From 3bc839c00ee03491a7bf8c74923198779a8cc2bb Mon Sep 17 00:00:00 2001
From: jnthn <jnthn@jnthn.net>
Date: Sun, 2 Oct 2011 02:09:01 +0200
Subject: [PATCH] Make the shiftpush op a bunch more efficient when handling
 more than a single element. We still call it with 1 far, far too often, but
 this helps for the other cases. for 1..100000 { } gets 3 times faster with
 this patch, for example.

---
 src/ops/perl6.ops | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/ops/perl6.ops b/src/ops/perl6.ops
index 3d2c3ad929a..e917a2bf5b4 100644
--- a/src/ops/perl6.ops
+++ b/src/ops/perl6.ops
@@ -1064,21 +1064,18 @@ simply discarded.
 inline op perl6_shiftpush(inout PMC, in PMC, in INT) :base_core {
     INTVAL count = $3;
     INTVAL elems = VTABLE_elements(interp, $2);
-
     if (count > elems) count = elems;
 
     if (!PMC_IS_NULL($1)) {
+        INTVAL pos = 0;
         while (count > 0) {
-            VTABLE_push_pmc(interp, $1, VTABLE_shift_pmc(interp, $2));
-            count--;
-        }
-    }
-    else {
-        while (count > 0) {
-            VTABLE_shift_pmc(interp, $2);
+            VTABLE_push_pmc(interp, $1, VTABLE_get_pmc_keyed_int(interp, $2, pos));
             count--;
+            pos++;
         }
     }
+    if ($3 > 0)
+        VTABLE_splice(interp, $2, pmc_new(interp, enum_class_ResizablePMCArray), 0, $3);
 }