Add specialization benchmarks

Author: liufengyun

bench-run/src/main/scala/dotty/tools/benchmarks/specialization/Functions.scala

@@ -0,0 +1,55 @@
+package dotty.tools.benchmarks.specialization
+
+import org.openjdk.jmh.annotations._
+import scala.util.Random
+
+class Functions {
+  extension (x: Int)
+    inline def times(op: => Unit): Unit = {
+      var count = 0
+      while count < x do
+        op
+        count += x
+    }
+
+  class ByName {
+    def foo(x: => Int): Int = x
+  }
+
+  @Benchmark
+  def byNameBench() = 10000.times {
+    val a = new ByName
+    var list = List(a)
+    list.head.foo(6) + 10
+  }
+
+  @Benchmark
+  def lambdaBench() = 10000.times {
+    val fn = (x: Int) => x + 1
+    var list = List(fn)
+    list.head(2)
+  }
+
+  class Func1[T](fn: T => Int) extends Function1[T, Int] {
+    def apply(x: T): Int = fn(x)
+  }
+  class Fn extends Func1(identity[Int])
+
+  @Benchmark
+  def extendFun1Bench() = 10000.times {
+    val a: Function1[Int, Int] = new Fn
+    var list = List(a)
+    list.head(123) + 10
+  }
+
+  class Func2 extends Function2[Int, Int, Int] {
+    def apply(i: Int, j: Int) = i + j
+  }
+
+  @Benchmark
+  def extendFun2Bench() = 10000.times {
+    val a: Function2[Int, Int, Int] = new Func2
+    var list = List(a)
+    list.head(1300, 37) + 100
+  }
+}