diff options
| -rw-r--r-- | src/shared/macro.h | 9 | ||||
| -rw-r--r-- | src/test/test-util.c | 23 |
2 files changed, 32 insertions, 0 deletions
diff --git a/src/shared/macro.h b/src/shared/macro.h index 11bd8b3a93..179b24c983 100644 --- a/src/shared/macro.h +++ b/src/shared/macro.h @@ -140,6 +140,15 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) { _a > _b ? _a : _b; \ }) +/* evaluates to (void) if _A or _B are not constant or of different types */ +#define CONST_MAX(_A, _B) \ + __extension__ (__builtin_choose_expr( \ + __builtin_constant_p(_A) && \ + __builtin_constant_p(_B) && \ + __builtin_types_compatible_p(typeof(_A), typeof(_B)), \ + ((_A) > (_B)) ? (_A) : (_B), \ + (void)0)) + #define MAX3(x,y,z) \ __extension__ ({ \ const typeof(x) _c = MAX(x,y); \ diff --git a/src/test/test-util.c b/src/test/test-util.c index 7d81b0b7be..a8fa48aed2 100644 --- a/src/test/test-util.c +++ b/src/test/test-util.c @@ -70,6 +70,28 @@ static void test_align_power2(void) { } } +static void test_max(void) { + static const struct { + int a; + int b[CONST_MAX(10, 100)]; + } val1 = { + .a = CONST_MAX(10, 100), + }; + int d = 0; + + assert_cc(sizeof(val1.b) == sizeof(int) * 100); + + /* CONST_MAX returns (void) instead of a value if the passed arguments + * are not of the same type or not constant expressions. */ + assert_cc(__builtin_types_compatible_p(typeof(CONST_MAX(1, 10)), int)); + assert_cc(__builtin_types_compatible_p(typeof(CONST_MAX(d, 10)), void)); + assert_cc(__builtin_types_compatible_p(typeof(CONST_MAX(1, 1U)), void)); + + assert_se(val1.a == 100); + assert_se(MAX(++d, 0) == 1); + assert_se(d == 1); +} + static void test_first_word(void) { assert_se(first_word("Hello", "")); assert_se(first_word("Hello", "Hello")); @@ -927,6 +949,7 @@ int main(int argc, char *argv[]) { test_streq_ptr(); test_align_power2(); + test_max(); test_first_word(); test_close_many(); test_parse_boolean(); |