由于ChiselTest库不兼容，运行sbt test时遇到java.lang.NoClassDefFoundError: treadlestageTreadleTesterPhase$问题

由于ChiselTest库不兼容，运行sbt test时遇到java.lang.NoClassDefFoundError: treadle/stage/TreadleTesterPhase$问题 问题概况 1. error 输出

运行GCD电路的测试，遇到java.lang.NoClassDefFoundError问题：

[info] TestRealGCD *** ABORTED ***
[info]   java.lang.NoClassDefFoundError: treadle/stage/TreadleTesterPhase$
[info]   at chiseltest.backends.treadle.TreadleExecutive$.start(TreadleExecutive.scala:47)
[info]   at chiseltest.defaults.package$.createDefaultTester(defaults.scala:24)
[info]   at chiseltest.ChiselScalatestTester$TestBuilder.apply(ChiselScalatestTester.scala:30)
[info]   at TestRealGCD.$anonfun$new(test.scala:43)
[info]   at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   at org.scalatest.Transformer.apply(Transformer.scala:22)
[info]   at org.scalatest.Transformer.apply(Transformer.scala:20)
[info]   ...
[info]   Cause: java.lang.ClassNotFoundException: treadle.stage.TreadleTesterPhase$
[info]   at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
[info]   at sbt.internal.ManagedClassLoader.findClass(ManagedClassLoader.java:102)
[info]   at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
[info]   at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
[info]   at chiseltest.backends.treadle.TreadleExecutive$.start(TreadleExecutive.scala:47)
[info]   at chiseltest.defaults.package$.createDefaultTester(defaults.scala:24)
[info]   at chiseltest.ChiselScalatestTester$TestBuilder.apply(ChiselScalatestTester.scala:30)
[info]   at TestRealGCD.$anonfun$new(test.scala:43)
[info]   at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   ...
[error] Test suite TestRealGCD failed with java.lang.NoClassDefFoundError: treadle/stage/TreadleTesterPhase$.
[error] This may be due to the ClassLoaderLayeringStrategy (ScalaLibrary) used by your task.
[error] To improve performance and reduce memory, sbt attempts to cache the class loaders used to load the project dependencies.
[error] The project class files are loaded in a separate class loader that is created for each test run.
[error] The test class loader accesses the project dependency classes using the cached project dependency classloader.
[error] With this approach, class loading may fail under the following conditions:
[error] 
[error]  * Dependencies use reflection to access classes in your project's classpath.
[error]    Java serialization/deserialization may cause this.
[error]  * An open package is accessed across layers. If the project's classes access or extend
[error]    jvm package private classes defined in a project dependency, it may cause an IllegalAccessError
[error]    because the jvm enforces package private at the classloader level.
[error] 
[error] These issues, along with others that were not enumerated above, may be resolved by changing the class loader layering strategy.
[error] The Flat and ScalaLibrary strategies bundle the full project classpath in the same class loader.
[error] To use one of these strategies, set the  ClassLoaderLayeringStrategy ke
[error] in your configuration, for example:
[error] 
[error] set testrealgcd / Test / classLoaderLayeringStrategy := ClassLoaderLayeringStrategy.ScalaLibrary
[error] set testrealgcd / Test / classLoaderLayeringStrategy := ClassLoaderLayeringStrategy.Flat
[error] 
[error] See ClassLoaderLayeringStrategy.scala for the full list of options.

2. 测试代码

import org.scalatest._
import chiseltest._
import chisel3._
import chisel3.experimental.BundleLiterals._
import java.util.regex.Matcher

class TestRealGCD extends FlatSpec with ChiselScalatestTester with Matchers {
  behavior of "RealGCD"
    it should "calculate proper greatest common denominator" in {
      test(new DecoupledGcd(16)) { dut =>
        dut.input.initSource().setSourceClock(dut.clock)
        dut.output.initSink().setSinkClock(dut.clock)

        val testValues = for { x <- 1 to 4; y <- 1 to 4} yield (x, y)
        val inputSeq = testValues.map { case (x, y) =>
          (new GcdInputBundle(16)).Lit(_.value1 -> x.U, _.value2 -> y.U)
        }
        val resultSeq = testValues.map { case (x, y) =>
          new GcdOutputBundle(16).Lit(_.value1 -> x.U, _.value2 -> y.U, _.gcd -> BigInt(x).gcd(BigInt(y)).U)
        }

        fork {
          dut.input.enqueueSeq(inputSeq)
        }.fork {
          for (expected <- resultSeq) {
            dut.output.expectDequeue(expected)
            dut.clock.step(5) // wait some cycles before receiving the next output to create backpressure
          }
        }.join()
      }
    }
}

3. chisel硬件描述代码

class GcdInputBundle(val w: Int) extends Bundle {
  val value1 = UInt(w.W)
  val value2 = UInt(w.W)
}

class GcdOutputBundle(val w: Int) extends Bundle {
  val value1 = UInt(w.W)
  val value2 = UInt(w.W)
  val gcd    = UInt(w.W)
}

class DecoupledGcd(width: Int) extends MultiIOModule {

  val input = IO(Flipped(Decoupled(new GcdInputBundle(width))))
  val output = IO(Decoupled(new GcdOutputBundle(width)))

  val xInitial    = Reg(UInt())
  val yInitial    = Reg(UInt())
  val x           = Reg(UInt())
  val y           = Reg(UInt())
  val busy        = RegInit(false.B)
  val resultValid = RegInit(false.B)

  input.ready := ! busy
  output.valid := resultValid
  // 可一直使用其赋值而不需要等到计算完毕，因为计算完毕声明output.valid后才会发生传输，且传输之前x会保持。  
  output.bits.value1 := xInitial
  output.bits.value2 := yInitial
  output.bits.gcd := x

  when(busy)  {
    // during computation keep subtracting the smaller from the larger
    when(x > y) {
      x := x - y
    }.otherwise {
      y := y - x
    }
    when(y === 0.U) {
      // when y becomes zero computation is over,
      // signal valid data to output
      // data transfer if the output is ready SO non-asserted busy signal
      resultValid := true.B
      busy := ! output.ready
    }
  }.otherwise {
    when(input.valid) {
      // valid data available and no computation in progress, grab new values and start
      val bundle = input.deq()
      x := bundle.value1
      y := bundle.value2
      xInitial := bundle.value1
      yInitial := bundle.value2
      busy := true.B
      resultValid := false.B
    }
  }
}

4. build.sbt

scalaVersion := "2.12.13"

scalacOptions ++= Seq(
  "-deprecation",
  "-feature",
  "-unchecked",
  "-Xfatal-warnings",
  "-Xsource:2.11",
  "-language:reflectiveCalls",
  // Enables autoclonetype2
  "-P:chiselplugin:useBundlePlugin"
)

resolvers ++= Seq(
  Resolver.sonatypeRepo("snapshots"),
  Resolver.sonatypeRepo("releases")
)

// Chisel 3.4
addCompilerPlugin("edu.berkeley.cs" % "chisel3-plugin" % "3.4.3" cross CrossVersion.full)
libraryDependencies += "edu.berkeley.cs" %% "chisel-iotesters" % "1.5.3"
libraryDependencies += "edu.berkeley.cs" %% "chiseltest" % "0.2.1"
libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.5" % "test"

解决方法

• 将build.sbt文件中的库依赖libraryDependencies += "edu.berkeley.cs" %% "chiseltest" % "0.2.1"
  改成libraryDependencies += "edu.berkeley.cs" %% "chiseltest" % "0.3.3" % "test"

  在ChiselTest官网Chisel/FIRRTL: ChiselTest (chisel-lang.org)给出的示例是libraryDependencies += "edu.berkeley.cs" %% "chiseltest" % "0.2.1" 但可能因为久未更新。最终是参考chisel-template给出的项目模板做出的修改才解决：
  chisel-template: A template project for beginning new Chisel work 同时应该参考其中使用org.scalatest.FreeSpec而不是FlatSpec可以减少更多的 boiler plate

• 猜测原因：chiseltest 0.2.与scalaTest版本间的二进制不兼容问题

• 参考：
  chisel3/MultiIOModule not found whe running tests with Chisel 3.5-SNAPSHOT
  Latest merge with experimental fails · Issue #996 · chipsalliance/chisel3