perf cpumap: Add intersect function

The merge function gives the union of two cpu maps. Add an intersect
function which is necessary, for example, when intersecting a PMUs
supported CPUs with user requested.

Reviewed-by: Kan Liang <[e-mail]>
Signed-off-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ali Saidi <[e-mail]>
Cc: Athira Rajeev <[e-mail]>
Cc: Dmitrii Dolgov <[e-mail]>
Cc: Huacai Chen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jing Zhang <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: John Garry <[e-mail]>
Cc: Kajol Jain <[e-mail]>
Cc: Kang Minchul <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Madhavan Srinivasan <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Mike Leach <[e-mail]>
Cc: Ming Wang <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Ravi Bangoria <[e-mail]>
Cc: Rob Herring <[e-mail]>
Cc: Sandipan Das <[e-mail]>
Cc: Sean Christopherson <[e-mail]>
Cc: Suzuki Poulouse <[e-mail]>
Cc: Thomas Richter <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Xing Zhengjun <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/perf/cpumap.c

···
 	perf_cpu_map__put(orig);
 	return merged;
 }
+
+struct perf_cpu_map *perf_cpu_map__intersect(struct perf_cpu_map *orig,
+					     struct perf_cpu_map *other)
+{
+	struct perf_cpu *tmp_cpus;
+	int tmp_len;
+	int i, j, k;
+	struct perf_cpu_map *merged = NULL;
+
+	if (perf_cpu_map__is_subset(other, orig))
+		return perf_cpu_map__get(orig);
+	if (perf_cpu_map__is_subset(orig, other))
+		return perf_cpu_map__get(other);
+
+	tmp_len = max(orig->nr, other->nr);
+	tmp_cpus = malloc(tmp_len * sizeof(struct perf_cpu));
+	if (!tmp_cpus)
+		return NULL;
+
+	i = j = k = 0;
+	while (i < orig->nr && j < other->nr) {
+		if (orig->map[i].cpu < other->map[j].cpu)
+			i++;
+		else if (orig->map[i].cpu > other->map[j].cpu)
+			j++;
+		else {
+			j++;
+			tmp_cpus[k++] = orig->map[i++];
+		}
+	}
+	if (k)
+		merged = cpu_map__trim_new(k, tmp_cpus);
+	free(tmp_cpus);
+	return merged;
+}

tools/lib/perf/include/perf/cpumap.h

···
 LIBPERF_API struct perf_cpu_map *perf_cpu_map__get(struct perf_cpu_map *map);
 LIBPERF_API struct perf_cpu_map *perf_cpu_map__merge(struct perf_cpu_map *orig,
 						     struct perf_cpu_map *other);
+LIBPERF_API struct perf_cpu_map *perf_cpu_map__intersect(struct perf_cpu_map *orig,
+							 struct perf_cpu_map *other);
 LIBPERF_API void perf_cpu_map__put(struct perf_cpu_map *map);
 LIBPERF_API struct perf_cpu perf_cpu_map__cpu(const struct perf_cpu_map *cpus, int idx);
 LIBPERF_API int perf_cpu_map__nr(const struct perf_cpu_map *cpus);

tools/perf/tests/builtin-test.c

···
 	&suite__backward_ring_buffer,
 	&suite__cpu_map_print,
 	&suite__cpu_map_merge,
+	&suite__cpu_map_intersect,
 	&suite__sdt_event,
 	&suite__is_printable_array,
 	&suite__bitmap_print,

tools/perf/tests/cpumap.c

···
 	return 0;
 }
 
+static int __test__cpu_map_intersect(const char *lhs, const char *rhs, int nr, const char *expected)
+{
+	struct perf_cpu_map *a = perf_cpu_map__new(lhs);
+	struct perf_cpu_map *b = perf_cpu_map__new(rhs);
+	struct perf_cpu_map *c = perf_cpu_map__intersect(a, b);
+	char buf[100];
+
+	TEST_ASSERT_EQUAL("failed to intersect map: bad nr", perf_cpu_map__nr(c), nr);
+	cpu_map__snprint(c, buf, sizeof(buf));
+	TEST_ASSERT_VAL("failed to intersect map: bad result", !strcmp(buf, expected));
+	perf_cpu_map__put(a);
+	perf_cpu_map__put(b);
+	perf_cpu_map__put(c);
+	return 0;
+}
+
+static int test__cpu_map_intersect(struct test_suite *test __maybe_unused,
+				   int subtest __maybe_unused)
+{
+	int ret;
+
+	ret = __test__cpu_map_intersect("4,2,1", "4,5,7", 1, "4");
+	if (ret)
+		return ret;
+	ret = __test__cpu_map_intersect("1-8", "6-9", 3, "6-8");
+	if (ret)
+		return ret;
+	ret = __test__cpu_map_intersect("1-8,12-20", "6-9,15", 4, "6-8,15");
+	if (ret)
+		return ret;
+	ret = __test__cpu_map_intersect("4,2,1", "1", 1, "1");
+	if (ret)
+		return ret;
+	ret = __test__cpu_map_intersect("1", "4,2,1", 1, "1");
+	if (ret)
+		return ret;
+	ret = __test__cpu_map_intersect("1", "1", 1, "1");
+	return ret;
+}
+
 DEFINE_SUITE("Synthesize cpu map", cpu_map_synthesize);
 DEFINE_SUITE("Print cpu map", cpu_map_print);
 DEFINE_SUITE("Merge cpu map", cpu_map_merge);
+DEFINE_SUITE("Intersect cpu map", cpu_map_intersect);

tools/perf/tests/tests.h

···
 DECLARE_SUITE(backward_ring_buffer);
 DECLARE_SUITE(cpu_map_print);
 DECLARE_SUITE(cpu_map_merge);
+DECLARE_SUITE(cpu_map_intersect);
 DECLARE_SUITE(sdt_event);
 DECLARE_SUITE(is_printable_array);
 DECLARE_SUITE(bitmap_print);