void G1BlockOffsetSharedArray::set_offset_array(size_t index, HeapWord* high, HeapWord* low) {
  check_index(index, "index out of range");
  assert(high >= low, "addresses out of order");
  size_t offset = pointer_delta(high, low);
  check_offset(offset, "offset too large");
  set_offset_array(index, (u_char)offset);
}
void G1BlockOffsetSharedArray::set_offset_array(HeapWord* left, HeapWord* right, u_char offset) {
  set_offset_array(index_for(left), index_for(right -1), offset);
}