ewah_free(si->delete_bitmap);
        ewah_free(si->replace_bitmap);
-       free(si->saved_cache);
+       FREE_AND_NULL(si->saved_cache);
        si->delete_bitmap  = NULL;
        si->replace_bitmap = NULL;
-       si->saved_cache    = NULL;
        si->saved_cache_nr = 0;
 }
 
                istate->split_index->base->cache[new->index - 1] = new;
        }
 }
+
+void add_split_index(struct index_state *istate)
+{
+       if (!istate->split_index) {
+               init_split_index(istate);
+               istate->cache_changed |= SPLIT_INDEX_ORDERED;
+       }
+}
+
+void remove_split_index(struct index_state *istate)
+{
+       if (istate->split_index) {
+               /*
+                * can't discard_split_index(&the_index); because that
+                * will destroy split_index->base->cache[], which may
+                * be shared with the_index.cache[]. So yeah we're
+                * leaking a bit here.
+                */
+               istate->split_index = NULL;
+               istate->cache_changed |= SOMETHING_CHANGED;
+       }
+}