Expand the bitcount* API to support 64-bit integers, plain ints and longs

and create a "hidden" API that can be used in other system headers without
adding namespace pollution.
- If the POPCNT instruction is enabled at compile time, use
  __builtin_popcount*() to implement __bitcount*(), otherwise fall back
  to software implementations.
- Use the existing bitcount16() and bitcount32() from <sys/systm.h> to
  implement the non-POPCNT __bitcount16() and __bitcount32() in
  <sys/types.h>.
- For the non-POPCNT __bitcount64(), use a similar SWAR method on 64-bit
  systems.  For 32-bit systems, use two __bitcount32() operations on the
  two halves.
- Use __bitcount32() to provide a __bitcount() that operates on plain ints.
- Use either __bitcount32() or __bitcount64() to provide a
  __bitcountl() that operates on longs.
- Add public bitcount*() wrappers for __bitcount*() for use in the kernel
  in <sys/libkern.h>.
- Use __builtinl() instead of __builtin_popcountl() in BIT_COUNT().

Discussed with:	bde

sys/sys/bitset.h

@@ -182,7 +182,7 @@
 									\
 	__count = 0;							\
 	for (__i = 0; __i < __bitset_words((_s)); __i++)		\
-		__count += __builtin_popcountl((p)->__bits[__i]);	\
+		__count += __bitcountl((p)->__bits[__i]);		\
 	__count;							\
 })
 	

sys/sys/libkern.h

@@ -98,6 +98,11 @@ int	 flsl(long);
 #ifndef	HAVE_INLINE_FLSLL
 int	 flsll(long long);
 #endif
+#define	bitcount64(x)	__bitcount64((uint64_t)(x))
+#define	bitcount32(x)	__bitcount32((uint32_t)(x))
+#define	bitcount16(x)	__bitcount16((uint16_t)(x))
+#define	bitcountl(x)	__bitcountl((u_long)(x))
+#define	bitcount(x)	__bitcount((u_int)(x))
 
 int	 fnmatch(const char *, const char *, int);
 int	 locc(int, char *, u_int);

sys/sys/systm.h

@@ -428,33 +428,6 @@ int alloc_unr_specific(struct unrhdr *uh, u_int item);
 int alloc_unrl(struct unrhdr *uh);
 void free_unr(struct unrhdr *uh, u_int item);
 
-/*
- * Population count algorithm using SWAR approach
- * - "SIMD Within A Register".
- */
-static __inline uint32_t
-bitcount32(uint32_t x)
-{
-
-	x = (x & 0x55555555) + ((x & 0xaaaaaaaa) >> 1);
-	x = (x & 0x33333333) + ((x & 0xcccccccc) >> 2);
-	x = (x + (x >> 4)) & 0x0f0f0f0f;
-	x = (x + (x >> 8));
-	x = (x + (x >> 16)) & 0x000000ff;
-	return (x);
-}
-
-static __inline uint16_t
-bitcount16(uint32_t x)
-{
-
-	x = (x & 0x5555) + ((x & 0xaaaa) >> 1);
-	x = (x & 0x3333) + ((x & 0xcccc) >> 2);
-	x = (x + (x >> 4)) & 0x0f0f;
-	x = (x + (x >> 8)) & 0x00ff;
-	return (x);
-}
-
 void	intr_prof_stack_use(struct thread *td, struct trapframe *frame);
 
 #endif /* !_SYS_SYSTM_H_ */

sys/sys/types.h

@@ -294,6 +294,68 @@ typedef	_Bool	bool;
 
 #include <sys/select.h>
 
+#ifdef __POPCNT__
+#define	__bitcount64(x)	__builtin_popcountll((__uint64_t)(x))
+#define	__bitcount32(x)	__builtin_popcount((__uint32_t)(x))
+#define	__bitcount16(x)	__builtin_popcount((__uint16_t)(x))
+#define	__bitcountl(x)	__builtin_popcountl((unsigned long)(x))
+#define	__bitcount(x)	__builtin_popcount((unsigned int)(x))
+#else
+/*
+ * Population count algorithm using SWAR approach
+ * - "SIMD Within A Register".
+ */
+static __inline __uint16_t
+__bitcount16(__uint16_t _x)
+{
+
+	_x = (_x & 0x5555) + ((_x & 0xaaaa) >> 1);
+	_x = (_x & 0x3333) + ((_x & 0xcccc) >> 2);
+	_x = (_x + (_x >> 4)) & 0x0f0f;
+	_x = (_x + (_x >> 8)) & 0x00ff;
+	return (_x);
+}
+
+static __inline __uint32_t
+__bitcount32(__uint32_t _x)
+{
+
+	_x = (_x & 0x55555555) + ((_x & 0xaaaaaaaa) >> 1);
+	_x = (_x & 0x33333333) + ((_x & 0xcccccccc) >> 2);
+	_x = (_x + (_x >> 4)) & 0x0f0f0f0f;
+	_x = (_x + (_x >> 8));
+	_x = (_x + (_x >> 16)) & 0x000000ff;
+	return (_x);
+}
+
+#ifdef __LP64__
+static __inline __uint64_t
+__bitcount64(__uint64_t _x)
+{
+
+	_x = (_x & 0x5555555555555555) + ((_x & 0xaaaaaaaaaaaaaaaa) >> 1);
+	_x = (_x & 0x3333333333333333) + ((_x & 0xcccccccccccccccc) >> 2);
+	_x = (_x + (_x >> 4)) & 0x0f0f0f0f0f0f0f0f;
+	_x = (_x + (_x >> 8));
+	_x = (_x + (_x >> 16));
+	_x = (_x + (_x >> 32)) & 0x000000ff;
+	return (_x);
+}
+
+#define	__bitcountl(x)	__bitcount64((unsigned long)(x))
+#else
+static __inline __uint64_t
+__bitcount64(__uint64_t _x)
+{
+
+	return (__bitcount32(_x >> 32) + __bitcount32(_x));
+}
+
+#define	__bitcountl(x)	__bitcount32((unsigned long)(x))
+#endif
+#define	__bitcount(x)	__bitcount32((unsigned int)(x))
+#endif
+
 /*
  * minor() gives a cookie instead of an index since we don't want to
  * change the meanings of bits 0-15 or waste time and space shifting