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 (mailing list archive)
State Not Applicable
Delegated to: Netdev Maintainers
Headers show
Series ice: add PFCP filter support | expand

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netdev/series_format fail Series longer than 15 patches (and no cover letter)
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1048 this patch: 1048
netdev/build_tools success No tools touched, skip
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netdev/build_clang success Errors and warnings before: 1065 this patch: 1065
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netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1065 this patch: 1065
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 30 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

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);
 }
 
 /*