commit 13527123a100f4cd8620473ae8da4cb727279866
author Raymond Hettinger <python@rcn.com> Fri Nov 11 04:31:18 2016 -0800
committer Raymond Hettinger <python@rcn.com> Fri Nov 11 04:31:18 2016 -0800
tree 25c4dcc5d4021a43ac4b257b1e7ff8059f2f1137
parent a27c064428c9e3b601be69876ef7e7299a3e0b7f

Issue #28665: Harmonize STORE_DEREF with STORE_FAST and LOAD_DEREF giving a 40% speedup.

Python/ceval.c

diff --git a/Python/ceval.c b/Python/ceval.c
index b2c90cc..6bdc998 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2462,8 +2462,9 @@
         TARGET(STORE_DEREF) {
             PyObject *v = POP();
             PyObject *cell = freevars[oparg];
-            PyCell_Set(cell, v);
-            Py_DECREF(v);
+            PyObject *oldobj = PyCell_GET(cell);
+            PyCell_SET(cell, v);
+            Py_XDECREF(oldobj);
             DISPATCH();
         }