Merge branch 'sg/line-log-tree-diff-optim'

Optimize unnecessary full-tree diff away from "git log -L" machinery.

* sg/line-log-tree-diff-optim:
  line-log: avoid unnecessary full tree diffs
  line-log: extract pathspec parsing from line ranges into a helper function

2 files changed, 134 insertions, 19 deletions

diff --git a/line-log.c b/line-log.c
index 3aff1849e7..9010e00950 100644
--- a/line-log.c
+++ b/line-log.c
@@ -737,6 +737,38 @@ static struct line_log_data *lookup_line_range(struct rev_info *revs,
 	return ret;
 }
 
+static int same_paths_in_pathspec_and_range(struct pathspec *pathspec,
+					    struct line_log_data *range)
+{
+	int i;
+	struct line_log_data *r;
+
+	for (i = 0, r = range; i < pathspec->nr && r; i++, r = r->next)
+		if (strcmp(pathspec->items[i].match, r->path))
+			return 0;
+	if (i < pathspec->nr || r)
+		/* different number of pathspec items and ranges */
+		return 0;
+
+	return 1;
+}
+
+static void parse_pathspec_from_ranges(struct pathspec *pathspec,
+				       struct line_log_data *range)
+{
+	struct line_log_data *r;
+	struct argv_array array = ARGV_ARRAY_INIT;
+	const char **paths;
+
+	for (r = range; r; r = r->next)
+		argv_array_push(&array, r->path);
+	paths = argv_array_detach(&array);
+
+	parse_pathspec(pathspec, 0, PATHSPEC_PREFER_FULL, "", paths);
+	/* strings are now owned by pathspec */
+	free(paths);
+}
+
 void line_log_init(struct rev_info *rev, const char *prefix, struct string_list *args)
 {
 	struct commit *commit = NULL;
@@ -746,20 +778,7 @@ void line_log_init(struct rev_info *rev, const char *prefix, struct string_list
 	range = parse_lines(rev->diffopt.repo, commit, prefix, args);
 	add_line_range(rev, commit, range);
 
-	if (!rev->diffopt.detect_rename) {
-		struct line_log_data *r;
-		struct argv_array array = ARGV_ARRAY_INIT;
-		const char **paths;
-
-		for (r = range; r; r = r->next)
-			argv_array_push(&array, r->path);
-		paths = argv_array_detach(&array);
-
-		parse_pathspec(&rev->diffopt.pathspec, 0,
-			       PATHSPEC_PREFER_FULL, "", paths);
-		/* strings are now owned by pathspec */
-		free(paths);
-	}
+	parse_pathspec_from_ranges(&rev->diffopt.pathspec, range);
 }
 
 static void move_diff_queue(struct diff_queue_struct *dst,
@@ -817,15 +836,29 @@ static void queue_diffs(struct line_log_data *range,
 			struct diff_queue_struct *queue,
 			struct commit *commit, struct commit *parent)
 {
+	struct object_id *tree_oid, *parent_tree_oid;
+
 	assert(commit);
 
+	tree_oid = get_commit_tree_oid(commit);
+	parent_tree_oid = parent ? get_commit_tree_oid(parent) : NULL;
+
+	if (opt->detect_rename &&
+	    !same_paths_in_pathspec_and_range(&opt->pathspec, range)) {
+		clear_pathspec(&opt->pathspec);
+		parse_pathspec_from_ranges(&opt->pathspec, range);
+	}
 	DIFF_QUEUE_CLEAR(&diff_queued_diff);
-	diff_tree_oid(parent ? get_commit_tree_oid(parent) : NULL,
-		      get_commit_tree_oid(commit), "", opt);
-	if (opt->detect_rename) {
+	diff_tree_oid(parent_tree_oid, tree_oid, "", opt);
+	if (opt->detect_rename && diff_might_be_rename()) {
+		/* must look at the full tree diff to detect renames */
+		clear_pathspec(&opt->pathspec);
+		DIFF_QUEUE_CLEAR(&diff_queued_diff);
+
+		diff_tree_oid(parent_tree_oid, tree_oid, "", opt);
+
 		filter_diffs_for_paths(range, 1);
-		if (diff_might_be_rename())
-			diffcore_std(opt);
+		diffcore_std(opt);
 		filter_diffs_for_paths(range, 0);
 	}
 	move_diff_queue(queue, &diff_queued_diff);
diff --git a/t/t4211-line-log.sh b/t/t4211-line-log.sh
index 1db7bd0f59..8319163744 100755
--- a/t/t4211-line-log.sh
+++ b/t/t4211-line-log.sh
@@ -132,4 +132,86 @@ test_expect_success '--raw is forbidden' '
 	test_must_fail git log -L1,24:b.c --raw
 '
 
+test_expect_success 'setup for checking fancy rename following' '
+	git checkout --orphan moves-start &&
+	git reset --hard &&
+
+	printf "%s\n"    12 13 14 15      b c d e   >file-1 &&
+	printf "%s\n"    22 23 24 25      B C D E   >file-2 &&
+	git add file-1 file-2 &&
+	test_tick &&
+	git commit -m "Add file-1 and file-2" &&
+	oid_add_f1_f2=$(git rev-parse --short HEAD) &&
+
+	git checkout -b moves-main &&
+	printf "%s\n" 11 12 13 14 15      b c d e   >file-1 &&
+	git commit -a -m "Modify file-1 on main" &&
+	oid_mod_f1_main=$(git rev-parse --short HEAD) &&
+
+	printf "%s\n" 21 22 23 24 25      B C D E   >file-2 &&
+	git commit -a -m "Modify file-2 on main #1" &&
+	oid_mod_f2_main_1=$(git rev-parse --short HEAD) &&
+
+	git mv file-1 renamed-1 &&
+	git commit -m "Rename file-1 to renamed-1 on main" &&
+
+	printf "%s\n" 11 12 13 14 15      b c d e f >renamed-1 &&
+	git commit -a -m "Modify renamed-1 on main" &&
+	oid_mod_r1_main=$(git rev-parse --short HEAD) &&
+
+	printf "%s\n" 21 22 23 24 25      B C D E F >file-2 &&
+	git commit -a -m "Modify file-2 on main #2" &&
+	oid_mod_f2_main_2=$(git rev-parse --short HEAD) &&
+
+	git checkout -b moves-side moves-start &&
+	printf "%s\n"    12 13 14 15 16   b c d e   >file-1 &&
+	git commit -a -m "Modify file-1 on side #1" &&
+	oid_mod_f1_side_1=$(git rev-parse --short HEAD) &&
+
+	printf "%s\n"    22 23 24 25 26   B C D E   >file-2 &&
+	git commit -a -m "Modify file-2 on side" &&
+	oid_mod_f2_side=$(git rev-parse --short HEAD) &&
+
+	git mv file-2 renamed-2 &&
+	git commit -m "Rename file-2 to renamed-2 on side" &&
+
+	printf "%s\n"    12 13 14 15 16 a b c d e   >file-1 &&
+	git commit -a -m "Modify file-1 on side #2" &&
+	oid_mod_f1_side_2=$(git rev-parse --short HEAD) &&
+
+	printf "%s\n"    22 23 24 25 26 A B C D E   >renamed-2 &&
+	git commit -a -m "Modify renamed-2 on side" &&
+	oid_mod_r2_side=$(git rev-parse --short HEAD) &&
+
+	git checkout moves-main &&
+	git merge moves-side &&
+	oid_merge=$(git rev-parse --short HEAD)
+'
+
+test_expect_success 'fancy rename following #1' '
+	cat >expect <<-EOF &&
+	$oid_merge Merge branch '\''moves-side'\'' into moves-main
+	$oid_mod_f1_side_2 Modify file-1 on side #2
+	$oid_mod_f1_side_1 Modify file-1 on side #1
+	$oid_mod_r1_main Modify renamed-1 on main
+	$oid_mod_f1_main Modify file-1 on main
+	$oid_add_f1_f2 Add file-1 and file-2
+	EOF
+	git log -L1:renamed-1 --oneline --no-patch >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'fancy rename following #2' '
+	cat >expect <<-EOF &&
+	$oid_merge Merge branch '\''moves-side'\'' into moves-main
+	$oid_mod_r2_side Modify renamed-2 on side
+	$oid_mod_f2_side Modify file-2 on side
+	$oid_mod_f2_main_2 Modify file-2 on main #2
+	$oid_mod_f2_main_1 Modify file-2 on main #1
+	$oid_add_f1_f2 Add file-1 and file-2
+	EOF
+	git log -L1:renamed-2 --oneline --no-patch >actual &&
+	test_cmp expect actual
+'
+
 test_done