Merge branch 'en/ort-perf-batch-11'

Optimize out repeated rename detection in a sequence of mergy
operations.

* en/ort-perf-batch-11:
  merge-ort, diffcore-rename: employ cached renames when possible
  merge-ort: handle interactions of caching and rename/rename(1to1) cases
  merge-ort: add helper functions for using cached renames
  merge-ort: preserve cached renames for the appropriate side
  merge-ort: avoid accidental API mis-use
  merge-ort: add code to check for whether cached renames can be reused
  merge-ort: populate caches of rename detection results
  merge-ort: add data structures for in-memory caching of rename detection
  t6429: testcases for remembering renames
  fast-rebase: write conflict state to working tree, index, and HEAD
  fast-rebase: change assert() to BUG()
  Documentation/technical: describe remembering renames optimization
  t6423: rename file within directory that other side renamed

Author: gitster

Documentation/technical/remembering-renames.txt

@@ -568,7 +568,8 @@ static void update_dir_rename_counts(struct dir_rename_info *info,
 static void initialize_dir_rename_info(struct dir_rename_info *info,
 				       struct strintmap *relevant_sources,
 				       struct strintmap *dirs_removed,
-				       struct strmap *dir_rename_count)
+				       struct strmap *dir_rename_count,
+				       struct strmap *cached_pairs)
 {
 	struct hashmap_iter iter;
 	struct strmap_entry *entry;
@@ -633,6 +634,17 @@ static void initialize_dir_rename_info(struct dir_rename_info *info,
 					 rename_dst[i].p->two->path);
 	}
 
+	/* Add cached_pairs to counts */
+	strmap_for_each_entry(cached_pairs, &iter, entry) {
+		const char *old_name = entry->key;
+		const char *new_name = entry->value;
+		if (!new_name)
+			/* known delete; ignore it */
+			continue;
+
+		update_dir_rename_counts(info, dirs_removed, old_name, new_name);
+	}
+
 	/*
 	 * Now we collapse
 	 *    dir_rename_count: old_directory -> {new_directory -> count}
@@ -1247,7 +1259,8 @@ static void handle_early_known_dir_renames(struct dir_rename_info *info,
 void diffcore_rename_extended(struct diff_options *options,
 			      struct strintmap *relevant_sources,
 			      struct strintmap *dirs_removed,
-			      struct strmap *dir_rename_count)
+			      struct strmap *dir_rename_count,
+			      struct strmap *cached_pairs)
 {
 	int detect_rename = options->detect_rename;
 	int minimum_score = options->rename_score;
@@ -1363,7 +1376,8 @@ void diffcore_rename_extended(struct diff_options *options,
 		/* Preparation for basename-driven matching. */
 		trace2_region_enter("diff", "dir rename setup", options->repo);
 		initialize_dir_rename_info(&info, relevant_sources,
-					   dirs_removed, dir_rename_count);
+					   dirs_removed, dir_rename_count,
+					   cached_pairs);
 		trace2_region_leave("diff", "dir rename setup", options->repo);
 
 		/* Utilize file basenames to quickly find renames. */
@@ -1560,5 +1574,5 @@ void diffcore_rename_extended(struct diff_options *options,
 
 void diffcore_rename(struct diff_options *options)
 {
-	diffcore_rename_extended(options, NULL, NULL, NULL);
+	diffcore_rename_extended(options, NULL, NULL, NULL, NULL);
 }

diffcore-rename.c

@@ -181,7 +181,8 @@ void diffcore_rename(struct diff_options *);
 void diffcore_rename_extended(struct diff_options *options,
 			      struct strintmap *relevant_sources,
 			      struct strintmap *dirs_removed,
-			      struct strmap *dir_rename_count);
+			      struct strmap *dir_rename_count,
+			      struct strmap *cached_pairs);
 void diffcore_merge_broken(void);
 void diffcore_pickaxe(struct diff_options *);
 void diffcore_order(const char *orderfile);