Add a metaclass test

Author: tomasr8

Lib/test/test_capi/test_opt.py

@@ -2053,6 +2053,31 @@ def testfunc(n):
         self.assertNotIn("_TO_BOOL_BOOL", uops)
         self.assertIn("_GUARD_IS_TRUE_POP", uops)
 
+    def test_call_isinstance_metaclass(self):
+        class EvenNumberMeta(type):
+            def __instancecheck__(self, number):
+                return number % 2 == 0
+
+        class EvenNumber(metaclass=EvenNumberMeta):
+            pass
+
+        def testfunc(n):
+            x = 0
+            for _ in range(n):
+                # Only narrowed to bool
+                y = isinstance(42, EvenNumber)
+                if y:
+                    x += 1
+            return x
+
+        res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+        self.assertEqual(res, TIER2_THRESHOLD)
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+        self.assertIn("_CALL_ISINSTANCE", uops)
+        self.assertNotIn("_TO_BOOL_BOOL", uops)
+        self.assertIn("_GUARD_IS_TRUE_POP", uops)
+
 
 def global_identity(x):
     return x