perf metric: Compute referenced metrics

Adding computation (expr__parse call) of referenced metric at
the point when it needs to be resolved during the parent metric
computation.

Once the inner metric is computed, the result is stored and
used if there's another usage of that metric.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20200719181320.785305-12-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/expr.c

@@ -112,6 +112,7 @@ int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref)
 	 */
 	data_ptr->ref.metric_name = ref->metric_name;
 	data_ptr->ref.metric_expr = ref->metric_expr;
+	data_ptr->ref.counted = false;
 	data_ptr->is_ref = true;
 
 	ret = hashmap__set(&ctx->ids, name, data_ptr,
@@ -133,6 +134,34 @@ int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
 	return hashmap__find(&ctx->ids, id, (void **)data) ? 0 : -1;
 }
 
+int expr__resolve_id(struct expr_parse_ctx *ctx, const char *id,
+		     struct expr_id_data **datap)
+{
+	struct expr_id_data *data;
+
+	if (expr__get_id(ctx, id, datap) || !*datap) {
+		pr_debug("%s not found\n", id);
+		return -1;
+	}
+
+	data = *datap;
+
+	pr_debug2("lookup: is_ref %d, counted %d, val %f: %s\n",
+		  data->is_ref, data->ref.counted, data->val, id);
+
+	if (data->is_ref && !data->ref.counted) {
+		data->ref.counted = true;
+		pr_debug("processing metric: %s ENTRY\n", id);
+		if (expr__parse(&data->val, ctx, data->ref.metric_expr, 1)) {
+			pr_debug("%s failed to count\n", id);
+			return -1;
+		}
+		pr_debug("processing metric: %s EXIT: %f\n", id, data->val);
+	}
+
+	return 0;
+}
+
 void expr__del_id(struct expr_parse_ctx *ctx, const char *id)
 {
 	struct expr_id_data *old_val = NULL;
@@ -173,6 +202,8 @@ __expr__parse(double *val, struct expr_parse_ctx *ctx, const char *expr,
 	void *scanner;
 	int ret;
 
+	pr_debug2("parsing metric: %s\n", expr);
+
 	ret = expr_lex_init_extra(&scanner_ctx, &scanner);
 	if (ret)
 		return ret;

tools/perf/util/expr.h

@@ -23,6 +23,7 @@ struct expr_id_data {
 		struct {
 			const char *metric_name;
 			const char *metric_expr;
+			bool counted;
 		} ref;
 	};
 
@@ -42,6 +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);
+int expr__resolve_id(struct expr_parse_ctx *ctx, const char *id,
+		     struct expr_id_data **datap);
 int expr__parse(double *final_val, struct expr_parse_ctx *ctx,
 		const char *expr, int runtime);
 int expr__find_other(const char *expr, const char *one,

tools/perf/util/expr.y

@@ -88,11 +88,11 @@ expr:	  NUMBER
 	| ID			{
 					struct expr_id_data *data;
 
-					if (expr__get_id(ctx, $1, &data) || !data) {
-						pr_debug("%s not found\n", $1);
+					if (expr__resolve_id(ctx, $1, &data)) {
 						free($1);
 						YYABORT;
 					}
+
 					$$ = data->val;
 					free($1);
 				}