--- a/hotspot/src/share/vm/oops/instanceKlass.cpp	Wed Jul 05 16:34:33 2017 +0200
+++ b/hotspot/src/share/vm/oops/instanceKlass.cpp	Wed Mar 12 18:06:50 2008 -0700
@@ -2165,12 +2165,20 @@
   RC_TRACE(0x00000100, ("adding previous version ref for %s @%d, EMCP_cnt=%d",
     ikh->external_name(), _previous_versions->length(), emcp_method_count));
   constantPoolHandle cp_h(ikh->constants());
-  jweak cp_ref = JNIHandles::make_weak_global(cp_h);
+  jobject cp_ref;
+  if (cp_h->is_shared()) {
+    // a shared ConstantPool requires a regular reference; a weak
+    // reference would be collectible
+    cp_ref = JNIHandles::make_global(cp_h);
+  } else {
+    cp_ref = JNIHandles::make_weak_global(cp_h);
+  }
   PreviousVersionNode * pv_node = NULL;
   objArrayOop old_methods = ikh->methods();
 
   if (emcp_method_count == 0) {
-    pv_node = new PreviousVersionNode(cp_ref, NULL);
+    // non-shared ConstantPool gets a weak reference
+    pv_node = new PreviousVersionNode(cp_ref, !cp_h->is_shared(), NULL);
     RC_TRACE(0x00000400,
       ("add: all methods are obsolete; flushing any EMCP weak refs"));
   } else {
@@ -2190,7 +2198,8 @@
         }
       }
     }
-    pv_node = new PreviousVersionNode(cp_ref, method_refs);
+    // non-shared ConstantPool gets a weak reference
+    pv_node = new PreviousVersionNode(cp_ref, !cp_h->is_shared(), method_refs);
   }
 
   _previous_versions->append(pv_node);
@@ -2208,7 +2217,7 @@
     // check the previous versions array for a GC'ed weak refs
     pv_node = _previous_versions->at(i);
     cp_ref = pv_node->prev_constant_pool();
-    assert(cp_ref != NULL, "weak cp ref was unexpectedly cleared");
+    assert(cp_ref != NULL, "cp ref was unexpectedly cleared");
     if (cp_ref == NULL) {
       delete pv_node;
       _previous_versions->remove_at(i);
@@ -2281,7 +2290,7 @@
           // check the previous versions array for a GC'ed weak refs
           pv_node = _previous_versions->at(j);
           cp_ref = pv_node->prev_constant_pool();
-          assert(cp_ref != NULL, "weak cp ref was unexpectedly cleared");
+          assert(cp_ref != NULL, "cp ref was unexpectedly cleared");
           if (cp_ref == NULL) {
             delete pv_node;
             _previous_versions->remove_at(j);
@@ -2379,8 +2388,8 @@
     // been GC'ed
     PreviousVersionNode * pv_node = _previous_versions->at(i);
 
-    jweak cp_ref = pv_node->prev_constant_pool();
-    assert(cp_ref != NULL, "weak reference was unexpectedly cleared");
+    jobject cp_ref = pv_node->prev_constant_pool();
+    assert(cp_ref != NULL, "cp reference was unexpectedly cleared");
     if (cp_ref == NULL) {
       continue;  // robustness
     }
@@ -2440,10 +2449,11 @@
 
 // Construct a PreviousVersionNode entry for the array hung off
 // the instanceKlass.
-PreviousVersionNode::PreviousVersionNode(jweak prev_constant_pool,
-  GrowableArray<jweak>* prev_EMCP_methods) {
+PreviousVersionNode::PreviousVersionNode(jobject prev_constant_pool,
+  bool prev_cp_is_weak, GrowableArray<jweak>* prev_EMCP_methods) {
 
   _prev_constant_pool = prev_constant_pool;
+  _prev_cp_is_weak = prev_cp_is_weak;
   _prev_EMCP_methods = prev_EMCP_methods;
 }
 
@@ -2451,7 +2461,11 @@
 // Destroy a PreviousVersionNode
 PreviousVersionNode::~PreviousVersionNode() {
   if (_prev_constant_pool != NULL) {
-    JNIHandles::destroy_weak_global(_prev_constant_pool);
+    if (_prev_cp_is_weak) {
+      JNIHandles::destroy_weak_global(_prev_constant_pool);
+    } else {
+      JNIHandles::destroy_global(_prev_constant_pool);
+    }
   }
 
   if (_prev_EMCP_methods != NULL) {
@@ -2471,8 +2485,8 @@
   _prev_constant_pool_handle = constantPoolHandle();  // NULL handle
   _prev_EMCP_method_handles = NULL;
 
-  jweak cp_ref = pv_node->prev_constant_pool();
-  assert(cp_ref != NULL, "weak constant pool ref was unexpectedly cleared");
+  jobject cp_ref = pv_node->prev_constant_pool();
+  assert(cp_ref != NULL, "constant pool ref was unexpectedly cleared");
   if (cp_ref == NULL) {
     return;  // robustness
   }