src/java.base/share/classes/java/lang/Class.java

rev 17358 : 8182487: Add Unsafe.objectFieldOffset(Class, String)
Reviewed-by: dsimms, twisti, bchristi, mgerdin

*** 2854,2883 ****
      private static class Atomic {
          // initialize Unsafe machinery here, since we need to call Class.class instance method
          // and have to avoid calling it in the static initializer of the Class class...
          private static final Unsafe unsafe = Unsafe.getUnsafe();
          // offset of Class.reflectionData instance field
!         private static final long reflectionDataOffset;
          // offset of Class.annotationType instance field
!         private static final long annotationTypeOffset;
          // offset of Class.annotationData instance field
!         private static final long annotationDataOffset;
! 
!         static {
!             Field[] fields = Class.class.getDeclaredFields0(false); // bypass caches
!             reflectionDataOffset = objectFieldOffset(fields, "reflectionData");
!             annotationTypeOffset = objectFieldOffset(fields, "annotationType");
!             annotationDataOffset = objectFieldOffset(fields, "annotationData");
!         }
! 
!         private static long objectFieldOffset(Field[] fields, String fieldName) {
!             Field field = searchFields(fields, fieldName);
!             if (field == null) {
!                 throw new Error("No " + fieldName + " field found in java.lang.Class");
!             }
!             return unsafe.objectFieldOffset(field);
!         }
  
          static <T> boolean casReflectionData(Class<?> clazz,
                                               SoftReference<ReflectionData<T>> oldData,
                                               SoftReference<ReflectionData<T>> newData) {
              return unsafe.compareAndSetObject(clazz, reflectionDataOffset, oldData, newData);
--- 2854,2871 ----
      private static class Atomic {
          // initialize Unsafe machinery here, since we need to call Class.class instance method
          // and have to avoid calling it in the static initializer of the Class class...
          private static final Unsafe unsafe = Unsafe.getUnsafe();
          // offset of Class.reflectionData instance field
!         private static final long reflectionDataOffset
!                 = unsafe.objectFieldOffset(Class.class, "reflectionData");
          // offset of Class.annotationType instance field
!         private static final long annotationTypeOffset
!                 = unsafe.objectFieldOffset(Class.class, "annotationType");
          // offset of Class.annotationData instance field
!         private static final long annotationDataOffset
!                 = unsafe.objectFieldOffset(Class.class, "annotationData");
  
          static <T> boolean casReflectionData(Class<?> clazz,
                                               SoftReference<ReflectionData<T>> oldData,
                                               SoftReference<ReflectionData<T>> newData) {
              return unsafe.compareAndSetObject(clazz, reflectionDataOffset, oldData, newData);