gh-134584: Eliminate redundant refcounting from _LOAD_ATTR_WITH_HINT

Lib/test/test_capi/test_opt.py

@@ -2512,6 +2512,27 @@ class C():
         self.assertNotIn("_POP_TOP", uops)
         self.assertIn("_POP_TOP_NOP", uops)
 
+    def test_load_attr_with_hint(self):
+        def testfunc(n):
+            class C:
+                pass
+            c = C()
+            c.x = 42
+            for i in range(_testinternalcapi.SHARED_KEYS_MAX_SIZE - 1):
+                setattr(c, f"_{i}", None)
+            x = 0
+            for i in range(n):
+                x += c.x
+            return x
+        res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+        self.assertEqual(res, 42 * TIER2_THRESHOLD)
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+
+        self.assertIn("_LOAD_ATTR_WITH_HINT", uops)
+        self.assertNotIn("_POP_TOP", uops)
+        self.assertIn("_POP_TOP_NOP", uops)
+
     def test_int_add_op_refcount_elimination(self):
         def testfunc(n):
             c = 1

Python/bytecodes.c

@@ -2416,7 +2416,7 @@ dummy_func(
             unused/5 +
             _PUSH_NULL_CONDITIONAL;
 
-        op(_LOAD_ATTR_WITH_HINT, (hint/1, owner -- attr)) {
+        op(_LOAD_ATTR_WITH_HINT, (hint/1, owner -- attr, o)) {
             PyObject *owner_o = PyStackRef_AsPyObjectBorrow(owner);
             assert(Py_TYPE(owner_o)->tp_flags & Py_TPFLAGS_MANAGED_DICT);
             PyDictObject *dict = _PyObject_GetManagedDict(owner_o);
@@ -2452,13 +2452,15 @@ dummy_func(
 #else
             attr = PyStackRef_FromPyObjectNew(attr_o);
 #endif
-            PyStackRef_CLOSE(owner);
+            o = owner;
+            DEAD(owner);
         }
 
         macro(LOAD_ATTR_WITH_HINT) =
             unused/1 +
             _GUARD_TYPE_VERSION +
             _LOAD_ATTR_WITH_HINT +
+            POP_TOP +
             unused/5 +
             _PUSH_NULL_CONDITIONAL;
 

Python/optimizer_bytecodes.c

@@ -634,9 +634,10 @@ dummy_func(void) {
         }
     }
 
-    op(_LOAD_ATTR_WITH_HINT, (hint/1, owner -- attr)) {
+    op(_LOAD_ATTR_WITH_HINT, (hint/1, owner -- attr, o)) {
         attr = sym_new_not_null(ctx);
         (void)hint;
+        o = owner;
     }
 
     op(_LOAD_ATTR_SLOT, (index/1, owner -- attr)) {