From 306d6b1ea6bf2582b9284be2fd27275abbade3e1 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Sun, 24 Jan 2016 12:40:42 -0800
Subject: [PATCH] Convert another post-decrement while-loop to pre-decrement
 for consistency and better generated code (on both GCC and CLang).

---
 Modules/_collectionsmodule.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index cc9e4e890ed..b77ea652fbd 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -895,7 +895,8 @@ deque_reverse(dequeobject *deque, PyObject *unused)
     Py_ssize_t n = Py_SIZE(deque) >> 1;
     PyObject *tmp;
 
-    while (n-- > 0) {
+    n++;
+    while (--n) {
         /* Validate that pointers haven't met in the middle */
         assert(leftblock != rightblock || leftindex < rightindex);
         CHECK_NOT_END(leftblock);