changeset:   105056:d78d45436753
branch:      3.6
parent:      105053:1a88baaed7a0
user:        Raymond Hettinger <python@rcn.com>
date:        Fri Nov 11 04:31:18 2016 -0800
files:       Misc/NEWS Python/ceval.c
description:
Issue #28665: Harmonize STORE_DEREF with STORE_FAST and LOAD_DEREF giving a 40% speedup.


diff -r 1a88baaed7a0 -r d78d45436753 Misc/NEWS
--- a/Misc/NEWS	Fri Nov 11 12:06:38 2016 +0200
+++ b/Misc/NEWS	Fri Nov 11 04:31:18 2016 -0800
@@ -13,6 +13,8 @@
 - Issue #19398: Extra slash no longer added to sys.path components in case of
   empty compile-time PYTHONPATH components.
 
+- Issue #28665:  Improve speed of the STORE_DEREF opcode by 40%.
+
 - Issue #28583: PyDict_SetDefault didn't combine split table when needed.
   Patch by Xiang Zhang.
 
diff -r 1a88baaed7a0 -r d78d45436753 Python/ceval.c
--- a/Python/ceval.c	Fri Nov 11 12:06:38 2016 +0200
+++ b/Python/ceval.c	Fri Nov 11 04:31:18 2016 -0800
@@ -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();
         }