Use __builtin_popcount in __sched_cpucount [BZ #21696]

posix/sched_cpucount.c assumes that size of __cpu_mask == size of long,
which is incorrect for x32.  This patch uses __builtin_popcount, which
is availabe in GCC 4.9, in posix/sched_cpucount.c.

Tested on i686, x86-64 and x32 with multi-arch disabled.

	[BZ #21696]
	* posix/sched_cpucount.c: Don't include <limits.h>.
	(__sched_cpucount): Use __builtin_popcount.

1 files changed, 10 insertions, 17 deletions

diff --git a/posix/sched_cpucount.c b/posix/sched_cpucount.c
index eaddf61b1b..ab1ff49383 100644
--- a/posix/sched_cpucount.c
+++ b/posix/sched_cpucount.c
@@ -15,7 +15,6 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <limits.h>
 #include <sched.h>
 
 
@@ -36,22 +35,16 @@ __sched_cpucount (size_t setsize, const cpu_set_t *setp)
       if (l == 0)
 	continue;
 
-# if LONG_BIT > 32
-      l = (l & 0x5555555555555555ul) + ((l >> 1) & 0x5555555555555555ul);
-      l = (l & 0x3333333333333333ul) + ((l >> 2) & 0x3333333333333333ul);
-      l = (l & 0x0f0f0f0f0f0f0f0ful) + ((l >> 4) & 0x0f0f0f0f0f0f0f0ful);
-      l = (l & 0x00ff00ff00ff00fful) + ((l >> 8) & 0x00ff00ff00ff00fful);
-      l = (l & 0x0000ffff0000fffful) + ((l >> 16) & 0x0000ffff0000fffful);
-      l = (l & 0x00000000fffffffful) + ((l >> 32) & 0x00000000fffffffful);
-# else
-      l = (l & 0x55555555ul) + ((l >> 1) & 0x55555555ul);
-      l = (l & 0x33333333ul) + ((l >> 2) & 0x33333333ul);
-      l = (l & 0x0f0f0f0ful) + ((l >> 4) & 0x0f0f0f0ful);
-      l = (l & 0x00ff00fful) + ((l >> 8) & 0x00ff00fful);
-      l = (l & 0x0000fffful) + ((l >> 16) & 0x0000fffful);
-# endif
-
-      s += l;
+      _Static_assert (sizeof (l) == sizeof (unsigned int)
+		      || sizeof (l) == sizeof (unsigned long)
+		      || sizeof (l) == sizeof (unsigned long long),
+		      "sizeof (__cpu_mask");
+      if (sizeof (__cpu_mask) == sizeof (unsigned int))
+	s += __builtin_popcount (l);
+      else if (sizeof (__cpu_mask) == sizeof (unsigned long))
+	s += __builtin_popcountl (l);
+      else
+	s += __builtin_popcountll (l);
 #endif
     }