HEXAGON_P_vrmpyh_PP
sum0 = HEXAGON_P_vrmpyh_PP((sum0+sum1)^VR_NEGATE(0, 0, 0, 1),
sum0 = HEXAGON_P_vrmpyh_PP(sum0, VR_SELECT(0, 0, 1, 1));
sum = HEXAGON_P_vrmpyh_PP(x^VR_NEGATE(1, 1, 1, 1),
sum = HEXAGON_P_vrmpyh_PP(sum, VR_SELECT(0, 0, 1, 1));