Function compact_treesame

revision.c:871–916

* 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. */

 * 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, nth_parent))
			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)
{