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-inl.h b/runtime/read_barrier-inl.h
index 88e2f8f..4302c9e 100644
--- a/runtime/read_barrier-inl.h
+++ b/runtime/read_barrier-inl.h
@@ -43,6 +43,21 @@
}
}
+template <typename MirrorType, ReadBarrierOption kReadBarrierOption>
+inline MirrorType* ReadBarrier::BarrierForWeakRoot(MirrorType* ref) {
+ UNUSED(ref);
+ const bool with_read_barrier = kReadBarrierOption == kWithReadBarrier;
+ if (with_read_barrier && kUseBakerReadBarrier) {
+ // To be implemented.
+ return ref;
+ } else if (with_read_barrier && kUseBrooksReadBarrier) {
+ // To be implemented.
+ return ref;
+ } else {
+ return ref;
+ }
+}
+
} // namespace art
#endif // ART_RUNTIME_READ_BARRIER_INL_H_