Oilpan: Validate pointers stored in Persistent

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 03b40245e50172e374c89c84c9226df2987ef3bd..cd37794a8ddd3efe2dee64bd579eb7879a598257 100644
--- a/Source/platform/heap/HeapTest.cpp
+++ b/Source/platform/heap/HeapTest.cpp
@@ -3521,6 +3521,7 @@ TEST(HeapTest, WeakMembers)
             h5 = WithWeakMember::create(h2, h3);
             Heap::collectGarbage(ThreadState::HeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
             EXPECT_EQ(5u, Bar::s_live); // The on-stack pointer keeps h3 alive.
+            EXPECT_FALSE(h3->hasBeenFinalized());

[haraken, 2015/05/26 06:50:13]

OK, now I finally found the cause of the failure on win_rel_bot.

Without having this line, there is no user of h3 after the line 3519. So the
compiler can optimize out the h3 pointer from the stack. Then the GC can collect
the h3 and thus crash at the line 3523. Adding the line fixes the crash.

[Yuta Kitamura, 2015/05/26 09:26:29]

"volatile" can be used, maybe?

             EXPECT_TRUE(h4->strongIsThere());
             EXPECT_TRUE(h4->weakIsThere());
             EXPECT_TRUE(h5->strongIsThere());