src/hotspot/share/oops/klass.cpp

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.

@@ -617,10 +617,23 @@
 // Unless overridden, jvmti_class_status has no flags set.
 jint Klass::jvmti_class_status() const {
   return 0;
 }
 
+// Tell the GC to keep this klass alive
+void Klass::ensure_klass_alive(oop o) {
+  // A klass that was previously considered dead can be looked up in the 
+  // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
+  // or a reachable object making it alive again.
+  // The SATB part of G1 needs to get notified about this
+  // potential resurrection, otherwise the marking might not find the object.
+#if INCLUDE_ALL_GCS
+  if (UseG1GC && o != NULL) {
+    G1SATBCardTableModRefBS::enqueue(o);
+  }
+#endif
+}
 
 // Printing
 
 void Klass::print_on(outputStream* st) const {
   ResourceMark rm;