Oilpan: Support polymorphic objects in HeapVectorBackings

Source/platform/heap/HeapTest.cpp

Index: Source/platform/heap/HeapTest.cpp
diff --git a/Source/platform/heap/HeapTest.cpp b/Source/platform/heap/HeapTest.cpp
index 2773f740f33aa9c1446351464be889b14a23a87f..6ab59b333557b5d238ebb0b8d90b1fe790308be8 100644
--- a/Source/platform/heap/HeapTest.cpp
+++ b/Source/platform/heap/HeapTest.cpp
@@ -3943,6 +3943,26 @@ public:
 
 int InlinedVectorObject::s_destructorCalls = 0;
 
+class InlinedVectorObjectWithVtable {
+    ALLOW_ONLY_INLINE_ALLOCATION();
+public:
+    InlinedVectorObjectWithVtable()
+    {
+    }
+    ~InlinedVectorObjectWithVtable()
+    {
+        s_destructorCalls++;
+    }
+    virtual void virtualMethod() { }
+    DEFINE_INLINE_TRACE()
+    {
+    }
+
+    static int s_destructorCalls;
+};
+
+int InlinedVectorObjectWithVtable::s_destructorCalls = 0;
+
 } // namespace blink
 
 WTF_ALLOW_MOVE_AND_INIT_WITH_MEM_FUNCTIONS(blink::InlinedVectorObject);
@@ -3975,6 +3995,32 @@ private:
     HeapVector<InlinedVectorObject, 2> m_vector3;
 };
 
+class InlinedVectorObjectWithVtableWrapper final : public GarbageCollectedFinalized<InlinedVectorObjectWithVtableWrapper> {
+public:
+    InlinedVectorObjectWithVtableWrapper()
+    {
+        InlinedVectorObjectWithVtable i1, i2;
+        m_vector1.append(i1);
+        m_vector1.append(i2);
+        m_vector2.append(i1);
+        m_vector2.append(i2); // This allocates an out-of-line buffer.
+        m_vector3.append(i1);
+        m_vector3.append(i2);
+    }
+
+    DEFINE_INLINE_TRACE()
+    {
+        visitor->trace(m_vector1);
+        visitor->trace(m_vector2);
+        visitor->trace(m_vector3);
+    }
+
+private:
+    HeapVector<InlinedVectorObjectWithVtable> m_vector1;
+    HeapVector<InlinedVectorObjectWithVtable, 1> m_vector2;
+    HeapVector<InlinedVectorObjectWithVtable, 2> m_vector3;
+};
+
 TEST(HeapTest, VectorDestructors)
 {
     clearOutOldGarbage();
@@ -4022,6 +4068,49 @@ TEST(HeapTest, VectorDestructors)
     EXPECT_LE(8, InlinedVectorObject::s_destructorCalls);
 }
 
+TEST(HeapTest, VectorDestructorsWithVtable)
+{
+    clearOutOldGarbage();
+    InlinedVectorObjectWithVtable::s_destructorCalls = 0;
+    {
+        HeapVector<InlinedVectorObjectWithVtable> vector;
+        InlinedVectorObjectWithVtable i1, i2;
+        vector.append(i1);
+        vector.append(i2);
+    }
+    Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
+    EXPECT_EQ(4, InlinedVectorObjectWithVtable::s_destructorCalls);
+
+    InlinedVectorObjectWithVtable::s_destructorCalls = 0;
+    {
+        HeapVector<InlinedVectorObjectWithVtable, 1> vector;
+        InlinedVectorObjectWithVtable i1, i2;
+        vector.append(i1);
+        vector.append(i2); // This allocates an out-of-line buffer.
+    }
+    Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
+    EXPECT_EQ(5, InlinedVectorObjectWithVtable::s_destructorCalls);
+
+    InlinedVectorObjectWithVtable::s_destructorCalls = 0;
+    {
+        HeapVector<InlinedVectorObjectWithVtable, 2> vector;
+        InlinedVectorObjectWithVtable i1, i2;
+        vector.append(i1);
+        vector.append(i2);
+    }
+    Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
+    EXPECT_EQ(4, InlinedVectorObjectWithVtable::s_destructorCalls);
+
+    InlinedVectorObjectWithVtable::s_destructorCalls = 0;
+    {
+        new InlinedVectorObjectWithVtableWrapper();
+        Heap::collectGarbage(ThreadState::HeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
+        EXPECT_EQ(3, InlinedVectorObjectWithVtable::s_destructorCalls);
+    }
+    Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
+    EXPECT_EQ(9, InlinedVectorObjectWithVtable::s_destructorCalls);
+}
+
 template<typename Set>
 void rawPtrInHashHelper()
 {