| Message ID | 20241112190840.601378-6-mailhol.vincent@wanadoo.fr (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | add _statically_true() to simplify GENMASK_INPUT_CHECK() | expand |
diff --git a/include/linux/bits.h b/include/linux/bits.h index 60044b608817..01713e1eda56 100644 --- a/include/linux/bits.h +++ b/include/linux/bits.h @@ -20,9 +20,8 @@ */ #if !defined(__ASSEMBLY__) #include <linux/build_bug.h> -#define GENMASK_INPUT_CHECK(h, l) \ - (BUILD_BUG_ON_ZERO(__builtin_choose_expr( \ - __is_constexpr((l) > (h)), (l) > (h), 0))) +#include <linux/compiler.h> +#define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(_statically_true((l) > (h))) #else /* * BUILD_BUG_ON_ZERO is not available in h files included from asm files,
In GENMASK_INPUT_CHECK(), __builtin_choose_expr(__is_constexpr((l) > (h)), (l) > (h), 0) is the exact expansion of: _statically_true((l) > (h)) Apply _statically_true() to simplify GENMASK_INPUT_CHECK(). Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> --- This change passes the unit tests from CONFIG_BITS_TEST, including the extra negative tests provided under #ifdef TEST_GENMASK_FAILURES [1]. [1] commit 6d511020e13d ("lib/test_bits.c: add tests of GENMASK") Link: https://git.kernel.org/torvalds/c/6d511020e13d ** Changelog ** v2 -> v3: - split the single patch into a series of two patches. - add greater explanation of why _statically_true() is needed in addition of the existing statically_true(). Explain the pros and cons of both. - use __builtin_choose_expr() in _statically_true(). The _statically_true() of the v2 works perfectly fine when used in conjunction with BUILD_BUG_ON_ZERO() but fails if used in arrays or in static_assert() - update the patch description accordingly Link: https://lore.kernel.org/all/20241111164743.339117-2-mailhol.vincent@wanadoo.fr/ v1 -> v2: - introduce _statically_true(), taking inspiration from statically_true() as introduced in commit 22f546873149 ("minmax: improve macro expansion and type checking"). Link: https://lore.kernel.org/all/20240609073513.256179-1-mailhol.vincent@wanadoo.fr/ --- include/linux/bits.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)