From b7cbf741d55468ba34305a14ac3acc1c286af034 Mon Sep 17 00:00:00 2001 From: Doug Moore Date: Fri, 27 Sep 2024 18:43:07 -0500 Subject: [PATCH] libkern: avoid local var in order_base_2() order_base_2(n) is implemented with a variable, which keeps it from being used at file scope. Implement it instead as ilog2(2*n-1), which produces a different result when 2*n overflows, which appears unlikely in practice. Reviewed by: bz Differential Revision: https://reviews.freebsd.org/D46826 --- sys/sys/libkern.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/sys/sys/libkern.h b/sys/sys/libkern.h index 64744f57b5c3..ad64d0fb0a57 100644 --- a/sys/sys/libkern.h +++ b/sys/sys/libkern.h @@ -227,10 +227,7 @@ ilog2_long_long(long long n) #define ilog2(n) (__builtin_constant_p(n) ? ilog2_const(n) : ilog2_var(n)) #define rounddown_pow_of_two(n) ((__typeof(n))1 << ilog2(n)) -#define order_base_2(n) ({ \ - __typeof(n) _n = (n); \ - _n == 1 ? 0 : 1 + ilog2(_n - 1); \ -}) +#define order_base_2(n) ilog2(2*(n)-1) #define roundup_pow_of_two(n) ((__typeof(n))1 << order_base_2(n)) #define bitcount64(x) __bitcount64((uint64_t)(x))