perf evsel: Add hists helper

Not all tools need a hists instance per perf_evsel, so lets pave the way
to remove evsel->hists while leaving a way to access the hists from a
specially allocated evsel, one that comes with space at the end where
lives the evsel.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jean Pihet <jean.pihet@linaro.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-qlktkhe31w4mgtbd84035sr2@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index ac145fa..3750d63 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -288,12 +288,14 @@
 		evname = buf;
 
 		for_each_group_member(pos, evsel) {
+			const struct hists *pos_hists = evsel__hists(pos);
+
 			if (symbol_conf.filter_relative) {
-				nr_samples += pos->hists.stats.nr_non_filtered_samples;
-				nr_events += pos->hists.stats.total_non_filtered_period;
+				nr_samples += pos_hists->stats.nr_non_filtered_samples;
+				nr_events += pos_hists->stats.total_non_filtered_period;
 			} else {
-				nr_samples += pos->hists.stats.nr_events[PERF_RECORD_SAMPLE];
-				nr_events += pos->hists.stats.total_period;
+				nr_samples += pos_hists->stats.nr_events[PERF_RECORD_SAMPLE];
+				nr_events += pos_hists->stats.total_period;
 			}
 		}
 	}
@@ -318,7 +320,7 @@
 	struct perf_evsel *pos;
 
 	evlist__for_each(evlist, pos) {
-		struct hists *hists = &pos->hists;
+		struct hists *hists = evsel__hists(pos);
 		const char *evname = perf_evsel__name(pos);
 
 		if (symbol_conf.event_group &&
@@ -427,7 +429,7 @@
 	ui_progress__init(&prog, rep->nr_entries, "Merging related events...");
 
 	evlist__for_each(rep->session->evlist, pos) {
-		struct hists *hists = &pos->hists;
+		struct hists *hists = evsel__hists(pos);
 
 		if (pos->idx == 0)
 			hists->symbol_filter_str = rep->symbol_filter_str;
@@ -437,7 +439,7 @@
 		/* Non-group events are considered as leader */
 		if (symbol_conf.event_group &&
 		    !perf_evsel__is_group_leader(pos)) {
-			struct hists *leader_hists = &pos->leader->hists;
+			struct hists *leader_hists = evsel__hists(pos->leader);
 
 			hists__match(leader_hists, hists);
 			hists__link(leader_hists, hists);
@@ -500,7 +502,7 @@
 	}
 
 	evlist__for_each(session->evlist, pos)
-		hists__output_resort(&pos->hists);
+		hists__output_resort(evsel__hists(pos));
 
 	return report__browse_hists(rep);
 }