Add Definition and Instance API (#2045)

This introduces a new experimental API for module instantiation that disentagles
elaborating the definition (or implementation) from instantiation of
a given module. This solves Chisel's longstanding reliance on
"Deduplication" for generating Verilog with multiple instances of the
same module.

The new API resides in package chisel3.experimental.hierarchy. Please
see the hierarchy ScalaDoc, documentation, and tests for examples of
use.

Co-authored-by: Jack Koenig <koenig@sifive.com>
Co-authored-by: Megan Wachs <megan@sifive.com>
Co-authored-by: Schuyler Eldridge <schuyler.eldridge@sifive.com>

1 files changed, 22 insertions, 18 deletions

diff --git a/src/test/scala/chiselTests/experimental/DataView.scala b/src/test/scala/chiselTests/experimental/DataView.scala
index 381cfeb5..d1620e88 100644
--- a/src/test/scala/chiselTests/experimental/DataView.scala
+++ b/src/test/scala/chiselTests/experimental/DataView.scala
@@ -29,6 +29,27 @@ object VecBundleDataView {
   implicit val v2 = v1.invert(_ => new MyBundle)
 }
 
+object FlatDecoupledDataView {
+  class FizzBuzz extends Bundle {
+    val fizz = UInt(8.W)
+    val buzz = UInt(8.W)
+  }
+  class FlatDecoupled extends Bundle {
+    val valid = Output(Bool())
+    val ready = Input(Bool())
+    val fizz = Output(UInt(8.W))
+    val buzz = Output(UInt(8.W))
+  }
+  implicit val view = DataView[FlatDecoupled, DecoupledIO[FizzBuzz]](
+    _ => Decoupled(new FizzBuzz),
+    _.valid -> _.valid,
+    _.ready -> _.ready,
+    _.fizz -> _.bits.fizz,
+    _.buzz -> _.bits.buzz
+  )
+  implicit val view2 = view.invert(_ => new FlatDecoupled)
+}
+
 // This should become part of Chisel in a later PR
 object Tuple2DataProduct {
   implicit def tuple2DataProduct[A : DataProduct, B : DataProduct] = new DataProduct[(A, B)] {
@@ -177,24 +198,7 @@ class DataViewSpec extends ChiselFlatSpec {
   }
 
   it should "work with bidirectional connections for nested types" in {
-    class FizzBuzz extends Bundle {
-      val fizz = UInt(8.W)
-      val buzz = UInt(8.W)
-    }
-    class FlatDecoupled extends Bundle {
-      val valid = Output(Bool())
-      val ready = Input(Bool())
-      val fizz = Output(UInt(8.W))
-      val buzz = Output(UInt(8.W))
-    }
-    implicit val view = DataView[FlatDecoupled, DecoupledIO[FizzBuzz]](
-      _ => Decoupled(new FizzBuzz),
-      _.valid -> _.valid,
-      _.ready -> _.ready,
-      _.fizz -> _.bits.fizz,
-      _.buzz -> _.bits.buzz
-    )
-    implicit val view2 = view.invert(_ => new FlatDecoupled)
+    import FlatDecoupledDataView._
     class MyModule extends Module {
       val enq = IO(Flipped(Decoupled(new FizzBuzz)))
       val deq = IO(new FlatDecoupled)