diff options
Diffstat (limited to 'src/main')
| -rw-r--r-- | src/main/scala/firrtl/passes/ExpandWhens.scala | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/src/main/scala/firrtl/passes/ExpandWhens.scala b/src/main/scala/firrtl/passes/ExpandWhens.scala index 560a1c1c..956d54bc 100644 --- a/src/main/scala/firrtl/passes/ExpandWhens.scala +++ b/src/main/scala/firrtl/passes/ExpandWhens.scala @@ -73,7 +73,13 @@ object ExpandWhens extends Pass { def expandWhens(m: Module): (Netlist, Simlist, Seq[Attach], Statement, InfoMap) = { val namespace = Namespace(m) val simlist = new Simlist + + // Memoizes if an expression contains any WVoids inserted in this pass + val memoizedVoid = new mutable.HashSet[MemoizedHash[Expression]] += WVoid + + // Memoizes the node that holds a particular expression, if any val nodes = new NodeMap + // Seq of attaches in order lazy val attaches = mutable.ArrayBuffer.empty[Attach] @@ -171,7 +177,21 @@ object ExpandWhens extends Pass { conseqNetlist getOrElse (lvalue, altNetlist(lvalue)) } + // Does an expression contain WVoid inserted in this pass? + def containsVoid(e: Expression): Boolean = e match { + case WVoid => true + case ValidIf(_, value, _) => memoizedVoid(value) + case Mux(_, tv, fv, _) => memoizedVoid(tv) || memoizedVoid(fv) + case _ => false + } + res match { + // Don't create a node to hold mux trees with void values + // "Idiomatic" emission of these muxes isn't a concern because they represent bad code (latches) + case e if containsVoid(e) => + netlist(lvalue) = e + memoizedVoid += e // remember that this was void + EmptyStmt case _: ValidIf | _: Mux | _: DoPrim => nodes get res match { case Some(name) => netlist(lvalue) = WRef(name, res.tpe, NodeKind, MALE) |