gh-134584: Eliminate redundant refcounting from _BINARY_OP_SUBSCR_TUPLE_INT

Lib/test/test_capi/test_opt.py

@@ -3098,6 +3098,25 @@ def testfunc(n):
         self.assertNotIn("_POP_TOP_INT", uops)
         self.assertIn("_POP_TOP_NOP", uops)
 
+    def test_binary_subscr_tuple_int(self):
+        def testfunc(n):
+            t = (1,)
+            x = 0
+            for _ in range(n):
+                y = t[0]
+                x += y
+            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_TUPLE_INT", uops)
+        self.assertNotIn("_POP_TOP", uops)
+        self.assertNotIn("_POP_TOP_INT", uops)
+        self.assertIn("_POP_TOP_NOP", uops)
+
 def global_identity(x):
     return x
 

Python/bytecodes.c

@@ -975,9 +975,9 @@ dummy_func(
         }
 
         macro(BINARY_OP_SUBSCR_TUPLE_INT) =
-            _GUARD_TOS_INT + _GUARD_NOS_TUPLE + unused/5 + _BINARY_OP_SUBSCR_TUPLE_INT;
+            _GUARD_TOS_INT + _GUARD_NOS_TUPLE + unused/5 + _BINARY_OP_SUBSCR_TUPLE_INT + _POP_TOP_INT + POP_TOP;
 
-        op(_BINARY_OP_SUBSCR_TUPLE_INT, (tuple_st, sub_st -- res)) {
+        op(_BINARY_OP_SUBSCR_TUPLE_INT, (tuple_st, sub_st -- res, ts, ss)) {
             PyObject *sub = PyStackRef_AsPyObjectBorrow(sub_st);
             PyObject *tuple = PyStackRef_AsPyObjectBorrow(tuple_st);
 
@@ -991,9 +991,10 @@ dummy_func(
             STAT_INC(BINARY_OP, hit);
             PyObject *res_o = PyTuple_GET_ITEM(tuple, index);
             assert(res_o != NULL);
-            PyStackRef_CLOSE_SPECIALIZED(sub_st, _PyLong_ExactDealloc);
             res = PyStackRef_FromPyObjectNew(res_o);
-            DECREF_INPUTS();
+            ts = tuple_st;
+            ss = sub_st;
+            INPUTS_DEAD();
         }
 
         op(_GUARD_NOS_DICT, (nos, unused -- nos, unused)) {

Python/optimizer_bytecodes.c

@@ -335,7 +335,7 @@ dummy_func(void) {
         i = sub_st;
     }
 
-    op(_BINARY_OP_SUBSCR_TUPLE_INT, (tuple_st, sub_st -- res)) {
+    op(_BINARY_OP_SUBSCR_TUPLE_INT, (tuple_st, sub_st -- res, ts, ss)) {
         assert(sym_matches_type(tuple_st, &PyTuple_Type));
         if (sym_is_const(ctx, sub_st)) {
             assert(PyLong_CheckExact(sym_get_const(ctx, sub_st)));
@@ -354,6 +354,8 @@ dummy_func(void) {
         else {
             res = sym_new_not_null(ctx);
         }
+        ts = tuple_st;
+        ss = sub_st;
     }
 
     op(_TO_BOOL, (value -- res)) {