2 files changed, 61 insertions, 0 deletions

diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index c1de3b05fe09..7c6e73b1b7ea 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -717,6 +717,42 @@ void hists__inc_nr_events(struct hists *hists, u32 type)
         ++hists->stats.nr_events[type];
 }
 
+static struct hist_entry *hists__add_dummy_entry(struct hists *hists,
+                                                 struct hist_entry *pair)
+{
+        struct rb_node **p = &hists->entries.rb_node;
+        struct rb_node *parent = NULL;
+        struct hist_entry *he;
+        int cmp;
+
+        while (*p != NULL) {
+                parent = *p;
+                he = rb_entry(parent, struct hist_entry, rb_node);
+
+                cmp = hist_entry__cmp(pair, he);
+
+                if (!cmp)
+                        goto out;
+
+                if (cmp < 0)
+                        p = &(*p)->rb_left;
+                else
+                        p = &(*p)->rb_right;
+        }
+
+        he = hist_entry__new(pair);
+        if (he) {
+                he->stat.nr_events = 0;
+                he->stat.period    = 0;
+                he->hists          = hists;
+                rb_link_node(&he->rb_node, parent, p);
+                rb_insert_color(&he->rb_node, &hists->entries);
+                hists__inc_nr_entries(hists, he);
+        }
+out:
+        return he;
+}
+
 static struct hist_entry *hists__find_entry(struct hists *hists,
                                             struct hist_entry *he)
 {
@@ -753,3 +789,27 @@ void hists__match(struct hists *leader, struct hists *other)
                         hist__entry_add_pair(pos, pair);
         }
 }
+
+/*
+ * Look for entries in the other hists that are not present in the leader, if
+ * we find them, just add a dummy entry on the leader hists, with period=0,
+ * nr_events=0, to serve as the list header.
+ */
+int hists__link(struct hists *leader, struct hists *other)
+{
+        struct rb_node *nd;
+        struct hist_entry *pos, *pair;
+
+        for (nd = rb_first(&other->entries); nd; nd = rb_next(nd)) {
+                pos = rb_entry(nd, struct hist_entry, rb_node);
+
+                if (!hist_entry__has_pairs(pos)) {
+                        pair = hists__add_dummy_entry(leader, pos);
+                        if (pair == NULL)
+                                return -1;
+                        hist__entry_add_pair(pair, pos);
+                }
+        }
+
+        return 0;
+}
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index ff1c3963e04f..1278c2c72a96 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -116,6 +116,7 @@ void hists__reset_col_len(struct hists *hists);
 void hists__calc_col_len(struct hists *hists, struct hist_entry *he);
 
 void hists__match(struct hists *leader, struct hists *other);
+int hists__link(struct hists *leader, struct hists *other);
 
 struct perf_hpp {
         char *buf;