Re: [PATCH RFC bpf-next 3/4] bpf: replace min/max fields with struct cnum{32,64}

["Alexei Starovoitov" <alexei.starovoitov@gmail.com>]

On Tue Apr 21, 2026 at 3:28 AM PDT, Eduard Zingerman wrote:
>  
>  static void scalar32_min_max_udiv(struct bpf_reg_state *dst_reg,
> @@ -14119,7 +13548,6 @@ static void scalar32_min_max_udiv(struct bpf_reg_state *dst_reg,
>  			 reg_u32_max(dst_reg) / src_val);
>  
>  	/* Reset other ranges/tnum to unbounded/unknown. */
> -	reg_set_srange32(dst_reg, S32_MIN, S32_MAX);
>  	reset_reg64_and_tnum(dst_reg);
>  }

div/mod don't need special cnum_div ?

> @@ -15861,38 +15209,54 @@ static void regs_refine_cond_op(struct bpf_reg_state *reg1, struct bpf_reg_state
>  		break;
>  	case BPF_JLE:
>  		if (is_jmp32) {
> -			reg_set_urange32(reg1, reg_u32_min(reg1), min(reg_u32_max(reg1), reg_u32_max(reg2)));
> -			reg_set_urange32(reg2, max(reg_u32_min(reg1), reg_u32_min(reg2)), reg_u32_max(reg2));
> +			lo32 = cnum32_from_urange(0, reg_u32_max(reg2));
> +			hi32 = cnum32_from_urange(reg_u32_min(reg1), U32_MAX);
> +			reg1->r32 = cnum32_intersect(reg1->r32, lo32);
> +			reg2->r32 = cnum32_intersect(reg2->r32, hi32);
>  		} else {
> -			reg_set_urange64(reg1, reg_umin(reg1), min(reg_umax(reg1), reg_umax(reg2)));
> -			reg_set_urange64(reg2, max(reg_umin(reg1), reg_umin(reg2)), reg_umax(reg2));
> +			lo = cnum64_from_urange(0, reg_umax(reg2));
> +			hi = cnum64_from_urange(reg_umin(reg1), U64_MAX);
> +			reg1->r64 = cnum64_intersect(reg1->r64, lo);
> +			reg2->r64 = cnum64_intersect(reg2->r64, hi);

Maybe a helper like:
cnum64_intersect_with_range(&reg1->r64, 0, reg_umax(reg2));
?

Also I found only one case:
dst_reg->r64 = cnum64_intersect(u, s);

all others dst and src are the same.
So maybe:
cnum64_intersect(&dst_reg->r64, ..);
as a main helper and __cnum64_intersect(r->r64, ...) as a subhelper that returns cnum?