Optimize slice reverse (#5401)

larubujo · RX14 · commit c74c0bd7615d · 2017-12-18T22:38:25.000Z
diff --git a/src/slice.cr b/src/slice.cr
@@ -212,13 +212,17 @@ struct Slice(T)
   def reverse!
     check_writable
 
-    i = 0
-    j = size - 1
-    while i < j
-      @pointer.swap i, j
-      i += 1
-      j -= 1
+    return self if size <= 1
+
+    p = @pointer
+    q = @pointer + size - 1
+
+    while p < q
+      p.value, q.value = q.value, p.value
+      p += 1
+      q -= 1
     end
+
     self
   end
 
