Oilpan: Fix ASan instrumentation around heap object headers.

Source/platform/heap/Heap.cpp

Index: Source/platform/heap/Heap.cpp
diff --git a/Source/platform/heap/Heap.cpp b/Source/platform/heap/Heap.cpp
index c8e359c17277a8a700cbd1c404dcbfc10df98b35..4589276894091c85e23037e6fa79952fc66b3796 100644
--- a/Source/platform/heap/Heap.cpp
+++ b/Source/platform/heap/Heap.cpp
@@ -412,14 +412,15 @@ private:
     bool m_parkedAllThreads; // False if we fail to park all threads
 };
 
+NO_SANITIZE_ADDRESS
 bool HeapObjectHeader::isMarked() const
 {
     checkHeader();
-    // We need to unpoison/poison the header on ASAN since
-    // acquireLoad doesn't have the NO_SANITIZE_ADDRESS flag.
-    ASAN_UNPOISON_MEMORY_REGION(this, sizeof(this));
+#if defined(ADDRESS_SANITIZER)

[zerny-chromium, 2014/09/09 06:01:28]

ditto

[Mads Ager (chromium), 2014/09/09 08:22:14]

Done

+    unsigned size = asanAcquireLoad(&m_size);
+#else
     unsigned size = acquireLoad(&m_size);
-    ASAN_POISON_MEMORY_REGION(this, sizeof(this));
+#endif
     return size & markBitMask;
 }