GH-134584: Remove redundant refcount from _STORE_ATTR_SLOT

Lib/test/test_capi/test_opt.py

@@ -2517,6 +2517,24 @@ def testfunc(n):
         self.assertNotIn("_POP_TOP_INT", uops)
         self.assertIn("_POP_TOP_NOP", uops)
 
+    def test_store_attr_slot(self):
+        class C:
+            __slots__ = ('x',)
+
+        def testfunc(n):
+            c = C()
+            for _ in range(n):
+                c.x = 42
+                y = c.x
+            return y
+
+        res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+        self.assertEqual(res, 42)
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+        self.assertIn("_STORE_ATTR_SLOT", uops)
+        self.assertIn("_POP_TOP", uops)
+
     def test_attr_promotion_failure(self):
         # We're not testing for any specific uops here, just
         # testing it doesn't crash.

Python/bytecodes.c

@@ -2668,7 +2668,7 @@ dummy_func(
             _GUARD_TYPE_VERSION +
             _STORE_ATTR_WITH_HINT;
 
-        op(_STORE_ATTR_SLOT, (index/1, value, owner --)) {
+        op(_STORE_ATTR_SLOT, (index/1, value, owner -- o)) {
             PyObject *owner_o = PyStackRef_AsPyObjectBorrow(owner);
 
             DEOPT_IF(!LOCK_OBJECT(owner_o));
@@ -2677,14 +2677,16 @@ dummy_func(
             PyObject *old_value = *(PyObject **)addr;
             FT_ATOMIC_STORE_PTR_RELEASE(*(PyObject **)addr, PyStackRef_AsPyObjectSteal(value));
             UNLOCK_OBJECT(owner_o);
-            PyStackRef_CLOSE(owner);
+            INPUTS_DEAD();
+            o = owner;
             Py_XDECREF(old_value);
         }
 
         macro(STORE_ATTR_SLOT) =
             unused/1 +
             _GUARD_TYPE_VERSION +
-            _STORE_ATTR_SLOT;
+            _STORE_ATTR_SLOT +
+            POP_TOP;
 
         family(COMPARE_OP, INLINE_CACHE_ENTRIES_COMPARE_OP) = {
             COMPARE_OP_FLOAT,