Move treadle dependency to the tests (#1554)

Use inheritance to make TesterDriver Backend API extensible, then define
a TreadleBackend in the test project

3 files changed, 95 insertions, 2 deletions

diff --git a/src/test/scala/chisel3/testers/TestUtils.scala b/src/test/scala/chisel3/testers/TestUtils.scala
new file mode 100644
index 00000000..97cf9190
--- /dev/null
+++ b/src/test/scala/chisel3/testers/TestUtils.scala
@@ -0,0 +1,12 @@
+// See LICENSE for license details.
+
+package chisel3.testers
+
+import TesterDriver.Backend
+import firrtl.AnnotationSeq
+
+object TestUtils {
+  // Useful because TesterDriver.Backend is chisel3 package private
+  def containsBackend(annos: AnnotationSeq): Boolean =
+    annos.collectFirst { case b: Backend => b }.isDefined
+}
diff --git a/src/test/scala/chisel3/testers/TreadleBackend.scala b/src/test/scala/chisel3/testers/TreadleBackend.scala
new file mode 100644
index 00000000..e432ce35
--- /dev/null
+++ b/src/test/scala/chisel3/testers/TreadleBackend.scala
@@ -0,0 +1,77 @@
+// See LICENSE for license details.
+
+package chisel3.testers
+
+import TesterDriver.createTestDirectory
+import chisel3._
+import chisel3.stage._
+import firrtl.AnnotationSeq
+import firrtl.annotations.NoTargetAnnotation
+import firrtl.options.TargetDirAnnotation
+import treadle.stage.TreadleTesterPhase
+import treadle.executable.StopException
+import treadle.{CallResetAtStartupAnnotation, TreadleTesterAnnotation, WriteVcdAnnotation}
+
+import java.io.File
+
+case object TreadleBackend extends TesterDriver.Backend {
+  val MaxTreadleCycles = 10000L
+
+  def execute(t:                    () => BasicTester,
+              additionalVResources: Seq[String] = Seq(),
+              annotations:          AnnotationSeq = Seq(),
+              nameHint:             Option[String] = None): Boolean = {
+    val generatorAnnotation = chisel3.stage.ChiselGeneratorAnnotation(t)
+
+    // This provides an opportunity to translate from top level generic flags to backend specific annos
+    var annotationSeq = annotations :+ WriteVcdAnnotation
+
+    // This produces a chisel circuit annotation, a later pass will generate a firrtl circuit
+    // Can't do both at once currently because generating the latter deletes the former
+    annotationSeq = (new chisel3.stage.phases.Elaborate).transform(annotationSeq :+ generatorAnnotation)
+
+    val circuit = annotationSeq.collect { case x: ChiselCircuitAnnotation => x }.head.circuit
+
+    val targetName: File = createTestDirectory(circuit.name)
+
+    if (!annotationSeq.exists(_.isInstanceOf[NoTargetAnnotation])) {
+      annotationSeq = annotationSeq :+ TargetDirAnnotation(targetName.getPath)
+    }
+    if (!annotationSeq.exists { case CallResetAtStartupAnnotation => true ; case _ => false }) {
+      annotationSeq = annotationSeq :+ CallResetAtStartupAnnotation
+    }
+
+    // This generates the firrtl circuit needed by the TreadleTesterPhase
+    annotationSeq = (new ChiselStage).run(
+      annotationSeq ++ Seq(NoRunFirrtlCompilerAnnotation)
+    )
+
+    // This generates a TreadleTesterAnnotation with a treadle tester instance
+    annotationSeq = (new TreadleTesterPhase).transform(annotationSeq)
+
+    val treadleTester = annotationSeq.collectFirst { case TreadleTesterAnnotation(t) => t }.getOrElse(
+      throw new Exception(
+        s"TreadleTesterPhase could not build a treadle tester from these annotations" +
+          annotationSeq.mkString("Annotations:\n", "\n  ", "")
+      )
+    )
+
+    try {
+      var cycle = 0L
+      while (cycle < MaxTreadleCycles) {
+        cycle += 1
+        treadleTester.step()
+      }
+      throw new ChiselException(s"Treadle backend exceeded MaxTreadleCycles ($MaxTreadleCycles)")
+    } catch {
+      case _: StopException =>
+    }
+    treadleTester.finish
+
+    treadleTester.getStopResult match {
+      case None    => true
+      case Some(0) => true
+      case _       => false
+    }
+  }
+}
diff --git a/src/test/scala/chiselTests/ChiselSpec.scala b/src/test/scala/chiselTests/ChiselSpec.scala
index e50f26e8..eb3ec3e6 100644
--- a/src/test/scala/chiselTests/ChiselSpec.scala
+++ b/src/test/scala/chiselTests/ChiselSpec.scala
@@ -10,7 +10,7 @@ import chisel3._
 import chisel3.stage.{ChiselGeneratorAnnotation, ChiselStage}
 import chisel3.testers._
 import firrtl.{AnnotationSeq, CommonOptions, EmittedVerilogCircuitAnnotation, ExecutionOptionsManager, FirrtlExecutionFailure, FirrtlExecutionSuccess, HasFirrtlOptions}
-import firrtl.annotations.DeletedAnnotation
+import firrtl.annotations.{Annotation, DeletedAnnotation}
 import firrtl.util.BackendCompilationUtilities
 import java.io.ByteArrayOutputStream
 import java.security.Permission
@@ -26,7 +26,11 @@ trait ChiselRunners extends Assertions with BackendCompilationUtilities {
                 additionalVResources: Seq[String] = Seq(),
                 annotations: AnnotationSeq = Seq()
                ): Boolean = {
-    TesterDriver.execute(() => t, additionalVResources, annotations)
+    // Change this to enable Treadle as a backend
+    val defaultBackend = chisel3.testers.TesterDriver.defaultBackend
+    val hasBackend = TestUtils.containsBackend(annotations)
+    val annos: Seq[Annotation] = if (hasBackend) annotations else defaultBackend +: annotations
+    TesterDriver.execute(() => t, additionalVResources, annos)
   }
   def assertTesterPasses(t: => BasicTester,
                          additionalVResources: Seq[String] = Seq(),