2 files changed, 17 insertions, 0 deletions

diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index 5657222aaa25..77c6ad81a923 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -211,6 +211,21 @@ int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
 	return hashmap__find(ctx->ids, id, (void **)data) ? 0 : -1;
 }
 
+bool expr__subset_of_ids(struct expr_parse_ctx *haystack,
+			 struct expr_parse_ctx *needles)
+{
+	struct hashmap_entry *cur;
+	size_t bkt;
+	struct expr_id_data *data;
+
+	hashmap__for_each_entry(needles->ids, cur, bkt) {
+		if (expr__get_id(haystack, cur->key, &data))
+			return false;
+	}
+	return true;
+}
+
+
 int expr__resolve_id(struct expr_parse_ctx *ctx, const char *id,
 		     struct expr_id_data **datap)
 {
diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h
index c6e534f633c3..cf81f9166dbb 100644
--- a/tools/perf/util/expr.h
+++ b/tools/perf/util/expr.h
@@ -43,6 +43,8 @@ int expr__add_id_val(struct expr_parse_ctx *ctx, const char *id, double val);
 int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref);
 int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
 		 struct expr_id_data **data);
+bool expr__subset_of_ids(struct expr_parse_ctx *haystack,
+			 struct expr_parse_ctx *needles);
 int expr__resolve_id(struct expr_parse_ctx *ctx, const char *id,
 		     struct expr_id_data **datap);