From 2282c1bc60a9b37ca8b7fcf843a62413e328e324 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sun, 7 Jan 2018 01:51:02 -0800
Subject: tail: reduce calls to cdr.

* lib.c (tail): Don't call cdr on the same cell twice in the
loop body. tail is used in list_collect and friends, which are
used all over the place.
---
 lib.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib.c b/lib.c
index 48bf1807..a318aecc 100644
--- a/lib.c
+++ b/lib.c
@@ -655,8 +655,9 @@ val listref(val list, val ind)
 
 loc tail(val cons)
 {
-  while (consp(cdr(cons)))
-    cons = cdr(cons);
+  val d;
+  for (d = cdr(cons); consp(d); d = cdr(d))
+    cons = d;
   return cdr_l(cons);
 }
 
-- 
cgit v1.2.3