Infer reset (#1068)

* Add abstract "Reset" which can be inferred to AsyncReset or UInt<1>
* Enhance async reset initial value literal check to support aggregates

1 files changed, 9 insertions, 0 deletions

diff --git a/src/main/scala/firrtl/Utils.scala b/src/main/scala/firrtl/Utils.scala
index 72003608..206afc09 100644
--- a/src/main/scala/firrtl/Utils.scala
+++ b/src/main/scala/firrtl/Utils.scala
@@ -445,6 +445,7 @@ object Utils extends LazyLogging {
   }
 
   def get_valid_points(t1: Type, t2: Type, flip1: Orientation, flip2: Orientation): Seq[(Int,Int)] = {
+    import passes.CheckTypes.legalResetType
     //;println_all(["Inside with t1:" t1 ",t2:" t2 ",f1:" flip1 ",f2:" flip2])
     (t1, t2) match {
       case (_: UIntType, _: UIntType) => if (flip1 == flip2) Seq((0, 0)) else Nil
@@ -474,6 +475,14 @@ object Utils extends LazyLogging {
             ilen + get_size(t1x.tpe), jlen + get_size(t2x.tpe))
         }._1
       case (ClockType, ClockType) => if (flip1 == flip2) Seq((0, 0)) else Nil
+      case (AsyncResetType, AsyncResetType) => if (flip1 == flip2) Seq((0, 0)) else Nil
+      // The following two cases handle driving ResetType from other legal reset types
+      // Flippedness is important here because ResetType can be driven by other reset types, but it
+      //   cannot *drive* other reset types
+      case (ResetType, other) =>
+        if (legalResetType(other) && flip1 == Default && flip1 == flip2) Seq((0, 0)) else Nil
+      case (other, ResetType) =>
+        if (legalResetType(other) && flip1 == Flip && flip1 == flip2) Seq((0, 0)) else Nil
       case _ => throwInternalError(s"get_valid_points: shouldn't be here - ($t1, $t2)")
     }
   }