[PATCH v2] perf map: optimize maps__fixup_overlappings()

[Konstantin Khlebnikov]

This function splits and removes overlapping areas.

Maps in tree are ordered by start address thus we could find
first overlap and stop if next map does not overlap.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>

---

v2:
* add comments
* replace map__overlap with minimal check
* remove remove map__overlap, that was the only user
---
 tools/perf/util/map.c |   44 ++++++++++++++++++++++++++------------------
 tools/perf/util/map.h |    1 -
 2 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 89ac5b5dc218..36d0763311ef 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -381,20 +381,6 @@ struct map *map__clone(struct map *from)
 	return map;
 }
 
-int map__overlap(struct map *l, struct map *r)
-{
-	if (l->start > r->start) {
-		struct map *t = l;
-		l = r;
-		r = t;
-	}
-
-	if (l->end > r->start)
-		return 1;
-
-	return 0;
-}
-
 size_t map__fprintf(struct map *map, FILE *fp)
 {
 	return fprintf(fp, " %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s\n",
@@ -675,20 +661,42 @@ static void __map_groups__insert(struct map_groups *mg, struct map *map)
 static int maps__fixup_overlappings(struct maps *maps, struct map *map, FILE *fp)
 {
 	struct rb_root *root;
-	struct rb_node *next;
+	struct rb_node *next, *first;
 	int err = 0;
 
 	down_write(&maps->lock);
 
 	root = &maps->entries;
-	next = rb_first(root);
 
+	/*
+	 * Find first map where end > map->start.
+	 * Same as find_vma() in kernel.
+	 */
+	next = root->rb_node;
+	first = NULL;
+	while (next) {
+		struct map *pos = rb_entry(next, struct map, rb_node);
+
+		if (pos->end > map->start) {
+			first = next;
+			if (pos->start <= map->start)
+				break;
+			next = next->rb_left;
+		} else
+			next = next->rb_right;
+	}
+
+	next = first;
 	while (next) {
 		struct map *pos = rb_entry(next, struct map, rb_node);
 		next = rb_next(&pos->rb_node);
 
-		if (!map__overlap(pos, map))
-			continue;
+		/*
+		 * Stop if current map starts after map->end.
+		 * Maps are ordered by start: next will not overlap for sure.
+		 */
+		if (pos->start >= map->end)
+			break;
 
 		if (verbose >= 2) {
 
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index 4cb90f242bed..e0f327b51e66 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -166,7 +166,6 @@ static inline void __map__zput(struct map **map)
 
 #define map__zput(map) __map__zput(&map)
 
-int map__overlap(struct map *l, struct map *r);
 size_t map__fprintf(struct map *map, FILE *fp);
 size_t map__fprintf_dsoname(struct map *map, FILE *fp);
 char *map__srcline(struct map *map, u64 addr, struct symbol *sym);