Support Analog DontCare bulk-connect (#1056)

Short-term patch to enable this useful behavior. In the future, we may want to rearchitect the type system and/or rethink the more edge-case connect behavior.

2 files changed, 31 insertions, 18 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/internal/BiConnect.scala b/chiselFrontend/src/main/scala/chisel3/internal/BiConnect.scala
index e122f13a..f49deff4 100644
--- a/chiselFrontend/src/main/scala/chisel3/internal/BiConnect.scala
+++ b/chiselFrontend/src/main/scala/chisel3/internal/BiConnect.scala
@@ -61,11 +61,20 @@ private[chisel3] object BiConnect {
       // Handle element case (root case)
       case (left_a: Analog, right_a: Analog) =>
         try {
-          analogAttach(sourceInfo, left_a, right_a, context_mod)
-        } catch {
-          // If attach fails, convert to BiConnectException
+          markAnalogConnected(sourceInfo, left_a, context_mod)
+          markAnalogConnected(sourceInfo, right_a, context_mod)
+        } catch {  // convert attach exceptions to BiConnectExceptions
           case attach.AttachException(message) => throw BiConnectException(message)
         }
+        attach.impl(Seq(left_a, right_a), context_mod)(sourceInfo)
+      case (left_a: Analog, DontCare) =>
+        try {
+          markAnalogConnected(sourceInfo, left_a, context_mod)
+        } catch {  // convert attach exceptions to BiConnectExceptions
+          case attach.AttachException(message) => throw BiConnectException(message)
+        }
+        pushCommand(DefInvalid(sourceInfo, left_a.lref))
+      case (DontCare, right_a: Analog) => connect(sourceInfo, connectCompileOptions, right, left, context_mod)
       case (left_e: Element, right_e: Element) => {
         elemConnect(sourceInfo, connectCompileOptions, left_e, right_e, context_mod)
         // TODO(twigg): Verify the element-level classes are connectable
@@ -312,21 +321,13 @@ private[chisel3] object BiConnect {
     else throw UnknownRelationException
   }
 
-  // This function checks if analog element-level attaching is allowed
-  // Then it either issues it or throws the appropriate exception.
-  def analogAttach(implicit sourceInfo: SourceInfo, left: Analog, right: Analog, contextModule: RawModule): Unit = {
-    // Error if left or right is BICONNECTED in the current module already
-    for (elt <- left :: right :: Nil) {
-      elt.biConnectLocs.get(contextModule) match {
-        case Some(sl) => throw AttachAlreadyBulkConnectedException(sl)
-        case None => // Do nothing
-      }
+  // This function checks if analog element-level attaching is allowed, then marks the Analog as connected
+  def markAnalogConnected(implicit sourceInfo: SourceInfo, analog: Analog, contextModule: RawModule): Unit = {
+    analog.biConnectLocs.get(contextModule) match {
+      case Some(sl) => throw AttachAlreadyBulkConnectedException(sl)
+      case None => // Do nothing
     }
-
-    // Do the attachment
-    attach.impl(Seq(left, right), contextModule)
     // Mark bulk connected
-    left.biConnectLocs(contextModule) = sourceInfo
-    right.biConnectLocs(contextModule) = sourceInfo
+    analog.biConnectLocs(contextModule) = sourceInfo
   }
 }
diff --git a/chiselFrontend/src/main/scala/chisel3/internal/MonoConnect.scala b/chiselFrontend/src/main/scala/chisel3/internal/MonoConnect.scala
index 91f1bfd8..e07f980d 100644
--- a/chiselFrontend/src/main/scala/chisel3/internal/MonoConnect.scala
+++ b/chiselFrontend/src/main/scala/chisel3/internal/MonoConnect.scala
@@ -3,7 +3,7 @@
 package chisel3.internal
 
 import chisel3._
-import chisel3.experimental.{BaseModule, EnumType, FixedPoint, RawModule, UnsafeEnum}
+import chisel3.experimental.{Analog, BaseModule, EnumType, FixedPoint, RawModule, UnsafeEnum}
 import chisel3.internal.Builder.pushCommand
 import chisel3.internal.firrtl.{Connect, DefInvalid}
 import scala.language.experimental.macros
@@ -52,6 +52,12 @@ private[chisel3] object MonoConnect {
     MonoConnectException(s": Sink ($sink) and Source ($source) have different types.")
   def DontCareCantBeSink =
     MonoConnectException(": DontCare cannot be a connection sink (LHS)")
+  def AnalogCantBeMonoSink =
+    MonoConnectException(": Analog cannot participate in a mono connection (sink - LHS)")
+  def AnalogCantBeMonoSource =
+    MonoConnectException(": Analog cannot participate in a mono connection (source - RHS)")
+  def AnalogMonoConnectionException =
+    MonoConnectException(": Analog cannot participate in a mono connection (source and sink)")
   // scalastyle:on method.name public.methods.have.type
 
   /** This function is what recursively tries to connect a sink and source together
@@ -142,6 +148,12 @@ private[chisel3] object MonoConnect {
       case (sink, DontCare) => pushCommand(DefInvalid(sourceInfo, sink.lref))
       // DontCare as a sink is illegal.
       case (DontCare, _) => throw DontCareCantBeSink
+      // Analog is illegal in mono connections.
+      case (_: Analog, _:Analog) => throw AnalogMonoConnectionException
+      // Analog is illegal in mono connections.
+      case (_: Analog, _) => throw AnalogCantBeMonoSink
+      // Analog is illegal in mono connections.
+      case (_, _: Analog) => throw AnalogCantBeMonoSource
       // Sink and source are different subtypes of data so fail
       case (sink, source) => throw MismatchedException(sink.toString, source.toString)
     }