selftests/bpf: Update reg_bound range refinement logic

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.

Acked-by: Eduard Zingerman <[email protected]>
Signed-off-by: Paul Chaignon <[email protected]>
Link: https://lore.kernel.org/r/b7f6b1fbe03373cca4e1bb6a113035a6cd2b3ff7.1753695655.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: pchaigno

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