tnum_lshift
struct tnum tnum_lshift(struct tnum a, u8 shift);
b = tnum_lshift(b, 1);
return tnum_lshift(tnum_rshift(a, 32), 32);
dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val));
dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);