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-rw-r--r--lib/test_bitmap.c62
1 files changed, 62 insertions, 0 deletions
diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index d5923a640457..25967cfa4ab2 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -869,6 +869,67 @@ static void __init test_bitmap_print_buf(void)
}
}
+static void __init test_bitmap_const_eval(void)
+{
+ DECLARE_BITMAP(bitmap, BITS_PER_LONG);
+ unsigned long initvar = BIT(2);
+ unsigned long bitopvar = 0;
+ unsigned long var = 0;
+ int res;
+
+ /*
+ * Compilers must be able to optimize all of those to compile-time
+ * constants on any supported optimization level (-O2, -Os) and any
+ * architecture. Otherwise, trigger a build bug.
+ * The whole function gets optimized out then, there's nothing to do
+ * in runtime.
+ */
+
+ /*
+ * Equals to `unsigned long bitmap[1] = { GENMASK(6, 5), }`.
+ * Clang on s390 optimizes bitops at compile-time as intended, but at
+ * the same time stops treating @bitmap and @bitopvar as compile-time
+ * constants after regular test_bit() is executed, thus triggering the
+ * build bugs below. So, call const_test_bit() there directly until
+ * the compiler is fixed.
+ */
+ bitmap_clear(bitmap, 0, BITS_PER_LONG);
+#if defined(__s390__) && defined(__clang__)
+ if (!const_test_bit(7, bitmap))
+#else
+ if (!test_bit(7, bitmap))
+#endif
+ bitmap_set(bitmap, 5, 2);
+
+ /* Equals to `unsigned long bitopvar = BIT(20)` */
+ __change_bit(31, &bitopvar);
+ bitmap_shift_right(&bitopvar, &bitopvar, 11, BITS_PER_LONG);
+
+ /* Equals to `unsigned long var = BIT(25)` */
+ var |= BIT(25);
+ if (var & BIT(0))
+ var ^= GENMASK(9, 6);
+
+ /* __const_hweight<32|64>(GENMASK(6, 5)) == 2 */
+ res = bitmap_weight(bitmap, 20);
+ BUILD_BUG_ON(!__builtin_constant_p(res));
+ BUILD_BUG_ON(res != 2);
+
+ /* !(BIT(31) & BIT(18)) == 1 */
+ res = !test_bit(18, &bitopvar);
+ BUILD_BUG_ON(!__builtin_constant_p(res));
+ BUILD_BUG_ON(!res);
+
+ /* BIT(2) & GENMASK(14, 8) == 0 */
+ res = initvar & GENMASK(14, 8);
+ BUILD_BUG_ON(!__builtin_constant_p(res));
+ BUILD_BUG_ON(res);
+
+ /* ~BIT(25) */
+ BUILD_BUG_ON(!__builtin_constant_p(~var));
+ BUILD_BUG_ON(~var != ~BIT(25));
+}
+
static void __init selftest(void)
{
test_zero_clear();
@@ -884,6 +945,7 @@ static void __init selftest(void)
test_for_each_set_clump8();
test_bitmap_cut();
test_bitmap_print_buf();
+ test_bitmap_const_eval();
}
KSTM_MODULE_LOADERS(test_bitmap);