src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/PerfMemory.java

*** 45,60 ****
              });
      }
  
      private static synchronized void initialize(TypeDataBase db) {
          Type type = db.lookupType("PerfMemory");
!         startField = type.getAddressField("_start");
!         endField = type.getAddressField("_end");
!         topField = type.getAddressField("_top");
!         capacityField = type.getCIntegerField("_capacity");
!         prologueField = type.getAddressField("_prologue");
          initializedField = type.getJIntField("_initialized");
      }
  
      // Accessors
      public static Address start() {
          return startField.getValue();
--- 45,67 ----
              });
      }
  
      private static synchronized void initialize(TypeDataBase db) {
          Type type = db.lookupType("PerfMemory");
!         startField = type.getAddressField("_saved_start");
!         endField = type.getAddressField("_saved_end");
!         topField = type.getAddressField("_saved_top");
!         capacityField = type.getCIntegerField("_saved_capacity");
!         prologueField = type.getAddressField("_saved_prologue");
          initializedField = type.getJIntField("_initialized");
+ 
+         Objects.requireNonNull(startField, "PerfMemory::_saved_start");
+         Objects.requireNonNull(endField, "PerfMemory::_saved_end");
+         Objects.requireNonNull(topField, "PerfMemory::_saved_top");
+         Objects.requireNonNull(capacityField, "PerfMemory::_saved_capacity");
+         Objects.requireNonNull(prologueField, "PerfMemory::_saved_prologue");
+         Objects.requireNonNull(initializedField, "PerfMemory::_initialized");
      }
  
      // Accessors
      public static Address start() {
          return startField.getValue();