perf stat: Avoid merging/aggregating metric counts twice

The added perf_stat_merge_counters combines uncore counters. When
metrics are enabled, the counts are merged into a metric_leader via the
stat-shadow saved_value logic. As the leader now is passed an aggregated
count, it leads to all counters being added together twice and counts
appearing approximately doubled in metrics.

This change disables the saved_value merging of counts for evsels that
are merged. It is recommended that later changes remove the saved_value
entirely as the two layers of aggregation in the code is confusing.

Fixes: 942c559 ("perf stat: Add perf_stat_merge_counters()")
Reported-by: Perry Taylor <perry.taylor@intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Florian Fischer <florian.fischer@muhq.space>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20230209064447.83733-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: captain5050

tools/perf/util/stat-shadow.c

@@ -311,7 +311,7 @@ void perf_stat__update_shadow_stats(struct evsel *counter, u64 count,
 		update_stats(&v->stats, count);
 		if (counter->metric_leader)
 			v->metric_total += count;
-	} else if (counter->metric_leader) {
+	} else if (counter->metric_leader && !counter->merged_stat) {
 		v = saved_value_lookup(counter->metric_leader,
 				       map_idx, true, STAT_NONE, 0, st, rsd.cgrp);
 		v->metric_total += count;