1 files changed, 25 insertions, 0 deletions
diff --git a/src/main/scala/chisel3/stage/phases/AddImplicitOutputFile.scala b/src/main/scala/chisel3/stage/phases/AddImplicitOutputFile.scala
new file mode 100644
index 00000000..4a4dac72
--- /dev/null
+++ b/src/main/scala/chisel3/stage/phases/AddImplicitOutputFile.scala
@@ -0,0 +1,25 @@
+// See LICENSE for license details.
+
+package chisel3.stage.phases
+
+import firrtl.AnnotationSeq
+import firrtl.options.Phase
+
+import chisel3.stage.{ChiselCircuitAnnotation, ChiselOutputFileAnnotation}
+
+/** Add a output file for a Chisel circuit, derived from the top module in the circuit, if no
+  * [[ChiselOutputFileAnnotation]] already exists.
+  */
+class AddImplicitOutputFile extends Phase {
+
+  def transform(annotations: AnnotationSeq): AnnotationSeq =
+    annotations.collectFirst{ case _: ChiselOutputFileAnnotation  => annotations }.getOrElse{
+
+      val x: Option[AnnotationSeq] = annotations
+        .collectFirst{ case a: ChiselCircuitAnnotation =>
+          ChiselOutputFileAnnotation(a.circuit.name) +: annotations }
+
+      x.getOrElse(annotations)
+    }
+
+}