path: root/src/test/scala/chiselTests/CompatibilityInteroperabilitySpec.scala

// SPDX-License-Identifier: Apache-2.0

package chiselTests

import scala.collection.immutable.ListMap
import chisel3.stage.ChiselStage.emitChirrtl

// Keep Chisel._ separate from chisel3._ below
object CompatibilityComponents {
  import Chisel._
  import Chisel3Components._

  class ChiselBundle extends Bundle {
    val a = UInt(width = 32)
    val b = UInt(width = 32).flip
  }
  class ChiselRecord extends Record {
    val elements = ListMap("a" -> UInt(width = 32), "b" -> UInt(width = 32).flip)
    override def cloneType: this.type = (new ChiselRecord).asInstanceOf[this.type]
  }

  abstract class ChiselDriverModule(_io: => Record) extends Module {
    val io = _io
    io.elements("a").asUInt := UInt(123)
    assert(io.elements("b").asUInt === UInt(123))
  }
  abstract class ChiselPassthroughModule(_io: => Record) extends Module {
    val io = _io
    io.elements("b").asUInt := io.elements("a").asUInt
  }

  class ChiselBundleModuleA extends ChiselDriverModule(new ChiselBundle)
  class ChiselBundleModuleB extends ChiselPassthroughModule((new ChiselBundle).flip)
  class ChiselRecordModuleA extends ChiselDriverModule(new ChiselRecord)
  class ChiselRecordModuleB extends ChiselPassthroughModule((new ChiselRecord).flip)

  class ChiselModuleChisel3BundleA extends ChiselDriverModule(new Chisel3Bundle)
  class ChiselModuleChisel3BundleB extends ChiselPassthroughModule((new Chisel3Bundle).flip)
  class ChiselModuleChisel3RecordA extends ChiselDriverModule(new Chisel3Record)
  class ChiselModuleChisel3RecordB extends ChiselPassthroughModule((new Chisel3Record).flip)
}

object Chisel3Components {
  import chisel3._
  import CompatibilityComponents._

  class Chisel3Bundle extends Bundle {
    val a = Output(UInt(32.W))
    val b = Input(UInt(32.W))
  }

  class Chisel3Record extends Record {
    val elements = ListMap("a" -> Output(UInt(32.W)), "b" -> Input(UInt(32.W)))
    override def cloneType: this.type = (new Chisel3Record).asInstanceOf[this.type]
  }

  abstract class Chisel3DriverModule(_io: => Record) extends Module {
    val io = IO(_io)
    io.elements("a").asUInt := 123.U
    assert(io.elements("b").asUInt === 123.U)
  }
  abstract class Chisel3PassthroughModule(_io: => Record) extends Module {
    val io = IO(_io)
    io.elements("b").asUInt := io.elements("a").asUInt
  }

  class Chisel3BundleModuleA extends Chisel3DriverModule(new Chisel3Bundle)
  class Chisel3BundleModuleB extends Chisel3PassthroughModule(Flipped(new Chisel3Bundle))
  class Chisel3RecordModuleA extends Chisel3DriverModule(new Chisel3Record)
  class Chisel3RecordModuleB extends Chisel3PassthroughModule(Flipped(new Chisel3Record))

  class Chisel3ModuleChiselBundleA extends Chisel3DriverModule(new ChiselBundle)
  class Chisel3ModuleChiselBundleB extends Chisel3PassthroughModule(Flipped(new ChiselBundle))
  class Chisel3ModuleChiselRecordA extends Chisel3DriverModule(new ChiselRecord)
  class Chisel3ModuleChiselRecordB extends Chisel3PassthroughModule(Flipped(new ChiselRecord))
}

class CompatibilityInteroperabilitySpec extends ChiselFlatSpec {

  "Modules defined in the Chisel._" should "successfully bulk connect in chisel3._" in {
    import chisel3._
    import chisel3.testers.BasicTester
    import CompatibilityComponents._

    assertTesterPasses(new BasicTester {
      val a = Module(new ChiselBundleModuleA)
      val b = Module(new ChiselBundleModuleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new ChiselRecordModuleA)
      val b = Module(new ChiselRecordModuleB)
      b.io <> a.io
      stop()
    })
  }

  "Moduless defined in the chisel3._" should "successfully bulk connect in Chisel._" in {
    import Chisel._
    import chisel3.testers.BasicTester
    import Chisel3Components._

    assertTesterPasses(new BasicTester {
      val a = Module(new Chisel3BundleModuleA)
      val b = Module(new Chisel3BundleModuleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new Chisel3RecordModuleA)
      val b = Module(new Chisel3RecordModuleB)
      b.io <> a.io
      stop()
    })
  }

  "Bundles defined in Chisel._" should "work in chisel3._ Modules" in {
    import chisel3._
    import chisel3.testers.BasicTester
    import Chisel3Components._

    assertTesterPasses(new BasicTester {
      val a = Module(new Chisel3ModuleChiselBundleA)
      val b = Module(new Chisel3ModuleChiselBundleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new Chisel3ModuleChiselRecordA)
      val b = Module(new Chisel3ModuleChiselRecordB)
      b.io <> a.io
      stop()
    })
  }

  "Bundles defined in chisel3._" should "work in Chisel._ Modules" in {
    import chisel3._
    import chisel3.testers.BasicTester
    import CompatibilityComponents._

    assertTesterPasses(new BasicTester {
      val a = Module(new ChiselModuleChisel3BundleA)
      val b = Module(new ChiselModuleChisel3BundleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new ChiselModuleChisel3RecordA)
      val b = Module(new ChiselModuleChisel3RecordB)
      b.io <> a.io
      stop()
    })
  }

  "Similar Bundles defined in the chisel3._ and Chisel._" should
    "successfully bulk connect in chisel3._" in {
    import chisel3._
    import chisel3.testers.BasicTester
    import Chisel3Components._
    import CompatibilityComponents._

    assertTesterPasses(new BasicTester {
      val a = Module(new ChiselBundleModuleA)
      val b = Module(new Chisel3BundleModuleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new Chisel3BundleModuleA)
      val b = Module(new ChiselBundleModuleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new ChiselRecordModuleA)
      val b = Module(new Chisel3RecordModuleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new Chisel3RecordModuleA)
      val b = Module(new ChiselRecordModuleB)
      b.io <> a.io
      stop()
    })
  }
  they should "successfully bulk connect in Chisel._" in {
    import Chisel._
    import chisel3.testers.BasicTester
    import Chisel3Components._
    import CompatibilityComponents._

    assertTesterPasses(new BasicTester {
      val a = Module(new ChiselBundleModuleA)
      val b = Module(new Chisel3BundleModuleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new Chisel3BundleModuleA)
      val b = Module(new ChiselBundleModuleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new ChiselRecordModuleA)
      val b = Module(new Chisel3RecordModuleB)
      b.io <> a.io
      stop()
    })
    assertTesterPasses(new BasicTester {
      val a = Module(new Chisel3RecordModuleA)
      val b = Module(new ChiselRecordModuleB)
      b.io <> a.io
      stop()
    })
  }

  "An instance of a chisel3.Module inside a Chisel.Module" should "have its inputs invalidated" in {
    compile {
      import Chisel._
      new Module {
        val io = new Bundle {
          val in = UInt(INPUT, width = 32)
          val cond = Bool(INPUT)
          val out = UInt(OUTPUT, width = 32)
        }
        val children =
          Seq(Module(new PassthroughModule), Module(new PassthroughMultiIOModule), Module(new PassthroughRawModule))
        io.out := children.map(_.io.out).reduce(_ + _)
        children.foreach { child =>
          when(io.cond) {
            child.io.in := io.in
          }
        }
      }
    }
  }

  "Compatibility Modules" should "have Bool as their reset type" in {
    compile {
      import Chisel._
      class Intf extends Bundle {
        val in = Bool(INPUT)
        val en = Bool(INPUT)
        val out = Bool(OUTPUT)
      }
      class Child extends Module {
        val io = new Intf
        io.out := Mux(io.en, io.in, reset)
      }
      new Module {
        val io = new Intf
        val child = Module(new Child)
        io <> child.io
      }
    }
  }

  "Compatibility Modules" should "be instantiable inside chisel3 Modules" in {
    compile {
      object Compat {
        import Chisel._
        class Intf extends Bundle {
          val in = Input(UInt(8.W))
          val out = Output(UInt(8.W))
        }
        class OldMod extends Module {
          val io = IO(new Intf)
          io.out := Reg(next = io.in)
        }
      }
      import chisel3._
      import Compat._
      new Module {
        val io = IO(new Intf)
        io <> Module(new Module {
          val io = IO(new Intf)
          val inst = Module(new OldMod)
          io <> inst.io
        }).io
      }
    }
  }

  "A chisel3 Bundle that instantiates a Chisel Bundle" should "bulk connect correctly" in {
    compile {
      object Compat {
        import Chisel._
        class BiDir extends Bundle {
          val a = Input(UInt(8.W))
          val b = Output(UInt(8.W))
        }
        class Struct extends Bundle {
          val a = UInt(8.W)
        }
      }
      import chisel3._
      import Compat._
      class Bar extends Bundle {
        val bidir1 = new BiDir
        val bidir2 = Flipped(new BiDir)
        val struct1 = Output(new Struct)
        val struct2 = Input(new Struct)
      }
      // Check every connection both ways to see that chisel3 <>'s commutativity holds
      class Child extends RawModule {
        val deq = IO(new Bar)
        val enq = IO(Flipped(new Bar))
        enq <> deq
        deq <> enq
      }
      new RawModule {
        val deq = IO(new Bar)
        val enq = IO(Flipped(new Bar))
        // Also important to check connections to child ports
        val c1 = Module(new Child)
        val c2 = Module(new Child)
        c1.enq <> enq
        enq <> c1.enq
        c2.enq <> c1.deq
        c1.deq <> c2.enq
        deq <> c2.deq
        c2.deq <> deq
      }
    }
  }

  "A unidirectional but flipped Bundle" should "bulk connect in import chisel3._ code correctly" in {
    object Compat {
      import Chisel._
      class MyBundle(extraFlip: Boolean) extends Bundle {
        private def maybeFlip[T <: Data](t: T): T = if (extraFlip) t.flip else t
        val foo = maybeFlip(new Bundle {
          val bar = UInt(INPUT, width = 8)
        })
      }
    }
    import chisel3._
    import Compat._
    class Top(extraFlip: Boolean) extends RawModule {
      val port = IO(new MyBundle(extraFlip))
      val wire = Wire(new MyBundle(extraFlip))
      port <> DontCare
      wire <> DontCare
      port <> wire
      wire <> port
      port.foo <> wire.foo
      wire.foo <> port.foo
    }
    compile(new Top(true))
    compile(new Top(false))
  }

  "A unidirectional but flipped Bundle with something close to NotStrict compileOptions, but not exactly" should "bulk connect in import chisel3._ code correctly" in {
    object Compat {
      import Chisel.{defaultCompileOptions => _, _}
      // arbitrary thing to make this *not* exactly NotStrict
      implicit val defaultCompileOptions = new chisel3.ExplicitCompileOptions.CompileOptionsClass(
        connectFieldsMustMatch = false,
        declaredTypeMustBeUnbound = false,
        dontTryConnectionsSwapped = false,
        dontAssumeDirectionality = false,
        checkSynthesizable = false,
        explicitInvalidate = false,
        inferModuleReset = true // different from NotStrict, to ensure case class equivalence to NotStrict is false
      ) {
        override def emitStrictConnects = false
      }

      class MyBundle(extraFlip: Boolean) extends Bundle {
        private def maybeFlip[T <: Data](t: T): T = if (extraFlip) t.flip else t
        val foo = maybeFlip(new Bundle {
          val bar = UInt(INPUT, width = 8)
        })
      }
    }
    import chisel3._
    import Compat.{defaultCompileOptions => _, _}
    class Top(extraFlip: Boolean) extends RawModule {
      val port = IO(new MyBundle(extraFlip))
      val wire = Wire(new MyBundle(extraFlip))
      port <> DontCare
      wire <> DontCare
      port <> wire
      wire <> port
      port.foo <> wire.foo
      wire.foo <> port.foo
    }
    compile(new Top(true))
    compile(new Top(false))
  }

  "A Chisel.Bundle with only unspecified directions" should "work with D/I" in {

    object Compat {
      import Chisel._
      import chisel3.experimental.hierarchy.{instantiable, public}

      class CompatBiDirUnspecifiedBundle extends Bundle {
        val out = Bool()
        val in = Flipped(Bool())
      }

      @instantiable
      class CompatModule extends Module {
        @public val io = IO(new CompatBiDirUnspecifiedBundle)
      }
    }

    object Chisel3 {
      import chisel3._
      import chisel3.experimental.hierarchy.Instance
      class Example extends Module {
        val mod = Module(new Compat.CompatModule())
        mod.io.in <> DontCare
        val inst = Instance(mod.toDefinition)
        inst.io.in <> mod.io.out
        mod.io.in <> inst.io.out
      }
    }
    compile(new Chisel3.Example)
  }

  "A Chisel.Bundle with mixed Specified and Unspecified directions" should "work with D/I" in {

    object Compat {
      import Chisel._
      import chisel3.experimental.hierarchy.{instantiable, public}

      class CompatBiDirMixedBundle extends Bundle {
        val out = Bool()
        val in = Flipped(Bool())
        val explicit = Output(Bool())
      }

      @instantiable
      class CompatModule extends Module {
        @public val io = IO(new CompatBiDirMixedBundle)
      }
    }

    object Chisel3 {
      import chisel3._
      import chisel3.experimental.hierarchy.Instance
      class Example extends Module {
        val mod = Module(new Compat.CompatModule)
        mod.io.in <> DontCare
        val inst = Instance(mod.toDefinition)
        inst.io.in <> mod.io.out
        mod.io.in <> inst.io.out
      }
    }
    compile(new Chisel3.Example)
  }

  "A Chisel.Bundle with only unspecified vec direction" should "work with D/I" in {

    object Compat {
      import Chisel._
      import chisel3.experimental.hierarchy.{instantiable, public}

      class CompatBiDirUnspecifiedVecBundle extends Bundle {
        val out = Vec(3, Bool())
        val in = Flipped(Vec(3, Bool()))
      }

      @instantiable
      class CompatModule extends Module {
        @public val io = IO(new CompatBiDirUnspecifiedVecBundle)
      }
    }

    object Chisel3 {
      import chisel3._
      import chisel3.experimental.hierarchy.Instance
      class Example extends Module {
        val mod = Module(new Compat.CompatModule())
        mod.io.in <> DontCare
        val inst = Instance(mod.toDefinition)
        inst.io.in <> mod.io.out
        mod.io.in <> inst.io.out
      }
    }
    compile(new Chisel3.Example)
  }

  "A chisel3.Bundle with only unspecified directions" should "work with D/I" in {

    object Chisel3 {
      import chisel3._
      import chisel3.experimental.hierarchy.{instantiable, public, Instance}

      class BiDirUnspecifiedBundle extends Bundle {
        val out = Bool()
        val in = Flipped(Bool())
      }

      @instantiable
      class MyModule extends Module {
        @public val io = IO(new BiDirUnspecifiedBundle)
        io <> DontCare
      }

      class Example extends Module {
        val mod = Module(new MyModule())
        mod.io.in <> DontCare
        val inst = Instance(mod.toDefinition)
        inst.io.in <> mod.io.out
        mod.io.in <> inst.io.out
      }
    }
    compile(new Chisel3.Example)
  }

  "A chisel3.Bundle with mixed Specified and Unspecified directions" should "work with D/I" in {

    object Chisel3 {
      import chisel3._
      import chisel3.experimental.hierarchy.{instantiable, public, Instance}

      class BiDirMixedBundle extends Bundle {
        val out = Bool()
        val in = Flipped(Bool())
        val explicit = Output(Bool())
      }

      @instantiable
      class MyModule extends Module {
        @public val io = IO(new BiDirMixedBundle)
        io <> DontCare
      }
      class Example extends Module {
        val mod = Module(new MyModule)
        mod.io.in <> DontCare
        val inst = Instance(mod.toDefinition)
        inst.io.in <> mod.io.out
        mod.io.in <> inst.io.out
      }
    }
    compile(new Chisel3.Example)
  }

  "A chisel3.Bundle with only unspecified vec direction" should "work with D/I" in {

    object Chisel3 {
      import chisel3._
      import chisel3.experimental.hierarchy.{instantiable, public, Instance}

      class BiDirUnspecifiedVecBundle extends Bundle {
        val out = Vec(3, Bool())
        val in = Flipped(Vec(3, Bool()))
      }

      @instantiable
      class MyModule extends Module {
        @public val io = IO(new BiDirUnspecifiedVecBundle)
        io <> DontCare
      }

      class Example extends Module {
        val mod = Module(new MyModule())
        mod.io.in <> DontCare
        val inst = Instance(mod.toDefinition)
        inst.io.in <> mod.io.out
        mod.io.in <> inst.io.out
      }
    }
    compile(new Chisel3.Example)
  }

  "A chisel3.Bundle with only unspecified vec direction within an unspecified direction parent Bundle" should "work with D/I" in {

    object Chisel3 {
      import chisel3._
      import chisel3.experimental.hierarchy.{instantiable, public, Instance}

      class UnspecifiedVecBundle extends Bundle {
        val vec = Vec(3, Bool())
      }

      class UnspecifiedParentBundle extends Bundle {
        val out = new UnspecifiedVecBundle
      }

      @instantiable
      class MyModule extends Module {
        @public val io = IO(new UnspecifiedParentBundle)
        io <> DontCare
      }

      class Example extends Module {
        val mod = Module(new MyModule())

        val wire = Wire(new UnspecifiedParentBundle)
        wire.out.vec <> mod.io.out.vec
        val inst = Instance(mod.toDefinition)
        wire.out.vec <> inst.io.out.vec

      }
    }
    compile(new Chisel3.Example)
  }

  "A undirectioned Chisel.Bundle used in a MixedVec " should "bulk connect in import chisel3._ code correctly" in {

    object Compat {

      import Chisel._
      import chisel3.util.MixedVec

      class ChiselModule extends Module {
        val io = IO(new Bundle {
          val out = MixedVec(Seq.fill(3) { Bool() })
          val in = Flipped(MixedVec(Seq.fill(3) { Bool() }))
        })
        io.out := RegNext(io.in)
      }

    }
    object Chisel3 {
      import chisel3._

      class Chisel3Module extends Compat.ChiselModule

      class Example extends Module {
        val oldMod = Module(new Compat.ChiselModule)
        val newMod = Module(new Chisel3Module)

        oldMod.io.in <> DontCare
        newMod.io.in <> DontCare

      }
    }
    compile(new Chisel3.Example)
  }

  "A undirectioned Chisel.Bundle with Records with undirectioned and directioned fields " should "work" in {

    object Compat {

      import Chisel._

      class ChiselModule(gen: () => Data) extends Module {
        val io = IO(new Bundle {
          val mixed = new Chisel3.MyRecord(gen)
        })
      }

    }
    object Chisel3 {
      import chisel3._
      import scala.collection.immutable.SeqMap

      class MyRecord(gen: () => Data) extends Record with chisel3.experimental.AutoCloneType {
        val elements = SeqMap("genDirectioned" -> Output(gen()), "genUndirectioned" -> gen())
      }

      class Example extends Module {
        val newMod = Module(new Compat.ChiselModule(() => Bool()))
      }
    }
    compile(new Chisel3.Example)
  }

  "A BlackBox with Chisel._ fields in its IO" should "bulk connect in import chisel3._ code correctly" in {
    object Compat {
      import Chisel._
      class LegacyChiselIO extends Bundle {
        val foo = Output(Bool())
        val bar = Output(Bool())
      }
    }
    object Chisel3 {
      import chisel3._
      import chisel3.util.Valid

      class FooModuleIO extends Bundle {
        val quz = Input(new QuzIO)
        val foo = Output(Bool())
        val bar = Input(Bool())
      }
      class QuzIO extends Bundle {
        val q = Flipped(Valid(new Compat.LegacyChiselIO))
      }
      class FooModule extends Module {
        val io = IO(new FooModuleIO)
        io <> DontCare
      }
      class FooMirrorBlackBox extends BlackBox {
        val io = IO(Flipped(new FooModuleIO))
      }
      class Top extends Module {
        val foo = Module(new FooModule)
        val mirror = Module(new FooMirrorBlackBox)
        foo.io <> mirror.io
      }
    }
    val chirrtl = emitChirrtl(new Chisel3.Top)
    chirrtl should include("foo.io.bar <= mirror.bar")
    chirrtl should include("mirror.foo <= foo.io.foo")
    chirrtl should include("foo.io.quz.q.bits <- mirror.quz.q.bits")
    chirrtl should include("foo.io.quz.q.valid <= mirror.quz.q.valid")
  }

  "A chisel3.Bundle bulk connected to a Chisel Bundle in either direction" should "work even with mismatched fields" in {
    object Compat {
      import Chisel._
      class FooBundle extends Bundle {
        val foo = UInt(width = 8)
      }
    }
    object Chisel3 {
      import chisel3._
      class BarBundle extends Bundle {
        val bar = UInt(8.W)
      }
      class MyModule(swap: Boolean) extends Module {
        val in = IO(Input(if (swap) new Compat.FooBundle else new BarBundle))
        val out = IO(Output(if (swap) new BarBundle else new Compat.FooBundle))
        out <> DontCare
        out <> in
      }
    }
    val chirrtl0 = emitChirrtl(new Chisel3.MyModule(true))
    chirrtl0 shouldNot include("<=")
    chirrtl0 should include("out <- in")
    val chirrtl1 = emitChirrtl(new Chisel3.MyModule(true))
    chirrtl1 shouldNot include("<=")
    chirrtl1 should include("out <- in")
  }

  it should "work with missing fields in the Chisel._" in {
    object Compat {
      import Chisel._
      class FooBundle extends Bundle {
        val foo = UInt(width = 8)
      }
    }
    object Chisel3 {
      import chisel3._
      class FooBarBundle extends Bundle {
        val foo = UInt(8.W)
        val bar = UInt(8.W)
      }

      class MyModule(swap: Boolean) extends Module {
        val in = IO(Input(if (swap) new Compat.FooBundle else new FooBarBundle))
        val out = IO(Output(if (swap) new FooBarBundle else new Compat.FooBundle))
        out <> DontCare
        out <> in
      }
    }
    val chirrtl0 = emitChirrtl(new Chisel3.MyModule(true))
    chirrtl0 shouldNot include("<=")
    chirrtl0 should include("out <- in")
    val chirrtl1 = emitChirrtl(new Chisel3.MyModule(true))
    chirrtl1 shouldNot include("<=")
    chirrtl1 should include("out <- in")
  }

  it should "work with missing fields in the chisel3._" in {
    object Compat {
      import Chisel._
      class FooBundle extends Bundle {
        val foo = UInt(width = 8)
      }
    }
    object Chisel3 {
      import chisel3._
      class FooBarBundle extends Bundle {
        val foo = UInt(8.W)
        val bar = UInt(8.W)
      }

      class MyModule(swap: Boolean) extends Module {
        val in = IO(Input(if (swap) new Compat.FooBundle else new FooBarBundle))
        val out = IO(Output(if (swap) new FooBarBundle else new Compat.FooBundle))
        out <> DontCare
        out <> in
      }
    }
    val chirrtl0 = emitChirrtl(new Chisel3.MyModule(true))
    chirrtl0 shouldNot include("<=")
    chirrtl0 should include("out <- in")
    val chirrtl1 = emitChirrtl(new Chisel3.MyModule(true))
    chirrtl1 shouldNot include("<=")
    chirrtl1 should include("out <- in")
  }

  it should "emit FIRRTL connects if possible" in {
    object Compat {
      import Chisel._
      class FooBarBundle extends Bundle {
        val foo = UInt(8.W)
        val bar = Flipped(UInt(8.W))
      }
    }
    object Chisel3 {
      import chisel3._
      class FooBarBundle extends Bundle {
        val foo = Output(UInt(8.W))
        val bar = Input(UInt(8.W))
      }
      class MyModule(swap: Boolean) extends Module {
        val in = IO(Flipped((if (swap) new Compat.FooBarBundle else new FooBarBundle)))
        val out = IO(if (swap) new FooBarBundle else new Compat.FooBarBundle)
        out <> DontCare
        out <> in
      }
    }
    val chirrtl0 = emitChirrtl(new Chisel3.MyModule(true))
    chirrtl0 should include("out <= in")
    chirrtl0 shouldNot include("out <- in")
    val chirrtl1 = emitChirrtl(new Chisel3.MyModule(true))
    chirrtl1 should include("out <= in")
    chirrtl1 shouldNot include("out <- in")
  }
}