perf auxtrace: Fix multiple use of --itrace option

If the --itrace option is used more than once, the options are
combined, but "i" and "y" (sub-)options can be corrupted because
itrace_do_parse_synth_opts() incorrectly overwrites the period type and
period with default values.

For example, with:

	--itrace=i0ns --itrace=e

The processing of "--itrace=e", resets the "i" period from 0 nanoseconds
to the default 100 microseconds.

Fix by performing the default setting of period type and period only if
"i" or "y" are present in the currently processed --itrace value.

Fixes: f6986c95af ("perf session: Add instruction tracing options")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240315071334.3478-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/auxtrace.c

@@ -1466,6 +1466,7 @@ int itrace_do_parse_synth_opts(struct itrace_synth_opts *synth_opts,
 	char *endptr;
 	bool period_type_set = false;
 	bool period_set = false;
+	bool iy = false;
 
 	synth_opts->set = true;
 
@@ -1484,6 +1485,7 @@ int itrace_do_parse_synth_opts(struct itrace_synth_opts *synth_opts,
 		switch (*p++) {
 		case 'i':
 		case 'y':
+			iy = true;
 			if (p[-1] == 'y')
 				synth_opts->cycles = true;
 			else
@@ -1649,7 +1651,7 @@ int itrace_do_parse_synth_opts(struct itrace_synth_opts *synth_opts,
 		}
 	}
 out:
-	if (synth_opts->instructions || synth_opts->cycles) {
+	if (iy) {
 		if (!period_type_set)
 			synth_opts->period_type =
 					PERF_ITRACE_DEFAULT_PERIOD_TYPE;