2 * from https://bitbucket.org/cherry9/plan9-loongson
5 MOVW 8(FP), R2 /* hi1 */
6 MOVW 4(FP), R3 /* lo1 */
7 MOVW 16(FP), R4 /* hi2 */
8 MOVW 12(FP), R5 /* lo2 */
9 MULU R5, R3 /* lo1*lo2 -> hi:lo*/
12 MULU R3, R4 /* lo1*hi2 -> _:hi */
15 MULU R2, R5 /* hi1*lo2 -> _:hi */
18 MOVW R6, 0(R1) /* lo */
19 MOVW R7, 4(R1) /* hi */