Can Record class be used to create RegInit?

I am trying to use Record class to generate RegInit. This can help to dynamically create RegInit with other information in Module.

I am trying to use Record class to generate RegInit. Here are my codes.

  class MyReg(reg_info: List[(String, UInt)]) extends Record {
    override def elements: ListMap[String, UInt] = ListMap(
      reg_info.map(
        x =>
          x._1 -> x._2
      ):_*
    )

    override def cloneType: MyReg.this.type = new MyReg(reg_info).asInstanceOf[this.type]
  }

class reg_test(reg_list: List[(String, String, List[(String, Int)])]) extends Module with RegSugar {
  val io = IO(new Bundle() {
    val a = Input(UInt(16.W))
    val b = Input(UInt(16.W))
    val d = Output(UInt(16.W))
    val e = Output(UInt(16.W))
  })

  val myBundle = new Bundle() {
    val a = UInt(16.W)
    val b = UInt(16.W)
  }
  val reg_init_bundle = RegInit(myBundle, 0.U.asTypeOf(myBundle))
  println(reg_init_bundle)
  reg_init_bundle.a := io.a
  reg_init_bundle.b := io.b

  val list_b = List(("a", UInt(16.W)), ("b", UInt(16.W)))
  val myRecord = new MyReg(list_b)

  val reg_init = RegInit(myRecord, 0.U.asTypeOf(myRecord))
  reg_init.elements("a") := io.a
  reg_init.elements("b") := io.b

  io.d := reg_init.elements("a") + reg_init.elements("b")
  io.e := reg_init_bundle.a + reg_init_bundle.b
}

In my sight, Bundle extends Record and if these code work on Bundle, they should also work on Record. However, the error is reported on the line:

val reg_init = RegInit(myRecord, 0.U.asTypeOf(myRecord))

Exception in thread "main" chisel3.package$RebindingException: Attempted reassignment of binding to reg_test.reg_init_?.a: Wire[UInt<16>], from: ChildBinding(reg_test.reg_init_?: Reg[MyReg])
    at ... ()
    at implicit_test.reg_test.$anonfun$reg_init$2(reg_test.scala:61)
    at chisel3.internal.prefix$.apply(prefix.scala:48)
    at implicit_test.reg_test.$anonfun$reg_init$1(reg_test.scala:61)
    at chisel3.internal.plugin.package$.autoNameRecursively(package.scala:33)
    at implicit_test.reg_test.<init>(reg_test.scala:61)
    at implicit_test.reg_test$.$anonfun$verilogString$1(reg_test.scala:77)
    at ... ()
    at ... (Stack trace trimmed to user code only. Rerun with --full-stacktrace to see the full stack trace)

It seems that these codes can successfully generate RegInit with Bundle but failed to generate RegInit with Record. Is that a way to generate RegInit with Record? or there is a compiler error?

Can you try changing your MyReg definition to

class MyReg(reg_info: List[(String, UInt)]) extends Record {
  override val elements: ListMap[String, UInt] = ListMap(
    reg_info.map(
      x =>
        x._1 -> x._2.cloneType
    ):_*
  )
}

I believe this might fix your problem. Cloning x._2 makes sure you don't end up with multiple instances pointing to the same Data instance. Changing the def elements to val elements prevents chisel from complaining that multiple calls to elements returns the same thing.