perf hists: Introduce hists__match_hierarchy()

The hists__match_hierarchy() is to find matching hist entries in a
group.  A matching entry has the same values for all sort keys given.

With an event group (e.g.: -e "{cycles,instructions}"), a leader event
should show other members in a group.  So each entry in the leader
should be able to find its pair entries which have same values.

With hierarchy mode, it needs to search all matching children in a
hierarchy.

An example output looks like:

  #               Overhead  Command / Shared Object / Symbol
  # ......................  ..................................
  #
      25.74%  27.18%        sh
         19.96%  24.14%        libc-2.24.so
            9.55%  14.64%        [.] __strcmp_sse2
            1.54%   0.00%        [.] __tfind
            1.07%   1.13%        [.] _int_malloc
  ...

In the above example, two overheads are shown - one for the leader and
another for the other group member.  They were matched since their
command, dso and symbol have the same values.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20160913074552.13284-2-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/hist.c

@@ -2174,6 +2174,51 @@ static struct hist_entry *hists__find_entry(struct hists *hists,
 	return NULL;
 }
 
+static struct hist_entry *hists__find_hierarchy_entry(struct rb_root *root,
+						      struct hist_entry *he)
+{
+	struct rb_node *n = root->rb_node;
+
+	while (n) {
+		struct hist_entry *iter;
+		struct perf_hpp_fmt *fmt;
+		int64_t cmp = 0;
+
+		iter = rb_entry(n, struct hist_entry, rb_node_in);
+		perf_hpp_list__for_each_sort_list(he->hpp_list, fmt) {
+			cmp = fmt->collapse(fmt, iter, he);
+			if (cmp)
+				break;
+		}
+
+		if (cmp < 0)
+			n = n->rb_left;
+		else if (cmp > 0)
+			n = n->rb_right;
+		else
+			return iter;
+	}
+
+	return NULL;
+}
+
+static void hists__match_hierarchy(struct rb_root *leader_root,
+				   struct rb_root *other_root)
+{
+	struct rb_node *nd;
+	struct hist_entry *pos, *pair;
+
+	for (nd = rb_first(leader_root); nd; nd = rb_next(nd)) {
+		pos  = rb_entry(nd, struct hist_entry, rb_node_in);
+		pair = hists__find_hierarchy_entry(other_root, pos);
+
+		if (pair) {
+			hist_entry__add_pair(pair, pos);
+			hists__match_hierarchy(&pos->hroot_in, &pair->hroot_in);
+		}
+	}
+}
+
 /*
  * Look for pairs to link to the leader buckets (hist_entries):
  */
@@ -2183,6 +2228,12 @@ void hists__match(struct hists *leader, struct hists *other)
 	struct rb_node *nd;
 	struct hist_entry *pos, *pair;
 
+	if (symbol_conf.report_hierarchy) {
+		/* hierarchy report always collapses entries */
+		return hists__match_hierarchy(&leader->entries_collapsed,
+					      &other->entries_collapsed);
+	}
+
 	if (hists__has(leader, need_collapse))
 		root = &leader->entries_collapsed;
 	else