From c9d3e257bff74235a75ff5530051e419b9ce8005 Mon Sep 17 00:00:00 2001
From: Jack Koenig
Date: Tue, 30 Jan 2018 12:53:56 -0800
Subject: Make Constant Propagation respect dontTouch on registers

---
 src/main/scala/firrtl/transforms/ConstantPropagation.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'src/main')

diff --git a/src/main/scala/firrtl/transforms/ConstantPropagation.scala b/src/main/scala/firrtl/transforms/ConstantPropagation.scala
index b767ef65..d08a7e6b 100644
--- a/src/main/scala/firrtl/transforms/ConstantPropagation.scala
+++ b/src/main/scala/firrtl/transforms/ConstantPropagation.scala
@@ -367,7 +367,7 @@ class ConstantPropagation extends Transform {
         // Const prop registers that are fed only a constant or a mux between and constant and the
         // register itself
         // This requires that reset has been made explicit
-        case Connect(_, lref @ WRef(lname, ltpe, RegKind, _), expr) => expr match {
+        case Connect(_, lref @ WRef(lname, ltpe, RegKind, _), expr) if !dontTouches.contains(lname) => expr match {
           case lit: Literal =>
             nodeMap(lname) = constPropExpression(pad(lit, ltpe))
           case Mux(_, tval: WRef, fval: Literal, _) if weq(lref, tval) =>
-- 
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