Add a read barrier for weak roots in monitors.
A weak root requires a read barrier for the to-space invariant to hold
because the object pointed to by a weak root can't be marked/forwarded
like the one pointed to by a strong root (GC does not know if it's
alive or not at that point) and because, without a read barrier, a
mutator could access it and obtain a from-space reference, which would
violate the to-space invariant.
TODO: do similar for the other types of weak roots.
Bug: 12687968
Change-Id: I563a0fa4f875e0c21ac96f57696959454e13b15a
diff --git a/runtime/read_barrier.h b/runtime/read_barrier.h
index 73c3d43..e40e8ea 100644
--- a/runtime/read_barrier.h
+++ b/runtime/read_barrier.h
@@ -37,6 +37,10 @@
ALWAYS_INLINE static MirrorType* Barrier(
mirror::Object* obj, MemberOffset offset, mirror::HeapReference<MirrorType>* ref_addr)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+
+ template <typename MirrorType, ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
+ ALWAYS_INLINE static MirrorType* BarrierForWeakRoot(MirrorType* ref)
+ SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
};
} // namespace art