tnum_intersect
struct tnum tnum_intersect(struct tnum a, struct tnum b);
t = tnum_intersect(tnum_subreg(reg1->var_off), tnum_subreg(reg2->var_off));
reg1->var_off = tnum_intersect(reg1->var_off, reg2->var_off);
reg->var_off = tnum_intersect(reg->var_off,
struct tnum var64_off = tnum_intersect(reg->var_off,
struct tnum var32_off = tnum_intersect(tnum_subreg(var64_off),