Add benchmarks for tuple split

Author: Antoine Brunner

bench-run/inputs/split.in

@@ -0,0 +1 @@
+size:0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50

bench-run/src/main/scala/tuples/Split.scala

@@ -0,0 +1,34 @@
+package dotty.tools.benchmarks.tuples
+
+import org.openjdk.jmh.annotations._
+import scala.runtime.DynamicTuple
+
+@State(Scope.Thread)
+class Split {
+  @Param(Array("0"))
+  var size: Int = _
+  var tuple: Tuple = _
+  var array: Array[Object] = _
+  var half: Int = _
+
+  @Setup
+  def setup(): Unit = {
+    tuple = ()
+    half = size / 2
+
+    for (i <- 1 to size)
+      tuple = "elem" *: tuple
+
+    array = new Array[Object](size)
+  }
+
+  @Benchmark
+  def tupleSplit(): (Tuple, Tuple) = {
+    DynamicTuple.dynamicSplitAt(tuple, half)
+  }
+
+  @Benchmark
+  def arraySplit(): (Array[Object], Array[Object]) = {
+    array.splitAt(half)
+  }
+}