src/hotspot/share/oops/klass.cpp

Access_GetLoadedClasses

 #include "memory/metadataFactory.hpp"
 #include "memory/metaspaceClosure.hpp"
 #include "memory/metaspaceShared.hpp"
 #include "memory/oopFactory.hpp"
 #include "memory/resourceArea.hpp"
+#include "oops/access.inline.hpp"
 #include "oops/instanceKlass.hpp"
 #include "oops/klass.inline.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/atomic.hpp"
 #include "runtime/orderAccess.inline.hpp"

@@ -52,10 +53,22
 
 oop Klass::java_mirror() const {
   return _java_mirror.resolve();
 }
 
+oop Klass::java_mirror_phantom() {
+  // Loading the klass_holder as a phantom oop ref keeps the class alive.
+  // After the holder has been kept alive, it is safe to return the mirror.
+  (void)klass_holder_phantom();
+  return java_mirror();
+}
+
+oop Klass::klass_holder_phantom() {
+  oop* addr = &class_loader_data()->_class_loader;
+  return RootAccess<IN_CONCURRENT_ROOT | ON_PHANTOM_OOP_REF>::oop_load(addr);
+}
+
 bool Klass::is_cloneable() const {
   return _access_flags.is_cloneable_fast() ||
          is_subtype_of(SystemDictionary::Cloneable_klass());
 }