revision --simplify-merges: use decoration instead of commit->util field

The users of revision walking machinery may want to use the util pointer
for their own use.  Use decoration to hold the data needed during merge
simplification instead.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/revision.c b/revision.c
index 0aaa4c10b9692b39eb3dfb1cf0e45890d598550e..33cb207f281f97f0eb1c24dd0b5200feda49848d 100644 (file)
--- a/revision.c
+++ b/revision.c
@@ -1408,16 +1408,34 @@ static int remove_duplicate_parents(struct commit *commit)
        return surviving_parents;
 }
 
-static struct commit_list **simplify_one(struct commit *commit, struct commit_list **tail)
+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 struct commit_list **simplify_one(struct rev_info *revs, struct commit *commit, struct commit_list **tail)
 {
        struct commit_list *p;
+       struct merge_simplify_state *st, *pst;
        int cnt;
 
+       st = locate_simplify_state(revs, commit);
+
        /*
-        * We store which commit each one simplifies to in its util field.
         * Have we handled this one?
         */
-       if (commit->util)
+       if (st->simplified)
                return tail;
 
        /*
@@ -1426,7 +1444,7 @@ static struct commit_list **simplify_one(struct commit *commit, struct commit_li
         * anyway.
         */
        if ((commit->object.flags & UNINTERESTING) || !commit->parents) {
-               commit->util = commit;
+               st->simplified = commit;
                return tail;
        }
 
@@ -1435,7 +1453,8 @@ static struct commit_list **simplify_one(struct commit *commit, struct commit_li
         * Otherwise we are not ready to rewrite this one yet.
         */
        for (cnt = 0, p = commit->parents; p; p = p->next) {
-               if (!p->item->util) {
+               pst = locate_simplify_state(revs, p->item);
+               if (!pst->simplified) {
                        tail = &commit_list_insert(p->item, tail)->next;
                        cnt++;
                }
@@ -1446,8 +1465,10 @@ static struct commit_list **simplify_one(struct commit *commit, struct commit_li
        /*
         * Rewrite our list of parents.
         */
-       for (p = commit->parents; p; p = p->next)
-               p->item = p->item->util;
+       for (p = commit->parents; p; p = p->next) {
+               pst = locate_simplify_state(revs, p->item);
+               p->item = pst->simplified;
+       }
        cnt = remove_duplicate_parents(commit);
 
        /*
@@ -1482,9 +1503,11 @@ static struct commit_list **simplify_one(struct commit *commit, struct commit_li
            (commit->object.flags & UNINTERESTING) ||
            !(commit->object.flags & TREESAME) ||
            (1 < cnt))
-               commit->util = commit;
-       else
-               commit->util = commit->parents->item->util;
+               st->simplified = commit;
+       else {
+               pst = locate_simplify_state(revs, commit->parents->item);
+               st->simplified = pst->simplified;
+       }
        return tail;
 }
 
@@ -1508,7 +1531,7 @@ static void simplify_merges(struct rev_info *revs)
                        struct commit_list *next = list->next;
                        free(list);
                        list = next;
-                       tail = simplify_one(commit, tail);
+                       tail = simplify_one(revs, commit, tail);
                }
        }
 
@@ -1519,9 +1542,11 @@ static void simplify_merges(struct rev_info *revs)
        while (list) {
                struct commit *commit = list->item;
                struct commit_list *next = list->next;
+               struct merge_simplify_state *st;
                free(list);
                list = next;
-               if (commit->util == commit)
+               st = locate_simplify_state(revs, commit);
+               if (st->simplified == commit)
                        tail = &commit_list_insert(commit, tail)->next;
        }
 }

diff --git a/revision.h b/revision.h
index dfa06b52106da5ac3dfc65676ea5dd043c95d3cf..765ef6c5e2f3bf0fbf84479cf83e0c0e4c82dda4 100644 (file)
--- a/revision.h
+++ b/revision.h
@@ -110,6 +110,7 @@ struct rev_info {
 
        struct reflog_walk_info *reflog_info;
        struct decoration children;
+       struct decoration merge_simplification;
 };
 
 #define REV_TREE_SAME          0