From 2882912385c744389092b4f8d426379908d01ed7 Mon Sep 17 00:00:00 2001
From: Kevin Laeufer
Date: Tue, 19 Jan 2021 13:14:24 -0800
Subject: smt: run DeadCodeElimination after PropagatePresetAnnotations (#2036)

---
 .../experimental/smt/FirrtlToTransitionSystem.scala   | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

(limited to 'src/main')

diff --git a/src/main/scala/firrtl/backends/experimental/smt/FirrtlToTransitionSystem.scala b/src/main/scala/firrtl/backends/experimental/smt/FirrtlToTransitionSystem.scala
index 145b5b0f..9c309917 100644
--- a/src/main/scala/firrtl/backends/experimental/smt/FirrtlToTransitionSystem.scala
+++ b/src/main/scala/firrtl/backends/experimental/smt/FirrtlToTransitionSystem.scala
@@ -10,18 +10,8 @@ import firrtl.options.Dependency
 import firrtl.passes.PassException
 import firrtl.stage.Forms
 import firrtl.stage.TransformManager.TransformDependency
-import firrtl.transforms.PropagatePresetAnnotations
-import firrtl.{
-  ir,
-  CircuitState,
-  DependencyAPIMigration,
-  MemoryArrayInit,
-  MemoryInitValue,
-  MemoryScalarInit,
-  Namespace,
-  Transform,
-  Utils
-}
+import firrtl.transforms.{DeadCodeElimination, PropagatePresetAnnotations}
+import firrtl.{CircuitState, DependencyAPIMigration, MemoryArrayInit, MemoryInitValue, MemoryScalarInit, Namespace, Transform, Utils, ir}
 import logger.LazyLogging
 
 import scala.collection.mutable
@@ -67,9 +57,12 @@ object FirrtlToTransitionSystem extends Transform with DependencyAPIMigration {
   // Verilog emission passes.
   // Ideally we would go in and enable the [[PropagatePresetAnnotations]] to only depend on LowForm.
   private val presetPass = new PropagatePresetAnnotations
+  // We also need to run the DeadCodeElimination since PropagatePresets does not remove possible remaining
+  // AsyncReset nodes.
+  private val deadCodeElimination = new DeadCodeElimination
   override protected def execute(state: CircuitState): CircuitState = {
     // run the preset pass to extract all preset registers and remove preset reset signals
-    val afterPreset = presetPass.execute(state)
+    val afterPreset = deadCodeElimination.execute(presetPass.execute(state))
     val circuit = afterPreset.circuit
     val presetRegs = afterPreset.annotations.collect {
       case PresetRegAnnotation(target) if target.module == circuit.main => target.ref
-- 
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