perf tests: Add parse metric test for frontend metric

Adding new metric test for frontend metric. It's stolen from x86 pmu
events.

Committer testing:

  # perf test "Parse and process metrics"
  67: Parse and process metrics                             : Ok
  # perf test -v "Parse and process metrics"
  #
  67: Parse and process metrics                             :
  --- start ---
  test child forked, pid 104881
  metric expr inst_retired.any / cpu_clk_unhalted.thread for IPC
  found event inst_retired.any
  found event cpu_clk_unhalted.thread
  adding {inst_retired.any,cpu_clk_unhalted.thread}:W
  metric expr idq_uops_not_delivered.core / (4 * (( ( cpu_clk_unhalted.thread / 2 ) * ( 1 + cpu_clk_unhalted.one_thread_active / cpu_clk_unhalted.ref_xclk ) ))) for Frontend_Bound_SMT
  found event cpu_clk_unhalted.one_thread_active
  found event cpu_clk_unhalted.ref_xclk
  found event idq_uops_not_delivered.core
  found event cpu_clk_unhalted.thread
  adding {cpu_clk_unhalted.one_thread_active,cpu_clk_unhalted.ref_xclk,idq_uops_not_delivered.core,cpu_clk_unhalted.thread}:W
  test child finished with 0
  ---- end ----
  Parse and process metrics: Ok
  #

Had to fix it to initialize that 'struct value' array sentinel with a
named initializer to fix the build with some versions of clang:

  tests/parse-metric.c:154:7: error: missing field 'val' initializer [-Werror,-Wmissing-field-initializers]
                { 0 },
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20200602214741.1218986-14-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/parse-metric.c

@@ -17,6 +17,11 @@ static struct pmu_event pme_test[] = {
 	.metric_expr	= "inst_retired.any / cpu_clk_unhalted.thread",
 	.metric_name	= "IPC",
 },
+{
+	.metric_expr	= "idq_uops_not_delivered.core / (4 * (( ( cpu_clk_unhalted.thread / 2 ) * "
+			  "( 1 + cpu_clk_unhalted.one_thread_active / cpu_clk_unhalted.ref_xclk ) )))",
+	.metric_name	= "Frontend_Bound_SMT",
+},
 };
 
 static struct pmu_events_map map = {
@@ -138,8 +143,28 @@ static int test_ipc(void)
 	return 0;
 }
 
+static int test_frontend(void)
+{
+	double ratio;
+	struct value vals[] = {
+		{ .event = "idq_uops_not_delivered.core",        .val = 300 },
+		{ .event = "cpu_clk_unhalted.thread",            .val = 200 },
+		{ .event = "cpu_clk_unhalted.one_thread_active", .val = 400 },
+		{ .event = "cpu_clk_unhalted.ref_xclk",          .val = 600 },
+		{ .event = NULL, },
+	};
+
+	TEST_ASSERT_VAL("failed to compute metric",
+			compute_metric("Frontend_Bound_SMT", vals, &ratio) == 0);
+
+	TEST_ASSERT_VAL("Frontend_Bound_SMT failed, wrong ratio",
+			ratio == 0.45);
+	return 0;
+}
+
 int test__parse_metric(struct test *test __maybe_unused, int subtest __maybe_unused)
 {
 	TEST_ASSERT_VAL("IPC failed", test_ipc() == 0);
+	TEST_ASSERT_VAL("frontend failed", test_frontend() == 0);
 	return 0;
 }