Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 3964 insertions, 0 deletions

diff --git a/revision.c b/revision.c
new file mode 100644
index 000000000000..07412297f024
--- /dev/null
+++ b/revision.c
@@ -0,0 +1,3964 @@
+#include "cache.h"
+#include "object-store.h"
+#include "tag.h"
+#include "blob.h"
+#include "tree.h"
+#include "commit.h"
+#include "diff.h"
+#include "refs.h"
+#include "revision.h"
+#include "repository.h"
+#include "graph.h"
+#include "grep.h"
+#include "reflog-walk.h"
+#include "patch-ids.h"
+#include "decorate.h"
+#include "log-tree.h"
+#include "string-list.h"
+#include "line-log.h"
+#include "mailmap.h"
+#include "commit-slab.h"
+#include "dir.h"
+#include "cache-tree.h"
+#include "bisect.h"
+#include "packfile.h"
+#include "worktree.h"
+#include "argv-array.h"
+#include "commit-reach.h"
+#include "commit-graph.h"
+#include "prio-queue.h"
+#include "hashmap.h"
+
+volatile show_early_output_fn_t show_early_output;
+
+static const char *term_bad;
+static const char *term_good;
+
+implement_shared_commit_slab(revision_sources, char *);
+
+void show_object_with_name(FILE *out, struct object *obj, const char *name)
+{
+	const char *p;
+
+	fprintf(out, "%s ", oid_to_hex(&obj->oid));
+	for (p = name; *p && *p != '\n'; p++)
+		fputc(*p, out);
+	fputc('\n', out);
+}
+
+static void mark_blob_uninteresting(struct blob *blob)
+{
+	if (!blob)
+		return;
+	if (blob->object.flags & UNINTERESTING)
+		return;
+	blob->object.flags |= UNINTERESTING;
+}
+
+static void mark_tree_contents_uninteresting(struct repository *r,
+					     struct tree *tree)
+{
+	struct tree_desc desc;
+	struct name_entry entry;
+
+	if (parse_tree_gently(tree, 1) < 0)
+		return;
+
+	init_tree_desc(&desc, tree->buffer, tree->size);
+	while (tree_entry(&desc, &entry)) {
+		switch (object_type(entry.mode)) {
+		case OBJ_TREE:
+			mark_tree_uninteresting(r, lookup_tree(r, &entry.oid));
+			break;
+		case OBJ_BLOB:
+			mark_blob_uninteresting(lookup_blob(r, &entry.oid));
+			break;
+		default:
+			/* Subproject commit - not in this repository */
+			break;
+		}
+	}
+
+	/*
+	 * We don't care about the tree any more
+	 * after it has been marked uninteresting.
+	 */
+	free_tree_buffer(tree);
+}
+
+void mark_tree_uninteresting(struct repository *r, struct tree *tree)
+{
+	struct object *obj;
+
+	if (!tree)
+		return;
+
+	obj = &tree->object;
+	if (obj->flags & UNINTERESTING)
+		return;
+	obj->flags |= UNINTERESTING;
+	mark_tree_contents_uninteresting(r, tree);
+}
+
+struct path_and_oids_entry {
+	struct hashmap_entry ent;
+	char *path;
+	struct oidset trees;
+};
+
+static int path_and_oids_cmp(const void *hashmap_cmp_fn_data,
+			     const struct path_and_oids_entry *e1,
+			     const struct path_and_oids_entry *e2,
+			     const void *keydata)
+{
+	return strcmp(e1->path, e2->path);
+}
+
+static void paths_and_oids_init(struct hashmap *map)
+{
+	hashmap_init(map, (hashmap_cmp_fn) path_and_oids_cmp, NULL, 0);
+}
+
+static void paths_and_oids_clear(struct hashmap *map)
+{
+	struct hashmap_iter iter;
+	struct path_and_oids_entry *entry;
+	hashmap_iter_init(map, &iter);
+
+	while ((entry = (struct path_and_oids_entry *)hashmap_iter_next(&iter))) {
+		oidset_clear(&entry->trees);
+		free(entry->path);
+	}
+
+	hashmap_free(map, 1);
+}
+
+static void paths_and_oids_insert(struct hashmap *map,
+				  const char *path,
+				  const struct object_id *oid)
+{
+	int hash = strhash(path);
+	struct path_and_oids_entry key;
+	struct path_and_oids_entry *entry;
+
+	hashmap_entry_init(&key, hash);
+
+	/* use a shallow copy for the lookup */
+	key.path = (char *)path;
+	oidset_init(&key.trees, 0);
+
+	if (!(entry = (struct path_and_oids_entry *)hashmap_get(map, &key, NULL))) {
+		entry = xcalloc(1, sizeof(struct path_and_oids_entry));
+		hashmap_entry_init(entry, hash);
+		entry->path = xstrdup(key.path);
+		oidset_init(&entry->trees, 16);
+		hashmap_put(map, entry);
+	}
+
+	oidset_insert(&entry->trees, oid);
+}
+
+static void add_children_by_path(struct repository *r,
+				 struct tree *tree,
+				 struct hashmap *map)
+{
+	struct tree_desc desc;
+	struct name_entry entry;
+
+	if (!tree)
+		return;
+
+	if (parse_tree_gently(tree, 1) < 0)
+		return;
+
+	init_tree_desc(&desc, tree->buffer, tree->size);
+	while (tree_entry(&desc, &entry)) {
+		switch (object_type(entry.mode)) {
+		case OBJ_TREE:
+			paths_and_oids_insert(map, entry.path, &entry.oid);
+
+			if (tree->object.flags & UNINTERESTING) {
+				struct tree *child = lookup_tree(r, &entry.oid);
+				if (child)
+					child->object.flags |= UNINTERESTING;
+			}
+			break;
+		case OBJ_BLOB:
+			if (tree->object.flags & UNINTERESTING) {
+				struct blob *child = lookup_blob(r, &entry.oid);
+				if (child)
+					child->object.flags |= UNINTERESTING;
+			}
+			break;
+		default:
+			/* Subproject commit - not in this repository */
+			break;
+		}
+	}
+
+	free_tree_buffer(tree);
+}
+
+void mark_trees_uninteresting_sparse(struct repository *r,
+				     struct oidset *trees)
+{
+	unsigned has_interesting = 0, has_uninteresting = 0;
+	struct hashmap map;
+	struct hashmap_iter map_iter;
+	struct path_and_oids_entry *entry;
+	struct object_id *oid;
+	struct oidset_iter iter;
+
+	oidset_iter_init(trees, &iter);
+	while ((!has_interesting || !has_uninteresting) &&
+	       (oid = oidset_iter_next(&iter))) {
+		struct tree *tree = lookup_tree(r, oid);
+
+		if (!tree)
+			continue;
+
+		if (tree->object.flags & UNINTERESTING)
+			has_uninteresting = 1;
+		else
+			has_interesting = 1;
+	}
+
+	/* Do not walk unless we have both types of trees. */
+	if (!has_uninteresting || !has_interesting)
+		return;
+
+	paths_and_oids_init(&map);
+
+	oidset_iter_init(trees, &iter);
+	while ((oid = oidset_iter_next(&iter))) {
+		struct tree *tree = lookup_tree(r, oid);
+		add_children_by_path(r, tree, &map);
+	}
+
+	hashmap_iter_init(&map, &map_iter);
+	while ((entry = hashmap_iter_next(&map_iter)))
+		mark_trees_uninteresting_sparse(r, &entry->trees);
+
+	paths_and_oids_clear(&map);
+}
+
+struct commit_stack {
+	struct commit **items;
+	size_t nr, alloc;
+};
+#define COMMIT_STACK_INIT { NULL, 0, 0 }
+
+static void commit_stack_push(struct commit_stack *stack, struct commit *commit)
+{
+	ALLOC_GROW(stack->items, stack->nr + 1, stack->alloc);
+	stack->items[stack->nr++] = commit;
+}
+
+static struct commit *commit_stack_pop(struct commit_stack *stack)
+{
+	return stack->nr ? stack->items[--stack->nr] : NULL;
+}
+
+static void commit_stack_clear(struct commit_stack *stack)
+{
+	FREE_AND_NULL(stack->items);
+	stack->nr = stack->alloc = 0;
+}
+
+static void mark_one_parent_uninteresting(struct commit *commit,
+					  struct commit_stack *pending)
+{
+	struct commit_list *l;
+
+	if (commit->object.flags & UNINTERESTING)
+		return;
+	commit->object.flags |= UNINTERESTING;
+
+	/*
+	 * Normally we haven't parsed the parent
+	 * yet, so we won't have a parent of a parent
+	 * here. However, it may turn out that we've
+	 * reached this commit some other way (where it
+	 * wasn't uninteresting), in which case we need
+	 * to mark its parents recursively too..
+	 */
+	for (l = commit->parents; l; l = l->next)
+		commit_stack_push(pending, l->item);
+}
+
+void mark_parents_uninteresting(struct commit *commit)
+{
+	struct commit_stack pending = COMMIT_STACK_INIT;
+	struct commit_list *l;
+
+	for (l = commit->parents; l; l = l->next)
+		mark_one_parent_uninteresting(l->item, &pending);
+
+	while (pending.nr > 0)
+		mark_one_parent_uninteresting(commit_stack_pop(&pending),
+					      &pending);
+
+	commit_stack_clear(&pending);
+}
+
+static void add_pending_object_with_path(struct rev_info *revs,
+					 struct object *obj,
+					 const char *name, unsigned mode,
+					 const char *path)
+{
+	if (!obj)
+		return;
+	if (revs->no_walk && (obj->flags & UNINTERESTING))
+		revs->no_walk = 0;
+	if (revs->reflog_info && obj->type == OBJ_COMMIT) {
+		struct strbuf buf = STRBUF_INIT;
+		int len = interpret_branch_name(name, 0, &buf, 0);
+
+		if (0 < len && name[len] && buf.len)
+			strbuf_addstr(&buf, name + len);
+		add_reflog_for_walk(revs->reflog_info,
+				    (struct commit *)obj,
+				    buf.buf[0] ? buf.buf: name);
+		strbuf_release(&buf);
+		return; /* do not add the commit itself */
+	}
+	add_object_array_with_path(obj, name, &revs->pending, mode, path);
+}
+
+static void add_pending_object_with_mode(struct rev_info *revs,
+					 struct object *obj,
+					 const char *name, unsigned mode)
+{
+	add_pending_object_with_path(revs, obj, name, mode, NULL);
+}
+
+void add_pending_object(struct rev_info *revs,
+			struct object *obj, const char *name)
+{
+	add_pending_object_with_mode(revs, obj, name, S_IFINVALID);
+}
+
+void add_head_to_pending(struct rev_info *revs)
+{
+	struct object_id oid;
+	struct object *obj;
+	if (get_oid("HEAD", &oid))
+		return;
+	obj = parse_object(revs->repo, &oid);
+	if (!obj)
+		return;
+	add_pending_object(revs, obj, "HEAD");
+}
+
+static struct object *get_reference(struct rev_info *revs, const char *name,
+				    const struct object_id *oid,
+				    unsigned int flags)
+{
+	struct object *object;
+
+	/*
+	 * If the repository has commit graphs, repo_parse_commit() avoids
+	 * reading the object buffer, so use it whenever possible.
+	 */
+	if (oid_object_info(revs->repo, oid, NULL) == OBJ_COMMIT) {
+		struct commit *c = lookup_commit(revs->repo, oid);
+		if (!repo_parse_commit(revs->repo, c))
+			object = (struct object *) c;
+		else
+			object = NULL;
+	} else {
+		object = parse_object(revs->repo, oid);
+	}
+
+	if (!object) {
+		if (revs->ignore_missing)
+			return object;
+		if (revs->exclude_promisor_objects && is_promisor_object(oid))
+			return NULL;
+		die("bad object %s", name);
+	}
+	object->flags |= flags;
+	return object;
+}
+
+void add_pending_oid(struct rev_info *revs, const char *name,
+		      const struct object_id *oid, unsigned int flags)
+{
+	struct object *object = get_reference(revs, name, oid, flags);
+	add_pending_object(revs, object, name);
+}
+
+static struct commit *handle_commit(struct rev_info *revs,
+				    struct object_array_entry *entry)
+{
+	struct object *object = entry->item;
+	const char *name = entry->name;
+	const char *path = entry->path;
+	unsigned int mode = entry->mode;
+	unsigned long flags = object->flags;
+
+	/*
+	 * Tag object? Look what it points to..
+	 */
+	while (object->type == OBJ_TAG) {
+		struct tag *tag = (struct tag *) object;
+		if (revs->tag_objects && !(flags & UNINTERESTING))
+			add_pending_object(revs, object, tag->tag);
+		if (!tag->tagged)
+			die("bad tag");
+		object = parse_object(revs->repo, &tag->tagged->oid);
+		if (!object) {
+			if (revs->ignore_missing_links || (flags & UNINTERESTING))
+				return NULL;
+			if (revs->exclude_promisor_objects &&
+			    is_promisor_object(&tag->tagged->oid))
+				return NULL;
+			die("bad object %s", oid_to_hex(&tag->tagged->oid));
+		}
+		object->flags |= flags;
+		/*
+		 * We'll handle the tagged object by looping or dropping
+		 * through to the non-tag handlers below. Do not
+		 * propagate path data from the tag's pending entry.
+		 */
+		path = NULL;
+		mode = 0;
+	}
+
+	/*
+	 * Commit object? Just return it, we'll do all the complex
+	 * reachability crud.
+	 */
+	if (object->type == OBJ_COMMIT) {
+		struct commit *commit = (struct commit *)object;
+
+		if (parse_commit(commit) < 0)
+			die("unable to parse commit %s", name);
+		if (flags & UNINTERESTING) {
+			mark_parents_uninteresting(commit);
+
+			if (!revs->topo_order || !generation_numbers_enabled(the_repository))
+				revs->limited = 1;
+		}
+		if (revs->sources) {
+			char **slot = revision_sources_at(revs->sources, commit);
+
+			if (!*slot)
+				*slot = xstrdup(name);
+		}
+		return commit;
+	}
+
+	/*
+	 * Tree object? Either mark it uninteresting, or add it
+	 * to the list of objects to look at later..
+	 */
+	if (object->type == OBJ_TREE) {
+		struct tree *tree = (struct tree *)object;
+		if (!revs->tree_objects)
+			return NULL;
+		if (flags & UNINTERESTING) {
+			mark_tree_contents_uninteresting(revs->repo, tree);
+			return NULL;
+		}
+		add_pending_object_with_path(revs, object, name, mode, path);
+		return NULL;
+	}
+
+	/*
+	 * Blob object? You know the drill by now..
+	 */
+	if (object->type == OBJ_BLOB) {
+		if (!revs->blob_objects)
+			return NULL;
+		if (flags & UNINTERESTING)
+			return NULL;
+		add_pending_object_with_path(revs, object, name, mode, path);
+		return NULL;
+	}
+	die("%s is unknown object", name);
+}
+
+static int everybody_uninteresting(struct commit_list *orig,
+				   struct commit **interesting_cache)
+{
+	struct commit_list *list = orig;
+
+	if (*interesting_cache) {
+		struct commit *commit = *interesting_cache;
+		if (!(commit->object.flags & UNINTERESTING))
+			return 0;
+	}
+
+	while (list) {
+		struct commit *commit = list->item;
+		list = list->next;
+		if (commit->object.flags & UNINTERESTING)
+			continue;
+
+		*interesting_cache = commit;
+		return 0;
+	}
+	return 1;
+}
+
+/*
+ * A definition of "relevant" commit that we can use to simplify limited graphs
+ * by eliminating side branches.
+ *
+ * A "relevant" commit is one that is !UNINTERESTING (ie we are including it
+ * in our list), or that is a specified BOTTOM commit. Then after computing
+ * a limited list, during processing we can generally ignore boundary merges
+ * coming from outside the graph, (ie from irrelevant parents), and treat
+ * those merges as if they were single-parent. TREESAME is defined to consider
+ * only relevant parents, if any. If we are TREESAME to our on-graph parents,
+ * we don't care if we were !TREESAME to non-graph parents.
+ *
+ * Treating bottom commits as relevant ensures that a limited graph's
+ * connection to the actual bottom commit is not viewed as a side branch, but
+ * treated as part of the graph. For example:
+ *
+ *   ....Z...A---X---o---o---B
+ *        .     /
+ *         W---Y
+ *
+ * When computing "A..B", the A-X connection is at least as important as
+ * Y-X, despite A being flagged UNINTERESTING.
+ *
+ * And when computing --ancestry-path "A..B", the A-X connection is more
+ * important than Y-X, despite both A and Y being flagged UNINTERESTING.
+ */
+static inline int relevant_commit(struct commit *commit)
+{
+	return (commit->object.flags & (UNINTERESTING | BOTTOM)) != UNINTERESTING;
+}
+
+/*
+ * Return a single relevant commit from a parent list. If we are a TREESAME
+ * commit, and this selects one of our parents, then we can safely simplify to
+ * that parent.
+ */
+static struct commit *one_relevant_parent(const struct rev_info *revs,
+					  struct commit_list *orig)
+{
+	struct commit_list *list = orig;
+	struct commit *relevant = NULL;
+
+	if (!orig)
+		return NULL;
+
+	/*
+	 * For 1-parent commits, or if first-parent-only, then return that
+	 * first parent (even if not "relevant" by the above definition).
+	 * TREESAME will have been set purely on that parent.
+	 */
+	if (revs->first_parent_only || !orig->next)
+		return orig->item;
+
+	/*
+	 * For multi-parent commits, identify a sole relevant parent, if any.
+	 * If we have only one relevant parent, then TREESAME will be set purely
+	 * with regard to that parent, and we can simplify accordingly.
+	 *
+	 * If we have more than one relevant parent, or no relevant parents
+	 * (and multiple irrelevant ones), then we can't select a parent here
+	 * and return NULL.
+	 */
+	while (list) {
+		struct commit *commit = list->item;
+		list = list->next;
+		if (relevant_commit(commit)) {
+			if (relevant)
+				return NULL;
+			relevant = commit;
+		}
+	}
+	return relevant;
+}
+
+/*
+ * The goal is to get REV_TREE_NEW as the result only if the
+ * diff consists of all '+' (and no other changes), REV_TREE_OLD
+ * if the whole diff is removal of old data, and otherwise
+ * REV_TREE_DIFFERENT (of course if the trees are the same we
+ * want REV_TREE_SAME).
+ *
+ * The only time we care about the distinction is when
+ * remove_empty_trees is in effect, in which case we care only about
+ * whether the whole change is REV_TREE_NEW, or if there's another type
+ * of change. Which means we can stop the diff early in either of these
+ * cases:
+ *
+ *   1. We're not using remove_empty_trees at all.
+ *
+ *   2. We saw anything except REV_TREE_NEW.
+ */
+static int tree_difference = REV_TREE_SAME;
+
+static void file_add_remove(struct diff_options *options,
+		    int addremove, unsigned mode,
+		    const struct object_id *oid,
+		    int oid_valid,
+		    const char *fullpath, unsigned dirty_submodule)
+{
+	int diff = addremove == '+' ? REV_TREE_NEW : REV_TREE_OLD;
+	struct rev_info *revs = options->change_fn_data;
+
+	tree_difference |= diff;
+	if (!revs->remove_empty_trees || tree_difference != REV_TREE_NEW)
+		options->flags.has_changes = 1;
+}
+
+static void file_change(struct diff_options *options,
+		 unsigned old_mode, unsigned new_mode,
+		 const struct object_id *old_oid,
+		 const struct object_id *new_oid,
+		 int old_oid_valid, int new_oid_valid,
+		 const char *fullpath,
+		 unsigned old_dirty_submodule, unsigned new_dirty_submodule)
+{
+	tree_difference = REV_TREE_DIFFERENT;
+	options->flags.has_changes = 1;
+}
+
+static int rev_compare_tree(struct rev_info *revs,
+			    struct commit *parent, struct commit *commit)
+{
+	struct tree *t1 = get_commit_tree(parent);
+	struct tree *t2 = get_commit_tree(commit);
+
+	if (!t1)
+		return REV_TREE_NEW;
+	if (!t2)
+		return REV_TREE_OLD;
+
+	if (revs->simplify_by_decoration) {
+		/*
+		 * If we are simplifying by decoration, then the commit
+		 * is worth showing if it has a tag pointing at it.
+		 */
+		if (get_name_decoration(&commit->object))
+			return REV_TREE_DIFFERENT;
+		/*
+		 * A commit that is not pointed by a tag is uninteresting
+		 * if we are not limited by path.  This means that you will
+		 * see the usual "commits that touch the paths" plus any
+		 * tagged commit by specifying both --simplify-by-decoration
+		 * and pathspec.
+		 */
+		if (!revs->prune_data.nr)
+			return REV_TREE_SAME;
+	}
+
+	tree_difference = REV_TREE_SAME;
+	revs->pruning.flags.has_changes = 0;
+	if (diff_tree_oid(&t1->object.oid, &t2->object.oid, "",
+			   &revs->pruning) < 0)
+		return REV_TREE_DIFFERENT;
+	return tree_difference;
+}
+
+static int rev_same_tree_as_empty(struct rev_info *revs, struct commit *commit)
+{
+	int retval;
+	struct tree *t1 = get_commit_tree(commit);
+
+	if (!t1)
+		return 0;
+
+	tree_difference = REV_TREE_SAME;
+	revs->pruning.flags.has_changes = 0;
+	retval = diff_tree_oid(NULL, &t1->object.oid, "", &revs->pruning);
+
+	return retval >= 0 && (tree_difference == REV_TREE_SAME);
+}
+
+struct treesame_state {
+	unsigned int nparents;
+	unsigned char treesame[FLEX_ARRAY];
+};
+
+static struct treesame_state *initialise_treesame(struct rev_info *revs, struct commit *commit)
+{
+	unsigned n = commit_list_count(commit->parents);
+	struct treesame_state *st = xcalloc(1, st_add(sizeof(*st), n));
+	st->nparents = n;
+	add_decoration(&revs->treesame, &commit->object, st);
+	return st;
+}
+
+/*
+ * Must be called immediately after removing the nth_parent from a commit's
+ * parent list, if we are maintaining the per-parent treesame[] decoration.
+ * This does not recalculate the master TREESAME flag - update_treesame()
+ * should be called to update it after a sequence of treesame[] modifications
+ * that may have affected it.
+ */
+static int compact_treesame(struct rev_info *revs, struct commit *commit, unsigned nth_parent)
+{
+	struct treesame_state *st;
+	int old_same;
+
+	if (!commit->parents) {
+		/*
+		 * Have just removed the only parent from a non-merge.
+		 * Different handling, as we lack decoration.
+		 */
+		if (nth_parent != 0)
+			die("compact_treesame %u", nth_parent);
+		old_same = !!(commit->object.flags & TREESAME);
+		if (rev_same_tree_as_empty(revs, commit))
+			commit->object.flags |= TREESAME;
+		else
+			commit->object.flags &= ~TREESAME;
+		return old_same;
+	}
+
+	st = lookup_decoration(&revs->treesame, &commit->object);
+	if (!st || nth_parent >= st->nparents)
+		die("compact_treesame %u", nth_parent);
+
+	old_same = st->treesame[nth_parent];
+	memmove(st->treesame + nth_parent,
+		st->treesame + nth_parent + 1,
+		st->nparents - nth_parent - 1);
+
+	/*
+	 * If we've just become a non-merge commit, update TREESAME
+	 * immediately, and remove the no-longer-needed decoration.
+	 * If still a merge, defer update until update_treesame().
+	 */
+	if (--st->nparents == 1) {
+		if (commit->parents->next)
+			die("compact_treesame parents mismatch");
+		if (st->treesame[0] && revs->dense)
+			commit->object.flags |= TREESAME;
+		else
+			commit->object.flags &= ~TREESAME;
+		free(add_decoration(&revs->treesame, &commit->object, NULL));
+	}
+
+	return old_same;
+}
+
+static unsigned update_treesame(struct rev_info *revs, struct commit *commit)
+{
+	if (commit->parents && commit->parents->next) {
+		unsigned n;
+		struct treesame_state *st;
+		struct commit_list *p;
+		unsigned relevant_parents;
+		unsigned relevant_change, irrelevant_change;
+
+		st = lookup_decoration(&revs->treesame, &commit->object);
+		if (!st)
+			die("update_treesame %s", oid_to_hex(&commit->object.oid));
+		relevant_parents = 0;
+		relevant_change = irrelevant_change = 0;
+		for (p = commit->parents, n = 0; p; n++, p = p->next) {
+			if (relevant_commit(p->item)) {
+				relevant_change |= !st->treesame[n];
+				relevant_parents++;
+			} else
+				irrelevant_change |= !st->treesame[n];
+		}
+		if (relevant_parents ? relevant_change : irrelevant_change)
+			commit->object.flags &= ~TREESAME;
+		else
+			commit->object.flags |= TREESAME;
+	}
+
+	return commit->object.flags & TREESAME;
+}
+
+static inline int limiting_can_increase_treesame(const struct rev_info *revs)
+{
+	/*
+	 * TREESAME is irrelevant unless prune && dense;
+	 * if simplify_history is set, we can't have a mixture of TREESAME and
+	 *    !TREESAME INTERESTING parents (and we don't have treesame[]
+	 *    decoration anyway);
+	 * if first_parent_only is set, then the TREESAME flag is locked
+	 *    against the first parent (and again we lack treesame[] decoration).
+	 */
+	return revs->prune && revs->dense &&
+	       !revs->simplify_history &&
+	       !revs->first_parent_only;
+}
+
+static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
+{
+	struct commit_list **pp, *parent;
+	struct treesame_state *ts = NULL;
+	int relevant_change = 0, irrelevant_change = 0;
+	int relevant_parents, nth_parent;
+
+	/*
+	 * If we don't do pruning, everything is interesting
+	 */
+	if (!revs->prune)
+		return;
+
+	if (!get_commit_tree(commit))
+		return;
+
+	if (!commit->parents) {
+		if (rev_same_tree_as_empty(revs, commit))
+			commit->object.flags |= TREESAME;
+		return;
+	}
+
+	/*
+	 * Normal non-merge commit? If we don't want to make the
+	 * history dense, we consider it always to be a change..
+	 */
+	if (!revs->dense && !commit->parents->next)
+		return;
+
+	for (pp = &commit->parents, nth_parent = 0, relevant_parents = 0;
+	     (parent = *pp) != NULL;
+	     pp = &parent->next, nth_parent++) {
+		struct commit *p = parent->item;
+		if (relevant_commit(p))
+			relevant_parents++;
+
+		if (nth_parent == 1) {
+			/*
+			 * This our second loop iteration - so we now know
+			 * we're dealing with a merge.
+			 *
+			 * Do not compare with later parents when we care only about
+			 * the first parent chain, in order to avoid derailing the
+			 * traversal to follow a side branch that brought everything
+			 * in the path we are limited to by the pathspec.
+			 */
+			if (revs->first_parent_only)
+				break;
+			/*
+			 * If this will remain a potentially-simplifiable
+			 * merge, remember per-parent treesame if needed.
+			 * Initialise the array with the comparison from our
+			 * first iteration.
+			 */
+			if (revs->treesame.name &&
+			    !revs->simplify_history &&
+			    !(commit->object.flags & UNINTERESTING)) {
+				ts = initialise_treesame(revs, commit);
+				if (!(irrelevant_change || relevant_change))
+					ts->treesame[0] = 1;
+			}
+		}
+		if (parse_commit(p) < 0)
+			die("cannot simplify commit %s (because of %s)",
+			    oid_to_hex(&commit->object.oid),
+			    oid_to_hex(&p->object.oid));
+		switch (rev_compare_tree(revs, p, commit)) {
+		case REV_TREE_SAME:
+			if (!revs->simplify_history || !relevant_commit(p)) {
+				/* Even if a merge with an uninteresting
+				 * side branch brought the entire change
+				 * we are interested in, we do not want
+				 * to lose the other branches of this
+				 * merge, so we just keep going.
+				 */
+				if (ts)
+					ts->treesame[nth_parent] = 1;
+				continue;
+			}
+			parent->next = NULL;
+			commit->parents = parent;
+			commit->object.flags |= TREESAME;
+			return;
+
+		case REV_TREE_NEW:
+			if (revs->remove_empty_trees &&
+			    rev_same_tree_as_empty(revs, p)) {
+				/* We are adding all the specified
+				 * paths from this parent, so the
+				 * history beyond this parent is not
+				 * interesting.  Remove its parents
+				 * (they are grandparents for us).
+				 * IOW, we pretend this parent is a
+				 * "root" commit.
+				 */
+				if (parse_commit(p) < 0)
+					die("cannot simplify commit %s (invalid %s)",
+					    oid_to_hex(&commit->object.oid),
+					    oid_to_hex(&p->object.oid));
+				p->parents = NULL;
+			}
+		/* fallthrough */
+		case REV_TREE_OLD:
+		case REV_TREE_DIFFERENT:
+			if (relevant_commit(p))
+				relevant_change = 1;
+			else
+				irrelevant_change = 1;
+			continue;
+		}
+		die("bad tree compare for commit %s", oid_to_hex(&commit->object.oid));
+	}
+
+	/*
+	 * TREESAME is straightforward for single-parent commits. For merge
+	 * commits, it is most useful to define it so that "irrelevant"
+	 * parents cannot make us !TREESAME - if we have any relevant
+	 * parents, then we only consider TREESAMEness with respect to them,
+	 * allowing irrelevant merges from uninteresting branches to be
+	 * simplified away. Only if we have only irrelevant parents do we
+	 * base TREESAME on them. Note that this logic is replicated in
+	 * update_treesame, which should be kept in sync.
+	 */
+	if (relevant_parents ? !relevant_change : !irrelevant_change)
+		commit->object.flags |= TREESAME;
+}
+
+static int process_parents(struct rev_info *revs, struct commit *commit,
+			   struct commit_list **list, struct prio_queue *queue)
+{
+	struct commit_list *parent = commit->parents;
+	unsigned left_flag;
+
+	if (commit->object.flags & ADDED)
+		return 0;
+	commit->object.flags |= ADDED;
+
+	if (revs->include_check &&
+	    !revs->include_check(commit, revs->include_check_data))
+		return 0;
+
+	/*
+	 * If the commit is uninteresting, don't try to
+	 * prune parents - we want the maximal uninteresting
+	 * set.
+	 *
+	 * Normally we haven't parsed the parent
+	 * yet, so we won't have a parent of a parent
+	 * here. However, it may turn out that we've
+	 * reached this commit some other way (where it
+	 * wasn't uninteresting), in which case we need
+	 * to mark its parents recursively too..
+	 */
+	if (commit->object.flags & UNINTERESTING) {
+		while (parent) {
+			struct commit *p = parent->item;
+			parent = parent->next;
+			if (p)
+				p->object.flags |= UNINTERESTING;
+			if (parse_commit_gently(p, 1) < 0)
+				continue;
+			if (p->parents)
+				mark_parents_uninteresting(p);
+			if (p->object.flags & SEEN)
+				continue;
+			p->object.flags |= SEEN;
+			if (list)
+				commit_list_insert_by_date(p, list);
+			if (queue)
+				prio_queue_put(queue, p);
+		}
+		return 0;
+	}
+
+	/*
+	 * Ok, the commit wasn't uninteresting. Try to
+	 * simplify the commit history and find the parent
+	 * that has no differences in the path set if one exists.
+	 */
+	try_to_simplify_commit(revs, commit);
+
+	if (revs->no_walk)
+		return 0;
+
+	left_flag = (commit->object.flags & SYMMETRIC_LEFT);
+
+	for (parent = commit->parents; parent; parent = parent->next) {
+		struct commit *p = parent->item;
+		int gently = revs->ignore_missing_links ||
+			     revs->exclude_promisor_objects;
+		if (parse_commit_gently(p, gently) < 0) {
+			if (revs->exclude_promisor_objects &&
+			    is_promisor_object(&p->object.oid)) {
+				if (revs->first_parent_only)
+					break;
+				continue;
+			}
+			return -1;
+		}
+		if (revs->sources) {
+			char **slot = revision_sources_at(revs->sources, p);
+
+			if (!*slot)
+				*slot = *revision_sources_at(revs->sources, commit);
+		}
+		p->object.flags |= left_flag;
+		if (!(p->object.flags & SEEN)) {
+			p->object.flags |= SEEN;
+			if (list)
+				commit_list_insert_by_date(p, list);
+			if (queue)
+				prio_queue_put(queue, p);
+		}
+		if (revs->first_parent_only)
+			break;
+	}
+	return 0;
+}
+
+static void cherry_pick_list(struct commit_list *list, struct rev_info *revs)
+{
+	struct commit_list *p;
+	int left_count = 0, right_count = 0;
+	int left_first;
+	struct patch_ids ids;
+	unsigned cherry_flag;
+
+	/* First count the commits on the left and on the right */
+	for (p = list; p; p = p->next) {
+		struct commit *commit = p->item;
+		unsigned flags = commit->object.flags;
+		if (flags & BOUNDARY)
+			;
+		else if (flags & SYMMETRIC_LEFT)
+			left_count++;
+		else
+			right_count++;
+	}
+
+	if (!left_count || !right_count)
+		return;
+
+	left_first = left_count < right_count;
+	init_patch_ids(revs->repo, &ids);
+	ids.diffopts.pathspec = revs->diffopt.pathspec;
+
+	/* Compute patch-ids for one side */
+	for (p = list; p; p = p->next) {
+		struct commit *commit = p->item;
+		unsigned flags = commit->object.flags;
+
+		if (flags & BOUNDARY)
+			continue;
+		/*
+		 * If we have fewer left, left_first is set and we omit
+		 * commits on the right branch in this loop.  If we have
+		 * fewer right, we skip the left ones.
+		 */
+		if (left_first != !!(flags & SYMMETRIC_LEFT))
+			continue;
+		add_commit_patch_id(commit, &ids);
+	}
+
+	/* either cherry_mark or cherry_pick are true */
+	cherry_flag = revs->cherry_mark ? PATCHSAME : SHOWN;
+
+	/* Check the other side */
+	for (p = list; p; p = p->next) {
+		struct commit *commit = p->item;
+		struct patch_id *id;
+		unsigned flags = commit->object.flags;
+
+		if (flags & BOUNDARY)
+			continue;
+		/*
+		 * If we have fewer left, left_first is set and we omit
+		 * commits on the left branch in this loop.
+		 */
+		if (left_first == !!(flags & SYMMETRIC_LEFT))
+			continue;
+
+		/*
+		 * Have we seen the same patch id?
+		 */
+		id = has_commit_patch_id(commit, &ids);
+		if (!id)
+			continue;
+
+		commit->object.flags |= cherry_flag;
+		id->commit->object.flags |= cherry_flag;
+	}
+
+	free_patch_ids(&ids);
+}
+
+/* How many extra uninteresting commits we want to see.. */
+#define SLOP 5
+
+static int still_interesting(struct commit_list *src, timestamp_t date, int slop,
+			     struct commit **interesting_cache)
+{
+	/*
+	 * No source list at all? We're definitely done..
+	 */
+	if (!src)
+		return 0;
+
+	/*
+	 * Does the destination list contain entries with a date
+	 * before the source list? Definitely _not_ done.
+	 */
+	if (date <= src->item->date)
+		return SLOP;
+
+	/*
+	 * Does the source list still have interesting commits in
+	 * it? Definitely not done..
+	 */
+	if (!everybody_uninteresting(src, interesting_cache))
+		return SLOP;
+
+	/* Ok, we're closing in.. */
+	return slop-1;
+}
+
+/*
+ * "rev-list --ancestry-path A..B" computes commits that are ancestors
+ * of B but not ancestors of A but further limits the result to those
+ * that are descendants of A.  This takes the list of bottom commits and
+ * the result of "A..B" without --ancestry-path, and limits the latter
+ * further to the ones that can reach one of the commits in "bottom".
+ */
+static void limit_to_ancestry(struct commit_list *bottom, struct commit_list *list)
+{
+	struct commit_list *p;
+	struct commit_list *rlist = NULL;
+	int made_progress;
+
+	/*
+	 * Reverse the list so that it will be likely that we would
+	 * process parents before children.
+	 */
+	for (p = list; p; p = p->next)
+		commit_list_insert(p->item, &rlist);
+
+	for (p = bottom; p; p = p->next)
+		p->item->object.flags |= TMP_MARK;
+
+	/*
+	 * Mark the ones that can reach bottom commits in "list",
+	 * in a bottom-up fashion.
+	 */
+	do {
+		made_progress = 0;
+		for (p = rlist; p; p = p->next) {
+			struct commit *c = p->item;
+			struct commit_list *parents;
+			if (c->object.flags & (TMP_MARK | UNINTERESTING))
+				continue;
+			for (parents = c->parents;
+			     parents;
+			     parents = parents->next) {
+				if (!(parents->item->object.flags & TMP_MARK))
+					continue;
+				c->object.flags |= TMP_MARK;
+				made_progress = 1;
+				break;
+			}
+		}
+	} while (made_progress);
+
+	/*
+	 * NEEDSWORK: decide if we want to remove parents that are
+	 * not marked with TMP_MARK from commit->parents for commits
+	 * in the resulting list.  We may not want to do that, though.
+	 */
+
+	/*
+	 * The ones that are not marked with TMP_MARK are uninteresting
+	 */
+	for (p = list; p; p = p->next) {
+		struct commit *c = p->item;
+		if (c->object.flags & TMP_MARK)
+			continue;
+		c->object.flags |= UNINTERESTING;
+	}
+
+	/* We are done with the TMP_MARK */
+	for (p = list; p; p = p->next)
+		p->item->object.flags &= ~TMP_MARK;
+	for (p = bottom; p; p = p->next)
+		p->item->object.flags &= ~TMP_MARK;
+	free_commit_list(rlist);
+}
+
+/*
+ * Before walking the history, keep the set of "negative" refs the
+ * caller has asked to exclude.
+ *
+ * This is used to compute "rev-list --ancestry-path A..B", as we need
+ * to filter the result of "A..B" further to the ones that can actually
+ * reach A.
+ */
+static struct commit_list *collect_bottom_commits(struct commit_list *list)
+{
+	struct commit_list *elem, *bottom = NULL;
+	for (elem = list; elem; elem = elem->next)
+		if (elem->item->object.flags & BOTTOM)
+			commit_list_insert(elem->item, &bottom);
+	return bottom;
+}
+
+/* Assumes either left_only or right_only is set */
+static void limit_left_right(struct commit_list *list, struct rev_info *revs)
+{
+	struct commit_list *p;
+
+	for (p = list; p; p = p->next) {
+		struct commit *commit = p->item;
+
+		if (revs->right_only) {
+			if (commit->object.flags & SYMMETRIC_LEFT)
+				commit->object.flags |= SHOWN;
+		} else	/* revs->left_only is set */
+			if (!(commit->object.flags & SYMMETRIC_LEFT))
+				commit->object.flags |= SHOWN;
+	}
+}
+
+static int limit_list(struct rev_info *revs)
+{
+	int slop = SLOP;
+	timestamp_t date = TIME_MAX;
+	struct commit_list *list = revs->commits;
+	struct commit_list *newlist = NULL;
+	struct commit_list **p = &newlist;
+	struct commit_list *bottom = NULL;
+	struct commit *interesting_cache = NULL;
+
+	if (revs->ancestry_path) {
+		bottom = collect_bottom_commits(list);
+		if (!bottom)
+			die("--ancestry-path given but there are no bottom commits");
+	}
+
+	while (list) {
+		struct commit *commit = pop_commit(&list);
+		struct object *obj = &commit->object;
+		show_early_output_fn_t show;
+
+		if (commit == interesting_cache)
+			interesting_cache = NULL;
+
+		if (revs->max_age != -1 && (commit->date < revs->max_age))
+			obj->flags |= UNINTERESTING;
+		if (process_parents(revs, commit, &list, NULL) < 0)
+			return -1;
+		if (obj->flags & UNINTERESTING) {
+			mark_parents_uninteresting(commit);
+			slop = still_interesting(list, date, slop, &interesting_cache);
+			if (slop)
+				continue;
+			break;
+		}
+		if (revs->min_age != -1 && (commit->date > revs->min_age))
+			continue;
+		date = commit->date;
+		p = &commit_list_insert(commit, p)->next;
+
+		show = show_early_output;
+		if (!show)
+			continue;
+
+		show(revs, newlist);
+		show_early_output = NULL;
+	}
+	if (revs->cherry_pick || revs->cherry_mark)
+		cherry_pick_list(newlist, revs);
+
+	if (revs->left_only || revs->right_only)
+		limit_left_right(newlist, revs);
+
+	if (bottom) {
+		limit_to_ancestry(bottom, newlist);
+		free_commit_list(bottom);
+	}
+
+	/*
+	 * Check if any commits have become TREESAME by some of their parents
+	 * becoming UNINTERESTING.
+	 */
+	if (limiting_can_increase_treesame(revs))
+		for (list = newlist; list; list = list->next) {
+			struct commit *c = list->item;
+			if (c->object.flags & (UNINTERESTING | TREESAME))
+				continue;
+			update_treesame(revs, c);
+		}
+
+	revs->commits = newlist;
+	return 0;
+}
+
+/*
+ * Add an entry to refs->cmdline with the specified information.
+ * *name is copied.
+ */
+static void add_rev_cmdline(struct rev_info *revs,
+			    struct object *item,
+			    const char *name,
+			    int whence,
+			    unsigned flags)
+{
+	struct rev_cmdline_info *info = &revs->cmdline;
+	unsigned int nr = info->nr;
+
+	ALLOC_GROW(info->rev, nr + 1, info->alloc);
+	info->rev[nr].item = item;
+	info->rev[nr].name = xstrdup(name);
+	info->rev[nr].whence = whence;
+	info->rev[nr].flags = flags;
+	info->nr++;
+}
+
+static void add_rev_cmdline_list(struct rev_info *revs,
+				 struct commit_list *commit_list,
+				 int whence,
+				 unsigned flags)
+{
+	while (commit_list) {
+		struct object *object = &commit_list->item->object;
+		add_rev_cmdline(revs, object, oid_to_hex(&object->oid),
+				whence, flags);
+		commit_list = commit_list->next;
+	}
+}
+
+struct all_refs_cb {
+	int all_flags;
+	int warned_bad_reflog;
+	struct rev_info *all_revs;
+	const char *name_for_errormsg;
+	struct worktree *wt;
+};
+
+int ref_excluded(struct string_list *ref_excludes, const char *path)
+{
+	struct string_list_item *item;
+
+	if (!ref_excludes)
+		return 0;
+	for_each_string_list_item(item, ref_excludes) {
+		if (!wildmatch(item->string, path, 0))
+			return 1;
+	}
+	return 0;
+}
+
+static int handle_one_ref(const char *path, const struct object_id *oid,
+			  int flag, void *cb_data)
+{
+	struct all_refs_cb *cb = cb_data;
+	struct object *object;
+
+	if (ref_excluded(cb->all_revs->ref_excludes, path))
+	    return 0;
+
+	object = get_reference(cb->all_revs, path, oid, cb->all_flags);
+	add_rev_cmdline(cb->all_revs, object, path, REV_CMD_REF, cb->all_flags);
+	add_pending_oid(cb->all_revs, path, oid, cb->all_flags);
+	return 0;
+}
+
+static void init_all_refs_cb(struct all_refs_cb *cb, struct rev_info *revs,
+	unsigned flags)
+{
+	cb->all_revs = revs;
+	cb->all_flags = flags;
+	revs->rev_input_given = 1;
+	cb->wt = NULL;
+}
+
+void clear_ref_exclusion(struct string_list **ref_excludes_p)
+{
+	if (*ref_excludes_p) {
+		string_list_clear(*ref_excludes_p, 0);
+		free(*ref_excludes_p);
+	}
+	*ref_excludes_p = NULL;
+}
+
+void add_ref_exclusion(struct string_list **ref_excludes_p, const char *exclude)
+{
+	if (!*ref_excludes_p) {
+		*ref_excludes_p = xcalloc(1, sizeof(**ref_excludes_p));
+		(*ref_excludes_p)->strdup_strings = 1;
+	}
+	string_list_append(*ref_excludes_p, exclude);
+}
+
+static void handle_refs(struct ref_store *refs,
+			struct rev_info *revs, unsigned flags,
+			int (*for_each)(struct ref_store *, each_ref_fn, void *))
+{
+	struct all_refs_cb cb;
+
+	if (!refs) {
+		/* this could happen with uninitialized submodules */
+		return;
+	}
+
+	init_all_refs_cb(&cb, revs, flags);
+	for_each(refs, handle_one_ref, &cb);
+}
+
+static void handle_one_reflog_commit(struct object_id *oid, void *cb_data)
+{
+	struct all_refs_cb *cb = cb_data;
+	if (!is_null_oid(oid)) {
+		struct object *o = parse_object(cb->all_revs->repo, oid);
+		if (o) {
+			o->flags |= cb->all_flags;
+			/* ??? CMDLINEFLAGS ??? */
+			add_pending_object(cb->all_revs, o, "");
+		}
+		else if (!cb->warned_bad_reflog) {
+			warning("reflog of '%s' references pruned commits",
+				cb->name_for_errormsg);
+			cb->warned_bad_reflog = 1;
+		}
+	}
+}
+
+static int handle_one_reflog_ent(struct object_id *ooid, struct object_id *noid,
+		const char *email, timestamp_t timestamp, int tz,
+		const char *message, void *cb_data)
+{
+	handle_one_reflog_commit(ooid, cb_data);
+	handle_one_reflog_commit(noid, cb_data);
+	return 0;
+}
+
+static int handle_one_reflog(const char *refname_in_wt,
+			     const struct object_id *oid,
+			     int flag, void *cb_data)
+{
+	struct all_refs_cb *cb = cb_data;
+	struct strbuf refname = STRBUF_INIT;
+
+	cb->warned_bad_reflog = 0;
+	strbuf_worktree_ref(cb->wt, &refname, refname_in_wt);
+	cb->name_for_errormsg = refname.buf;
+	refs_for_each_reflog_ent(get_main_ref_store(the_repository),
+				 refname.buf,
+				 handle_one_reflog_ent, cb_data);
+	strbuf_release(&refname);
+	return 0;
+}
+
+static void add_other_reflogs_to_pending(struct all_refs_cb *cb)
+{
+	struct worktree **worktrees, **p;
+
+	worktrees = get_worktrees(0);
+	for (p = worktrees; *p; p++) {
+		struct worktree *wt = *p;
+
+		if (wt->is_current)
+			continue;
+
+		cb->wt = wt;
+		refs_for_each_reflog(get_worktree_ref_store(wt),
+				     handle_one_reflog,
+				     cb);
+	}
+	free_worktrees(worktrees);
+}
+
+void add_reflogs_to_pending(struct rev_info *revs, unsigned flags)
+{
+	struct all_refs_cb cb;
+
+	cb.all_revs = revs;
+	cb.all_flags = flags;
+	cb.wt = NULL;
+	for_each_reflog(handle_one_reflog, &cb);
+
+	if (!revs->single_worktree)
+		add_other_reflogs_to_pending(&cb);
+}
+
+static void add_cache_tree(struct cache_tree *it, struct rev_info *revs,
+			   struct strbuf *path, unsigned int flags)
+{
+	size_t baselen = path->len;
+	int i;
+
+	if (it->entry_count >= 0) {
+		struct tree *tree = lookup_tree(revs->repo, &it->oid);
+		tree->object.flags |= flags;
+		add_pending_object_with_path(revs, &tree->object, "",
+					     040000, path->buf);
+	}
+
+	for (i = 0; i < it->subtree_nr; i++) {
+		struct cache_tree_sub *sub = it->down[i];
+		strbuf_addf(path, "%s%s", baselen ? "/" : "", sub->name);
+		add_cache_tree(sub->cache_tree, revs, path, flags);
+		strbuf_setlen(path, baselen);
+	}
+
+}
+
+static void do_add_index_objects_to_pending(struct rev_info *revs,
+					    struct index_state *istate,
+					    unsigned int flags)
+{
+	int i;
+
+	for (i = 0; i < istate->cache_nr; i++) {
+		struct cache_entry *ce = istate->cache[i];
+		struct blob *blob;
+
+		if (S_ISGITLINK(ce->ce_mode))
+			continue;
+
+		blob = lookup_blob(revs->repo, &ce->oid);
+		if (!blob)
+			die("unable to add index blob to traversal");
+		blob->object.flags |= flags;
+		add_pending_object_with_path(revs, &blob->object, "",
+					     ce->ce_mode, ce->name);
+	}
+
+	if (istate->cache_tree) {
+		struct strbuf path = STRBUF_INIT;
+		add_cache_tree(istate->cache_tree, revs, &path, flags);
+		strbuf_release(&path);
+	}
+}
+
+void add_index_objects_to_pending(struct rev_info *revs, unsigned int flags)
+{
+	struct worktree **worktrees, **p;
+
+	repo_read_index(revs->repo);
+	do_add_index_objects_to_pending(revs, revs->repo->index, flags);
+
+	if (revs->single_worktree)
+		return;
+
+	worktrees = get_worktrees(0);
+	for (p = worktrees; *p; p++) {
+		struct worktree *wt = *p;
+		struct index_state istate = { NULL };
+
+		if (wt->is_current)
+			continue; /* current index already taken care of */
+
+		if (read_index_from(&istate,
+				    worktree_git_path(wt, "index"),
+				    get_worktree_git_dir(wt)) > 0)
+			do_add_index_objects_to_pending(revs, &istate, flags);
+		discard_index(&istate);
+	}
+	free_worktrees(worktrees);
+}
+
+struct add_alternate_refs_data {
+	struct rev_info *revs;
+	unsigned int flags;
+};
+
+static void add_one_alternate_ref(const struct object_id *oid,
+				  void *vdata)
+{
+	const char *name = ".alternate";
+	struct add_alternate_refs_data *data = vdata;
+	struct object *obj;
+
+	obj = get_reference(data->revs, name, oid, data->flags);
+	add_rev_cmdline(data->revs, obj, name, REV_CMD_REV, data->flags);
+	add_pending_object(data->revs, obj, name);
+}
+
+static void add_alternate_refs_to_pending(struct rev_info *revs,
+					  unsigned int flags)
+{
+	struct add_alternate_refs_data data;
+	data.revs = revs;
+	data.flags = flags;
+	for_each_alternate_ref(add_one_alternate_ref, &data);
+}
+
+static int add_parents_only(struct rev_info *revs, const char *arg_, int flags,
+			    int exclude_parent)
+{
+	struct object_id oid;
+	struct object *it;
+	struct commit *commit;
+	struct commit_list *parents;
+	int parent_number;
+	const char *arg = arg_;
+
+	if (*arg == '^') {
+		flags ^= UNINTERESTING | BOTTOM;
+		arg++;
+	}
+	if (get_oid_committish(arg, &oid))
+		return 0;
+	while (1) {
+		it = get_reference(revs, arg, &oid, 0);
+		if (!it && revs->ignore_missing)
+			return 0;
+		if (it->type != OBJ_TAG)
+			break;
+		if (!((struct tag*)it)->tagged)
+			return 0;
+		oidcpy(&oid, &((struct tag*)it)->tagged->oid);
+	}
+	if (it->type != OBJ_COMMIT)
+		return 0;
+	commit = (struct commit *)it;
+	if (exclude_parent &&
+	    exclude_parent > commit_list_count(commit->parents))
+		return 0;
+	for (parents = commit->parents, parent_number = 1;
+	     parents;
+	     parents = parents->next, parent_number++) {
+		if (exclude_parent && parent_number != exclude_parent)
+			continue;
+
+		it = &parents->item->object;
+		it->flags |= flags;
+		add_rev_cmdline(revs, it, arg_, REV_CMD_PARENTS_ONLY, flags);
+		add_pending_object(revs, it, arg);
+	}
+	return 1;
+}
+
+void repo_init_revisions(struct repository *r,
+			 struct rev_info *revs,
+			 const char *prefix)
+{
+	memset(revs, 0, sizeof(*revs));
+
+	revs->repo = r;
+	revs->abbrev = DEFAULT_ABBREV;
+	revs->ignore_merges = 1;
+	revs->simplify_history = 1;
+	revs->pruning.repo = r;
+	revs->pruning.flags.recursive = 1;
+	revs->pruning.flags.quick = 1;
+	revs->pruning.add_remove = file_add_remove;
+	revs->pruning.change = file_change;
+	revs->pruning.change_fn_data = revs;
+	revs->sort_order = REV_SORT_IN_GRAPH_ORDER;
+	revs->dense = 1;
+	revs->prefix = prefix;
+	revs->max_age = -1;
+	revs->min_age = -1;
+	revs->skip_count = -1;
+	revs->max_count = -1;
+	revs->max_parents = -1;
+	revs->expand_tabs_in_log = -1;
+
+	revs->commit_format = CMIT_FMT_DEFAULT;
+	revs->expand_tabs_in_log_default = 8;
+
+	init_grep_defaults(revs->repo);
+	grep_init(&revs->grep_filter, revs->repo, prefix);
+	revs->grep_filter.status_only = 1;
+
+	repo_diff_setup(revs->repo, &revs->diffopt);
+	if (prefix && !revs->diffopt.prefix) {
+		revs->diffopt.prefix = prefix;
+		revs->diffopt.prefix_length = strlen(prefix);
+	}
+
+	revs->notes_opt.use_default_notes = -1;
+}
+
+static void add_pending_commit_list(struct rev_info *revs,
+				    struct commit_list *commit_list,
+				    unsigned int flags)
+{
+	while (commit_list) {
+		struct object *object = &commit_list->item->object;
+		object->flags |= flags;
+		add_pending_object(revs, object, oid_to_hex(&object->oid));
+		commit_list = commit_list->next;
+	}
+}
+
+static void prepare_show_merge(struct rev_info *revs)
+{
+	struct commit_list *bases;
+	struct commit *head, *other;
+	struct object_id oid;
+	const char **prune = NULL;
+	int i, prune_num = 1; /* counting terminating NULL */
+	struct index_state *istate = revs->repo->index;
+
+	if (get_oid("HEAD", &oid))
+		die("--merge without HEAD?");
+	head = lookup_commit_or_die(&oid, "HEAD");
+	if (get_oid("MERGE_HEAD", &oid))
+		die("--merge without MERGE_HEAD?");
+	other = lookup_commit_or_die(&oid, "MERGE_HEAD");
+	add_pending_object(revs, &head->object, "HEAD");
+	add_pending_object(revs, &other->object, "MERGE_HEAD");
+	bases = get_merge_bases(head, other);
+	add_rev_cmdline_list(revs, bases, REV_CMD_MERGE_BASE, UNINTERESTING | BOTTOM);
+	add_pending_commit_list(revs, bases, UNINTERESTING | BOTTOM);
+	free_commit_list(bases);
+	head->object.flags |= SYMMETRIC_LEFT;
+
+	if (!istate->cache_nr)
+		repo_read_index(revs->repo);
+	for (i = 0; i < istate->cache_nr; i++) {
+		const struct cache_entry *ce = istate->cache[i];
+		if (!ce_stage(ce))
+			continue;
+		if (ce_path_match(istate, ce, &revs->prune_data, NULL)) {
+			prune_num++;
+			REALLOC_ARRAY(prune, prune_num);
+			prune[prune_num-2] = ce->name;
+			prune[prune_num-1] = NULL;
+		}
+		while ((i+1 < istate->cache_nr) &&
+		       ce_same_name(ce, istate->cache[i+1]))
+			i++;
+	}
+	clear_pathspec(&revs->prune_data);
+	parse_pathspec(&revs->prune_data, PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
+		       PATHSPEC_PREFER_FULL | PATHSPEC_LITERAL_PATH, "", prune);
+	revs->limited = 1;
+}
+
+static int dotdot_missing(const char *arg, char *dotdot,
+			  struct rev_info *revs, int symmetric)
+{
+	if (revs->ignore_missing)
+		return 0;
+	/* de-munge so we report the full argument */
+	*dotdot = '.';
+	die(symmetric
+	    ? "Invalid symmetric difference expression %s"
+	    : "Invalid revision range %s", arg);
+}
+
+static int handle_dotdot_1(const char *arg, char *dotdot,
+			   struct rev_info *revs, int flags,
+			   int cant_be_filename,
+			   struct object_context *a_oc,
+			   struct object_context *b_oc)
+{
+	const char *a_name, *b_name;
+	struct object_id a_oid, b_oid;
+	struct object *a_obj, *b_obj;
+	unsigned int a_flags, b_flags;
+	int symmetric = 0;
+	unsigned int flags_exclude = flags ^ (UNINTERESTING | BOTTOM);
+	unsigned int oc_flags = GET_OID_COMMITTISH | GET_OID_RECORD_PATH;
+
+	a_name = arg;
+	if (!*a_name)
+		a_name = "HEAD";
+
+	b_name = dotdot + 2;
+	if (*b_name == '.') {
+		symmetric = 1;
+		b_name++;
+	}
+	if (!*b_name)
+		b_name = "HEAD";
+
+	if (get_oid_with_context(revs->repo, a_name, oc_flags, &a_oid, a_oc) ||
+	    get_oid_with_context(revs->repo, b_name, oc_flags, &b_oid, b_oc))
+		return -1;
+
+	if (!cant_be_filename) {
+		*dotdot = '.';
+		verify_non_filename(revs->prefix, arg);
+		*dotdot = '\0';
+	}
+
+	a_obj = parse_object(revs->repo, &a_oid);
+	b_obj = parse_object(revs->repo, &b_oid);
+	if (!a_obj || !b_obj)
+		return dotdot_missing(arg, dotdot, revs, symmetric);
+
+	if (!symmetric) {
+		/* just A..B */
+		b_flags = flags;
+		a_flags = flags_exclude;
+	} else {
+		/* A...B -- find merge bases between the two */
+		struct commit *a, *b;
+		struct commit_list *exclude;
+
+		a = lookup_commit_reference(revs->repo, &a_obj->oid);
+		b = lookup_commit_reference(revs->repo, &b_obj->oid);
+		if (!a || !b)
+			return dotdot_missing(arg, dotdot, revs, symmetric);
+
+		exclude = get_merge_bases(a, b);
+		add_rev_cmdline_list(revs, exclude, REV_CMD_MERGE_BASE,
+				     flags_exclude);
+		add_pending_commit_list(revs, exclude, flags_exclude);
+		free_commit_list(exclude);
+
+		b_flags = flags;
+		a_flags = flags | SYMMETRIC_LEFT;
+	}
+
+	a_obj->flags |= a_flags;
+	b_obj->flags |= b_flags;
+	add_rev_cmdline(revs, a_obj, a_name, REV_CMD_LEFT, a_flags);
+	add_rev_cmdline(revs, b_obj, b_name, REV_CMD_RIGHT, b_flags);
+	add_pending_object_with_path(revs, a_obj, a_name, a_oc->mode, a_oc->path);
+	add_pending_object_with_path(revs, b_obj, b_name, b_oc->mode, b_oc->path);
+	return 0;
+}
+
+static int handle_dotdot(const char *arg,
+			 struct rev_info *revs, int flags,
+			 int cant_be_filename)
+{
+	struct object_context a_oc, b_oc;
+	char *dotdot = strstr(arg, "..");
+	int ret;
+
+	if (!dotdot)
+		return -1;
+
+	memset(&a_oc, 0, sizeof(a_oc));
+	memset(&b_oc, 0, sizeof(b_oc));
+
+	*dotdot = '\0';
+	ret = handle_dotdot_1(arg, dotdot, revs, flags, cant_be_filename,
+			      &a_oc, &b_oc);
+	*dotdot = '.';
+
+	free(a_oc.path);
+	free(b_oc.path);
+
+	return ret;
+}
+
+int handle_revision_arg(const char *arg_, struct rev_info *revs, int flags, unsigned revarg_opt)
+{
+	struct object_context oc;
+	char *mark;
+	struct object *object;
+	struct object_id oid;
+	int local_flags;
+	const char *arg = arg_;
+	int cant_be_filename = revarg_opt & REVARG_CANNOT_BE_FILENAME;
+	unsigned get_sha1_flags = GET_OID_RECORD_PATH;
+
+	flags = flags & UNINTERESTING ? flags | BOTTOM : flags & ~BOTTOM;
+
+	if (!cant_be_filename && !strcmp(arg, "..")) {
+		/*
+		 * Just ".."?  That is not a range but the
+		 * pathspec for the parent directory.
+		 */
+		return -1;
+	}
+
+	if (!handle_dotdot(arg, revs, flags, revarg_opt))
+		return 0;
+
+	mark = strstr(arg, "^@");
+	if (mark && !mark[2]) {
+		*mark = 0;
+		if (add_parents_only(revs, arg, flags, 0))
+			return 0;
+		*mark = '^';
+	}
+	mark = strstr(arg, "^!");
+	if (mark && !mark[2]) {
+		*mark = 0;
+		if (!add_parents_only(revs, arg, flags ^ (UNINTERESTING | BOTTOM), 0))
+			*mark = '^';
+	}
+	mark = strstr(arg, "^-");
+	if (mark) {
+		int exclude_parent = 1;
+
+		if (mark[2]) {
+			char *end;
+			exclude_parent = strtoul(mark + 2, &end, 10);
+			if (*end != '\0' || !exclude_parent)
+				return -1;
+		}
+
+		*mark = 0;
+		if (!add_parents_only(revs, arg, flags ^ (UNINTERESTING | BOTTOM), exclude_parent))
+			*mark = '^';
+	}
+
+	local_flags = 0;
+	if (*arg == '^') {
+		local_flags = UNINTERESTING | BOTTOM;
+		arg++;
+	}
+
+	if (revarg_opt & REVARG_COMMITTISH)
+		get_sha1_flags |= GET_OID_COMMITTISH;
+
+	if (get_oid_with_context(revs->repo, arg, get_sha1_flags, &oid, &oc))
+		return revs->ignore_missing ? 0 : -1;
+	if (!cant_be_filename)
+		verify_non_filename(revs->prefix, arg);
+	object = get_reference(revs, arg, &oid, flags ^ local_flags);
+	if (!object)
+		return revs->ignore_missing ? 0 : -1;
+	add_rev_cmdline(revs, object, arg_, REV_CMD_REV, flags ^ local_flags);
+	add_pending_object_with_path(revs, object, arg, oc.mode, oc.path);
+	free(oc.path);
+	return 0;
+}
+
+static void read_pathspec_from_stdin(struct strbuf *sb,
+				     struct argv_array *prune)
+{
+	while (strbuf_getline(sb, stdin) != EOF)
+		argv_array_push(prune, sb->buf);
+}
+
+static void read_revisions_from_stdin(struct rev_info *revs,
+				      struct argv_array *prune)
+{
+	struct strbuf sb;
+	int seen_dashdash = 0;
+	int save_warning;
+
+	save_warning = warn_on_object_refname_ambiguity;
+	warn_on_object_refname_ambiguity = 0;
+
+	strbuf_init(&sb, 1000);
+	while (strbuf_getline(&sb, stdin) != EOF) {
+		int len = sb.len;
+		if (!len)
+			break;
+		if (sb.buf[0] == '-') {
+			if (len == 2 && sb.buf[1] == '-') {
+				seen_dashdash = 1;
+				break;
+			}
+			die("options not supported in --stdin mode");
+		}
+		if (handle_revision_arg(sb.buf, revs, 0,
+					REVARG_CANNOT_BE_FILENAME))
+			die("bad revision '%s'", sb.buf);
+	}
+	if (seen_dashdash)
+		read_pathspec_from_stdin(&sb, prune);
+
+	strbuf_release(&sb);
+	warn_on_object_refname_ambiguity = save_warning;
+}
+
+static void add_grep(struct rev_info *revs, const char *ptn, enum grep_pat_token what)
+{
+	append_grep_pattern(&revs->grep_filter, ptn, "command line", 0, what);
+}
+
+static void add_header_grep(struct rev_info *revs, enum grep_header_field field, const char *pattern)
+{
+	append_header_grep_pattern(&revs->grep_filter, field, pattern);
+}
+
+static void add_message_grep(struct rev_info *revs, const char *pattern)
+{
+	add_grep(revs, pattern, GREP_PATTERN_BODY);
+}
+
+static int handle_revision_opt(struct rev_info *revs, int argc, const char **argv,
+			       int *unkc, const char **unkv,
+			       const struct setup_revision_opt* opt)
+{
+	const char *arg = argv[0];
+	const char *optarg;
+	int argcount;
+	const unsigned hexsz = the_hash_algo->hexsz;
+
+	/* pseudo revision arguments */
+	if (!strcmp(arg, "--all") || !strcmp(arg, "--branches") ||
+	    !strcmp(arg, "--tags") || !strcmp(arg, "--remotes") ||
+	    !strcmp(arg, "--reflog") || !strcmp(arg, "--not") ||
+	    !strcmp(arg, "--no-walk") || !strcmp(arg, "--do-walk") ||
+	    !strcmp(arg, "--bisect") || starts_with(arg, "--glob=") ||
+	    !strcmp(arg, "--indexed-objects") ||
+	    !strcmp(arg, "--alternate-refs") ||
+	    starts_with(arg, "--exclude=") ||
+	    starts_with(arg, "--branches=") || starts_with(arg, "--tags=") ||
+	    starts_with(arg, "--remotes=") || starts_with(arg, "--no-walk="))
+	{
+		unkv[(*unkc)++] = arg;
+		return 1;
+	}
+
+	if ((argcount = parse_long_opt("max-count", argv, &optarg))) {
+		revs->max_count = atoi(optarg);
+		revs->no_walk = 0;
+		return argcount;
+	} else if ((argcount = parse_long_opt("skip", argv, &optarg))) {
+		revs->skip_count = atoi(optarg);
+		return argcount;
+	} else if ((*arg == '-') && isdigit(arg[1])) {
+		/* accept -<digit>, like traditional "head" */
+		if (strtol_i(arg + 1, 10, &revs->max_count) < 0 ||
+		    revs->max_count < 0)
+			die("'%s': not a non-negative integer", arg + 1);
+		revs->no_walk = 0;
+	} else if (!strcmp(arg, "-n")) {
+		if (argc <= 1)
+			return error("-n requires an argument");
+		revs->max_count = atoi(argv[1]);
+		revs->no_walk = 0;
+		return 2;
+	} else if (skip_prefix(arg, "-n", &optarg)) {
+		revs->max_count = atoi(optarg);
+		revs->no_walk = 0;
+	} else if ((argcount = parse_long_opt("max-age", argv, &optarg))) {
+		revs->max_age = atoi(optarg);
+		return argcount;
+	} else if ((argcount = parse_long_opt("since", argv, &optarg))) {
+		revs->max_age = approxidate(optarg);
+		return argcount;
+	} else if ((argcount = parse_long_opt("after", argv, &optarg))) {
+		revs->max_age = approxidate(optarg);
+		return argcount;
+	} else if ((argcount = parse_long_opt("min-age", argv, &optarg))) {
+		revs->min_age = atoi(optarg);
+		return argcount;
+	} else if ((argcount = parse_long_opt("before", argv, &optarg))) {
+		revs->min_age = approxidate(optarg);
+		return argcount;
+	} else if ((argcount = parse_long_opt("until", argv, &optarg))) {
+		revs->min_age = approxidate(optarg);
+		return argcount;
+	} else if (!strcmp(arg, "--first-parent")) {
+		revs->first_parent_only = 1;
+	} else if (!strcmp(arg, "--ancestry-path")) {
+		revs->ancestry_path = 1;
+		revs->simplify_history = 0;
+		revs->limited = 1;
+	} else if (!strcmp(arg, "-g") || !strcmp(arg, "--walk-reflogs")) {
+		init_reflog_walk(&revs->reflog_info);
+	} else if (!strcmp(arg, "--default")) {
+		if (argc <= 1)
+			return error("bad --default argument");
+		revs->def = argv[1];
+		return 2;
+	} else if (!strcmp(arg, "--merge")) {
+		revs->show_merge = 1;
+	} else if (!strcmp(arg, "--topo-order")) {
+		revs->sort_order = REV_SORT_IN_GRAPH_ORDER;
+		revs->topo_order = 1;
+	} else if (!strcmp(arg, "--simplify-merges")) {
+		revs->simplify_merges = 1;
+		revs->topo_order = 1;
+		revs->rewrite_parents = 1;
+		revs->simplify_history = 0;
+		revs->limited = 1;
+	} else if (!strcmp(arg, "--simplify-by-decoration")) {
+		revs->simplify_merges = 1;
+		revs->topo_order = 1;
+		revs->rewrite_parents = 1;
+		revs->simplify_history = 0;
+		revs->simplify_by_decoration = 1;
+		revs->limited = 1;
+		revs->prune = 1;
+		load_ref_decorations(NULL, DECORATE_SHORT_REFS);
+	} else if (!strcmp(arg, "--date-order")) {
+		revs->sort_order = REV_SORT_BY_COMMIT_DATE;
+		revs->topo_order = 1;
+	} else if (!strcmp(arg, "--author-date-order")) {
+		revs->sort_order = REV_SORT_BY_AUTHOR_DATE;
+		revs->topo_order = 1;
+	} else if (!strcmp(arg, "--early-output")) {
+		revs->early_output = 100;
+		revs->topo_order = 1;
+	} else if (skip_prefix(arg, "--early-output=", &optarg)) {
+		if (strtoul_ui(optarg, 10, &revs->early_output) < 0)
+			die("'%s': not a non-negative integer", optarg);
+		revs->topo_order = 1;
+	} else if (!strcmp(arg, "--parents")) {
+		revs->rewrite_parents = 1;
+		revs->print_parents = 1;
+	} else if (!strcmp(arg, "--dense")) {
+		revs->dense = 1;
+	} else if (!strcmp(arg, "--sparse")) {
+		revs->dense = 0;
+	} else if (!strcmp(arg, "--in-commit-order")) {
+		revs->tree_blobs_in_commit_order = 1;
+	} else if (!strcmp(arg, "--remove-empty")) {
+		revs->remove_empty_trees = 1;
+	} else if (!strcmp(arg, "--merges")) {
+		revs->min_parents = 2;
+	} else if (!strcmp(arg, "--no-merges")) {
+		revs->max_parents = 1;
+	} else if (skip_prefix(arg, "--min-parents=", &optarg)) {
+		revs->min_parents = atoi(optarg);
+	} else if (!strcmp(arg, "--no-min-parents")) {
+		revs->min_parents = 0;
+	} else if (skip_prefix(arg, "--max-parents=", &optarg)) {
+		revs->max_parents = atoi(optarg);
+	} else if (!strcmp(arg, "--no-max-parents")) {
+		revs->max_parents = -1;
+	} else if (!strcmp(arg, "--boundary")) {
+		revs->boundary = 1;
+	} else if (!strcmp(arg, "--left-right")) {
+		revs->left_right = 1;
+	} else if (!strcmp(arg, "--left-only")) {
+		if (revs->right_only)
+			die("--left-only is incompatible with --right-only"
+			    " or --cherry");
+		revs->left_only = 1;
+	} else if (!strcmp(arg, "--right-only")) {
+		if (revs->left_only)
+			die("--right-only is incompatible with --left-only");
+		revs->right_only = 1;
+	} else if (!strcmp(arg, "--cherry")) {
+		if (revs->left_only)
+			die("--cherry is incompatible with --left-only");
+		revs->cherry_mark = 1;
+		revs->right_only = 1;
+		revs->max_parents = 1;
+		revs->limited = 1;
+	} else if (!strcmp(arg, "--count")) {
+		revs->count = 1;
+	} else if (!strcmp(arg, "--cherry-mark")) {
+		if (revs->cherry_pick)
+			die("--cherry-mark is incompatible with --cherry-pick");
+		revs->cherry_mark = 1;
+		revs->limited = 1; /* needs limit_list() */
+	} else if (!strcmp(arg, "--cherry-pick")) {
+		if (revs->cherry_mark)
+			die("--cherry-pick is incompatible with --cherry-mark");
+		revs->cherry_pick = 1;
+		revs->limited = 1;
+	} else if (!strcmp(arg, "--objects")) {
+		revs->tag_objects = 1;
+		revs->tree_objects = 1;
+		revs->blob_objects = 1;
+	} else if (!strcmp(arg, "--objects-edge")) {
+		revs->tag_objects = 1;
+		revs->tree_objects = 1;
+		revs->blob_objects = 1;
+		revs->edge_hint = 1;
+	} else if (!strcmp(arg, "--objects-edge-aggressive")) {
+		revs->tag_objects = 1;
+		revs->tree_objects = 1;
+		revs->blob_objects = 1;
+		revs->edge_hint = 1;
+		revs->edge_hint_aggressive = 1;
+	} else if (!strcmp(arg, "--verify-objects")) {
+		revs->tag_objects = 1;
+		revs->tree_objects = 1;
+		revs->blob_objects = 1;
+		revs->verify_objects = 1;
+	} else if (!strcmp(arg, "--unpacked")) {
+		revs->unpacked = 1;
+	} else if (starts_with(arg, "--unpacked=")) {
+		die("--unpacked=<packfile> no longer supported.");
+	} else if (!strcmp(arg, "-r")) {
+		revs->diff = 1;
+		revs->diffopt.flags.recursive = 1;
+	} else if (!strcmp(arg, "-t")) {
+		revs->diff = 1;
+		revs->diffopt.flags.recursive = 1;
+		revs->diffopt.flags.tree_in_recursive = 1;
+	} else if (!strcmp(arg, "-m")) {
+		revs->ignore_merges = 0;
+	} else if (!strcmp(arg, "-c")) {
+		revs->diff = 1;
+		revs->dense_combined_merges = 0;
+		revs->combine_merges = 1;
+	} else if (!strcmp(arg, "--combined-all-paths")) {
+		revs->diff = 1;
+		revs->combined_all_paths = 1;
+	} else if (!strcmp(arg, "--cc")) {
+		revs->diff = 1;
+		revs->dense_combined_merges = 1;
+		revs->combine_merges = 1;
+	} else if (!strcmp(arg, "-v")) {
+		revs->verbose_header = 1;
+	} else if (!strcmp(arg, "--pretty")) {
+		revs->verbose_header = 1;
+		revs->pretty_given = 1;
+		get_commit_format(NULL, revs);
+	} else if (skip_prefix(arg, "--pretty=", &optarg) ||
+		   skip_prefix(arg, "--format=", &optarg)) {
+		/*
+		 * Detached form ("--pretty X" as opposed to "--pretty=X")
+		 * not allowed, since the argument is optional.
+		 */
+		revs->verbose_header = 1;
+		revs->pretty_given = 1;
+		get_commit_format(optarg, revs);
+	} else if (!strcmp(arg, "--expand-tabs")) {
+		revs->expand_tabs_in_log = 8;
+	} else if (!strcmp(arg, "--no-expand-tabs")) {
+		revs->expand_tabs_in_log = 0;
+	} else if (skip_prefix(arg, "--expand-tabs=", &arg)) {
+		int val;
+		if (strtol_i(arg, 10, &val) < 0 || val < 0)
+			die("'%s': not a non-negative integer", arg);
+		revs->expand_tabs_in_log = val;
+	} else if (!strcmp(arg, "--show-notes") || !strcmp(arg, "--notes")) {
+		revs->show_notes = 1;
+		revs->show_notes_given = 1;
+		revs->notes_opt.use_default_notes = 1;
+	} else if (!strcmp(arg, "--show-signature")) {
+		revs->show_signature = 1;
+	} else if (!strcmp(arg, "--no-show-signature")) {
+		revs->show_signature = 0;
+	} else if (!strcmp(arg, "--show-linear-break")) {
+		revs->break_bar = "                    ..........";
+		revs->track_linear = 1;
+		revs->track_first_time = 1;
+	} else if (skip_prefix(arg, "--show-linear-break=", &optarg)) {
+		revs->break_bar = xstrdup(optarg);
+		revs->track_linear = 1;
+		revs->track_first_time = 1;
+	} else if (skip_prefix(arg, "--show-notes=", &optarg) ||
+		   skip_prefix(arg, "--notes=", &optarg)) {
+		struct strbuf buf = STRBUF_INIT;
+		revs->show_notes = 1;
+		revs->show_notes_given = 1;
+		if (starts_with(arg, "--show-notes=") &&
+		    revs->notes_opt.use_default_notes < 0)
+			revs->notes_opt.use_default_notes = 1;
+		strbuf_addstr(&buf, optarg);
+		expand_notes_ref(&buf);
+		string_list_append(&revs->notes_opt.extra_notes_refs,
+				   strbuf_detach(&buf, NULL));
+	} else if (!strcmp(arg, "--no-notes")) {
+		revs->show_notes = 0;
+		revs->show_notes_given = 1;
+		revs->notes_opt.use_default_notes = -1;
+		/* we have been strdup'ing ourselves, so trick
+		 * string_list into free()ing strings */
+		revs->notes_opt.extra_notes_refs.strdup_strings = 1;
+		string_list_clear(&revs->notes_opt.extra_notes_refs, 0);
+		revs->notes_opt.extra_notes_refs.strdup_strings = 0;
+	} else if (!strcmp(arg, "--standard-notes")) {
+		revs->show_notes_given = 1;
+		revs->notes_opt.use_default_notes = 1;
+	} else if (!strcmp(arg, "--no-standard-notes")) {
+		revs->notes_opt.use_default_notes = 0;
+	} else if (!strcmp(arg, "--oneline")) {
+		revs->verbose_header = 1;
+		get_commit_format("oneline", revs);
+		revs->pretty_given = 1;
+		revs->abbrev_commit = 1;
+	} else if (!strcmp(arg, "--graph")) {
+		revs->topo_order = 1;
+		revs->rewrite_parents = 1;
+		revs->graph = graph_init(revs);
+	} else if (!strcmp(arg, "--root")) {
+		revs->show_root_diff = 1;
+	} else if (!strcmp(arg, "--no-commit-id")) {
+		revs->no_commit_id = 1;
+	} else if (!strcmp(arg, "--always")) {
+		revs->always_show_header = 1;
+	} else if (!strcmp(arg, "--no-abbrev")) {
+		revs->abbrev = 0;
+	} else if (!strcmp(arg, "--abbrev")) {
+		revs->abbrev = DEFAULT_ABBREV;
+	} else if (skip_prefix(arg, "--abbrev=", &optarg)) {
+		revs->abbrev = strtoul(optarg, NULL, 10);
+		if (revs->abbrev < MINIMUM_ABBREV)
+			revs->abbrev = MINIMUM_ABBREV;
+		else if (revs->abbrev > hexsz)
+			revs->abbrev = hexsz;
+	} else if (!strcmp(arg, "--abbrev-commit")) {
+		revs->abbrev_commit = 1;
+		revs->abbrev_commit_given = 1;
+	} else if (!strcmp(arg, "--no-abbrev-commit")) {
+		revs->abbrev_commit = 0;
+	} else if (!strcmp(arg, "--full-diff")) {
+		revs->diff = 1;
+		revs->full_diff = 1;
+	} else if (!strcmp(arg, "--full-history")) {
+		revs->simplify_history = 0;
+	} else if (!strcmp(arg, "--relative-date")) {
+		revs->date_mode.type = DATE_RELATIVE;
+		revs->date_mode_explicit = 1;
+	} else if ((argcount = parse_long_opt("date", argv, &optarg))) {
+		parse_date_format(optarg, &revs->date_mode);
+		revs->date_mode_explicit = 1;
+		return argcount;
+	} else if (!strcmp(arg, "--log-size")) {
+		revs->show_log_size = 1;
+	}
+	/*
+	 * Grepping the commit log
+	 */
+	else if ((argcount = parse_long_opt("author", argv, &optarg))) {
+		add_header_grep(revs, GREP_HEADER_AUTHOR, optarg);
+		return argcount;
+	} else if ((argcount = parse_long_opt("committer", argv, &optarg))) {
+		add_header_grep(revs, GREP_HEADER_COMMITTER, optarg);
+		return argcount;
+	} else if ((argcount = parse_long_opt("grep-reflog", argv, &optarg))) {
+		add_header_grep(revs, GREP_HEADER_REFLOG, optarg);
+		return argcount;
+	} else if ((argcount = parse_long_opt("grep", argv, &optarg))) {
+		add_message_grep(revs, optarg);
+		return argcount;
+	} else if (!strcmp(arg, "--grep-debug")) {
+		revs->grep_filter.debug = 1;
+	} else if (!strcmp(arg, "--basic-regexp")) {
+		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_BRE;
+	} else if (!strcmp(arg, "--extended-regexp") || !strcmp(arg, "-E")) {
+		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_ERE;
+	} else if (!strcmp(arg, "--regexp-ignore-case") || !strcmp(arg, "-i")) {
+		revs->grep_filter.ignore_case = 1;
+		revs->diffopt.pickaxe_opts |= DIFF_PICKAXE_IGNORE_CASE;
+	} else if (!strcmp(arg, "--fixed-strings") || !strcmp(arg, "-F")) {
+		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_FIXED;
+	} else if (!strcmp(arg, "--perl-regexp") || !strcmp(arg, "-P")) {
+		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_PCRE;
+	} else if (!strcmp(arg, "--all-match")) {
+		revs->grep_filter.all_match = 1;
+	} else if (!strcmp(arg, "--invert-grep")) {
+		revs->invert_grep = 1;
+	} else if ((argcount = parse_long_opt("encoding", argv, &optarg))) {
+		if (strcmp(optarg, "none"))
+			git_log_output_encoding = xstrdup(optarg);
+		else
+			git_log_output_encoding = "";
+		return argcount;
+	} else if (!strcmp(arg, "--reverse")) {
+		revs->reverse ^= 1;
+	} else if (!strcmp(arg, "--children")) {
+		revs->children.name = "children";
+		revs->limited = 1;
+	} else if (!strcmp(arg, "--ignore-missing")) {
+		revs->ignore_missing = 1;
+	} else if (opt && opt->allow_exclude_promisor_objects &&
+		   !strcmp(arg, "--exclude-promisor-objects")) {
+		if (fetch_if_missing)
+			BUG("exclude_promisor_objects can only be used when fetch_if_missing is 0");
+		revs->exclude_promisor_objects = 1;
+	} else {
+		int opts = diff_opt_parse(&revs->diffopt, argv, argc, revs->prefix);
+		if (!opts)
+			unkv[(*unkc)++] = arg;
+		return opts;
+	}
+	if (revs->graph && revs->track_linear)
+		die("--show-linear-break and --graph are incompatible");
+
+	return 1;
+}
+
+void parse_revision_opt(struct rev_info *revs, struct parse_opt_ctx_t *ctx,
+			const struct option *options,
+			const char * const usagestr[])
+{
+	int n = handle_revision_opt(revs, ctx->argc, ctx->argv,
+				    &ctx->cpidx, ctx->out, NULL);
+	if (n <= 0) {
+		error("unknown option `%s'", ctx->argv[0]);
+		usage_with_options(usagestr, options);
+	}
+	ctx->argv += n;
+	ctx->argc -= n;
+}
+
+static int for_each_bisect_ref(struct ref_store *refs, each_ref_fn fn,
+			       void *cb_data, const char *term)
+{
+	struct strbuf bisect_refs = STRBUF_INIT;
+	int status;
+	strbuf_addf(&bisect_refs, "refs/bisect/%s", term);
+	status = refs_for_each_fullref_in(refs, bisect_refs.buf, fn, cb_data, 0);
+	strbuf_release(&bisect_refs);
+	return status;
+}
+
+static int for_each_bad_bisect_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+	return for_each_bisect_ref(refs, fn, cb_data, term_bad);
+}
+
+static int for_each_good_bisect_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
+{
+	return for_each_bisect_ref(refs, fn, cb_data, term_good);
+}
+
+static int handle_revision_pseudo_opt(const char *submodule,
+				struct rev_info *revs,
+				int argc, const char **argv, int *flags)
+{
+	const char *arg = argv[0];
+	const char *optarg;
+	struct ref_store *refs;
+	int argcount;
+
+	if (submodule) {
+		/*
+		 * We need some something like get_submodule_worktrees()
+		 * before we can go through all worktrees of a submodule,
+		 * .e.g with adding all HEADs from --all, which is not
+		 * supported right now, so stick to single worktree.
+		 */
+		if (!revs->single_worktree)
+			BUG("--single-worktree cannot be used together with submodule");
+		refs = get_submodule_ref_store(submodule);
+	} else
+		refs = get_main_ref_store(revs->repo);
+
+	/*
+	 * NOTE!
+	 *
+	 * Commands like "git shortlog" will not accept the options below
+	 * unless parse_revision_opt queues them (as opposed to erroring
+	 * out).
+	 *
+	 * When implementing your new pseudo-option, remember to
+	 * register it in the list at the top of handle_revision_opt.
+	 */
+	if (!strcmp(arg, "--all")) {
+		handle_refs(refs, revs, *flags, refs_for_each_ref);
+		handle_refs(refs, revs, *flags, refs_head_ref);
+		if (!revs->single_worktree) {
+			struct all_refs_cb cb;
+
+			init_all_refs_cb(&cb, revs, *flags);
+			other_head_refs(handle_one_ref, &cb);
+		}
+		clear_ref_exclusion(&revs->ref_excludes);
+	} else if (!strcmp(arg, "--branches")) {
+		handle_refs(refs, revs, *flags, refs_for_each_branch_ref);
+		clear_ref_exclusion(&revs->ref_excludes);
+	} else if (!strcmp(arg, "--bisect")) {
+		read_bisect_terms(&term_bad, &term_good);
+		handle_refs(refs, revs, *flags, for_each_bad_bisect_ref);
+		handle_refs(refs, revs, *flags ^ (UNINTERESTING | BOTTOM),
+			    for_each_good_bisect_ref);
+		revs->bisect = 1;
+	} else if (!strcmp(arg, "--tags")) {
+		handle_refs(refs, revs, *flags, refs_for_each_tag_ref);
+		clear_ref_exclusion(&revs->ref_excludes);
+	} else if (!strcmp(arg, "--remotes")) {
+		handle_refs(refs, revs, *flags, refs_for_each_remote_ref);
+		clear_ref_exclusion(&revs->ref_excludes);
+	} else if ((argcount = parse_long_opt("glob", argv, &optarg))) {
+		struct all_refs_cb cb;
+		init_all_refs_cb(&cb, revs, *flags);
+		for_each_glob_ref(handle_one_ref, optarg, &cb);
+		clear_ref_exclusion(&revs->ref_excludes);
+		return argcount;
+	} else if ((argcount = parse_long_opt("exclude", argv, &optarg))) {
+		add_ref_exclusion(&revs->ref_excludes, optarg);
+		return argcount;
+	} else if (skip_prefix(arg, "--branches=", &optarg)) {
+		struct all_refs_cb cb;
+		init_all_refs_cb(&cb, revs, *flags);
+		for_each_glob_ref_in(handle_one_ref, optarg, "refs/heads/", &cb);
+		clear_ref_exclusion(&revs->ref_excludes);
+	} else if (skip_prefix(arg, "--tags=", &optarg)) {
+		struct all_refs_cb cb;
+		init_all_refs_cb(&cb, revs, *flags);
+		for_each_glob_ref_in(handle_one_ref, optarg, "refs/tags/", &cb);
+		clear_ref_exclusion(&revs->ref_excludes);
+	} else if (skip_prefix(arg, "--remotes=", &optarg)) {
+		struct all_refs_cb cb;
+		init_all_refs_cb(&cb, revs, *flags);
+		for_each_glob_ref_in(handle_one_ref, optarg, "refs/remotes/", &cb);
+		clear_ref_exclusion(&revs->ref_excludes);
+	} else if (!strcmp(arg, "--reflog")) {
+		add_reflogs_to_pending(revs, *flags);
+	} else if (!strcmp(arg, "--indexed-objects")) {
+		add_index_objects_to_pending(revs, *flags);
+	} else if (!strcmp(arg, "--alternate-refs")) {
+		add_alternate_refs_to_pending(revs, *flags);
+	} else if (!strcmp(arg, "--not")) {
+		*flags ^= UNINTERESTING | BOTTOM;
+	} else if (!strcmp(arg, "--no-walk")) {
+		revs->no_walk = REVISION_WALK_NO_WALK_SORTED;
+	} else if (skip_prefix(arg, "--no-walk=", &optarg)) {
+		/*
+		 * Detached form ("--no-walk X" as opposed to "--no-walk=X")
+		 * not allowed, since the argument is optional.
+		 */
+		if (!strcmp(optarg, "sorted"))
+			revs->no_walk = REVISION_WALK_NO_WALK_SORTED;
+		else if (!strcmp(optarg, "unsorted"))
+			revs->no_walk = REVISION_WALK_NO_WALK_UNSORTED;
+		else
+			return error("invalid argument to --no-walk");
+	} else if (!strcmp(arg, "--do-walk")) {
+		revs->no_walk = 0;
+	} else if (!strcmp(arg, "--single-worktree")) {
+		revs->single_worktree = 1;
+	} else {
+		return 0;
+	}
+
+	return 1;
+}
+
+static void NORETURN diagnose_missing_default(const char *def)
+{
+	int flags;
+	const char *refname;
+
+	refname = resolve_ref_unsafe(def, 0, NULL, &flags);
+	if (!refname || !(flags & REF_ISSYMREF) || (flags & REF_ISBROKEN))
+		die(_("your current branch appears to be broken"));
+
+	skip_prefix(refname, "refs/heads/", &refname);
+	die(_("your current branch '%s' does not have any commits yet"),
+	    refname);
+}
+
+/*
+ * Parse revision information, filling in the "rev_info" structure,
+ * and removing the used arguments from the argument list.
+ *
+ * Returns the number of arguments left that weren't recognized
+ * (which are also moved to the head of the argument list)
+ */
+int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct setup_revision_opt *opt)
+{
+	int i, flags, left, seen_dashdash, got_rev_arg = 0, revarg_opt;
+	struct argv_array prune_data = ARGV_ARRAY_INIT;
+	const char *submodule = NULL;
+
+	if (opt)
+		submodule = opt->submodule;
+
+	/* First, search for "--" */
+	if (opt && opt->assume_dashdash) {
+		seen_dashdash = 1;
+	} else {
+		seen_dashdash = 0;
+		for (i = 1; i < argc; i++) {
+			const char *arg = argv[i];
+			if (strcmp(arg, "--"))
+				continue;
+			argv[i] = NULL;
+			argc = i;
+			if (argv[i + 1])
+				argv_array_pushv(&prune_data, argv + i + 1);
+			seen_dashdash = 1;
+			break;
+		}
+	}
+
+	/* Second, deal with arguments and options */
+	flags = 0;
+	revarg_opt = opt ? opt->revarg_opt : 0;
+	if (seen_dashdash)
+		revarg_opt |= REVARG_CANNOT_BE_FILENAME;
+	for (left = i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+		if (*arg == '-') {
+			int opts;
+
+			opts = handle_revision_pseudo_opt(submodule,
+						revs, argc - i, argv + i,
+						&flags);
+			if (opts > 0) {
+				i += opts - 1;
+				continue;
+			}
+
+			if (!strcmp(arg, "--stdin")) {
+				if (revs->disable_stdin) {
+					argv[left++] = arg;
+					continue;
+				}
+				if (revs->read_from_stdin++)
+					die("--stdin given twice?");
+				read_revisions_from_stdin(revs, &prune_data);
+				continue;
+			}
+
+			opts = handle_revision_opt(revs, argc - i, argv + i,
+						   &left, argv, opt);
+			if (opts > 0) {
+				i += opts - 1;
+				continue;
+			}
+			if (opts < 0)
+				exit(128);
+			continue;
+		}
+
+
+		if (handle_revision_arg(arg, revs, flags, revarg_opt)) {
+			int j;
+			if (seen_dashdash || *arg == '^')
+				die("bad revision '%s'", arg);
+
+			/* If we didn't have a "--":
+			 * (1) all filenames must exist;
+			 * (2) all rev-args must not be interpretable
+			 *     as a valid filename.
+			 * but the latter we have checked in the main loop.
+			 */
+			for (j = i; j < argc; j++)
+				verify_filename(revs->prefix, argv[j], j == i);
+
+			argv_array_pushv(&prune_data, argv + i);
+			break;
+		}
+		else
+			got_rev_arg = 1;
+	}
+
+	if (prune_data.argc) {
+		/*
+		 * If we need to introduce the magic "a lone ':' means no
+		 * pathspec whatsoever", here is the place to do so.
+		 *
+		 * if (prune_data.nr == 1 && !strcmp(prune_data[0], ":")) {
+		 *	prune_data.nr = 0;
+		 *	prune_data.alloc = 0;
+		 *	free(prune_data.path);
+		 *	prune_data.path = NULL;
+		 * } else {
+		 *	terminate prune_data.alloc with NULL and
+		 *	call init_pathspec() to set revs->prune_data here.
+		 * }
+		 */
+		parse_pathspec(&revs->prune_data, 0, 0,
+			       revs->prefix, prune_data.argv);
+	}
+	argv_array_clear(&prune_data);
+
+	if (revs->def == NULL)
+		revs->def = opt ? opt->def : NULL;
+	if (opt && opt->tweak)
+		opt->tweak(revs, opt);
+	if (revs->show_merge)
+		prepare_show_merge(revs);
+	if (revs->def && !revs->pending.nr && !revs->rev_input_given && !got_rev_arg) {
+		struct object_id oid;
+		struct object *object;
+		struct object_context oc;
+		if (get_oid_with_context(revs->repo, revs->def, 0, &oid, &oc))
+			diagnose_missing_default(revs->def);
+		object = get_reference(revs, revs->def, &oid, 0);
+		add_pending_object_with_mode(revs, object, revs->def, oc.mode);
+	}
+
+	/* Did the user ask for any diff output? Run the diff! */
+	if (revs->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT)
+		revs->diff = 1;
+
+	/* Pickaxe, diff-filter and rename following need diffs */
+	if ((revs->diffopt.pickaxe_opts & DIFF_PICKAXE_KINDS_MASK) ||
+	    revs->diffopt.filter ||
+	    revs->diffopt.flags.follow_renames)
+		revs->diff = 1;
+
+	if (revs->diffopt.objfind)
+		revs->simplify_history = 0;
+
+	if (revs->topo_order && !generation_numbers_enabled(the_repository))
+		revs->limited = 1;
+
+	if (revs->prune_data.nr) {
+		copy_pathspec(&revs->pruning.pathspec, &revs->prune_data);
+		/* Can't prune commits with rename following: the paths change.. */
+		if (!revs->diffopt.flags.follow_renames)
+			revs->prune = 1;
+		if (!revs->full_diff)
+			copy_pathspec(&revs->diffopt.pathspec,
+				      &revs->prune_data);
+	}
+	if (revs->combine_merges)
+		revs->ignore_merges = 0;
+	if (revs->combined_all_paths && !revs->combine_merges)
+		die("--combined-all-paths makes no sense without -c or --cc");
+
+	revs->diffopt.abbrev = revs->abbrev;
+
+	if (revs->line_level_traverse) {
+		revs->limited = 1;
+		revs->topo_order = 1;
+	}
+
+	diff_setup_done(&revs->diffopt);
+
+	grep_commit_pattern_type(GREP_PATTERN_TYPE_UNSPECIFIED,
+				 &revs->grep_filter);
+	compile_grep_patterns(&revs->grep_filter);
+
+	if (revs->reverse && revs->reflog_info)
+		die("cannot combine --reverse with --walk-reflogs");
+	if (revs->reflog_info && revs->limited)
+		die("cannot combine --walk-reflogs with history-limiting options");
+	if (revs->rewrite_parents && revs->children.name)
+		die("cannot combine --parents and --children");
+
+	/*
+	 * Limitations on the graph functionality
+	 */
+	if (revs->reverse && revs->graph)
+		die("cannot combine --reverse with --graph");
+
+	if (revs->reflog_info && revs->graph)
+		die("cannot combine --walk-reflogs with --graph");
+	if (revs->no_walk && revs->graph)
+		die("cannot combine --no-walk with --graph");
+	if (!revs->reflog_info && revs->grep_filter.use_reflog_filter)
+		die("cannot use --grep-reflog without --walk-reflogs");
+
+	if (revs->first_parent_only && revs->bisect)
+		die(_("--first-parent is incompatible with --bisect"));
+
+	if (revs->line_level_traverse &&
+	    (revs->diffopt.output_format & ~(DIFF_FORMAT_PATCH | DIFF_FORMAT_NO_OUTPUT)))
+		die(_("-L does not yet support diff formats besides -p and -s"));
+
+	if (revs->expand_tabs_in_log < 0)
+		revs->expand_tabs_in_log = revs->expand_tabs_in_log_default;
+
+	return left;
+}
+
+static void add_child(struct rev_info *revs, struct commit *parent, struct commit *child)
+{
+	struct commit_list *l = xcalloc(1, sizeof(*l));
+
+	l->item = child;
+	l->next = add_decoration(&revs->children, &parent->object, l);
+}
+
+static int remove_duplicate_parents(struct rev_info *revs, struct commit *commit)
+{
+	struct treesame_state *ts = lookup_decoration(&revs->treesame, &commit->object);
+	struct commit_list **pp, *p;
+	int surviving_parents;
+
+	/* Examine existing parents while marking ones we have seen... */
+	pp = &commit->parents;
+	surviving_parents = 0;
+	while ((p = *pp) != NULL) {
+		struct commit *parent = p->item;
+		if (parent->object.flags & TMP_MARK) {
+			*pp = p->next;
+			if (ts)
+				compact_treesame(revs, commit, surviving_parents);
+			continue;
+		}
+		parent->object.flags |= TMP_MARK;
+		surviving_parents++;
+		pp = &p->next;
+	}
+	/* clear the temporary mark */
+	for (p = commit->parents; p; p = p->next) {
+		p->item->object.flags &= ~TMP_MARK;
+	}
+	/* no update_treesame() - removing duplicates can't affect TREESAME */
+	return surviving_parents;
+}
+
+struct merge_simplify_state {
+	struct commit *simplified;
+};
+
+static struct merge_simplify_state *locate_simplify_state(struct rev_info *revs, struct commit *commit)
+{
+	struct merge_simplify_state *st;
+
+	st = lookup_decoration(&revs->merge_simplification, &commit->object);
+	if (!st) {
+		st = xcalloc(1, sizeof(*st));
+		add_decoration(&revs->merge_simplification, &commit->object, st);
+	}
+	return st;
+}
+
+static int mark_redundant_parents(struct commit *commit)
+{
+	struct commit_list *h = reduce_heads(commit->parents);
+	int i = 0, marked = 0;
+	struct commit_list *po, *pn;
+
+	/* Want these for sanity-checking only */
+	int orig_cnt = commit_list_count(commit->parents);
+	int cnt = commit_list_count(h);
+
+	/*
+	 * Not ready to remove items yet, just mark them for now, based
+	 * on the output of reduce_heads(). reduce_heads outputs the reduced
+	 * set in its original order, so this isn't too hard.
+	 */
+	po = commit->parents;
+	pn = h;
+	while (po) {
+		if (pn && po->item == pn->item) {
+			pn = pn->next;
+			i++;
+		} else {
+			po->item->object.flags |= TMP_MARK;
+			marked++;
+		}
+		po=po->next;
+	}
+
+	if (i != cnt || cnt+marked != orig_cnt)
+		die("mark_redundant_parents %d %d %d %d", orig_cnt, cnt, i, marked);
+
+	free_commit_list(h);
+
+	return marked;
+}
+
+static int mark_treesame_root_parents(struct commit *commit)
+{
+	struct commit_list *p;
+	int marked = 0;
+
+	for (p = commit->parents; p; p = p->next) {
+		struct commit *parent = p->item;
+		if (!parent->parents && (parent->object.flags & TREESAME)) {
+			parent->object.flags |= TMP_MARK;
+			marked++;
+		}
+	}
+
+	return marked;
+}
+
+/*
+ * Awkward naming - this means one parent we are TREESAME to.
+ * cf mark_treesame_root_parents: root parents that are TREESAME (to an
+ * empty tree). Better name suggestions?
+ */
+static int leave_one_treesame_to_parent(struct rev_info *revs, struct commit *commit)
+{
+	struct treesame_state *ts = lookup_decoration(&revs->treesame, &commit->object);
+	struct commit *unmarked = NULL, *marked = NULL;
+	struct commit_list *p;
+	unsigned n;
+
+	for (p = commit->parents, n = 0; p; p = p->next, n++) {
+		if (ts->treesame[n]) {
+			if (p->item->object.flags & TMP_MARK) {
+				if (!marked)
+					marked = p->item;
+			} else {
+				if (!unmarked) {
+					unmarked = p->item;
+					break;
+				}
+			}
+		}
+	}
+
+	/*
+	 * If we are TREESAME to a marked-for-deletion parent, but not to any
+	 * unmarked parents, unmark the first TREESAME parent. This is the
+	 * parent that the default simplify_history==1 scan would have followed,
+	 * and it doesn't make sense to omit that path when asking for a
+	 * simplified full history. Retaining it improves the chances of
+	 * understanding odd missed merges that took an old version of a file.
+	 *
+	 * Example:
+	 *
+	 *   I--------*X       A modified the file, but mainline merge X used
+	 *    \       /        "-s ours", so took the version from I. X is
+	 *     `-*A--'         TREESAME to I and !TREESAME to A.
+	 *
+	 * Default log from X would produce "I". Without this check,
+	 * --full-history --simplify-merges would produce "I-A-X", showing
+	 * the merge commit X and that it changed A, but not making clear that
+	 * it had just taken the I version. With this check, the topology above
+	 * is retained.
+	 *
+	 * Note that it is possible that the simplification chooses a different
+	 * TREESAME parent from the default, in which case this test doesn't
+	 * activate, and we _do_ drop the default parent. Example:
+	 *
+	 *   I------X         A modified the file, but it was reverted in B,
+	 *    \    /          meaning mainline merge X is TREESAME to both
+	 *    *A-*B           parents.
+	 *
+	 * Default log would produce "I" by following the first parent;
+	 * --full-history --simplify-merges will produce "I-A-B". But this is a
+	 * reasonable result - it presents a logical full history leading from
+	 * I to X, and X is not an important merge.
+	 */
+	if (!unmarked && marked) {
+		marked->object.flags &= ~TMP_MARK;
+		return 1;
+	}
+
+	return 0;
+}
+
+static int remove_marked_parents(struct rev_info *revs, struct commit *commit)
+{
+	struct commit_list **pp, *p;
+	int nth_parent, removed = 0;
+
+	pp = &commit->parents;
+	nth_parent = 0;
+	while ((p = *pp) != NULL) {
+		struct commit *parent = p->item;
+		if (parent->object.flags & TMP_MARK) {
+			parent->object.flags &= ~TMP_MARK;
+			*pp = p->next;
+			free(p);
+			removed++;
+			compact_treesame(revs, commit, nth_parent);
+			continue;
+		}
+		pp = &p->next;
+		nth_parent++;
+	}
+
+	/* Removing parents can only increase TREESAMEness */
+	if (removed && !(commit->object.flags & TREESAME))
+		update_treesame(revs, commit);
+
+	return nth_parent;
+}
+
+static struct commit_list **simplify_one(struct rev_info *revs, struct commit *commit, struct commit_list **tail)
+{
+	struct commit_list *p;
+	struct commit *parent;
+	struct merge_simplify_state *st, *pst;
+	int cnt;
+
+	st = locate_simplify_state(revs, commit);
+
+	/*
+	 * Have we handled this one?
+	 */
+	if (st->simplified)
+		return tail;
+
+	/*
+	 * An UNINTERESTING commit simplifies to itself, so does a
+	 * root commit.  We do not rewrite parents of such commit
+	 * anyway.
+	 */
+	if ((commit->object.flags & UNINTERESTING) || !commit->parents) {
+		st->simplified = commit;
+		return tail;
+	}
+
+	/*
+	 * 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)
+		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);
+}
+
+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 (parse_commit_gently(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)) &&
+	       c->generation >= 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 (parse_commit_gently(c, 1) < 0)
+		return;
+
+	explore_to_depth(revs, c->generation);
+
+	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)) &&
+	       c->generation >= gen_cutoff)
+		indegree_walk_step(revs);
+}
+
+static void init_topo_walk(struct rev_info *revs)
+{
+	struct topo_walk_info *info;
+	struct commit_list *list;
+	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;
+	}
+
+	info->explore_queue.compare = compare_commits_by_gen_then_commit_date;
+	info->indegree_queue.compare = compare_commits_by_gen_then_commit_date;
+
+	info->min_generation = GENERATION_NUMBER_INFINITY;
+	for (list = revs->commits; list; list = list->next) {
+		struct commit *c = list->item;
+
+		if (parse_commit_gently(c, 1))
+			continue;
+
+		test_flag_and_insert(&info->explore_queue, c, TOPO_WALK_EXPLORED);
+		test_flag_and_insert(&info->indegree_queue, c, TOPO_WALK_INDEGREE);
+
+		if (c->generation < info->min_generation)
+			info->min_generation = c->generation;
+
+		*(indegree_slab_at(&info->indegree, c)) = 1;
+
+		if (revs->sort_order == REV_SORT_BY_AUTHOR_DATE)
+			record_author_date(&info->author_date, c);
+	}
+	compute_indegrees_to_depth(revs, info->min_generation);
+
+	for (list = revs->commits; list; list = list->next) {
+		struct commit *c = list->item;
+
+		if (*(indegree_slab_at(&info->indegree, c)) == 1)
+			prio_queue_put(&info->topo_queue, c);
+	}
+
+	/*
+	 * This is unfortunate; the initial tips need to be shown
+	 * in the order given from the revision traversal machinery.
+	 */
+	if (revs->sort_order == REV_SORT_IN_GRAPH_ORDER)
+		prio_queue_reverse(&info->topo_queue);
+}
+
+static struct commit *next_topo_commit(struct rev_info *revs)
+{
+	struct commit *c;
+	struct topo_walk_info *info = revs->topo_walk_info;
+
+	/* pop next off of topo_queue */
+	c = prio_queue_get(&info->topo_queue);
+
+	if (c)
+		*(indegree_slab_at(&info->indegree, c)) = 0;
+
+	return c;
+}
+
+static void expand_topo_walk(struct rev_info *revs, struct commit *commit)
+{
+	struct commit_list *p;
+	struct topo_walk_info *info = revs->topo_walk_info;
+	if (process_parents(revs, commit, NULL, NULL) < 0) {
+		if (!revs->ignore_missing_links)
+			die("Failed to traverse parents of commit %s",
+			    oid_to_hex(&commit->object.oid));
+	}
+
+	for (p = commit->parents; p; p = p->next) {
+		struct commit *parent = p->item;
+		int *pi;
+
+		if (parent->object.flags & UNINTERESTING)
+			continue;
+
+		if (parse_commit_gently(parent, 1) < 0)
+			continue;
+
+		if (parent->generation < info->min_generation) {
+			info->min_generation = parent->generation;
+			compute_indegrees_to_depth(revs, info->min_generation);
+		}
+
+		pi = indegree_slab_at(&info->indegree, parent);
+
+		(*pi)--;
+		if (*pi == 1)
+			prio_queue_put(&info->topo_queue, parent);
+
+		if (revs->first_parent_only)
+			return;
+	}
+}
+
+int prepare_revision_walk(struct rev_info *revs)
+{
+	int i;
+	struct object_array old_pending;
+	struct commit_list **next = &revs->commits;
+
+	memcpy(&old_pending, &revs->pending, sizeof(old_pending));
+	revs->pending.nr = 0;
+	revs->pending.alloc = 0;
+	revs->pending.objects = NULL;
+	for (i = 0; i < old_pending.nr; i++) {
+		struct object_array_entry *e = old_pending.objects + i;
+		struct commit *commit = handle_commit(revs, e);
+		if (commit) {
+			if (!(commit->object.flags & SEEN)) {
+				commit->object.flags |= SEEN;
+				next = commit_list_append(commit, next);
+			}
+		}
+	}
+	object_array_clear(&old_pending);
+
+	/* Signal whether we need per-parent treesame decoration */
+	if (revs->simplify_merges ||
+	    (revs->limited && limiting_can_increase_treesame(revs)))
+		revs->treesame.name = "treesame";
+
+	if (revs->exclude_promisor_objects) {
+		for_each_packed_object(mark_uninteresting, revs,
+				       FOR_EACH_OBJECT_PROMISOR_ONLY);
+	}
+
+	if (revs->no_walk != REVISION_WALK_NO_WALK_UNSORTED)
+		commit_list_sort_by_date(&revs->commits);
+	if (revs->no_walk)
+		return 0;
+	if (revs->limited) {
+		if (limit_list(revs) < 0)
+			return -1;
+		if (revs->topo_order)
+			sort_in_topological_order(&revs->commits, revs->sort_order);
+	} else if (revs->topo_order)
+		init_topo_walk(revs);
+	if (revs->line_level_traverse)
+		line_log_filter(revs);
+	if (revs->simplify_merges)
+		simplify_merges(revs);
+	if (revs->children.name)
+		set_children(revs);
+	return 0;
+}
+
+static enum rewrite_result rewrite_one_1(struct rev_info *revs,
+					 struct commit **pp,
+					 struct prio_queue *queue)
+{
+	for (;;) {
+		struct commit *p = *pp;
+		if (!revs->limited)
+			if (process_parents(revs, p, NULL, queue) < 0)
+				return rewrite_one_error;
+		if (p->object.flags & UNINTERESTING)
+			return rewrite_one_ok;
+		if (!(p->object.flags & TREESAME))
+			return rewrite_one_ok;
+		if (!p->parents)
+			return rewrite_one_noparents;
+		if ((p = one_relevant_parent(revs, p->parents)) == NULL)
+			return rewrite_one_ok;
+		*pp = p;
+	}
+}
+
+static void merge_queue_into_list(struct prio_queue *q, struct commit_list **list)
+{
+	while (q->nr) {
+		struct commit *item = prio_queue_peek(q);
+		struct commit_list *p = *list;
+
+		if (p && p->item->date >= item->date)
+			list = &p->next;
+		else {
+			p = commit_list_insert(item, list);
+			list = &p->next; /* skip newly added item */
+			prio_queue_get(q); /* pop item */
+		}
+	}
+}
+
+static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
+{
+	struct prio_queue queue = { compare_commits_by_commit_date };
+	enum rewrite_result ret = rewrite_one_1(revs, pp, &queue);
+	merge_queue_into_list(&queue, &revs->commits);
+	clear_prio_queue(&queue);
+	return ret;
+}
+
+int rewrite_parents(struct rev_info *revs, struct commit *commit,
+	rewrite_parent_fn_t rewrite_parent)
+{
+	struct commit_list **pp = &commit->parents;
+	while (*pp) {
+		struct commit_list *parent = *pp;
+		switch (rewrite_parent(revs, &parent->item)) {
+		case rewrite_one_ok:
+			break;
+		case rewrite_one_noparents:
+			*pp = parent->next;
+			continue;
+		case rewrite_one_error:
+			return -1;
+		}
+		pp = &parent->next;
+	}
+	remove_duplicate_parents(revs, commit);
+	return 0;
+}
+
+static int commit_rewrite_person(struct strbuf *buf, const char *what, struct string_list *mailmap)
+{
+	char *person, *endp;
+	size_t len, namelen, maillen;
+	const char *name;
+	const char *mail;
+	struct ident_split ident;
+
+	person = strstr(buf->buf, what);
+	if (!person)
+		return 0;
+
+	person += strlen(what);
+	endp = strchr(person, '\n');
+	if (!endp)
+		return 0;
+
+	len = endp - person;
+
+	if (split_ident_line(&ident, person, len))
+		return 0;
+
+	mail = ident.mail_begin;
+	maillen = ident.mail_end - ident.mail_begin;
+	name = ident.name_begin;
+	namelen = ident.name_end - ident.name_begin;
+
+	if (map_user(mailmap, &mail, &maillen, &name, &namelen)) {
+		struct strbuf namemail = STRBUF_INIT;
+
+		strbuf_addf(&namemail, "%.*s <%.*s>",
+			    (int)namelen, name, (int)maillen, mail);
+
+		strbuf_splice(buf, ident.name_begin - buf->buf,
+			      ident.mail_end - ident.name_begin + 1,
+			      namemail.buf, namemail.len);
+
+		strbuf_release(&namemail);
+
+		return 1;
+	}
+
+	return 0;
+}
+
+static int commit_match(struct commit *commit, struct rev_info *opt)
+{
+	int retval;
+	const char *encoding;
+	const char *message;
+	struct strbuf buf = STRBUF_INIT;
+
+	if (!opt->grep_filter.pattern_list && !opt->grep_filter.header_list)
+		return 1;
+
+	/* Prepend "fake" headers as needed */
+	if (opt->grep_filter.use_reflog_filter) {
+		strbuf_addstr(&buf, "reflog ");
+		get_reflog_message(&buf, opt->reflog_info);
+		strbuf_addch(&buf, '\n');
+	}
+
+	/*
+	 * We grep in the user's output encoding, under the assumption that it
+	 * is the encoding they are most likely to write their grep pattern
+	 * for. In addition, it means we will match the "notes" encoding below,
+	 * so we will not end up with a buffer that has two different encodings
+	 * in it.
+	 */
+	encoding = get_log_output_encoding();
+	message = logmsg_reencode(commit, NULL, encoding);
+
+	/* Copy the commit to temporary if we are using "fake" headers */
+	if (buf.len)
+		strbuf_addstr(&buf, message);
+
+	if (opt->grep_filter.header_list && opt->mailmap) {
+		if (!buf.len)
+			strbuf_addstr(&buf, message);
+
+		commit_rewrite_person(&buf, "\nauthor ", opt->mailmap);
+		commit_rewrite_person(&buf, "\ncommitter ", opt->mailmap);
+	}
+
+	/* Append "fake" message parts as needed */
+	if (opt->show_notes) {
+		if (!buf.len)
+			strbuf_addstr(&buf, message);
+		format_display_notes(&commit->object.oid, &buf, encoding, 1);
+	}
+
+	/*
+	 * Find either in the original commit message, or in the temporary.
+	 * Note that we cast away the constness of "message" here. It is
+	 * const because it may come from the cached commit buffer. That's OK,
+	 * because we know that it is modifiable heap memory, and that while
+	 * grep_buffer may modify it for speed, it will restore any
+	 * changes before returning.
+	 */
+	if (buf.len)
+		retval = grep_buffer(&opt->grep_filter, buf.buf, buf.len);
+	else
+		retval = grep_buffer(&opt->grep_filter,
+				     (char *)message, strlen(message));
+	strbuf_release(&buf);
+	unuse_commit_buffer(commit, message);
+	return opt->invert_grep ? !retval : retval;
+}
+
+static inline int want_ancestry(const struct rev_info *revs)
+{
+	return (revs->rewrite_parents || revs->children.name);
+}
+
+/*
+ * Return a timestamp to be used for --since/--until comparisons for this
+ * commit, based on the revision options.
+ */
+static timestamp_t comparison_date(const struct rev_info *revs,
+				   struct commit *commit)
+{
+	return revs->reflog_info ?
+		get_reflog_timestamp(revs->reflog_info) :
+		commit->date;
+}
+
+enum commit_action get_commit_action(struct rev_info *revs, struct commit *commit)
+{
+	if (commit->object.flags & SHOWN)
+		return commit_ignore;
+	if (revs->unpacked && has_object_pack(&commit->object.oid))
+		return commit_ignore;
+	if (commit->object.flags & UNINTERESTING)
+		return commit_ignore;
+	if (revs->min_age != -1 &&
+	    comparison_date(revs, commit) > revs->min_age)
+			return commit_ignore;
+	if (revs->min_parents || (revs->max_parents >= 0)) {
+		int n = commit_list_count(commit->parents);
+		if ((n < revs->min_parents) ||
+		    ((revs->max_parents >= 0) && (n > revs->max_parents)))
+			return commit_ignore;
+	}
+	if (!commit_match(commit, revs))
+		return commit_ignore;
+	if (revs->prune && revs->dense) {
+		/* Commit without changes? */
+		if (commit->object.flags & TREESAME) {
+			int n;
+			struct commit_list *p;
+			/* drop merges unless we want parenthood */
+			if (!want_ancestry(revs))
+				return commit_ignore;
+			/*
+			 * If we want ancestry, then need to keep any merges
+			 * between relevant commits to tie together topology.
+			 * For consistency with TREESAME and simplification
+			 * use "relevant" here rather than just INTERESTING,
+			 * to treat bottom commit(s) as part of the topology.
+			 */
+			for (n = 0, p = commit->parents; p; p = p->next)
+				if (relevant_commit(p->item))
+					if (++n >= 2)
+						return commit_show;
+			return commit_ignore;
+		}
+	}
+	return commit_show;
+}
+
+define_commit_slab(saved_parents, struct commit_list *);
+
+#define EMPTY_PARENT_LIST ((struct commit_list *)-1)
+
+/*
+ * You may only call save_parents() once per commit (this is checked
+ * for non-root commits).
+ */
+static void save_parents(struct rev_info *revs, struct commit *commit)
+{
+	struct commit_list **pp;
+
+	if (!revs->saved_parents_slab) {
+		revs->saved_parents_slab = xmalloc(sizeof(struct saved_parents));
+		init_saved_parents(revs->saved_parents_slab);
+	}
+
+	pp = saved_parents_at(revs->saved_parents_slab, commit);
+
+	/*
+	 * When walking with reflogs, we may visit the same commit
+	 * several times: once for each appearance in the reflog.
+	 *
+	 * In this case, save_parents() will be called multiple times.
+	 * We want to keep only the first set of parents.  We need to
+	 * store a sentinel value for an empty (i.e., NULL) parent
+	 * list to distinguish it from a not-yet-saved list, however.
+	 */
+	if (*pp)
+		return;
+	if (commit->parents)
+		*pp = copy_commit_list(commit->parents);
+	else
+		*pp = EMPTY_PARENT_LIST;
+}
+
+static void free_saved_parents(struct rev_info *revs)
+{
+	if (revs->saved_parents_slab)
+		clear_saved_parents(revs->saved_parents_slab);
+}
+
+struct commit_list *get_saved_parents(struct rev_info *revs, const struct commit *commit)
+{
+	struct commit_list *parents;
+
+	if (!revs->saved_parents_slab)
+		return commit->parents;
+
+	parents = *saved_parents_at(revs->saved_parents_slab, commit);
+	if (parents == EMPTY_PARENT_LIST)
+		return NULL;
+	return parents;
+}
+
+enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit)
+{
+	enum commit_action action = get_commit_action(revs, commit);
+
+	if (action == commit_show &&
+	    revs->prune && revs->dense && want_ancestry(revs)) {
+		/*
+		 * --full-diff on simplified parents is no good: it
+		 * will show spurious changes from the commits that
+		 * were elided.  So we save the parents on the side
+		 * when --full-diff is in effect.
+		 */
+		if (revs->full_diff)
+			save_parents(revs, commit);
+		if (rewrite_parents(revs, commit, rewrite_one) < 0)
+			return commit_error;
+	}
+	return action;
+}
+
+static void track_linear(struct rev_info *revs, struct commit *commit)
+{
+	if (revs->track_first_time) {
+		revs->linear = 1;
+		revs->track_first_time = 0;
+	} else {
+		struct commit_list *p;
+		for (p = revs->previous_parents; p; p = p->next)
+			if (p->item == NULL || /* first commit */
+			    oideq(&p->item->object.oid, &commit->object.oid))
+				break;
+		revs->linear = p != NULL;
+	}
+	if (revs->reverse) {
+		if (revs->linear)
+			commit->object.flags |= TRACK_LINEAR;
+	}
+	free_commit_list(revs->previous_parents);
+	revs->previous_parents = copy_commit_list(commit->parents);
+}
+
+static struct commit *get_revision_1(struct rev_info *revs)
+{
+	while (1) {
+		struct commit *commit;
+
+		if (revs->reflog_info)
+			commit = next_reflog_entry(revs->reflog_info);
+		else if (revs->topo_walk_info)
+			commit = next_topo_commit(revs);
+		else
+			commit = pop_commit(&revs->commits);
+
+		if (!commit)
+			return NULL;
+
+		if (revs->reflog_info)
+			commit->object.flags &= ~(ADDED | SEEN | SHOWN);
+
+		/*
+		 * If we haven't done the list limiting, we need to look at
+		 * the parents here. We also need to do the date-based limiting
+		 * that we'd otherwise have done in limit_list().
+		 */
+		if (!revs->limited) {
+			if (revs->max_age != -1 &&
+			    comparison_date(revs, commit) < revs->max_age)
+				continue;
+
+			if (revs->reflog_info)
+				try_to_simplify_commit(revs, commit);
+			else if (revs->topo_walk_info)
+				expand_topo_walk(revs, commit);
+			else if (process_parents(revs, commit, &revs->commits, NULL) < 0) {
+				if (!revs->ignore_missing_links)
+					die("Failed to traverse parents of commit %s",
+						oid_to_hex(&commit->object.oid));
+			}
+		}
+
+		switch (simplify_commit(revs, commit)) {
+		case commit_ignore:
+			continue;
+		case commit_error:
+			die("Failed to simplify parents of commit %s",
+			    oid_to_hex(&commit->object.oid));
+		default:
+			if (revs->track_linear)
+				track_linear(revs, commit);
+			return commit;
+		}
+	}
+}
+
+/*
+ * Return true for entries that have not yet been shown.  (This is an
+ * object_array_each_func_t.)
+ */
+static int entry_unshown(struct object_array_entry *entry, void *cb_data_unused)
+{
+	return !(entry->item->flags & SHOWN);
+}
+
+/*
+ * If array is on the verge of a realloc, garbage-collect any entries
+ * that have already been shown to try to free up some space.
+ */
+static void gc_boundary(struct object_array *array)
+{
+	if (array->nr == array->alloc)
+		object_array_filter(array, entry_unshown, NULL);
+}
+
+static void create_boundary_commit_list(struct rev_info *revs)
+{
+	unsigned i;
+	struct commit *c;
+	struct object_array *array = &revs->boundary_commits;
+	struct object_array_entry *objects = array->objects;
+
+	/*
+	 * If revs->commits is non-NULL at this point, an error occurred in
+	 * get_revision_1().  Ignore the error and continue printing the
+	 * boundary commits anyway.  (This is what the code has always
+	 * done.)
+	 */
+	if (revs->commits) {
+		free_commit_list(revs->commits);
+		revs->commits = NULL;
+	}
+
+	/*
+	 * Put all of the actual boundary commits from revs->boundary_commits
+	 * into revs->commits
+	 */
+	for (i = 0; i < array->nr; i++) {
+		c = (struct commit *)(objects[i].item);
+		if (!c)
+			continue;
+		if (!(c->object.flags & CHILD_SHOWN))
+			continue;
+		if (c->object.flags & (SHOWN | BOUNDARY))
+			continue;
+		c->object.flags |= BOUNDARY;
+		commit_list_insert(c, &revs->commits);
+	}
+
+	/*
+	 * If revs->topo_order is set, sort the boundary commits
+	 * in topological order
+	 */
+	sort_in_topological_order(&revs->commits, revs->sort_order);
+}
+
+static struct commit *get_revision_internal(struct rev_info *revs)
+{
+	struct commit *c = NULL;
+	struct commit_list *l;
+
+	if (revs->boundary == 2) {
+		/*
+		 * All of the normal commits have already been returned,
+		 * and we are now returning boundary commits.
+		 * create_boundary_commit_list() has populated
+		 * revs->commits with the remaining commits to return.
+		 */
+		c = pop_commit(&revs->commits);
+		if (c)
+			c->object.flags |= SHOWN;
+		return c;
+	}
+
+	/*
+	 * If our max_count counter has reached zero, then we are done. We
+	 * don't simply return NULL because we still might need to show
+	 * boundary commits. But we want to avoid calling get_revision_1, which
+	 * might do a considerable amount of work finding the next commit only
+	 * for us to throw it away.
+	 *
+	 * If it is non-zero, then either we don't have a max_count at all
+	 * (-1), or it is still counting, in which case we decrement.
+	 */
+	if (revs->max_count) {
+		c = get_revision_1(revs);
+		if (c) {
+			while (revs->skip_count > 0) {
+				revs->skip_count--;
+				c = get_revision_1(revs);
+				if (!c)
+					break;
+			}
+		}
+
+		if (revs->max_count > 0)
+			revs->max_count--;
+	}
+
+	if (c)
+		c->object.flags |= SHOWN;
+
+	if (!revs->boundary)
+		return c;
+
+	if (!c) {
+		/*
+		 * get_revision_1() runs out the commits, and
+		 * we are done computing the boundaries.
+		 * switch to boundary commits output mode.
+		 */
+		revs->boundary = 2;
+
+		/*
+		 * Update revs->commits to contain the list of
+		 * boundary commits.
+		 */
+		create_boundary_commit_list(revs);
+
+		return get_revision_internal(revs);
+	}
+
+	/*
+	 * boundary commits are the commits that are parents of the
+	 * ones we got from get_revision_1() but they themselves are
+	 * not returned from get_revision_1().  Before returning
+	 * 'c', we need to mark its parents that they could be boundaries.
+	 */
+
+	for (l = c->parents; l; l = l->next) {
+		struct object *p;
+		p = &(l->item->object);
+		if (p->flags & (CHILD_SHOWN | SHOWN))
+			continue;
+		p->flags |= CHILD_SHOWN;
+		gc_boundary(&revs->boundary_commits);
+		add_object_array(p, NULL, &revs->boundary_commits);
+	}
+
+	return c;
+}
+
+struct commit *get_revision(struct rev_info *revs)
+{
+	struct commit *c;
+	struct commit_list *reversed;
+
+	if (revs->reverse) {
+		reversed = NULL;
+		while ((c = get_revision_internal(revs)))
+			commit_list_insert(c, &reversed);
+		revs->commits = reversed;
+		revs->reverse = 0;
+		revs->reverse_output_stage = 1;
+	}
+
+	if (revs->reverse_output_stage) {
+		c = pop_commit(&revs->commits);
+		if (revs->track_linear)
+			revs->linear = !!(c && c->object.flags & TRACK_LINEAR);
+		return c;
+	}
+
+	c = get_revision_internal(revs);
+	if (c && revs->graph)
+		graph_update(revs->graph, c);
+	if (!c) {
+		free_saved_parents(revs);
+		if (revs->previous_parents) {
+			free_commit_list(revs->previous_parents);
+			revs->previous_parents = NULL;
+		}
+	}
+	return c;
+}
+
+char *get_revision_mark(const struct rev_info *revs, const struct commit *commit)
+{
+	if (commit->object.flags & BOUNDARY)
+		return "-";
+	else if (commit->object.flags & UNINTERESTING)
+		return "^";
+	else if (commit->object.flags & PATCHSAME)
+		return "=";
+	else if (!revs || revs->left_right) {
+		if (commit->object.flags & SYMMETRIC_LEFT)
+			return "<";
+		else
+			return ">";
+	} else if (revs->graph)
+		return "*";
+	else if (revs->cherry_mark)
+		return "+";
+	return "";
+}
+
+void put_revision_mark(const struct rev_info *revs, const struct commit *commit)
+{
+	char *mark = get_revision_mark(revs, commit);
+	if (!strlen(mark))
+		return;
+	fputs(mark, stdout);
+	putchar(' ');
+}