perf tools: Avoid a malloc() for array events

Use realloc() rather than malloc()+memcpy() to possibly avoid a memory
allocation when appending array elements.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: clang-built-linux@googlegroups.com
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20191023005337.196160-6-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/parse-events.y

@@ -689,14 +689,12 @@ array_terms ',' array_term
 	struct parse_events_array new_array;
 
 	new_array.nr_ranges = $1.nr_ranges + $3.nr_ranges;
-	new_array.ranges = malloc(sizeof(new_array.ranges[0]) *
-				  new_array.nr_ranges);
+	new_array.ranges = realloc($1.ranges,
+				sizeof(new_array.ranges[0]) *
+				new_array.nr_ranges);
 	ABORT_ON(!new_array.ranges);
-	memcpy(&new_array.ranges[0], $1.ranges,
-	       $1.nr_ranges * sizeof(new_array.ranges[0]));
 	memcpy(&new_array.ranges[$1.nr_ranges], $3.ranges,
 	       $3.nr_ranges * sizeof(new_array.ranges[0]));
-	free($1.ranges);
 	free($3.ranges);
 	$$ = new_array;
 }