commit b46ad5431d2643f61e929c1ffec48766b2fafd75
author Raymond Hettinger <rhettinger@users.noreply.github.com> Fri Sep 21 01:46:41 2018 -0700
committer GitHub <noreply@github.com> Fri Sep 21 01:46:41 2018 -0700
tree d82d6b7498df61a8f86afdb38f5396c826b7c4a3
parent fb3e9c00ed79f4d880ab9a67aab861eb3660ec75

Minor performance tweak for deque.index() with a start argument (GH-9440)

Modules/_collectionsmodule.c

diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 935b434..267cf07 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -1050,8 +1050,10 @@
         start = stop;
     assert(0 <= start && start <= stop && stop <= Py_SIZE(deque));
 
-    /* XXX Replace this loop with faster code from deque_item() */
-    for (i=0 ; i<start ; i++) {
+    for (i=0 ; i < start - BLOCKLEN ; i += BLOCKLEN) {
+        b = b->rightlink;
+    }
+    for ( ; i < start ; i++) {
         index++;
         if (index == BLOCKLEN) {
             b = b->rightlink;