+static bool
+tag_is_worth_adding(const struct tag_set *set, tag_type tag)
+{
+ if (!tag) {
+ /* Nothing to add. */
+ return false;
+ } else if ((set->total & tag) != tag) {
+ /* 'set' doesn't have all the bits in 'tag', so we need to add it. */
+ return true;
+ } else {
+ /* We can drop it if some member of 'set' already includes all of the
+ * 1-bits in 'tag'. (tag_set_intersects() does a different test:
+ * whether some member of 'set' has at least two 1-bit in common with
+ * 'tag'.) */
+ int i;
+
+ for (i = 0; i < TAG_SET_SIZE; i++) {
+ if ((set->tags[i] & tag) == tag) {
+ return false;
+ }
+ }
+ return true;
+ }
+}
+