Changeset 782 for git/branches/dmik/revision.c

Timestamp:

Jun 23, 2014, 9:45:51 PM (11 years ago)

Author:

dmik

Message:

git: Merge version 2.0.0 from vendor to dmik branch.

Location:

git/branches/dmik

Files:

• . (modified) (1 prop)
• revision.c (modified) (104 diffs)

git/branches/dmik/revision.c ¶

@@ -14 +14 @@
 #include "log-tree.h"
 #include "string-list.h"
+#include "line-log.h"
+#include "mailmap.h"
+#include "commit-slab.h"
+#include "dir.h"
 
 volatile show_early_output_fn_t show_early_output;
@@ -70 +74 @@
 }
 
-void show_object_with_name(FILE *out, struct object *obj, const struct name_path *path, const char *component)
+void show_object_with_name(FILE *out, struct object *obj,
+                           const struct name_path *path, const char *component)
 {
         struct name_path leaf;
@@ -87 +92 @@
                 const char *name)
 {
-        add_object_array(obj, path_name(path, name), p);
+        char *pn = path_name(path, name);
+        add_object_array(obj, pn, p);
+        free(pn);
 }
 
@@ -99 +106 @@
 }
 
-void mark_tree_uninteresting(struct tree *tree)
+static void mark_tree_contents_uninteresting(struct tree *tree)
 {
         struct tree_desc desc;
@@ -105 +112 @@
         struct object *obj = &tree->object;
 
-        if (!tree)
-                return;
-        if (obj->flags & UNINTERESTING)
-                return;
-        obj->flags |= UNINTERESTING;
         if (!has_sha1_file(obj->sha1))
                 return;
@@ -134 +136 @@
          * after it has been marked uninteresting.
          */
-        free(tree->buffer);
-        tree->buffer = NULL;
+        free_tree_buffer(tree);
+}
+
+void mark_tree_uninteresting(struct tree *tree)
+{
+        struct object *obj = &tree->object;
+
+        if (!tree)
+                return;
+        if (obj->flags & UNINTERESTING)
+                return;
+        obj->flags |= UNINTERESTING;
+        mark_tree_contents_uninteresting(tree);
 }
 
 void mark_parents_uninteresting(struct commit *commit)
 {
-        struct commit_list *parents = commit->parents;
+        struct commit_list *parents = NULL, *l;
+
+        for (l = commit->parents; l; l = l->next)
+                commit_list_insert(l->item, &parents);
 
         while (parents) {
                 struct commit *commit = parents->item;
-                if (!(commit->object.flags & UNINTERESTING)) {
+                l = parents;
+                parents = parents->next;
+                free(l);
+
+                while (commit) {
+                        /*
+                         * A missing commit is ok iff its parent is marked
+                         * uninteresting.
+                         *
+                         * We just mark such a thing parsed, so that when
+                         * it is popped next time around, we won't be trying
+                         * to parse it and get an error.
+                         */
+                        if (!has_sha1_file(commit->object.sha1))
+                                commit->object.parsed = 1;
+
+                        if (commit->object.flags & UNINTERESTING)
+                                break;
+
                         commit->object.flags |= UNINTERESTING;
 
@@ -155 +189 @@
                          * to mark its parents recursively too..
                          */
-                        if (commit->parents)
-                                mark_parents_uninteresting(commit);
-                }
-
-                /*
-                 * A missing commit is ok iff its parent is marked
-                 * uninteresting.
-                 *
-                 * We just mark such a thing parsed, so that when
-                 * it is popped next time around, we won't be trying
-                 * to parse it and get an error.
-                 */
-                if (!has_sha1_file(commit->object.sha1))
-                        commit->object.parsed = 1;
-                parents = parents->next;
-        }
-}
-
-static void add_pending_object_with_mode(struct rev_info *revs, struct object *obj, const char *name, unsigned mode)
+                        if (!commit->parents)
+                                break;
+
+                        for (l = commit->parents->next; l; l = l->next)
+                                commit_list_insert(l->item, &parents);
+                        commit = commit->parents->item;
+                }
+        }
+}
+
+static void add_pending_object_with_mode(struct rev_info *revs,
+                                         struct object *obj,
+                                         const char *name, unsigned mode)
 {
         if (!obj)
@@ -181 +209 @@
         if (revs->reflog_info && obj->type == OBJ_COMMIT) {
                 struct strbuf buf = STRBUF_INIT;
-                int len = interpret_branch_name(name, &buf);
+                int len = interpret_branch_name(name, 0, &buf);
                 int st;
 
@@ -196 +224 @@
 }
 
-void add_pending_object(struct rev_info *revs, struct object *obj, const char *name)
+void add_pending_object(struct rev_info *revs,
+                        struct object *obj, const char *name)
 {
         add_pending_object_with_mode(revs, obj, name, S_IFINVALID);
@@ -213 +242 @@
 }
 
-static struct object *get_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
+static struct object *get_reference(struct rev_info *revs, const char *name,
+                                    const unsigned char *sha1,
+                                    unsigned int flags)
 {
         struct object *object;
@@ -234 +265 @@
 }
 
-static struct commit *handle_commit(struct rev_info *revs, struct object *object, const char *name)
+static struct commit *handle_commit(struct rev_info *revs,
+                                    struct object *object, const char *name)
 {
         unsigned long flags = object->flags;
@@ -253 +285 @@
                         die("bad object %s", sha1_to_hex(tag->tagged->sha1));
                 }
+                object->flags |= flags;
         }
 
@@ -264 +297 @@
                         die("unable to parse commit %s", name);
                 if (flags & UNINTERESTING) {
-                        commit->object.flags |= UNINTERESTING;
                         mark_parents_uninteresting(commit);
                         revs->limited = 1;
@@ -282 +314 @@
                         return NULL;
                 if (flags & UNINTERESTING) {
-                        mark_tree_uninteresting(tree);
+                        mark_tree_contents_uninteresting(tree);
                         return NULL;
                 }
@@ -293 +325 @@
          */
         if (object->type == OBJ_BLOB) {
-                struct blob *blob = (struct blob *)object;
                 if (!revs->blob_objects)
                         return NULL;
-                if (flags & UNINTERESTING) {
-                        mark_blob_uninteresting(blob);
+                if (flags & UNINTERESTING)
                         return NULL;
-                }
                 add_pending_object(revs, object, "");
                 return NULL;
@@ -317 +346 @@
         }
         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;
 }
 
@@ -333 +436 @@
                     int addremove, unsigned mode,
                     const unsigned char *sha1,
+                    int sha1_valid,
                     const char *fullpath, unsigned dirty_submodule)
 {
@@ -346 +450 @@
                  const unsigned char *old_sha1,
                  const unsigned char *new_sha1,
+                 int old_sha1_valid, int new_sha1_valid,
                  const char *fullpath,
                  unsigned old_dirty_submodule, unsigned new_dirty_submodule)
@@ -353 +458 @@
 }
 
-static int rev_compare_tree(struct rev_info *revs, struct commit *parent, struct commit *commit)
+static int rev_compare_tree(struct rev_info *revs,
+                            struct commit *parent, struct commit *commit)
 {
         struct tree *t1 = parent->tree;
@@ -392 +498 @@
 {
         int retval;
-        void *tree;
-        unsigned long size;
-        struct tree_desc empty, real;
         struct tree *t1 = commit->tree;
 
@@ -400 +503 @@
                 return 0;
 
-        tree = read_object_with_reference(t1->object.sha1, tree_type, &size, NULL);
-        if (!tree)
-                return 0;
-        init_tree_desc(&real, tree, size);
-        init_tree_desc(&empty, "", 0);
-
         tree_difference = REV_TREE_SAME;
         DIFF_OPT_CLR(&revs->pruning, HAS_CHANGES);
-        retval = diff_tree(&empty, &real, "", &revs->pruning);
-        free(tree);
+        retval = diff_tree_sha1(NULL, t1->object.sha1, "", &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, 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", sha1_to_hex(commit->object.sha1));
+                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;
-        int tree_changed = 0, tree_same = 0, nth_parent = 0;
+        struct treesame_state *ts = NULL;
+        int relevant_change = 0, irrelevant_change = 0;
+        int relevant_parents, nth_parent;
 
         /*
@@ -441 +652 @@
                 return;
 
-        pp = &commit->parents;
-        while ((parent = *pp) != NULL) {
+        for (pp = &commit->parents, nth_parent = 0, relevant_parents = 0;
+             (parent = *pp) != NULL;
+             pp = &parent->next, nth_parent++) {
                 struct commit *p = parent->item;
-
-                /*
-                 * 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 && nth_parent++)
-                        break;
+                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)",
@@ -459 +691 @@
                 switch (rev_compare_tree(revs, p, commit)) {
                 case REV_TREE_SAME:
-                        tree_same = 1;
-                        if (!revs->simplify_history || (p->object.flags & UNINTERESTING)) {
+                        if (!revs->simplify_history || !relevant_commit(p)) {
                                 /* Even if a merge with an uninteresting
                                  * side branch brought the entire change
@@ -467 +698 @@
                                  * merge, so we just keep going.
                                  */
-                                pp = &parent->next;
+                                if (ts)
+                                        ts->treesame[nth_parent] = 1;
                                 continue;
                         }
@@ -495 +727 @@
                 case REV_TREE_OLD:
                 case REV_TREE_DIFFERENT:
-                        tree_changed = 1;
-                        pp = &parent->next;
+                        if (relevant_commit(p))
+                                relevant_change = 1;
+                        else
+                                irrelevant_change = 1;
                         continue;
                 }
                 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
         }
-        if (tree_changed && !tree_same)
-                return;
-        commit->object.flags |= TREESAME;
+
+        /*
+         * 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;
 }
 
@@ -530 +774 @@
                 return 0;
         commit->object.flags |= ADDED;
+
+        if (revs->include_check &&
+            !revs->include_check(commit, revs->include_check_data))
+                return 0;
 
         /*
@@ -694 +942 @@
          * before the source list? Definitely _not_ done.
          */
-        if (date < src->item->date)
+        if (date <= src->item->date)
                 return SLOP;
 
@@ -786 +1034 @@
  * reach A.
  */
-static struct commit_list *collect_bottom_commits(struct rev_info *revs)
-{
-        struct commit_list *bottom = NULL;
-        int i;
-        for (i = 0; i < revs->cmdline.nr; i++) {
-                struct rev_cmdline_entry *elem = &revs->cmdline.rev[i];
-                if ((elem->flags & UNINTERESTING) &&
-                    elem->item->type == OBJ_COMMIT)
-                        commit_list_insert((struct commit *)elem->item, &bottom);
-        }
+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;
 }
@@ -826 +1070 @@
 
         if (revs->ancestry_path) {
-                bottom = collect_bottom_commits(revs);
+                bottom = collect_bottom_commits(list);
                 if (!bottom)
                         die("--ancestry-path given but there are no bottom commits");
@@ -879 +1123 @@
         }
 
+        /*
+         * 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,
@@ -894 +1154 @@
         ALLOC_GROW(info->rev, nr + 1, info->alloc);
         info->rev[nr].item = item;
-        info->rev[nr].name = name;
+        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, sha1_to_hex(object->sha1),
+                                whence, flags);
+                commit_list = commit_list->next;
+        }
 }
 
@@ -907 +1180 @@
 };
 
+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, NULL))
+                        return 1;
+        }
+        return 0;
+}
+
 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 {
         struct all_refs_cb *cb = cb_data;
-        struct object *object = get_reference(cb->all_revs, path, sha1,
-                                              cb->all_flags);
+        struct object *object;
+
+        if (ref_excluded(cb->all_revs->ref_excludes, path))
+            return 0;
+
+        object = get_reference(cb->all_revs, path, sha1, cb->all_flags);
         add_rev_cmdline(cb->all_revs, object, path, REV_CMD_REF, cb->all_flags);
         add_pending_sha1(cb->all_revs, path, sha1, cb->all_flags);
@@ -922 +1212 @@
         cb->all_revs = revs;
         cb->all_flags = flags;
+}
+
+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);
 }
 
@@ -985 +1293 @@
 
         if (*arg == '^') {
-                flags ^= UNINTERESTING;
+                flags ^= UNINTERESTING | BOTTOM;
                 arg++;
         }
-        if (get_sha1(arg, sha1))
+        if (get_sha1_committish(arg, sha1))
                 return 0;
         while (1) {
@@ -1023 +1331 @@
         revs->pruning.add_remove = file_add_remove;
         revs->pruning.change = file_change;
-        revs->lifo = 1;
+        revs->sort_order = REV_SORT_IN_GRAPH_ORDER;
         revs->dense = 1;
         revs->prefix = prefix;
@@ -1034 +1342 @@
         revs->commit_format = CMIT_FMT_DEFAULT;
 
+        init_grep_defaults();
+        grep_init(&revs->grep_filter, prefix);
         revs->grep_filter.status_only = 1;
-        revs->grep_filter.pattern_tail = &(revs->grep_filter.pattern_list);
-        revs->grep_filter.header_tail = &(revs->grep_filter.header_list);
         revs->grep_filter.regflags = REG_NEWLINE;
 
@@ -1077 +1385 @@
         add_pending_object(revs, &other->object, "MERGE_HEAD");
         bases = get_merge_bases(head, other, 1);
-        add_pending_commit_list(revs, bases, UNINTERESTING);
+        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;
@@ -1084 +1393 @@
                 read_cache();
         for (i = 0; i < active_nr; i++) {
-                struct cache_entry *ce = active_cache[i];
+                const struct cache_entry *ce = active_cache[i];
                 if (!ce_stage(ce))
                         continue;
-                if (ce_path_match(ce, &revs->prune_data)) {
+                if (ce_path_match(ce, &revs->prune_data, NULL)) {
                         prune_num++;
                         prune = xrealloc(prune, sizeof(*prune) * prune_num);
@@ -1098 +1407 @@
         }
         free_pathspec(&revs->prune_data);
-        init_pathspec(&revs->prune_data, prune);
+        parse_pathspec(&revs->prune_data, PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
+                       PATHSPEC_PREFER_FULL | PATHSPEC_LITERAL_PATH, "", prune);
         revs->limited = 1;
 }
 
-int handle_revision_arg(const char *arg_, struct rev_info *revs,
-                        int flags,
-                        int cant_be_filename)
-{
-        unsigned mode;
+int handle_revision_arg(const char *arg_, struct rev_info *revs, int flags, unsigned revarg_opt)
+{
+        struct object_context oc;
         char *dotdot;
         struct object *object;
@@ -1112 +1420 @@
         int local_flags;
         const char *arg = arg_;
+        int cant_be_filename = revarg_opt & REVARG_CANNOT_BE_FILENAME;
+        unsigned get_sha1_flags = 0;
+
+        flags = flags & UNINTERESTING ? flags | BOTTOM : flags & ~BOTTOM;
 
         dotdot = strstr(arg, "..");
@@ -1119 +1431 @@
                 const char *this = arg;
                 int symmetric = *next == '.';
-                unsigned int flags_exclude = flags ^ UNINTERESTING;
+                unsigned int flags_exclude = flags ^ (UNINTERESTING | BOTTOM);
+                static const char head_by_default[] = "HEAD";
                 unsigned int a_flags;
 
@@ -1126 +1439 @@
 
                 if (!*next)
-                        next = "HEAD";
+                        next = head_by_default;
                 if (dotdot == arg)
-                        this = "HEAD";
-                if (!get_sha1(this, from_sha1) &&
-                    !get_sha1(next, sha1)) {
-                        struct commit *a, *b;
-                        struct commit_list *exclude;
-
-                        a = lookup_commit_reference(from_sha1);
-                        b = lookup_commit_reference(sha1);
-                        if (!a || !b) {
-                                if (revs->ignore_missing)
-                                        return 0;
-                                die(symmetric ?
-                                    "Invalid symmetric difference expression %s...%s" :
-                                    "Invalid revision range %s..%s",
-                                    arg, next);
+                        this = head_by_default;
+                if (this == head_by_default && next == head_by_default &&
+                    !symmetric) {
+                        /*
+                         * Just ".."?  That is not a range but the
+                         * pathspec for the parent directory.
+                         */
+                        if (!cant_be_filename) {
+                                *dotdot = '.';
+                                return -1;
                         }
+                }
+                if (!get_sha1_committish(this, from_sha1) &&
+                    !get_sha1_committish(next, sha1)) {
+                        struct object *a_obj, *b_obj;
 
                         if (!cant_be_filename) {
@@ -1150 +1462 @@
                         }
 
-                        if (symmetric) {
+                        a_obj = parse_object(from_sha1);
+                        b_obj = parse_object(sha1);
+                        if (!a_obj || !b_obj) {
+                        missing:
+                                if (revs->ignore_missing)
+                                        return 0;
+                                die(symmetric
+                                    ? "Invalid symmetric difference expression %s"
+                                    : "Invalid revision range %s", arg);
+                        }
+
+                        if (!symmetric) {
+                                /* just A..B */
+                                a_flags = flags_exclude;
+                        } else {
+                                /* A...B -- find merge bases between the two */
+                                struct commit *a, *b;
+                                struct commit_list *exclude;
+
+                                a = (a_obj->type == OBJ_COMMIT
+                                     ? (struct commit *)a_obj
+                                     : lookup_commit_reference(a_obj->sha1));
+                                b = (b_obj->type == OBJ_COMMIT
+                                     ? (struct commit *)b_obj
+                                     : lookup_commit_reference(b_obj->sha1));
+                                if (!a || !b)
+                                        goto missing;
                                 exclude = get_merge_bases(a, b, 1);
+                                add_rev_cmdline_list(revs, exclude,
+                                                     REV_CMD_MERGE_BASE,
+                                                     flags_exclude);
                                 add_pending_commit_list(revs, exclude,
                                                         flags_exclude);
                                 free_commit_list(exclude);
+
                                 a_flags = flags | SYMMETRIC_LEFT;
-                        } else
-                                a_flags = flags_exclude;
-                        a->object.flags |= a_flags;
-                        b->object.flags |= flags;
-                        add_rev_cmdline(revs, &a->object, this,
+                        }
+
+                        a_obj->flags |= a_flags;
+                        b_obj->flags |= flags;
+                        add_rev_cmdline(revs, a_obj, this,
                                         REV_CMD_LEFT, a_flags);
-                        add_rev_cmdline(revs, &b->object, next,
+                        add_rev_cmdline(revs, b_obj, next,
                                         REV_CMD_RIGHT, flags);
-                        add_pending_object(revs, &a->object, this);
-                        add_pending_object(revs, &b->object, next);
+                        add_pending_object(revs, a_obj, this);
+                        add_pending_object(revs, b_obj, next);
                         return 0;
                 }
@@ -1180 +1522 @@
         if (dotdot && !dotdot[2]) {
                 *dotdot = 0;
-                if (!add_parents_only(revs, arg, flags ^ UNINTERESTING))
+                if (!add_parents_only(revs, arg, flags ^ (UNINTERESTING | BOTTOM)))
                         *dotdot = '^';
         }
@@ -1186 +1528 @@
         local_flags = 0;
         if (*arg == '^') {
-                local_flags = UNINTERESTING;
+                local_flags = UNINTERESTING | BOTTOM;
                 arg++;
         }
-        if (get_sha1_with_mode(arg, sha1, &mode))
+
+        if (revarg_opt & REVARG_COMMITTISH)
+                get_sha1_flags = GET_SHA1_COMMITTISH;
+
+        if (get_sha1_with_context(arg, get_sha1_flags, sha1, &oc))
                 return revs->ignore_missing ? 0 : -1;
         if (!cant_be_filename)
@@ -1195 +1541 @@
         object = get_reference(revs, arg, sha1, flags ^ local_flags);
         add_rev_cmdline(revs, object, arg_, REV_CMD_REV, flags ^ local_flags);
-        add_pending_object_with_mode(revs, object, arg, mode);
+        add_pending_object_with_mode(revs, object, arg, oc.mode);
         return 0;
 }
@@ -1208 +1554 @@
 {
         while (*av) {
-                ALLOC_GROW(prune->path, prune->nr+1, prune->alloc);
+                ALLOC_GROW(prune->path, prune->nr + 1, prune->alloc);
                 prune->path[prune->nr++] = *(av++);
         }
@@ -1220 +1566 @@
                 if (len && sb->buf[len - 1] == '\n')
                         sb->buf[--len] = '\0';
-                ALLOC_GROW(prune->path, prune->nr+1, prune->alloc);
+                ALLOC_GROW(prune->path, prune->nr + 1, prune->alloc);
                 prune->path[prune->nr++] = xstrdup(sb->buf);
         }
@@ -1230 +1576 @@
         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);
@@ -1245 +1595 @@
                         die("options not supported in --stdin mode");
                 }
-                if (handle_revision_arg(sb.buf, revs, 0, 1))
+                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(revs, &sb, prune);
+
         strbuf_release(&sb);
+        warn_on_object_refname_ambiguity = save_warning;
 }
 
@@ -1280 +1633 @@
             !strcmp(arg, "--reflog") || !strcmp(arg, "--not") ||
             !strcmp(arg, "--no-walk") || !strcmp(arg, "--do-walk") ||
-            !strcmp(arg, "--bisect") || !prefixcmp(arg, "--glob=") ||
-            !prefixcmp(arg, "--branches=") || !prefixcmp(arg, "--tags=") ||
-            !prefixcmp(arg, "--remotes="))
+            !strcmp(arg, "--bisect") || starts_with(arg, "--glob=") ||
+            starts_with(arg, "--branches=") || starts_with(arg, "--tags=") ||
+            starts_with(arg, "--remotes=") || starts_with(arg, "--no-walk="))
         {
                 unkv[(*unkc)++] = arg;
@@ -1305 +1658 @@
                 revs->no_walk = 0;
                 return 2;
-        } else if (!prefixcmp(arg, "-n")) {
+        } else if (starts_with(arg, "-n")) {
                 revs->max_count = atoi(arg + 2);
                 revs->no_walk = 0;
@@ -1342 +1695 @@
                 revs->show_merge = 1;
         } else if (!strcmp(arg, "--topo-order")) {
-                revs->lifo = 1;
+                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;
@@ -1351 +1705 @@
         } else if (!strcmp(arg, "--simplify-by-decoration")) {
                 revs->simplify_merges = 1;
+                revs->topo_order = 1;
                 revs->rewrite_parents = 1;
                 revs->simplify_history = 0;
@@ -1358 +1713 @@
                 load_ref_decorations(DECORATE_SHORT_REFS);
         } else if (!strcmp(arg, "--date-order")) {
-                revs->lifo = 0;
+                revs->sort_order = REV_SORT_BY_COMMIT_DATE;
                 revs->topo_order = 1;
-        } else if (!prefixcmp(arg, "--early-output")) {
+        } else if (!strcmp(arg, "--author-date-order")) {
+                revs->sort_order = REV_SORT_BY_AUTHOR_DATE;
+                revs->topo_order = 1;
+        } else if (starts_with(arg, "--early-output")) {
                 int count = 100;
                 switch (arg[14]) {
@@ -1385 +1743 @@
         } else if (!strcmp(arg, "--no-merges")) {
                 revs->max_parents = 1;
-        } else if (!prefixcmp(arg, "--min-parents=")) {
+        } else if (starts_with(arg, "--min-parents=")) {
                 revs->min_parents = atoi(arg+14);
-        } else if (!prefixcmp(arg, "--no-min-parents")) {
+        } else if (starts_with(arg, "--no-min-parents")) {
                 revs->min_parents = 0;
-        } else if (!prefixcmp(arg, "--max-parents=")) {
+        } else if (starts_with(arg, "--max-parents=")) {
                 revs->max_parents = atoi(arg+14);
-        } else if (!prefixcmp(arg, "--no-max-parents")) {
+        } else if (starts_with(arg, "--no-max-parents")) {
                 revs->max_parents = -1;
         } else if (!strcmp(arg, "--boundary")) {
@@ -1441 +1799 @@
         } else if (!strcmp(arg, "--unpacked")) {
                 revs->unpacked = 1;
-        } else if (!prefixcmp(arg, "--unpacked=")) {
+        } else if (starts_with(arg, "--unpacked=")) {
                 die("--unpacked=<packfile> no longer supported.");
         } else if (!strcmp(arg, "-r")) {
@@ -1466 +1824 @@
                 revs->pretty_given = 1;
                 get_commit_format(arg+8, revs);
-        } else if (!prefixcmp(arg, "--pretty=") || !prefixcmp(arg, "--format=")) {
+        } else if (starts_with(arg, "--pretty=") || starts_with(arg, "--format=")) {
                 /*
                  * Detached form ("--pretty X" as opposed to "--pretty=X")
@@ -1480 +1838 @@
         } else if (!strcmp(arg, "--show-signature")) {
                 revs->show_signature = 1;
-        } else if (!prefixcmp(arg, "--show-notes=") ||
-                   !prefixcmp(arg, "--notes=")) {
+        } else if (!strcmp(arg, "--show-linear-break") ||
+                   starts_with(arg, "--show-linear-break=")) {
+                if (starts_with(arg, "--show-linear-break="))
+                        revs->break_bar = xstrdup(arg + 20);
+                else
+                        revs->break_bar = "                    ..........";
+                revs->track_linear = 1;
+                revs->track_first_time = 1;
+        } else if (starts_with(arg, "--show-notes=") ||
+                   starts_with(arg, "--notes=")) {
                 struct strbuf buf = STRBUF_INIT;
                 revs->show_notes = 1;
                 revs->show_notes_given = 1;
-                if (!prefixcmp(arg, "--show-notes")) {
+                if (starts_with(arg, "--show-notes")) {
                         if (revs->notes_opt.use_default_notes < 0)
                                 revs->notes_opt.use_default_notes = 1;
@@ -1528 +1894 @@
         } else if (!strcmp(arg, "--abbrev")) {
                 revs->abbrev = DEFAULT_ABBREV;
-        } else if (!prefixcmp(arg, "--abbrev=")) {
+        } else if (starts_with(arg, "--abbrev=")) {
                 revs->abbrev = strtoul(arg + 9, NULL, 10);
                 if (revs->abbrev < MINIMUM_ABBREV)
@@ -1563 +1929 @@
                 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")) {
+                grep_set_pattern_type_option(GREP_PATTERN_TYPE_BRE, &revs->grep_filter);
         } else if (!strcmp(arg, "--extended-regexp") || !strcmp(arg, "-E")) {
-                revs->grep_filter.regflags |= REG_EXTENDED;
+                grep_set_pattern_type_option(GREP_PATTERN_TYPE_ERE, &revs->grep_filter);
         } else if (!strcmp(arg, "--regexp-ignore-case") || !strcmp(arg, "-i")) {
                 revs->grep_filter.regflags |= REG_ICASE;
+                DIFF_OPT_SET(&revs->diffopt, PICKAXE_IGNORE_CASE);
         } else if (!strcmp(arg, "--fixed-strings") || !strcmp(arg, "-F")) {
-                revs->grep_filter.fixed = 1;
+                grep_set_pattern_type_option(GREP_PATTERN_TYPE_FIXED, &revs->grep_filter);
+        } else if (!strcmp(arg, "--perl-regexp")) {
+                grep_set_pattern_type_option(GREP_PATTERN_TYPE_PCRE, &revs->grep_filter);
         } else if (!strcmp(arg, "--all-match")) {
                 revs->grep_filter.all_match = 1;
@@ -1593 +1969 @@
                 return opts;
         }
+        if (revs->graph && revs->track_linear)
+                die("--show-linear-break and --graph are incompatible");
 
         return 1;
@@ -1642 +2020 @@
                 handle_refs(submodule, revs, *flags, for_each_ref_submodule);
                 handle_refs(submodule, revs, *flags, head_ref_submodule);
+                clear_ref_exclusion(&revs->ref_excludes);
         } else if (!strcmp(arg, "--branches")) {
                 handle_refs(submodule, revs, *flags, for_each_branch_ref_submodule);
+                clear_ref_exclusion(&revs->ref_excludes);
         } else if (!strcmp(arg, "--bisect")) {
                 handle_refs(submodule, revs, *flags, for_each_bad_bisect_ref);
-                handle_refs(submodule, revs, *flags ^ UNINTERESTING, for_each_good_bisect_ref);
+                handle_refs(submodule, revs, *flags ^ (UNINTERESTING | BOTTOM), for_each_good_bisect_ref);
                 revs->bisect = 1;
         } else if (!strcmp(arg, "--tags")) {
                 handle_refs(submodule, revs, *flags, for_each_tag_ref_submodule);
+                clear_ref_exclusion(&revs->ref_excludes);
         } else if (!strcmp(arg, "--remotes")) {
                 handle_refs(submodule, revs, *flags, for_each_remote_ref_submodule);
+                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 (!prefixcmp(arg, "--branches=")) {
+        } else if ((argcount = parse_long_opt("exclude", argv, &optarg))) {
+                add_ref_exclusion(&revs->ref_excludes, optarg);
+                return argcount;
+        } else if (starts_with(arg, "--branches=")) {
                 struct all_refs_cb cb;
                 init_all_refs_cb(&cb, revs, *flags);
                 for_each_glob_ref_in(handle_one_ref, arg + 11, "refs/heads/", &cb);
-        } else if (!prefixcmp(arg, "--tags=")) {
+                clear_ref_exclusion(&revs->ref_excludes);
+        } else if (starts_with(arg, "--tags=")) {
                 struct all_refs_cb cb;
                 init_all_refs_cb(&cb, revs, *flags);
                 for_each_glob_ref_in(handle_one_ref, arg + 7, "refs/tags/", &cb);
-        } else if (!prefixcmp(arg, "--remotes=")) {
+                clear_ref_exclusion(&revs->ref_excludes);
+        } else if (starts_with(arg, "--remotes=")) {
                 struct all_refs_cb cb;
                 init_all_refs_cb(&cb, revs, *flags);
                 for_each_glob_ref_in(handle_one_ref, arg + 10, "refs/remotes/", &cb);
+                clear_ref_exclusion(&revs->ref_excludes);
         } else if (!strcmp(arg, "--reflog")) {
                 handle_reflog(revs, *flags);
         } else if (!strcmp(arg, "--not")) {
-                *flags ^= UNINTERESTING;
+                *flags ^= UNINTERESTING | BOTTOM;
         } else if (!strcmp(arg, "--no-walk")) {
-                revs->no_walk = 1;
+                revs->no_walk = REVISION_WALK_NO_WALK_SORTED;
+        } else if (starts_with(arg, "--no-walk=")) {
+                /*
+                 * Detached form ("--no-walk X" as opposed to "--no-walk=X")
+                 * not allowed, since the argument is optional.
+                 */
+                if (!strcmp(arg + 10, "sorted"))
+                        revs->no_walk = REVISION_WALK_NO_WALK_SORTED;
+                else if (!strcmp(arg + 10, "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;
@@ -1693 +2093 @@
 int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct setup_revision_opt *opt)
 {
-        int i, flags, left, seen_dashdash, read_from_stdin, got_rev_arg = 0;
+        int i, flags, left, seen_dashdash, read_from_stdin, got_rev_arg = 0, revarg_opt;
         struct cmdline_pathspec prune_data;
         const char *submodule = NULL;
@@ -1702 +2102 @@
 
         /* First, search for "--" */
-        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])
-                        append_prune_data(&prune_data, argv + i + 1);
+        if (opt && opt->assume_dashdash) {
                 seen_dashdash = 1;
-                break;
+        } 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])
+                                append_prune_data(&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;
         read_from_stdin = 0;
         for (left = i = 1; i < argc; i++) {
@@ -1752 +2159 @@
                 }
 
-                if (handle_revision_arg(arg, revs, flags, seen_dashdash)) {
+
+                if (handle_revision_arg(arg, revs, flags, revarg_opt)) {
                         int j;
                         if (seen_dashdash || *arg == '^')
@@ -1764 +2172 @@
                          */
                         for (j = i; j < argc; j++)
-                                verify_filename(revs->prefix, argv[j]);
+                                verify_filename(revs->prefix, argv[j], j == i);
 
                         append_prune_data(&prune_data, argv + i);
@@ -1788 +2196 @@
                  * }
                  */
-                ALLOC_GROW(prune_data.path, prune_data.nr+1, prune_data.alloc);
+                ALLOC_GROW(prune_data.path, prune_data.nr + 1, prune_data.alloc);
                 prune_data.path[prune_data.nr++] = NULL;
-                init_pathspec(&revs->prune_data,
-                              get_pathspec(revs->prefix, prune_data.path));
+                parse_pathspec(&revs->prune_data, 0, 0,
+                               revs->prefix, prune_data.path);
         }
 
@@ -1803 +2211 @@
                 unsigned char sha1[20];
                 struct object *object;
-                unsigned mode;
-                if (get_sha1_with_mode(revs->def, sha1, &mode))
+                struct object_context oc;
+                if (get_sha1_with_context(revs->def, 0, sha1, &oc))
                         die("bad default revision '%s'", revs->def);
                 object = get_reference(revs, revs->def, sha1, 0);
-                add_pending_object_with_mode(revs, object, revs->def, mode);
+                add_pending_object_with_mode(revs, object, revs->def, oc.mode);
         }
 
@@ -1824 +2232 @@
 
         if (revs->prune_data.nr) {
-                diff_tree_setup_paths(revs->prune_data.raw, &revs->pruning);
+                copy_pathspec(&revs->pruning.pathspec, &revs->prune_data);
                 /* Can't prune commits with rename following: the paths change.. */
                 if (!DIFF_OPT_TST(&revs->diffopt, FOLLOW_RENAMES))
                         revs->prune = 1;
                 if (!revs->full_diff)
-                        diff_tree_setup_paths(revs->prune_data.raw, &revs->diffopt);
+                        copy_pathspec(&revs->diffopt.pathspec,
+                                      &revs->prune_data);
         }
         if (revs->combine_merges)
                 revs->ignore_merges = 0;
         revs->diffopt.abbrev = revs->abbrev;
-        if (diff_setup_done(&revs->diffopt) < 0)
-                die("diff_setup_done failed");
-
+
+        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);
 
@@ -1852 +2268 @@
         if (revs->reflog_info && revs->graph)
                 die("cannot combine --walk-reflogs with --graph");
+        if (!revs->reflog_info && revs->grep_filter.use_reflog_filter)
+                die("cannot use --grep-reflog without --walk-reflogs");
 
         return left;
@@ -1864 +2282 @@
 }
 
-static int remove_duplicate_parents(struct commit *commit)
-{
+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;
@@ -1871 +2290 @@
         /* 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;
         }
-        /* count them while clearing the temporary mark */
-        surviving_parents = 0;
+        /* clear the temporary mark */
         for (p = commit->parents; p; p = p->next) {
                 p->item->object.flags &= ~TMP_MARK;
-                surviving_parents++;
-        }
+        }
+        /* no update_treesame() - removing duplicates can't affect TREESAME */
         return surviving_parents;
 }
@@ -1905 +2327 @@
 }
 
+static int mark_redundant_parents(struct rev_info *revs, 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 rev_info *revs, 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;
@@ -1930 +2500 @@
 
         /*
-         * Do we know what commit all of our parents should be rewritten to?
-         * Otherwise we are not ready to rewrite this one yet.
+         * 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) {
@@ -1939 +2510 @@
                         cnt++;
                 }
+                if (revs->first_parent_only)
+                        break;
         }
         if (cnt) {
@@ -1946 +2519 @@
 
         /*
-         * Rewrite our list of parents.
+         * 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;
-        }
-        cnt = remove_duplicate_parents(commit);
+                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 parents will be rewritten
-         * to different commits.
+         * 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;
@@ -1964 +2545 @@
          * ---o----'
          *
-         * Further reduce the parents by removing redundant parents.
+         * 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) {
-                struct commit_list *h = reduce_heads(commit->parents);
-                cnt = commit_list_count(h);
-                free_commit_list(commit->parents);
-                commit->parents = h;
+                int marked = mark_redundant_parents(revs, commit);
+                marked += mark_treesame_root_parents(revs, commit);
+                if (marked)
+                        marked -= leave_one_treesame_to_parent(revs, commit);
+                if (marked)
+                        cnt = remove_marked_parents(revs, commit);
         }
 
@@ -1976 +2566 @@
          * 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 simplifies to more than one commits
+         * 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 parent simplifies to.
+         * Otherwise, it simplifies to what its sole relevant parent
+         * simplifies to.
          */
         if (!cnt ||
             (commit->object.flags & UNINTERESTING) ||
             !(commit->object.flags & TREESAME) ||
-            (1 < cnt))
+            (parent = one_relevant_parent(revs, commit->parents)) == NULL)
                 st->simplified = commit;
         else {
-                pst = locate_simplify_state(revs, commit->parents->item);
+                pst = locate_simplify_state(revs, parent);
                 st->simplified = pst->simplified;
         }
@@ -1996 +2587 @@
 static void simplify_merges(struct rev_info *revs)
 {
-        struct commit_list *list;
+        struct commit_list *list, *next;
         struct commit_list *yet_to_do, **tail;
-
-        if (!revs->topo_order)
-                sort_in_topological_order(&revs->commits, revs->lifo);
+        struct commit *commit;
+
         if (!revs->prune)
                 return;
@@ -2006 +2596 @@
         /* feed the list reversed */
         yet_to_do = NULL;
-        for (list = revs->commits; list; list = list->next)
-                commit_list_insert(list->item, &yet_to_do);
+        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;
@@ -2013 +2610 @@
                 tail = &yet_to_do;
                 while (list) {
-                        struct commit *commit = list->item;
-                        struct commit_list *next = list->next;
+                        commit = list->item;
+                        next = list->next;
                         free(list);
                         list = next;
@@ -2026 +2623 @@
         tail = &revs->commits;
         while (list) {
-                struct commit *commit = list->item;
-                struct commit_list *next = list->next;
                 struct merge_simplify_state *st;
+
+                commit = list->item;
+                next = list->next;
                 free(list);
                 list = next;
@@ -2049 +2647 @@
 }
 
+void reset_revision_walk(void)
+{
+        clear_object_flags(SEEN | ADDED | SHOWN);
+}
+
 int prepare_revision_walk(struct rev_info *revs)
 {
         int nr = revs->pending.nr;
         struct object_array_entry *e, *list;
+        struct commit_list **next = &revs->commits;
 
         e = list = revs->pending.objects;
@@ -2063 +2667 @@
                         if (!(commit->object.flags & SEEN)) {
                                 commit->object.flags |= SEEN;
-                                commit_list_insert_by_date(commit, &revs->commits);
+                                next = commit_list_append(commit, next);
                         }
                 }
@@ -2071 +2675 @@
                 free(list);
 
+        /* 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->no_walk != REVISION_WALK_NO_WALK_UNSORTED)
+                commit_list_sort_by_date(&revs->commits);
         if (revs->no_walk)
                 return 0;
@@ -2077 +2688 @@
                         return -1;
         if (revs->topo_order)
-                sort_in_topological_order(&revs->commits, revs->lifo);
+                sort_in_topological_order(&revs->commits, revs->sort_order);
+        if (revs->line_level_traverse)
+                line_log_filter(revs);
         if (revs->simplify_merges)
                 simplify_merges(revs);
@@ -2085 +2698 @@
 }
 
-enum rewrite_result {
-        rewrite_one_ok,
-        rewrite_one_noparents,
-        rewrite_one_error
-};
-
 static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
 {
@@ -2100 +2707 @@
                         if (add_parents_to_list(revs, p, &revs->commits, &cache) < 0)
                                 return rewrite_one_error;
-                if (p->parents && p->parents->next)
-                        return rewrite_one_ok;
                 if (p->object.flags & UNINTERESTING)
                         return rewrite_one_ok;
@@ -2108 +2713 @@
                 if (!p->parents)
                         return rewrite_one_noparents;
-                *pp = p->parents->item;
-        }
-}
-
-static int rewrite_parents(struct rev_info *revs, struct commit *commit)
+                if ((p = one_relevant_parent(revs, p->parents)) == NULL)
+                        return rewrite_one_ok;
+                *pp = p;
+        }
+}
+
+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_one(revs, &parent->item)) {
+                switch (rewrite_parent(revs, &parent->item)) {
                 case rewrite_one_ok:
                         break;
@@ -2128 +2736 @@
                 pp = &parent->next;
         }
-        remove_duplicate_parents(commit);
+        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;
+        char *message;
+        struct strbuf buf = STRBUF_INIT;
+
         if (!opt->grep_filter.pattern_list && !opt->grep_filter.header_list)
                 return 1;
-        return grep_buffer(&opt->grep_filter,
-                           commit->buffer, strlen(commit->buffer));
-}
-
-static inline int want_ancestry(struct rev_info *revs)
+
+        /* 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.sha1, &buf, encoding, 1);
+        }
+
+        /* Find either in the original commit message, or in the temporary */
+        if (buf.len)
+                retval = grep_buffer(&opt->grep_filter, buf.buf, buf.len);
+        else
+                retval = grep_buffer(&opt->grep_filter,
+                                     message, strlen(message));
+        strbuf_release(&buf);
+        logmsg_free(message, commit);
+        return retval;
+}
+
+static inline int want_ancestry(const struct rev_info *revs)
 {
         return (revs->rewrite_parents || revs->children.name);
@@ -2158 +2860 @@
                 return commit_ignore;
         if (revs->min_parents || (revs->max_parents >= 0)) {
-                int n = 0;
-                struct commit_list *p;
-                for (p = commit->parents; p; p = p->next)
-                        n++;
+                int n = commit_list_count(commit->parents);
                 if ((n < revs->min_parents) ||
                     ((revs->max_parents >= 0) && (n > revs->max_parents)))
@@ -2171 +2870 @@
                 /* 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;
-                        /* non-merge - always ignore it */
-                        if (!commit->parents || !commit->parents->next)
-                                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;
                 }
         }
@@ -2189 +2899 @@
             !revs->show_all &&
             revs->prune && revs->dense && want_ancestry(revs)) {
-                if (rewrite_parents(revs, commit) < 0)
+                /*
+                 * --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 */
+                            !hashcmp(p->item->object.sha1, commit->object.sha1))
+                                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);
 }
 
@@ -2208 +2947 @@
 
                 if (revs->reflog_info) {
+                        save_parents(revs, commit);
                         fake_reflog_parent(revs->reflog_info, commit);
                         commit->object.flags &= ~(ADDED | SEEN | SHOWN);
@@ -2221 +2961 @@
                             (commit->date < revs->max_age))
                                 continue;
-                        if (add_parents_to_list(revs, commit, &revs->commits, NULL) < 0)
-                                die("Failed to traverse parents of commit %s",
-                                    sha1_to_hex(commit->object.sha1));
+                        if (add_parents_to_list(revs, commit, &revs->commits, NULL) < 0) {
+                                if (!revs->ignore_missing_links)
+                                        die("Failed to traverse parents of commit %s",
+                                                sha1_to_hex(commit->object.sha1));
+                        }
                 }
 
@@ -2233 +2975 @@
                             sha1_to_hex(commit->object.sha1));
                 default:
+                        if (revs->track_linear)
+                                track_linear(revs, commit);
                         return commit;
                 }
@@ -2239 +2983 @@
 }
 
+/*
+ * 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)
 {
-        unsigned nr = array->nr;
-        unsigned alloc = array->alloc;
-        struct object_array_entry *objects = array->objects;
-
-        if (alloc <= nr) {
-                unsigned i, j;
-                for (i = j = 0; i < nr; i++) {
-                        if (objects[i].item->flags & SHOWN)
-                                continue;
-                        if (i != j)
-                                objects[j] = objects[i];
-                        j++;
-                }
-                for (i = j; i < nr; i++)
-                        objects[i].item = NULL;
-                array->nr = j;
-        }
+        if (array->nr == array->alloc)
+                object_array_filter(array, entry_unshown, NULL);
 }
 
@@ -2298 +3040 @@
          * in topological order
          */
-        sort_in_topological_order(&revs->commits, revs->lifo);
+        sort_in_topological_order(&revs->commits, revs->sort_order);
 }
 
@@ -2320 +3062 @@
 
         /*
-         * Now pick up what they want to give us
-         */
-        c = get_revision_1(revs);
-        if (c) {
-                while (0 < revs->skip_count) {
-                        revs->skip_count--;
-                        c = get_revision_1(revs);
-                        if (!c)
-                                break;
-                }
-        }
-
-        /*
-         * Check the max_count.
-         */
-        switch (revs->max_count) {
-        case -1:
-                break;
-        case 0:
-                c = NULL;
-                break;
-        default:
-                revs->max_count--;
+         * 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--;
         }
 
@@ -2348 +3089 @@
                 c->object.flags |= SHOWN;
 
-        if (!revs->boundary) {
+        if (!revs->boundary)
                 return c;
-        }
 
         if (!c) {
@@ -2396 +3136 @@
         if (revs->reverse) {
                 reversed = NULL;
-                while ((c = get_revision_internal(revs))) {
+                while ((c = get_revision_internal(revs)))
                         commit_list_insert(c, &reversed);
-                }
                 revs->commits = reversed;
                 revs->reverse = 0;
@@ -2404 +3143 @@
         }
 
-        if (revs->reverse_output_stage)
-                return pop_commit(&revs->commits);
+        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;
 }
@@ -2441 +3191 @@
         putchar(' ');
 }
+
+define_commit_slab(saved_parents, struct commit_list *);
+
+#define EMPTY_PARENT_LIST ((struct commit_list *)-1)
+
+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;
+}
+
+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;
+}
+
+void free_saved_parents(struct rev_info *revs)
+{
+        if (revs->saved_parents_slab)
+                clear_saved_parents(revs->saved_parents_slab);
+}