bpo-42161: Micro-optimize _collections._count_elements() (GH-23008)

Move the _PyLong_GetOne() call outside the fast-path loop.

Author: vstinner

Modules/_collectionsmodule.c

@@ -2278,6 +2278,7 @@ _collections__count_elements_impl(PyObject *module, PyObject *mapping,
     PyObject *dict_get;
     PyObject *mapping_setitem;
     PyObject *dict_setitem;
+    PyObject *one = _PyLong_GetOne();  // borrowed reference
 
     it = PyObject_GetIter(iterable);
     if (it == NULL)
@@ -2324,10 +2325,10 @@ _collections__count_elements_impl(PyObject *module, PyObject *mapping,
             if (oldval == NULL) {
                 if (PyErr_Occurred())
                     goto done;
-                if (_PyDict_SetItem_KnownHash(mapping, key, _PyLong_GetOne(), hash) < 0)
+                if (_PyDict_SetItem_KnownHash(mapping, key, one, hash) < 0)
                     goto done;
             } else {
-                newval = PyNumber_Add(oldval, _PyLong_GetOne());
+                newval = PyNumber_Add(oldval, one);
                 if (newval == NULL)
                     goto done;
                 if (_PyDict_SetItem_KnownHash(mapping, key, newval, hash) < 0)
@@ -2336,13 +2337,13 @@ _collections__count_elements_impl(PyObject *module, PyObject *mapping,
             }
             Py_DECREF(key);
         }
-    } else {
+    }
+    else {
         bound_get = _PyObject_GetAttrId(mapping, &PyId_get);
         if (bound_get == NULL)
             goto done;
 
         PyObject *zero = _PyLong_GetZero();  // borrowed reference
-        PyObject *one = _PyLong_GetOne();  // borrowed reference
         while (1) {
             key = PyIter_Next(it);
             if (key == NULL)