perf tools: Add test_generic_metric function

Adding test_generic_metric that prepares and runs given metric over the
data from struct runtime_stat object.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.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/20200602214741.1218986-12-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/stat-shadow.c

@@ -842,6 +842,20 @@ static void generic_metric(struct perf_stat_config *config,
 	expr__ctx_clear(&pctx);
 }
 
+double test_generic_metric(struct metric_expr *mexp, int cpu, struct runtime_stat *st)
+{
+	struct expr_parse_ctx pctx;
+	double ratio;
+
+	if (prepare_metric(mexp->metric_events, &pctx, cpu, st) < 0)
+		return 0.;
+
+	if (expr__parse(&ratio, &pctx, mexp->metric_expr, 1))
+		return 0.;
+
+	return ratio;
+}
+
 void perf_stat__print_shadow_stats(struct perf_stat_config *config,
 				   struct evsel *evsel,
 				   double avg, int cpu,

tools/perf/util/stat.h

@@ -230,4 +230,7 @@ perf_evlist__print_counters(struct evlist *evlist,
 			    struct target *_target,
 			    struct timespec *ts,
 			    int argc, const char **argv);
+
+struct metric_expr;
+double test_generic_metric(struct metric_expr *mexp, int cpu, struct runtime_stat *st);
 #endif