perf stat: Fix group lookup for metric group

The metric group code tries to find a group it added earlier in the
evlist. Fix the lookup to handle groups with partially overlaps
correctly. When a sub string match fails and we reset the match, we have
to compare the first element again.

I also renamed the find_evsel function to find_evsel_group to make its
purpose clearer.

With the earlier changes this fixes:

Before:

  % perf stat -M UPI,IPC sleep 1
  ...
         1,032,922      uops_retired.retire_slots #      1.1 UPI
         1,896,096      inst_retired.any
         1,896,096      inst_retired.any
         1,177,254      cpu_clk_unhalted.thread

After:

  % perf stat -M UPI,IPC sleep 1
  ...
        1,013,193      uops_retired.retire_slots #      1.1 UPI
           932,033      inst_retired.any
           932,033      inst_retired.any          #      0.9 IPC
         1,091,245      cpu_clk_unhalted.thread
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Fixes: b18f3e36 ("perf stat: Support JSON metrics in perf stat")
Link: http://lkml.kernel.org/r/20190624193711.35241-4-andi@firstfloor.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/metricgroup.c

@@ -85,7 +85,22 @@ struct egroup {
 	const char *metric_expr;
 };
 
-static struct perf_evsel *find_evsel(struct perf_evlist *perf_evlist,
+static bool record_evsel(int *ind, struct perf_evsel **start,
+			 int idnum,
+			 struct perf_evsel **metric_events,
+			 struct perf_evsel *ev)
+{
+	metric_events[*ind] = ev;
+	if (*ind == 0)
+		*start = ev;
+	if (++*ind == idnum) {
+		metric_events[*ind] = NULL;
+		return true;
+	}
+	return false;
+}
+
+static struct perf_evsel *find_evsel_group(struct perf_evlist *perf_evlist,
 					   const char **ids,
 					   int idnum,
 					   struct perf_evsel **metric_events)
@@ -94,17 +109,25 @@ static struct perf_evsel *find_evsel(struct perf_evlist *perf_evlist,
 	int ind = 0;
 
 	evlist__for_each_entry (perf_evlist, ev) {
+		if (ev->collect_stat)
+			continue;
 		if (!strcmp(ev->name, ids[ind])) {
-			metric_events[ind] = ev;
-			if (ind == 0)
-				start = ev;
-			if (++ind == idnum) {
-				metric_events[ind] = NULL;
+			if (record_evsel(&ind, &start, idnum,
+					 metric_events, ev))
 				return start;
-			}
 		} else {
+			/*
+			 * We saw some other event that is not
+			 * in our list of events. Discard
+			 * the whole match and start again.
+			 */
 			ind = 0;
 			start = NULL;
+			if (!strcmp(ev->name, ids[ind])) {
+				if (record_evsel(&ind, &start, idnum,
+						 metric_events, ev))
+					return start;
+			}
 		}
 	}
 	/*
@@ -134,7 +157,7 @@ static int metricgroup__setup_events(struct list_head *groups,
 			ret = -ENOMEM;
 			break;
 		}
-		evsel = find_evsel(perf_evlist, eg->ids, eg->idnum,
+		evsel = find_evsel_group(perf_evlist, eg->ids, eg->idnum,
 					 metric_events);
 		if (!evsel) {
 			pr_debug("Cannot resolve %s: %s\n",