difftest: fix instances of generated Svh Interface

Previous in PR #483 we generate interface according to collected
instances by Gateway. However, these collected instances have
already been processed by Gateway and different from original.

To generated original interface, we use Instances from Jsonprofile
directly to avoid impact of Gateway optimization

src/main/scala/Difftest.scala

@@ -527,11 +527,11 @@ object DifftestModule {
     difftest
   }
 
-  def generateSvhInterface(numCores: Int): Unit = {
+  def generateSvhInterface(instances: Seq[DifftestBundle], numCores: Int): Unit = {
     // generate interface by jsonProfile, single-core interface will be copied numCore times
     val difftestSvh = ListBuffer.empty[String]
     val core_if_len = instances.length / numCores
-    val gateway_args = instances.toSeq.zipWithIndex.map { case (b, idx) =>
+    val gateway_args = instances.zipWithIndex.map { case (b, idx) =>
       val typeString = s"logic [${b.getWidth - 1}: 0]"
       val argName = s"gateway_$idx"
       (typeString, argName)

src/test/scala/DifftestTop.scala

@@ -20,6 +20,7 @@ import chisel3._
 
 import java.nio.file.{Files, Paths}
 import scala.annotation.tailrec
+import scala.collection.mutable.ListBuffer
 import org.json4s.DefaultFormats
 import org.json4s.native.JsonMethods.parse
 
@@ -64,6 +65,7 @@ class DifftestTop extends Module {
 
 // Generate simulation interface based on Profile describing the instantiated information of design
 class SimTop(profileName: String, numCores: Int) extends Module {
+  val instances = ListBuffer.empty[DifftestBundle]
   val profileStr = new String(Files.readAllBytes(Paths.get(profileName)))
   val profiles = parse(profileStr).extract[List[Map[String, Any]]](DefaultFormats, manifest[List[Map[String, Any]]])
   for (coreid <- 0 until numCores) {
@@ -77,12 +79,13 @@ class SimTop(profileName: String, numCores: Int) extends Module {
       val constructor = Class.forName(prof("className").toString).getConstructors()(0)
       val args = constructor.getParameters().toSeq.map { param => prof(param.getName.toString) }
       val inst = constructor.newInstance(args: _*).asInstanceOf[DifftestBundle]
+      instances += inst
       DifftestModule(inst, true, prof("delay").asInstanceOf[Int]).suggestName(s"gateway_${coreid}_$idx")
     }
   }
   val dutInfo = profiles.find(_.contains("cpu")).get
+  DifftestModule.generateSvhInterface(instances.toSeq, numCores)
   DifftestModule.finish(dutInfo("cpu").asInstanceOf[String])
-  DifftestModule.generateSvhInterface(numCores)
 }
 
 abstract class DifftestApp extends App {