[WIP] libsepol: optimize ebitmap_cardinality()

Make it linear in the bitmap size instead of quadratic

libsepol/src/ebitmap.c

@@ -125,12 +125,22 @@ int ebitmap_andnot(ebitmap_t *dst, ebitmap_t *e1, ebitmap_t *e2, unsigned int ma
 	return 0;
 }
 
+#include <assert.h>
 unsigned int ebitmap_cardinality(ebitmap_t *e1)
 {
 	unsigned int i, count = 0;
+	ebitmap_node_t *n;
+
+	for (n = e1->node; n; n = n->next) {
+		count += __builtin_popcountll(n->map);
+	}
+
+/* for testing the optimisation: keep the old inefficient implementation and verify equality */
+	unsigned int count2 = 0;
 	for (i=ebitmap_startbit(e1); i < ebitmap_length(e1); i++)
 		if (ebitmap_get_bit(e1, i))
-			count++;
+			count2++;
+	assert(count2 == count);
 	return count;
 }