diff mbox series

[net-next,v5,14/21] lib/bitmap: add compile-time test for __assign_bit() optimization

Message ID 20240201122216.2634007-15-aleksander.lobakin@intel.com
State New
Headers
Series ice: add PFCP filter support |

Commit Message

Alexander Lobakin Feb. 1, 2024, 12:22 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(-)

Comments

Yury Norov Feb. 28, 2024, 4:32 p.m. UTC | #1 
On Thu, Feb 01, 2024 at 01:22:09PM +0100, Alexander Lobakin wrote:
> 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>

Signed-off-by: Yury Norov <yury.norov@gmail.com>
diff mbox series

Patch

diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index a6e92cf5266a..4ee1f8ceb51d 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -1204,14 +1204,7 @@  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);
@@ -1243,6 +1236,15 @@  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);
 }
 
 /*