perf stat: Analyze front-end and back-end stall counts

Sample output:

 Performance counter stats for './loop_1b':

        873.691065 task-clock               #    1.000 CPUs utilized
                 1 context-switches         #    0.000 M/sec
                 1 CPU-migrations           #    0.000 M/sec
                96 page-faults              #    0.000 M/sec
     2,012,637,222 cycles                   #    2.304 GHz                      (66.58%)
     1,001,397,911 stalled-cycles-frontend  #   49.76% frontend cycles idle     (66.58%)
         7,523,398 stalled-cycles-backend   #    0.37%  backend cycles idle     (66.76%)
     2,004,551,046 instructions             #    1.00  insns per cycle
                                            #    0.50  stalled cycles per insn  (66.80%)
     1,001,304,992 branches                 # 1146.063 M/sec                    (66.76%)
            39,453 branch-misses            #    0.00% of all branches          (66.64%)

        0.874046121  seconds time elapsed

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-7y40wib8n003io7hjpn1dsrm@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 04d2f0a..8a407f3 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -60,7 +60,7 @@
 #define PERF_EVENT_TYPE(config)		__PERF_EVENT_FIELD(config, TYPE)
 #define PERF_EVENT_ID(config)		__PERF_EVENT_FIELD(config, EVENT)
 
-static const char *hw_event_names[] = {
+static const char *hw_event_names[PERF_COUNT_HW_MAX] = {
 	"cycles",
 	"instructions",
 	"cache-references",
@@ -68,10 +68,11 @@
 	"branches",
 	"branch-misses",
 	"bus-cycles",
-	"stalled-cycles",
+	"stalled-cycles-frontend",
+	"stalled-cycles-backend",
 };
 
-static const char *sw_event_names[] = {
+static const char *sw_event_names[PERF_COUNT_SW_MAX] = {
 	"cpu-clock",
 	"task-clock",
 	"page-faults",