@matheusbsbs / matheus-bagliano / commits / 0acbaf9000

merge: use repo_in_merge_bases for octopus up-to-date check

The octopus merge path checks whether each remote head is already an ancestor of HEAD by computing all merge-bases via repo_get_merge_bases() and comparing the first result's OID to the remote head. This is more expensive than necessary: repo_get_merge_bases() calls paint_down_to_common() with min_generation=0, performs the full STALE drain, and may run remove_redundant(), when all we need is a yes/no reachability answer. Replace this with repo_in_merge_bases(), which answers the is-ancestor question directly. When generation numbers are available, repo_in_merge_bases() uses can_all_from_reach() -- a DFS bounded by generation number that stops as soon as the target is found or ruled out, without entering paint_down_to_common() at all. Without generation numbers, it still benefits from a tighter min_generation floor. Signed-off-by: Kristofer Karlsson <krka@spotify.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Kristofer Karlsson committed May 12, 2026 at 06:11 UTC 0acbaf9000bd50bfbec24e5c40ab96bbd5e79281

2 files changed +14 -14

builtin/merge.c

+4 -14

@@ -1735,21 +1735,11 @@ int cmd_merge(int argc,

1735 struct commit_list *j;

1736

1737 for (j = remoteheads; j; j = j->next) {

1738 - struct commit_list *common_one = NULL;

1739 - struct commit *common_item;

1740 -

1741 - /*

1742 - * Here we *have* to calculate the individual

1743 - * merge_bases again, otherwise "git merge HEAD^

1744 - * HEAD^^" would be missed.

1745 - */

1746 - if (repo_get_merge_bases(the_repository, head_commit,

1747 - j->item, &common_one) < 0)

1738 + int ret = repo_in_merge_bases(the_repository,

1739 + j->item, head_commit);

1740 + if (ret < 0)

1741 exit(128);

1749 -

1750 - common_item = common_one->item;

1751 - commit_list_free(common_one);

1752 - if (!oideq(&common_item->object.oid, &j->item->object.oid)) {

1742 + if (!ret) {

1743 up_to_date = 0;

1744 break;

1745 }

t/t6408-merge-up-to-date.sh

+10

@@ -89,4 +89,14 @@ test_expect_success 'merge fast-forward octopus' '

89 test "$expect" = "$current"

90 '

92 +test_expect_success 'merge octopus already up to date' '

93 +

94 + git reset --hard c2 &&

95 + test_tick &&

96 + git merge c0 c1 &&

97 + expect=$(git rev-parse c2) &&

98 + current=$(git rev-parse HEAD) &&

99 + test "$expect" = "$current"

100 +'

101 +

102 test_done