1 files changed, 23 insertions, 0 deletions
diff --git a/src/main/scala/firrtl/transforms/SortModules.scala b/src/main/scala/firrtl/transforms/SortModules.scala
new file mode 100644
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--- /dev/null
+++ b/src/main/scala/firrtl/transforms/SortModules.scala
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+// SPDX-License-Identifier: Apache-2.0
+
+package firrtl.transforms
+
+import firrtl.{CircuitState, DependencyAPIMigration, Transform}
+import firrtl.analyses.InstanceKeyGraph
+import firrtl.options.Dependency
+import firrtl.stage.Forms
+
+/** Return a circuit where all modules (and external modules) are defined before use. */
+class SortModules extends Transform with DependencyAPIMigration {
+
+  override def prerequisites = Seq(Dependency(firrtl.passes.CheckChirrtl))
+  override def optionalPrerequisites = Seq.empty
+  override def optionalPrerequisiteOf = Forms.ChirrtlEmitters
+  override def invalidates(a: Transform) = false
+
+  override def execute(state: CircuitState): CircuitState = {
+    val modulesx = InstanceKeyGraph(state.circuit).moduleOrder.reverse
+    state.copy(circuit = state.circuit.copy(modules = modulesx))
+  }
+
+}