Quick and dirty benchmark of different approaches to Range specialization

Ranged.scala

package test

class Super[+A] {
  def foreach[U](f: A => U): Unit = ???
}

final class Ranged(i0: Int, iN: Int) extends Super[Int] {
  override def foreach[@specialized(Unit) U](f: Int => U) {
    var i = i0
    while (i < iN) {
      f(i)
      i += 1
    }
  }
}

final class Runged(i0: Int, iN: Int) extends Super[Int] {
  def foreachIntUnit(f: Int => Unit) {
    var i = 0
    while (i < iN) {
      f(i)
      i += 1
    }
  }
  override def foreach[U](f: Int => U) {
    if (f.isInstanceOf[scala.runtime.AbstractFunction1$mcVI$sp]) foreachIntUnit(f.asInstanceOf[Int => Unit])
    else {
      var i = 0
      while (i < iN) {
        f(i)
        i += 1
      }
    }
  }
}

object Bench {
  def main(args: Array[String]) {
    val th = new ichi.bench.Thyme
    println("Ignore a few of these, I didn't warm everything up")
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ var s = 0; var i = 1; while (i <= 1000) { s += i*i; i += 1 }; s }
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ var s = 0; var i = 1; while (i <= 1000) { s += i*i; i += 1 }; s }
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ var s = 0; var i = 1; while (i <= 1000) { s += i*i; i += 1 }; s }
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ var s = 0; var i = 1; while (i <= 1000) { s += i*i; i += 1 }; s }
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ var s = 0; var i = 1; while (i <= 1000) { s += i*i; i += 1 }; s }
    println
    println("Okay, now maybe the quick and dirty tests will mean something.")
    println("While loop")
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ var s = 0; var i = 1; while (i <= 1000) { s += i*i; i += 1 }; s }
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ var s = 0; var i = 1; while (i <= 1000) { s += i*i; i += 1 }; s }
    println
    println("Ranged")
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ val r = new test.Ranged(1, 1001); var s = 0; r.foreach(i => s += i*i); s }
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ val r = new test.Ranged(1, 1001); var s = 0; r.foreach(i => s += i*i); s }
    println
    println("Runged")
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ val r = new test.Runged(1, 1001); var s = 0; r.foreach(i => s += i*i); s }
    th.pbenchOff(){ var s = 0; for (i <- 1 to 1000) s += i*i; s }{ val r = new test.Runged(1, 1001); var s = 0; r.foreach(i => s += i*i); s }
    println
    var s = 0
    val f: (Int => Unit) = i => { s += i*i }
    val f2:(Int => Int)  = i => { s += i*i; i }
    println
    println("Ranged f")
    th.pbenchOff(){ s = 0; (1 to 1000).foreach(f); s }{ val r = new test.Ranged(1, 1001); s = 0; r.foreach(f); s }
    th.pbenchOff(){ s = 0; (1 to 1000).foreach(f); s }{ val r = new test.Ranged(1, 1001); s = 0; r.foreach(f); s }
    println
    println("Runged f")
    th.pbenchOff(){ s = 0; (1 to 1000).foreach(f); s }{ val r = new test.Runged(1, 1001); s = 0; r.foreach(f); s }
    th.pbenchOff(){ s = 0; (1 to 1000).foreach(f); s }{ val r = new test.Runged(1, 1001); s = 0; r.foreach(f); s }
  }
}

result.txt

Ignore a few of these, I didn't warm everything up
Benchmark comparison (in 1.251 s)
Significantly different (p ~= 0)
  Time ratio:    0.56578   95% CI 0.55955 - 0.57201   (n=30)
    First     566.8 ns   95% CI 563.8 ns - 569.9 ns
    Second    320.7 ns   95% CI 317.6 ns - 323.8 ns
  Individual benchmarks not fully consistent with head-to-head (p ~= 0)
    First     560.9 ns   95% CI 560.5 ns - 561.3 ns
    Second    347.3 ns   95% CI 347.1 ns - 347.5 ns
Benchmark comparison (in 558.1 ms)
Significantly different (p ~= 0)
  Time ratio:    0.50093   95% CI 0.47807 - 0.52379   (n=20)
    First     554.4 ns   95% CI 543.1 ns - 565.7 ns
    Second    277.7 ns   95% CI 266.4 ns - 289.1 ns
  Individual benchmarks not fully consistent with head-to-head (p ~= 0)
    First     312.5 ns   95% CI 311.1 ns - 314.0 ns
    Second    304.7 ns   95% CI 304.5 ns - 304.9 ns
Benchmark comparison (in 473.1 ms)
Significantly different (p ~= 0.0020)
  Time ratio:    0.97379   95% CI 0.95812 - 0.98946   (n=20)
    First     317.6 ns   95% CI 314.1 ns - 321.2 ns
    Second    309.3 ns   95% CI 305.7 ns - 312.9 ns
Benchmark comparison (in 474.9 ms)
Significantly different (p ~= 8.825e-08)
  Time ratio:    0.96410   95% CI 0.95334 - 0.97486   (n=20)
    First     319.2 ns   95% CI 316.8 ns - 321.7 ns
    Second    307.8 ns   95% CI 305.3 ns - 310.2 ns
Benchmark comparison (in 475.6 ms)
Significantly different (p ~= 1.878e-05)
  Time ratio:    0.96636   95% CI 0.95276 - 0.97997   (n=20)
    First     319.4 ns   95% CI 316.3 ns - 322.6 ns
    Second    308.7 ns   95% CI 305.6 ns - 311.8 ns

Okay, now maybe the quick and dirty tests will mean something.
While loop
Benchmark comparison (in 472.2 ms)
Significantly different (p ~= 1.992e-07)
  Time ratio:    0.96530   95% CI 0.95447 - 0.97613   (n=20)
    First     318.7 ns   95% CI 316.2 ns - 321.2 ns
    Second    307.6 ns   95% CI 305.1 ns - 310.1 ns
Benchmark comparison (in 473.1 ms)
Significantly different (p ~= 5.946e-07)
  Time ratio:    0.96623   95% CI 0.95507 - 0.97738   (n=20)
    First     318.2 ns   95% CI 315.7 ns - 320.8 ns
    Second    307.5 ns   95% CI 304.9 ns - 310.0 ns

Ranged
Benchmark comparison (in 475.0 ms)
Significantly different (p ~= 3.270e-05)
  Time ratio:    0.95943   95% CI 0.94245 - 0.97640   (n=20)
    First     320.8 ns   95% CI 316.9 ns - 324.7 ns
    Second    307.8 ns   95% CI 303.9 ns - 311.7 ns
Benchmark comparison (in 473.6 ms)
Significantly different (p ~= 2.054e-06)
  Time ratio:    0.95900   95% CI 0.94455 - 0.97344   (n=20)
    First     319.8 ns   95% CI 316.5 ns - 323.2 ns
    Second    306.7 ns   95% CI 303.4 ns - 310.1 ns

Runged
Benchmark comparison (in 475.1 ms)
Significantly different (p ~= 2.171e-08)
  Time ratio:    0.96164   95% CI 0.95089 - 0.97239   (n=20)
    First     318.7 ns   95% CI 316.3 ns - 321.2 ns
    Second    306.5 ns   95% CI 304.0 ns - 309.0 ns
Benchmark comparison (in 480.0 ms)
Significantly different (p ~= 7.151e-05)
  Time ratio:    0.96200   95% CI 0.94518 - 0.97883   (n=20)
    First     320.0 ns   95% CI 316.1 ns - 323.9 ns
    Second    307.9 ns   95% CI 304.0 ns - 311.7 ns


Ranged f
Benchmark comparison (in 493.2 ms)
Not significantly different (p ~= 0.3170)
  Time ratio:    1.00557   95% CI 0.99450 - 1.01664   (n=20)
    First     322.0 ns   95% CI 319.5 ns - 324.5 ns
    Second    323.8 ns   95% CI 321.3 ns - 326.3 ns
Benchmark comparison (in 494.8 ms)
Not significantly different (p ~= 0.4968)
  Time ratio:    1.00470   95% CI 0.99089 - 1.01852   (n=20)
    First     323.4 ns   95% CI 320.3 ns - 326.6 ns
    Second    324.9 ns   95% CI 321.8 ns - 328.1 ns

Runged f
Benchmark comparison (in 501.8 ms)
Not significantly different (p ~= 0.3357)
  Time ratio:    1.00642   95% CI 0.99314 - 1.01971   (n=20)
    First     323.2 ns   95% CI 320.2 ns - 326.2 ns
    Second    325.3 ns   95% CI 322.2 ns - 328.3 ns
Benchmark comparison (in 498.4 ms)
Not significantly different (p ~= 0.2173)
  Time ratio:    1.00677   95% CI 0.99588 - 1.01766   (n=20)
    First     321.8 ns   95% CI 319.4 ns - 324.3 ns
    Second    324.0 ns   95% CI 321.5 ns - 326.5 ns