diff mbox series

[12/14] lib/bitmap: add compile-time test for __assign_bit() optimization

Message ID 20231009151026.66145-13-aleksander.lobakin@intel.com
State New
Headers
Series ip_tunnel: convert __be16 tunnel flags to bitmaps |

Commit Message

Alexander Lobakin Oct. 9, 2023, 3:10 p.m. UTC 
  Commit dc34d5036692 ("lib: test_bitmap: add compile-time
optimization/evaluations assertions") initially missed __assign_bit(),
which led to that quite a time passed before I realized it doesn't get
optimized at compilation time. Now that it does, add test for that just
to make sure nothing will break one day.
To make things more interesting, use bitmap_complement() and
bitmap_full(), thus checking their compile-time evaluation as well. And
remove the misleading comment mentioning the workaround removed recently
in favor of adding the whole file to GCov exceptions.

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
---
 lib/test_bitmap.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)
diff mbox series

Patch

diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index f2ea9f30c7c5..cbf1b9611616 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -1181,14 +1181,7 @@  static void __init test_bitmap_const_eval(void)
 	 * 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.
-	 */
+	/* Equals to `unsigned long bitmap[1] = { GENMASK(6, 5), }` */
 	bitmap_clear(bitmap, 0, BITS_PER_LONG);
 	if (!test_bit(7, bitmap))
 		bitmap_set(bitmap, 5, 2);
@@ -1220,6 +1213,15 @@  static void __init test_bitmap_const_eval(void)
 	/* ~BIT(25) */
 	BUILD_BUG_ON(!__builtin_constant_p(~var));
 	BUILD_BUG_ON(~var != ~BIT(25));
+
+	/* ~BIT(25) | BIT(25) == ~0UL */
+	bitmap_complement(&var, &var, BITS_PER_LONG);
+	__assign_bit(25, &var, true);
+
+	/* !(~(~0UL)) == 1 */
+	res = bitmap_full(&var, BITS_PER_LONG);
+	BUILD_BUG_ON(!__builtin_constant_p(res));
+	BUILD_BUG_ON(!res);
 }
 
 static void __init selftest(void)