Fix concurrent access to VMState::current_state_.

src/vm-state-inl.h

Index: src/vm-state-inl.h
diff --git a/src/vm-state-inl.h b/src/vm-state-inl.h
index 4df2cfda73b4f47cc584287afffa986d26f91d1d..aa4cedbb134b532e20020f160ba8930a827b3c9d 100644
--- a/src/vm-state-inl.h
+++ b/src/vm-state-inl.h
@@ -74,8 +74,10 @@ VMState::VMState(StateTag state)
   if (state == EXTERNAL) state = OTHER;
 #endif
   state_ = state;
-  previous_ = current_state_;  // Save the previous state.
-  current_state_ = this;       // Install the new state.
+  // Save the previous state.
+  previous_ = reinterpret_cast<VMState*>(current_state_);
+  // Install the new state.
+  OS::ReleaseStore(&current_state_, reinterpret_cast<AtomicWord>(this));
 
 #ifdef ENABLE_LOGGING_AND_PROFILING
   if (FLAG_log_state_changes) {
@@ -103,7 +105,8 @@ VMState::VMState(StateTag state)
 
 VMState::~VMState() {
   if (disabled_) return;
-  current_state_ = previous_;  // Return to the previous state.
+  // Return to the previous state.
+  OS::ReleaseStore(&current_state_, reinterpret_cast<AtomicWord>(previous_));
 
 #ifdef ENABLE_LOGGING_AND_PROFILING
   if (FLAG_log_state_changes) {