GH-134584: Remove redundant refcount from _STORE_ATTR_SLOT

Lib/test/test_capi/test_opt.py

@@ -2612,7 +2612,25 @@ def testfunc(n):
  self.assertNotIn("_POP_TOP_INT", uops)
  self.assertIn("_POP_TOP_NOP", uops)
 
- def test_store_susbscr_dict(self):
+ 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_NOP", uops)
+
+ def test_store_subscr_dict(self):
  def testfunc(n):
  d = {}
  for _ in range(n):

Python/bytecodes.c

@@ -2640,7 +2640,7 @@ 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));
@@ -2649,14 +2649,16 @@ 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,

Python/optimizer_bytecodes.c

@@ -114,6 +114,12 @@ dummy_func(void) {
  ss = sub_st;
  }
 
+ op(_STORE_ATTR_SLOT, (index/1, value, owner -- o)) {
+ (void)index;
+ (void)value;
+ o = owner;
+ }
+
  op(_STORE_SUBSCR_DICT, (value, dict_st, sub -- st)) {
  (void)value;
  st = dict_st;