+ /*
+ * Do we know what commit all of our parents that matter
+ * should be rewritten to? Otherwise we are not ready to
+ * rewrite this one yet.
+ */
+ for (cnt = 0, p = commit->parents; p; p = p->next) {
+ pst = locate_simplify_state(revs, p->item);
+ if (!pst->simplified) {
+ tail = &commit_list_insert(p->item, tail)->next;
+ cnt++;
+ }
+ if (revs->first_parent_only)
+ break;
+ }
+ if (cnt) {
+ tail = &commit_list_insert(commit, tail)->next;
+ return tail;
+ }
+
+ /*
+ * Rewrite our list of parents. Note that this cannot
+ * affect our TREESAME flags in any way - a commit is
+ * always TREESAME to its simplification.
+ */
+ for (p = commit->parents; p; p = p->next) {
+ pst = locate_simplify_state(revs, p->item);
+ p->item = pst->simplified;
+ if (revs->first_parent_only)
+ break;
+ }
+
+ if (revs->first_parent_only)
+ cnt = 1;
+ else
+ cnt = remove_duplicate_parents(revs, commit);
+
+ /*
+ * It is possible that we are a merge and one side branch
+ * does not have any commit that touches the given paths;
+ * in such a case, the immediate parent from that branch
+ * will be rewritten to be the merge base.
+ *
+ * o----X X: the commit we are looking at;
+ * / / o: a commit that touches the paths;
+ * ---o----'
+ *
+ * Further, a merge of an independent branch that doesn't
+ * touch the path will reduce to a treesame root parent:
+ *
+ * ----o----X X: the commit we are looking at;
+ * / o: a commit that touches the paths;
+ * r r: a root commit not touching the paths
+ *
+ * Detect and simplify both cases.
+ */
+ if (1 < cnt) {
+ int marked = mark_redundant_parents(commit);
+ marked += mark_treesame_root_parents(commit);
+ if (marked)
+ marked -= leave_one_treesame_to_parent(revs, commit);
+ if (marked)
+ cnt = remove_marked_parents(revs, commit);
+ }
+
+ /*
+ * A commit simplifies to itself if it is a root, if it is
+ * UNINTERESTING, if it touches the given paths, or if it is a
+ * merge and its parents don't simplify to one relevant commit
+ * (the first two cases are already handled at the beginning of
+ * this function).
+ *
+ * Otherwise, it simplifies to what its sole relevant parent
+ * simplifies to.
+ */
+ if (!cnt ||
+ (commit->object.flags & UNINTERESTING) ||
+ !(commit->object.flags & TREESAME) ||
+ (parent = one_relevant_parent(revs, commit->parents)) == NULL ||
+ (revs->show_pulls && (commit->object.flags & PULL_MERGE)))
+ st->simplified = commit;
+ else {
+ pst = locate_simplify_state(revs, parent);
+ st->simplified = pst->simplified;
+ }
+ return tail;
+}
+
+static void simplify_merges(struct rev_info *revs)
+{
+ struct commit_list *list, *next;
+ struct commit_list *yet_to_do, **tail;
+ struct commit *commit;
+
+ if (!revs->prune)
+ return;
+
+ /* feed the list reversed */
+ yet_to_do = NULL;
+ for (list = revs->commits; list; list = next) {
+ commit = list->item;
+ next = list->next;
+ /*
+ * Do not free(list) here yet; the original list
+ * is used later in this function.
+ */
+ commit_list_insert(commit, &yet_to_do);
+ }
+ while (yet_to_do) {
+ list = yet_to_do;
+ yet_to_do = NULL;
+ tail = &yet_to_do;
+ while (list) {
+ commit = pop_commit(&list);
+ tail = simplify_one(revs, commit, tail);
+ }
+ }
+
+ /* clean up the result, removing the simplified ones */
+ list = revs->commits;
+ revs->commits = NULL;
+ tail = &revs->commits;
+ while (list) {
+ struct merge_simplify_state *st;
+
+ commit = pop_commit(&list);
+ st = locate_simplify_state(revs, commit);
+ if (st->simplified == commit)
+ tail = &commit_list_insert(commit, tail)->next;
+ }
+}
+
+static void set_children(struct rev_info *revs)
+{
+ struct commit_list *l;
+ for (l = revs->commits; l; l = l->next) {
+ struct commit *commit = l->item;
+ struct commit_list *p;
+
+ for (p = commit->parents; p; p = p->next)
+ add_child(revs, p->item, commit);
+ }
+}
+
+void reset_revision_walk(void)
+{
+ clear_object_flags(SEEN | ADDED | SHOWN | TOPO_WALK_EXPLORED | TOPO_WALK_INDEGREE);
+}
+
+static int mark_uninteresting(const struct object_id *oid,
+ struct packed_git *pack,
+ uint32_t pos,
+ void *cb)
+{
+ struct rev_info *revs = cb;
+ struct object *o = parse_object(revs->repo, oid);
+ o->flags |= UNINTERESTING | SEEN;
+ return 0;
+}
+
+define_commit_slab(indegree_slab, int);
+define_commit_slab(author_date_slab, timestamp_t);
+
+struct topo_walk_info {
+ uint32_t min_generation;
+ struct prio_queue explore_queue;
+ struct prio_queue indegree_queue;
+ struct prio_queue topo_queue;
+ struct indegree_slab indegree;
+ struct author_date_slab author_date;
+};
+
+static inline void test_flag_and_insert(struct prio_queue *q, struct commit *c, int flag)
+{
+ if (c->object.flags & flag)
+ return;
+
+ c->object.flags |= flag;
+ prio_queue_put(q, c);
+}
+
+static void explore_walk_step(struct rev_info *revs)
+{
+ struct topo_walk_info *info = revs->topo_walk_info;
+ struct commit_list *p;
+ struct commit *c = prio_queue_get(&info->explore_queue);
+
+ if (!c)
+ return;
+
+ if (repo_parse_commit_gently(revs->repo, c, 1) < 0)
+ return;
+
+ if (revs->sort_order == REV_SORT_BY_AUTHOR_DATE)
+ record_author_date(&info->author_date, c);
+
+ if (revs->max_age != -1 && (c->date < revs->max_age))
+ c->object.flags |= UNINTERESTING;
+
+ if (process_parents(revs, c, NULL, NULL) < 0)
+ return;
+
+ if (c->object.flags & UNINTERESTING)
+ mark_parents_uninteresting(c);
+
+ for (p = c->parents; p; p = p->next)
+ test_flag_and_insert(&info->explore_queue, p->item, TOPO_WALK_EXPLORED);
+}
+
+static void explore_to_depth(struct rev_info *revs,
+ uint32_t gen_cutoff)
+{
+ struct topo_walk_info *info = revs->topo_walk_info;
+ struct commit *c;
+ while ((c = prio_queue_peek(&info->explore_queue)) &&
+ commit_graph_generation(c) >= gen_cutoff)
+ explore_walk_step(revs);
+}
+
+static void indegree_walk_step(struct rev_info *revs)
+{
+ struct commit_list *p;
+ struct topo_walk_info *info = revs->topo_walk_info;
+ struct commit *c = prio_queue_get(&info->indegree_queue);
+
+ if (!c)
+ return;
+
+ if (repo_parse_commit_gently(revs->repo, c, 1) < 0)
+ return;
+
+ explore_to_depth(revs, commit_graph_generation(c));
+
+ for (p = c->parents; p; p = p->next) {
+ struct commit *parent = p->item;
+ int *pi = indegree_slab_at(&info->indegree, parent);
+
+ if (*pi)
+ (*pi)++;
+ else
+ *pi = 2;
+
+ test_flag_and_insert(&info->indegree_queue, parent, TOPO_WALK_INDEGREE);
+
+ if (revs->first_parent_only)
+ return;
+ }
+}
+
+static void compute_indegrees_to_depth(struct rev_info *revs,
+ uint32_t gen_cutoff)
+{
+ struct topo_walk_info *info = revs->topo_walk_info;
+ struct commit *c;
+ while ((c = prio_queue_peek(&info->indegree_queue)) &&
+ commit_graph_generation(c) >= gen_cutoff)
+ indegree_walk_step(revs);
+}
+
+static void reset_topo_walk(struct rev_info *revs)
+{
+ struct topo_walk_info *info = revs->topo_walk_info;
+
+ clear_prio_queue(&info->explore_queue);
+ clear_prio_queue(&info->indegree_queue);
+ clear_prio_queue(&info->topo_queue);
+ clear_indegree_slab(&info->indegree);
+ clear_author_date_slab(&info->author_date);
+
+ FREE_AND_NULL(revs->topo_walk_info);
+}
+
+static void init_topo_walk(struct rev_info *revs)
+{
+ struct topo_walk_info *info;
+ struct commit_list *list;
+ if (revs->topo_walk_info)
+ reset_topo_walk(revs);
+
+ revs->topo_walk_info = xmalloc(sizeof(struct topo_walk_info));
+ info = revs->topo_walk_info;
+ memset(info, 0, sizeof(struct topo_walk_info));
+
+ init_indegree_slab(&info->indegree);
+ memset(&info->explore_queue, 0, sizeof(info->explore_queue));
+ memset(&info->indegree_queue, 0, sizeof(info->indegree_queue));
+ memset(&info->topo_queue, 0, sizeof(info->topo_queue));
+
+ switch (revs->sort_order) {
+ default: /* REV_SORT_IN_GRAPH_ORDER */
+ info->topo_queue.compare = NULL;
+ break;
+ case REV_SORT_BY_COMMIT_DATE:
+ info->topo_queue.compare = compare_commits_by_commit_date;
+ break;
+ case REV_SORT_BY_AUTHOR_DATE:
+ init_author_date_slab(&info->author_date);
+ info->topo_queue.compare = compare_commits_by_author_date;
+ info->topo_queue.cb_data = &info->author_date;
+ break;