selftests/bpf: activate the OP_NE logic in range_cond()

The edge range checking for the registers is supported by the verifier
now, so we can activate the extended logic in
tools/testing/selftests/bpf/prog_tests/reg_bounds.c/range_cond() to test
such logic.

Besides, I added some cases to the "crafted_cases" array for this logic.
These cases are mainly used to test the edge of the src reg and dst reg.

All reg bounds testings has passed in the SLOW_TESTS mode:

$ export SLOW_TESTS=1 && ./test_progs -t reg_bounds -j
Summary: 65/18959832 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Menglong Dong <menglong8.dong@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231219134800.1550388-4-menglong8.dong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: image-dragon

tools/testing/selftests/bpf/prog_tests/reg_bounds.c

@@ -590,12 +590,7 @@ static void range_cond(enum num_t t, struct range x, struct range y,
 		*newy = range(t, max_t(t, x.a, y.a), min_t(t, x.b, y.b));
 		break;
 	case OP_NE:
-		/* generic case, can't derive more information */
-		*newx = range(t, x.a, x.b);
-		*newy = range(t, y.a, y.b);
-		break;
-
-		/* below extended logic is not supported by verifier just yet */
+		/* below logic is supported by the verifier now */
 		if (x.a == x.b && x.a == y.a) {
 			/* X is a constant matching left side of Y */
 			*newx = range(t, x.a, x.b);
@@ -2101,6 +2096,18 @@ static struct subtest_case crafted_cases[] = {
 	{S32, S64, {(u32)S32_MIN, (u32)(s32)-255}, {(u32)(s32)-2, 0}},
 	{S32, S64, {0, 1}, {(u32)S32_MIN, (u32)S32_MIN}},
 	{S32, U32, {(u32)S32_MIN, (u32)S32_MIN}, {(u32)S32_MIN, (u32)S32_MIN}},
+
+	/* edge overlap testings for BPF_NE */
+	{U64, U64, {0, U64_MAX}, {U64_MAX, U64_MAX}},
+	{U64, U64, {0, U64_MAX}, {0, 0}},
+	{S64, U64, {S64_MIN, 0}, {S64_MIN, S64_MIN}},
+	{S64, U64, {S64_MIN, 0}, {0, 0}},
+	{S64, U64, {S64_MIN, S64_MAX}, {S64_MAX, S64_MAX}},
+	{U32, U32, {0, U32_MAX}, {0, 0}},
+	{U32, U32, {0, U32_MAX}, {U32_MAX, U32_MAX}},
+	{S32, U32, {(u32)S32_MIN, 0}, {0, 0}},
+	{S32, U32, {(u32)S32_MIN, 0}, {(u32)S32_MIN, (u32)S32_MIN}},
+	{S32, U32, {(u32)S32_MIN, S32_MAX}, {S32_MAX, S32_MAX}},
 };
 
 /* Go over crafted hard-coded cases. This is fast, so we do it as part of