void
overload_addeq (x, y, o)
    mpz_assume   x
    mpz_coerce   y
    order_noswap o
ALIAS:
    GMP::Mpz::overload_subeq = 1
    GMP::Mpz::overload_muleq = 2
    GMP::Mpz::overload_diveq = 3
    GMP::Mpz::overload_remeq = 4
    GMP::Mpz::overload_andeq = 5
    GMP::Mpz::overload_ioreq = 6
    GMP::Mpz::overload_xoreq = 7
PREINIT:
    static_functable const struct {
      void (*op) (mpz_ptr, mpz_srcptr, mpz_srcptr);
    } table[] = {
      { mpz_add    }, /* 0 */
      { mpz_sub    }, /* 1 */
      { mpz_mul    }, /* 2 */
      { mpz_tdiv_q }, /* 3 */
      { mpz_tdiv_r }, /* 4 */
      { mpz_and    }, /* 5 */
      { mpz_ior    }, /* 6 */
      { mpz_xor    }, /* 7 */
    };
PPCODE:
    assert_table (ix);
    (*table[ix].op) (x->m, x->m, y);
    XPUSHs (ST(0));