log2: move log2 functions from linuxkpi to libkern

Linux has a header file that defines an ilog2 function and some simple
functions/macros that use it: roundup_pow_of_two, is_power_of_2,
rounddown_pow_of_two, and order_base_2.  This change moves three of
those simple functions (all but is_power_of_2) from linuxkpi to
libkern.  It also deletes a few implementations of these functions
that have previously been copied into code for various device drivers,
so that they can use the libkern version.  The is_power_of_2 macro was
not moved because powerof2 in param.h provides almost the same service
already (except that they disagree about whether 0 is a power of two).

Since the linux definitions of these functions were copied into
FreeBSD 11 years ago, linux has improved them, and this change
provides those improvements.  In particular, a giant table of log
values for evaluating ilog2 for constant values is no longer
necessary.

Reviewed by:	alc, markj (previous version)
Differential Revision:	https://reviews.freebsd.org/D45536

(cherry picked from commit c8b0c33b03ac072413b27bed2bdae2ae27426f3a)

sys/compat/linuxkpi/common/include/linux/log2.h

@@ -33,24 +33,9 @@
 
 #include <sys/libkern.h>
 
-static inline unsigned long
-roundup_pow_of_two(unsigned long x)
-{
-	return (1UL << flsl(x - 1));
-}
-
-static inline int
-is_power_of_2(unsigned long n)
-{
-	return (n == roundup_pow_of_two(n));
-}
-
-static inline unsigned long
-rounddown_pow_of_two(unsigned long x)
-{
-	return (1UL << (flsl(x) - 1));
-}
-
-#define	order_base_2(x) ilog2(roundup_pow_of_two(x))
+#define	is_power_of_2(n) ({			\
+	__typeof(n) _n = (n);			\
+	_n != 0 && (_n & (_n - 1)) == 0;	\
+})
 
 #endif	/* _LINUXKPI_LINUX_LOG2_H_ */

sys/dev/drm2/drm_os_freebsd.h

@@ -234,13 +234,6 @@ typedef void			irqreturn_t;
 #define	div_u64(n, d)		((n) / (d))
 #define	hweight32(i)		bitcount32(i)
 
-static inline unsigned long
-roundup_pow_of_two(unsigned long x)
-{
-
-	return (1UL << flsl(x - 1));
-}
-
 /**
  * ror32 - rotate a 32-bit value right
  * @word: value to rotate

sys/dev/mana/gdma_util.h

@@ -170,18 +170,6 @@ find_first_zero_bit(const unsigned long *p, unsigned long max)
 	return (max);
 }
 
-static inline unsigned long
-roundup_pow_of_two(unsigned long x)
-{
-	return (1UL << flsl(x - 1));
-}
-
-static inline int
-is_power_of_2(unsigned long n)
-{
-	return (n == roundup_pow_of_two(n));
-}
-
 struct completion {
 	unsigned int done;
 	struct mtx lock;

sys/dev/qlnx/qlnxe/bcm_osal.h

@@ -102,24 +102,6 @@ extern void qlnx_vf_flr_update(void *p_hwfn);
 
 #ifndef QLNX_RDMA
 
-static __inline unsigned long
-roundup_pow_of_two(unsigned long x)
-{
-	return (1UL << flsl(x - 1));
-}
-
-static __inline int
-is_power_of_2(unsigned long n)
-{
-	return (n == roundup_pow_of_two(n));
-}
-
-static __inline unsigned long
-rounddown_pow_of_two(unsigned long x)
-{
-	return (1UL << (flsl(x) - 1));
-}
-
 #define max_t(type, val1, val2) \
 	((type)(val1) > (type)(val2) ? (type)(val1) : (val2))
 #define min_t(type, val1, val2) \

sys/sys/libkern.h

@@ -223,77 +223,17 @@ ilog2_long_long(long long n)
 	    unsigned long long: ilog2_long_long	\
 	)(n)
 
-#define	ilog2(n)				\
-(						\
-	__builtin_constant_p(n) ? (		\
-	    (n) < 1 ? -1 :			\
-	    (n) & (1ULL << 63) ? 63 :		\
-	    (n) & (1ULL << 62) ? 62 :		\
-	    (n) & (1ULL << 61) ? 61 :		\
-	    (n) & (1ULL << 60) ? 60 :		\
-	    (n) & (1ULL << 59) ? 59 :		\
-	    (n) & (1ULL << 58) ? 58 :		\
-	    (n) & (1ULL << 57) ? 57 :		\
-	    (n) & (1ULL << 56) ? 56 :		\
-	    (n) & (1ULL << 55) ? 55 :		\
-	    (n) & (1ULL << 54) ? 54 :		\
-	    (n) & (1ULL << 53) ? 53 :		\
-	    (n) & (1ULL << 52) ? 52 :		\
-	    (n) & (1ULL << 51) ? 51 :		\
-	    (n) & (1ULL << 50) ? 50 :		\
-	    (n) & (1ULL << 49) ? 49 :		\
-	    (n) & (1ULL << 48) ? 48 :		\
-	    (n) & (1ULL << 47) ? 47 :		\
-	    (n) & (1ULL << 46) ? 46 :		\
-	    (n) & (1ULL << 45) ? 45 :		\
-	    (n) & (1ULL << 44) ? 44 :		\
-	    (n) & (1ULL << 43) ? 43 :		\
-	    (n) & (1ULL << 42) ? 42 :		\
-	    (n) & (1ULL << 41) ? 41 :		\
-	    (n) & (1ULL << 40) ? 40 :		\
-	    (n) & (1ULL << 39) ? 39 :		\
-	    (n) & (1ULL << 38) ? 38 :		\
-	    (n) & (1ULL << 37) ? 37 :		\
-	    (n) & (1ULL << 36) ? 36 :		\
-	    (n) & (1ULL << 35) ? 35 :		\
-	    (n) & (1ULL << 34) ? 34 :		\
-	    (n) & (1ULL << 33) ? 33 :		\
-	    (n) & (1ULL << 32) ? 32 :		\
-	    (n) & (1ULL << 31) ? 31 :		\
-	    (n) & (1ULL << 30) ? 30 :		\
-	    (n) & (1ULL << 29) ? 29 :		\
-	    (n) & (1ULL << 28) ? 28 :		\
-	    (n) & (1ULL << 27) ? 27 :		\
-	    (n) & (1ULL << 26) ? 26 :		\
-	    (n) & (1ULL << 25) ? 25 :		\
-	    (n) & (1ULL << 24) ? 24 :		\
-	    (n) & (1ULL << 23) ? 23 :		\
-	    (n) & (1ULL << 22) ? 22 :		\
-	    (n) & (1ULL << 21) ? 21 :		\
-	    (n) & (1ULL << 20) ? 20 :		\
-	    (n) & (1ULL << 19) ? 19 :		\
-	    (n) & (1ULL << 18) ? 18 :		\
-	    (n) & (1ULL << 17) ? 17 :		\
-	    (n) & (1ULL << 16) ? 16 :		\
-	    (n) & (1ULL << 15) ? 15 :		\
-	    (n) & (1ULL << 14) ? 14 :		\
-	    (n) & (1ULL << 13) ? 13 :		\
-	    (n) & (1ULL << 12) ? 12 :		\
-	    (n) & (1ULL << 11) ? 11 :		\
-	    (n) & (1ULL << 10) ? 10 :		\
-	    (n) & (1ULL <<  9) ?  9 :		\
-	    (n) & (1ULL <<  8) ?  8 :		\
-	    (n) & (1ULL <<  7) ?  7 :		\
-	    (n) & (1ULL <<  6) ?  6 :		\
-	    (n) & (1ULL <<  5) ?  5 :		\
-	    (n) & (1ULL <<  4) ?  4 :		\
-	    (n) & (1ULL <<  3) ?  3 :		\
-	    (n) & (1ULL <<  2) ?  2 :		\
-	    (n) & (1ULL <<  1) ?  1 :		\
-	    (n) & (1ULL <<  0) ?  0 :		\
-	    -1) :				\
-	ilog2_var(n)				\
-)
+#define	ilog2_const(n)				\
+    (8 * (int)sizeof(unsigned long long) - 1 -	\
+    __builtin_clzll(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	roundup_pow_of_two(n)	((__typeof(n))1 << order_base_2(n))
 
 #define	bitcount64(x)	__bitcount64((uint64_t)(x))
 #define	bitcount32(x)	__bitcount32((uint32_t)(x))