Why we can't use Unsafe.copyMemory() with Objects as dest ?

[Andrew Kondratovich]

This is source of unsafe.cpp:

UNSAFE_ENTRY(void, Unsafe_CopyMemory2(JNIEnv *env, jobject unsafe,
jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset,
jlong size))
  UnsafeWrapper("Unsafe_CopyMemory");
  if (size == 0) {
    return;
  }
  size_t sz = (size_t)size;
  if (sz != (julong)size || size < 0) {
    THROW(vmSymbols::java_lang_IllegalArgumentException());
  }
  oop srcp = JNIHandles::resolve(srcObj);
  oop dstp = JNIHandles::resolve(dstObj);
  if (dstp != NULL && !dstp->is_typeArray()) {
    // NYI:  This works only for non-oop arrays at present.
    // Generalizing it would be reasonable, but requires card marking.
    // Also, autoboxing a Long from 0L in copyMemory(x,y, 0L,z, n) would be bad.
    THROW(vmSymbols::java_lang_IllegalArgumentException());
  }
  void* src = index_oop_from_field_offset_long(srcp, srcOffset);
  void* dst = index_oop_from_field_offset_long(dstp, dstOffset);
  Copy::conjoint_memory_atomic(src, dst, sz);
UNSAFE_END

Why is it allowed to copy memory only to primitive arrays as destination ?

Thanks.

-- Andrew