jint Klass::array_layout_helper(BasicType etype) {
assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
// Note that T_ARRAY is not allowed here.
int hsize = arrayOopDesc::base_offset_in_bytes(etype);
int esize = type2aelembytes(etype);
bool isobj = (etype == T_OBJECT);
int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
assert(lh < (int)_lh_neutral_value, "must look like an array layout");
assert(layout_helper_is_javaArray(lh), "correct kind");
assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
assert(layout_helper_header_size(lh) == hsize, "correct decode");
assert(layout_helper_element_type(lh) == etype, "correct decode");
assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
return lh;
}
// offset of first element, including any padding for the sake of alignment
int array_header_in_bytes() const { return layout_helper_header_size(layout_helper()); }