Use _PyObject_GET_BASIC_WEAKREFS_LISTPTR() in performance-sensitive locations.

Author: ericsnowcurrently

Modules/gcmodule.c

@@ -794,9 +794,12 @@ handle_weakrefs(PyGC_Head *unreachable, PyGC_Head *old)
         if (! _PyType_SUPPORTS_WEAKREFS(Py_TYPE(op)))
             continue;
 
-        /* It supports weakrefs.  Does it have any? */
-        wrlist = (PyWeakReference **)
-                                _PyObject_GET_WEAKREFS_LISTPTR(op);
+        /* It supports weakrefs.  Does it have any?
+         *
+         * This is never triggered for static types so we can avoid the
+         * (slightly) more costly _PyObject_GET_WEAKREFS_LISTPTR().
+         */
+        wrlist = (PyWeakReference **)_PyObject_GET_BASIC_WEAKREFS_LISTPTR(op);
 
         /* `op` may have some weakrefs.  March over the list, clear
          * all the weakrefs, and move the weakrefs with callbacks

Objects/typeobject.c

@@ -1507,7 +1507,10 @@ subtype_dealloc(PyObject *self)
            finalizers since they might rely on part of the object
            being finalized that has already been destroyed. */
         if (type->tp_weaklistoffset && !base->tp_weaklistoffset) {
-            /* Modeled after GET_WEAKREFS_LISTPTR() */
+            /* Modeled after GET_WEAKREFS_LISTPTR().
+
+               This is never triggered for static types so we can avoid the
+               (slightly) more costly _PyObject_GET_WEAKREFS_LISTPTR(). */
             PyWeakReference **list = (PyWeakReference **) \
                 _PyObject_GET_BASIC_WEAKREFS_LISTPTR(self);
             while (*list)