diff options
| -rw-r--r-- | lib/test_bitmap.c | 62 |
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); |