Heap.h b/third_party/WebKit/Source/platform/heap/Heap.h
index 67a8bc873ef643166d19459cecc0c07fab89dab3..2286438bb0b81e2862f0d57016d7225735f5778c 100644
--- a/third_party/WebKit/Source/platform/heap/Heap.h
+++ b/third_party/WebKit/Source/platform/heap/Heap.h
@@ -47,6 +47,8 @@ template<typename T> class Member;
 template<typename T> class WeakMember;
 template<typename T> class UntracedMember;
 
+// TODO(peria): Refactor following two sets of template.

[haraken, 2015/11/16 09:38:20]

templates

[peria, 2015/11/16 12:28:45]

Done.

+
 template<typename T, bool = NeedsAdjustAndMark<T>::value> class ObjectAliveTrait;
 
 template<typename T>
@@ -64,11 +66,36 @@ class ObjectAliveTrait<T, true> {
 public:
     static bool isHeapObjectAlive(T* object)
     {
-        static_assert(sizeof(T), "T must be fully defined");
         return object->isHeapObjectAlive();
     }
 };
 
+template<typename T, bool = IsGarbageCollectedMixin<T>::value> class HeapObjectHeaderTrait;
+
+template<typename T>
+class HeapObjectHeaderTrait<T, true> {
+public:
+    static HeapObjectHeader* heapObjectHeader(T* obj)
+    {
+        static_assert(sizeof(T), "T must be fully defined");
+        // TODO(peria): Update thi ASSERT() to check if |obj| is begin constructed.
+        // We can use this method for other GCMixin objects.

[haraken, 2015/11/16 09:38:20]

Slightly better:

// TODO(peria): This ASSERT is too restrictive. The ASSERT forbids to call
heapObjectHeader() for an object while another (totally independent) mixin
object is under construction.

[peria, 2015/11/16 12:28:45]

Done.

+        ASSERT(!ThreadState::current()->isConstructingGCMixin());
+        return obj->heapObjectHeader();
+    }
+};
+
+template<typename T>
+class HeapObjectHeaderTrait<T, false> {
+public:
+    static HeapObjectHeader* heapObjectHeader(T* obj)
+    {

[haraken, 2015/11/16 09:38:20]

Add ASSERT(!ThreadState::current()->isConstructingGCMixin()), just in case.

[peria, 2015/11/16 12:28:45]

Done.

+        if (!IsFullyDefined<T>::value)

[haraken, 2015/11/16 09:38:20]

What happens if you use static_assert(sizeof(T)) ?

[peria, 2015/11/16 12:28:45]

It fails in compiling some header files which calls Mebmer<>::get()
for a forward declared class.

e.g.
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

+            return nullptr;
+        return HeapObjectHeader::fromPayload(obj);
+    }
+};
+
 class PLATFORM_EXPORT Heap {
 public:
     static void init();
@@ -96,17 +123,17 @@ public:
     template<typename T>
     static inline bool isHeapObjectAlive(const Member<T>& member)
     {
-        return isHeapObjectAlive(member.get());
+        return isHeapObjectAlive(member.unsafeGet());
     }
     template<typename T>
     static inline bool isHeapObjectAlive(const WeakMember<T>& member)
     {
-        return isHeapObjectAlive(member.get());
+        return isHeapObjectAlive(member.unsafeGet());
     }
     template<typename T>
     static inline bool isHeapObjectAlive(const UntracedMember<T>& member)
     {
-        return isHeapObjectAlive(member.get());
+        return isHeapObjectAlive(member.unsafeGet());
     }
     template<typename T>
     static inline bool isHeapObjectAlive(const RawPtr<T>& ptr)
@@ -259,9 +286,7 @@ public:
     static void reportMemoryUsageHistogram();
     static void reportMemoryUsageForTracing();
 
-#if ENABLE(ASSERT)
-    static uint16_t gcGeneration() { return s_gcGeneration; }
-#endif
+    static uint32_t gcGeneration() { return s_gcGeneration; }
 
 private:
     // A RegionTree is a simple binary search tree of PageMemoryRegions sorted
@@ -308,9 +333,7 @@ private:
     static size_t s_collectedWrapperCount;
     static size_t s_partitionAllocSizeAtLastGC;
     static double s_estimatedMarkingTimePerByte;
-#if ENABLE(ASSERT)
-    static uint16_t s_gcGeneration;
-#endif
+    static uint32_t s_gcGeneration;
 
     friend class ThreadState;
 };
@@ -455,7 +478,7 @@ inline Address Heap::allocateOnHeapIndex(ThreadState* state, size_t size, int he
     ASSERT(state->isAllocationAllowed());
     ASSERT(heapIndex != BlinkGC::LargeObjectHeapIndex);
     NormalPageHeap* heap = static_cast<NormalPageHeap*>(state->heap(heapIndex));
-    return heap->allocateObject(allocationSizeFromSize(size), gcInfoIndex);
+    return heap->allocateObject(allocationSizeFromSize(size), gcInfoIndex, gcGeneration());
 }
 
 template<typename T>