Re: [PATCH bpf-next 2/4] selftests/bpf: Update reg_bound range refinement logic

[Eduard Zingerman <eddyz87@gmail.com>]

On Sat, 2025-07-19 at 16:22 +0200, Paul Chaignon wrote:
> This patch updates the range refinement logic in the reg_bound test to
> match the new logic from the previous commit. Without this change, tests
> would fail because we end with more precise ranges than the tests
> expect.
> 
> Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

>  .../testing/selftests/bpf/prog_tests/reg_bounds.c  | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
> index 39d42271cc46..e261b0e872db 100644
> --- a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
> +++ b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
> @@ -465,6 +465,20 @@ static struct range range_refine(enum num_t x_t, struct range x, enum num_t y_t,
>  		return range_improve(x_t, x, x_swap);
>  	}
>  
> +	if (!t_is_32(x_t) && !t_is_32(y_t) && x_t != y_t) {

Nit: I'd swap x and y if necessary, to avoid a second branch.

> +		if (x_t == S64 && x.a > x.b) {
> +			if (x.b < y.a && x.a <= y.b)
> +				return range(x_t, x.a, y.b);
> +			if (x.a > y.b && x.b >= y.a)
> +				return range(x_t, y.a, x.b);
> +		} else if (x_t == U64 && y.a > y.b) {
> +			if (y.b < x.a && y.a <= x.b)
> +				return range(x_t, y.a, x.b);
> +			if (y.a > x.b && y.b >= x.a)
> +				return range(x_t, x.a, y.b);

Nit: here returned type us U64, while above it is S64, I don't think
     it matters but having same type in both branches would be less
     confusing.

> +		}
> +	}
> +
>  	/* otherwise, plain range cast and intersection works */
>  	return range_improve(x_t, x, y_cast);
>  }