reduce4
reduce4(H, H2, H3, H4, tmp4, tmp3, tmp2, tmp1, &X);
reduce4(H, H2, H3, H4, tmp4, tmp3, tmp2, tmp1, &X);
reduce4(H, H2, H3, H4, tmp8, tmp7, tmp6, tmp5, &X);
reduce4(H, H2, H3, H4, tmp4, tmp3, tmp2, tmp1, &X);
reduce4(H, H2, H3, H4, tmp4, tmp3, tmp2, tmp1, &X);