Add boxing benchmark for report

Author: timotheeandres

bench-micro/src/main/scala/dotty/tools/benchmarks/inlinetraits/Boxing.scala

@@ -0,0 +1,27 @@
+package dotty.tools.benchmarks.inlinetraits
+
+import org.openjdk.jmh.annotations._
+import java.util.concurrent.TimeUnit.{SECONDS, MILLISECONDS}
+import scala.util.Random
+
+// @BenchmarkMode(Array(Mode.SampleTime))
+@Fork(3)
+@Threads(3)
+@Warmup(iterations = 5, time = 10, timeUnit = SECONDS)
+@Measurement(iterations = 10, time = 10, timeUnit = SECONDS)
+// @OutputTimeUnit(MILLISECONDS)
+@State(Scope.Benchmark)
+class Boxing {
+  class Wrapper[T](val x: T)
+  class IntWrapper(val x: Int)
+
+  val numbers = 1 to 1000000
+  val ws = numbers.map(Wrapper(_))
+  val iws = numbers.map(IntWrapper(_))
+
+  @Benchmark
+  def noUnboxing: Int = iws.map(w => IntWrapper(w.x*w.x + 2*w.x)).foldLeft(0)(_ + _.x)
+
+  @Benchmark
+  def withUnboxing: Int = ws.map(w => Wrapper(w.x*w.x + 2*w.x)).foldLeft(0)(_ + _.x)
+}