[PATCH v1 3/9] perf parse-events: Avoid copying an empty list

Ian Rogers
2024-04-15T06:36:49Z

In parse_events_add_pmu, delay copying the list of terms until it is
known the list contains terms.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/parse-events.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index bc4a5e3c6c21..7e23168deeb9 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1398,29 +1398,20 @@ static int parse_events_add_pmu(struct parse_events_state *parse_state,
struct parse_events_terms parsed_terms;
bool alias_rewrote_terms = false;

- parse_events_terms__init(&parsed_terms);
- if (const_parsed_terms) {
- int ret = parse_events_terms__copy(const_parsed_terms, &parsed_terms);
-
- if (ret)
- return ret;
- }
-
if (verbose > 1) {
struct strbuf sb;

strbuf_init(&sb, /*hint=*/ 0);
- if (pmu->selectable && list_empty(&parsed_terms.terms)) {
+ if (pmu->selectable && const_parsed_terms && list_empty(&const_parsed_terms->terms)) {
strbuf_addf(&sb, "%s//", pmu->name);
} else {
strbuf_addf(&sb, "%s/", pmu->name);
- parse_events_terms__to_strbuf(&parsed_terms, &sb);
+ parse_events_terms__to_strbuf(const_parsed_terms, &sb);
strbuf_addch(&sb, '/');
}
fprintf(stderr, "Attempt to add: %s\n", sb.buf);
strbuf_release(&sb);
}
- fix_raw(&parsed_terms, pmu);

memset(&attr, 0, sizeof(attr));
if (pmu->perf_event_attr_init_default)
@@ -1428,7 +1419,7 @@ static int parse_events_add_pmu(struct parse_events_state *parse_state,

attr.type = pmu->type;

- if (list_empty(&parsed_terms.terms)) {
+ if (!const_parsed_terms || list_empty(&const_parsed_terms->terms)) {
evsel = __add_event(list, &parse_state->idx, &attr,
/*init_attr=*/true, /*name=*/NULL,
/*metric_id=*/NULL, pmu,
@@ -1437,6 +1428,15 @@ static int parse_events_add_pmu(struct parse_events_state *parse_state,
return evsel ? 0 : -ENOMEM;
}

+ parse_events_terms__init(&parsed_terms);
+ if (const_parsed_terms) {
+ int ret = parse_events_terms__copy(const_parsed_terms, &parsed_terms);
+
+ if (ret)
+ return ret;
+ }
+ fix_raw(&parsed_terms, pmu);
+
/* Configure attr/terms with a known PMU, this will set hardcoded terms. */
if (config_attr(&attr, &parsed_terms, parse_state->error, config_term_pmu)) {
parse_events_terms__exit(&parsed_terms);