CREATE EXTENSION popcount;
ERROR:  extension "popcount" already exists
SELECT popcount32(15::bit(4));
 popcount32 
------------
          4
(1 row)

SELECT popcount32(7::bit(4));
 popcount32 
------------
          3
(1 row)

SELECT popcount32(15::bit(8));
 popcount32 
------------
          4
(1 row)

SELECT popcount32(7::bit(8));
 popcount32 
------------
          3
(1 row)

SELECT popcount32(15::bit(12));
 popcount32 
------------
          4
(1 row)

SELECT popcount32(7::bit(12));
 popcount32 
------------
          3
(1 row)

SELECT popcount32(15::bit(32));
 popcount32 
------------
          4
(1 row)

SELECT popcount32(7::bit(32));
 popcount32 
------------
          3
(1 row)

SELECT popcount32(30::bit(32));
 popcount32 
------------
          4
(1 row)

SELECT popcount32(127::bit(32));
 popcount32 
------------
          7
(1 row)

SELECT popcount32(b'10101010101010101010101010101010101101010101010101010101010101010101011010101010101010101010101010101010110101010101010101010101010101010101101010101010101010101010101010101011010101010101010101010101010101010110101010101010101010101010101010101101010101010101010101010101010101011010101010101010101010101010101010110101010101010101010101010101010101101010101010101010101010101010101011010101010101010101010101010101010110101010101010101010101010101010101101010101010101010101010101010101011010101010101010101010');
 popcount32 
------------
        263
(1 row)

SELECT sum(popcount32(x::bit(512))) from generate_series(1,1000000) x;
   sum   
---------
 9884999
(1 row)

SELECT sum(popcount32(x::bit(500))) from generate_series(1,1000000) x;
   sum   
---------
 9884999
(1 row)