public static void memcopy(Address dst, Address src, int cnt) { VM_SysCall.sysCopy(dst, src, Extent.fromIntSignExtend(cnt));
public static void memcopy(Address dst, Address src, Extent cnt) { VM_SysCall.sysCopy(dst, src, cnt);
  public static void memcopy(Address dst, Address src, int cnt) {    VM_SysCall.sysCopy(dst, src, Extent.fromIntSignExtend(cnt));  }