Merge branch 'sg/line-log-merge-optim'

"git log -L..." compared trees of multiple parents with the tree of the
merge result in an unnecessarily inefficient way.

* sg/line-log-merge-optim:
  line-log: simplify condition checking for merge commits
  line-log: initialize diff queue in process_ranges_ordinary_commit()
  line-log: get rid of the parents array in process_ranges_merge_commit()
  line-log: avoid unnecessary tree diffs when processing merge commits

Author: gitster

line-log.c

@@ -1087,13 +1087,6 @@ static struct diff_filepair *diff_filepair_dup(struct diff_filepair *pair)
 	return new_filepair;
 }
 
-static void free_diffqueues(int n, struct diff_queue_struct *dq)
-{
-	for (int i = 0; i < n; i++)
-		diff_queue_clear(&dq[i]);
-	free(dq);
-}
-
 static int process_all_files(struct line_log_data **range_out,
 			     struct rev_info *rev,
 			     struct diff_queue_struct *queue,
@@ -1189,7 +1182,7 @@ static int process_ranges_ordinary_commit(struct rev_info *rev, struct commit *c
 					  struct line_log_data *range)
 {
 	struct commit *parent = NULL;
-	struct diff_queue_struct queue;
+	struct diff_queue_struct queue = DIFF_QUEUE_INIT;
 	struct line_log_data *parent_range;
 	int changed;
 
@@ -1209,9 +1202,7 @@ static int process_ranges_ordinary_commit(struct rev_info *rev, struct commit *c
 static int process_ranges_merge_commit(struct rev_info *rev, struct commit *commit,
 				       struct line_log_data *range)
 {
-	struct diff_queue_struct *diffqueues;
 	struct line_log_data **cand;
-	struct commit **parents;
 	struct commit_list *p;
 	int i;
 	int nparents = commit_list_count(commit->parents);
@@ -1220,28 +1211,27 @@ static int process_ranges_merge_commit(struct rev_info *rev, struct commit *comm
 	if (nparents > 1 && rev->first_parent_only)
 		nparents = 1;
 
-	ALLOC_ARRAY(diffqueues, nparents);
 	CALLOC_ARRAY(cand, nparents);
-	ALLOC_ARRAY(parents, nparents);
-
-	p = commit->parents;
-	for (i = 0; i < nparents; i++) {
-		parents[i] = p->item;
-		p = p->next;
-		queue_diffs(range, &rev->diffopt, &diffqueues[i], commit, parents[i]);
-	}
 
-	for (i = 0; i < nparents; i++) {
+	for (p = commit->parents, i = 0;
+	     p && i < nparents;
+	     p = p->next, i++) {
+		struct commit *parent = p->item;
+		struct diff_queue_struct diffqueue = DIFF_QUEUE_INIT;
 		int changed;
-		changed = process_all_files(&cand[i], rev, &diffqueues[i], range);
+
+		queue_diffs(range, &rev->diffopt, &diffqueue, commit, parent);
+
+		changed = process_all_files(&cand[i], rev, &diffqueue, range);
+		diff_queue_clear(&diffqueue);
 		if (!changed) {
 			/*
 			 * This parent can take all the blame, so we
 			 * don't follow any other path in history
 			 */
-			add_line_range(rev, parents[i], cand[i]);
+			add_line_range(rev, parent, cand[i]);
 			free_commit_list(commit->parents);
-			commit_list_append(parents[i], &commit->parents);
+			commit_list_append(parent, &commit->parents);
 
 			ret = 0;
 			goto out;
@@ -1252,22 +1242,22 @@ static int process_ranges_merge_commit(struct rev_info *rev, struct commit *comm
 	 * No single parent took the blame.  We add the candidates
 	 * from the above loop to the parents.
 	 */
-	for (i = 0; i < nparents; i++)
-		add_line_range(rev, parents[i], cand[i]);
+	for (p = commit->parents, i = 0;
+	     p && i < nparents;
+	     p = p->next, i++)
+		add_line_range(rev, p->item, cand[i]);
 
 	ret = 1;
 
 out:
 	clear_commit_line_range(rev, commit);
-	free(parents);
 	for (i = 0; i < nparents; i++) {
 		if (!cand[i])
 			continue;
 		line_log_data_clear(cand[i]);
 		free(cand[i]);
 	}
 	free(cand);
-	free_diffqueues(nparents, diffqueues);
 	return ret;
 
 	/* NEEDSWORK evil merge detection stuff */
@@ -1283,10 +1273,10 @@ int line_log_process_ranges_arbitrary_commit(struct rev_info *rev, struct commit
 			struct line_log_data *prange = line_log_data_copy(range);
 			add_line_range(rev, commit->parents->item, prange);
 			clear_commit_line_range(rev, commit);
-		} else if (!commit->parents || !commit->parents->next)
-			changed = process_ranges_ordinary_commit(rev, commit, range);
-		else
+		} else if (commit->parents && commit->parents->next)
 			changed = process_ranges_merge_commit(rev, commit, range);
+		else
+			changed = process_ranges_ordinary_commit(rev, commit, range);
 	}
 
 	if (!changed)