[oilpan]: Explicitly unpoison the header when marking or checking if marked in ASAN.

Now that we are using atomics to read/write the mark bit we cannot rely on NO_SANITIZE_ADDRESS
since it doesn't propagate to called methods (in this case acquireLoad/releaseStore). We don't
want to add NO_SANITIZE_ADDRESS to acquireLoad/releaseStore so instead we explicitly
unpoison/poison the header.

R=ager@chromium.org, haraken@chromium.org, oilpan-reviews@chromium.org, zerny@chromium.org
BUG=

Review URL: https://codereview.chromium.org/544043003

git-svn-id: svn://svn.chromium.org/blink/trunk@181470 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -412,11 +412,14 @@ 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));
     unsigned size = acquireLoad(&m_size);
+    ASAN_POISON_MEMORY_REGION(this, sizeof(this));
     return size & markBitMask;
 }
 

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

@@ -1497,7 +1497,6 @@ Address HeapObjectHeader::payloadEnd()
     return reinterpret_cast<Address>(this) + size();
 }
 
-NO_SANITIZE_ADDRESS
 void HeapObjectHeader::mark()
 {
     checkHeader();
@@ -1506,8 +1505,12 @@ void HeapObjectHeader::mark()
     // Multiple threads can still read the old value and all store the
     // new value. However, the new value will be the same for all of
     // the threads and the end result is therefore consistent.
+    // We need to unpoison/poison the header on ASAN since
+    // acquireLoad/releaseStore don't have the NO_SANITIZE_ADDRESS flag.
+    ASAN_UNPOISON_MEMORY_REGION(this, sizeof(this));
     unsigned size = acquireLoad(&m_size);
     releaseStore(&m_size, size | markBitMask);
+    ASAN_POISON_MEMORY_REGION(this, sizeof(this));
 }
 
 Address FinalizedHeapObjectHeader::payload()