From 30091a8a9f965502c96926591af0cc95a5e3c746 Mon Sep 17 00:00:00 2001
From: Andrew Waterman
Date: Wed, 13 Apr 2016 14:51:47 -0700
Subject: Factor DCE re-running more cleanly

---
 src/main/scala/firrtl/passes/DeadCodeElimination.scala | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/main/scala/firrtl/passes/DeadCodeElimination.scala b/src/main/scala/firrtl/passes/DeadCodeElimination.scala
index 98ef296e..cb772556 100644
--- a/src/main/scala/firrtl/passes/DeadCodeElimination.scala
+++ b/src/main/scala/firrtl/passes/DeadCodeElimination.scala
@@ -36,8 +36,7 @@ import annotation.tailrec
 object DeadCodeElimination extends Pass {
   def name = "Dead Code Elimination"
 
-  @tailrec
-  private def dce(s: Stmt): Stmt = {
+  private def dceOnce(s: Stmt): (Stmt, Long) = {
     val referenced = collection.mutable.HashSet[String]()
     var nEliminated = 0L
 
@@ -66,8 +65,13 @@ object DeadCodeElimination extends Pass {
     }
 
     checkUse(s)
-    val res = removeUnused(s)
-    if (nEliminated > 0) dce(res) else res
+    (removeUnused(s), nEliminated)
+  }
+
+  @tailrec
+  private def dce(s: Stmt): Stmt = {
+    val (res, n) = dceOnce(s)
+    if (n > 0) dce(res) else res
   }
 
   def run(c: Circuit): Circuit = {
-- 
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