Support negative exponents when parsing from a json metric string by
making the numbers after the 'e' optional in the 'Event' insertion fix
up.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/pmu-events/metric.py      | 2 +-
 tools/perf/pmu-events/metric_test.py | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/perf/pmu-events/metric.py b/tools/perf/pmu-events/metric.py
index 847b614d40d5..31eea2f45152 100644
--- a/tools/perf/pmu-events/metric.py
+++ b/tools/perf/pmu-events/metric.py
@@ -573,7 +573,7 @@ def ParsePerfJson(orig: str) -> Expression:
   # a double by the Bison parser
   py = re.sub(r'0Event\(r"[xX]([0-9a-fA-F]*)"\)', r'Event("0x\1")', py)
   # Convert accidentally converted scientific notation constants back
-  py = re.sub(r'([0-9]+)Event\(r"(e[0-9]+)"\)', r'\1\2', py)
+  py = re.sub(r'([0-9]+)Event\(r"(e[0-9]*)"\)', r'\1\2', py)
   # Convert all the known keywords back from events to just the keyword
   keywords = ['if', 'else', 'min', 'max', 'd_ratio', 'source_count', 'has_event', 'strcmp_cpuid_str']
   for kw in keywords:
diff --git a/tools/perf/pmu-events/metric_test.py b/tools/perf/pmu-events/metric_test.py
index ee22ff43ddd7..8acfe4652b55 100755
--- a/tools/perf/pmu-events/metric_test.py
+++ b/tools/perf/pmu-events/metric_test.py
@@ -61,6 +61,10 @@ class TestMetricExpressions(unittest.TestCase):
     after = before
     self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
 
+    before = r'a + 3e-12 + b'
+    after = before
+    self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
+
   def test_IfElseTests(self):
     # if-else needs rewriting to Select and back.
     before = r'Event1 if #smt_on else Event2'
-- 
2.46.1.824.gd892dcdcdd-goog