From e4495877dd08b4d0568bb8a75ae5c69b3d91ff60 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Tue, 15 Dec 2015 00:42:30 -0800
Subject: Minor tweek.  Counting down rather than up reduces register pressure.

---
 Objects/setobject.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Objects/setobject.c b/Objects/setobject.c
index 4723b58..45aa200 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -678,7 +678,7 @@ set_merge(PySetObject *so, PyObject *otherset)
         size_t newmask = (size_t)so->mask;
         so->fill = other->used;
         so->used = other->used;
-        for (i = 0; i <= other->mask; i++, other_entry++) {
+        for (i = other->mask + 1; i > 0 ; i--, other_entry++) {
             key = other_entry->key;
             if (key != NULL && key != dummy) {
                 Py_INCREF(key);
-- 
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