GH-134584: Remove redundant refcount for BINARY_OP_SUBSCR_STR_INT

Lib/test/test_capi/test_opt.py

@@ -1877,6 +1877,26 @@ def testfunc(n):
         self.assertNotIn("_GUARD_TOS_UNICODE", uops)
         self.assertIn("_BINARY_OP_ADD_UNICODE", uops)
 
+    def test_binary_op_subscr_str_int(self):
+        def testfunc(n):
+            x = 0
+            s = "hello"
+            for _ in range(n):
+                c = s[1]  # _BINARY_OP_SUBSCR_STR_INT
+                if c == 'e':
+                    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("_BINARY_OP_SUBSCR_STR_INT", uops)
+        self.assertIn("_COMPARE_OP_STR", uops)
+        self.assertIn("_POP_TOP_NOP", uops)
+        self.assertNotIn("_POP_TOP", uops)
+        self.assertNotIn("_POP_TOP_INT", uops)
+
     def test_call_type_1_guards_removed(self):
         def testfunc(n):
             x = 0

Python/bytecodes.c

@@ -937,9 +937,9 @@ dummy_func(
         }
 
         macro(BINARY_OP_SUBSCR_STR_INT) =
-            _GUARD_TOS_INT + _GUARD_NOS_UNICODE + unused/5 + _BINARY_OP_SUBSCR_STR_INT;
+            _GUARD_TOS_INT + _GUARD_NOS_UNICODE + unused/5 + _BINARY_OP_SUBSCR_STR_INT + POP_TOP + _POP_TOP_INT;
 
-        op(_BINARY_OP_SUBSCR_STR_INT, (str_st, sub_st -- res)) {
+        op(_BINARY_OP_SUBSCR_STR_INT, (str_st, sub_st -- res, s, i)) {
             PyObject *sub = PyStackRef_AsPyObjectBorrow(sub_st);
             PyObject *str = PyStackRef_AsPyObjectBorrow(str_st);
 
@@ -954,9 +954,9 @@ dummy_func(
             assert(c < 128);
             STAT_INC(BINARY_OP, hit);
             PyObject *res_o = (PyObject*)&_Py_SINGLETON(strings).ascii[c];
-            PyStackRef_CLOSE_SPECIALIZED(sub_st, _PyLong_ExactDealloc);
-            DEAD(sub_st);
-            PyStackRef_CLOSE(str_st);
+            INPUTS_DEAD();
+            s = str_st;
+            i = sub_st;
             res = PyStackRef_FromPyObjectBorrow(res_o);
         }
 

Python/optimizer_bytecodes.c

@@ -322,8 +322,10 @@ dummy_func(void) {
         ctx->done = true;
     }
 
-    op(_BINARY_OP_SUBSCR_STR_INT, (str_st, sub_st -- res)) {
+    op(_BINARY_OP_SUBSCR_STR_INT, (str_st, sub_st -- res, s, i)) {
         res = sym_new_type(ctx, &PyUnicode_Type);
+        s = str_st;
+        i = sub_st;
     }
 
     op(_BINARY_OP_SUBSCR_TUPLE_INT, (tuple_st, sub_st -- res)) {