From 43cd047fb9d73c43f8fe2c35c457cfa8fc3523ec Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Tue, 16 Apr 2019 13:44:15 -0700
Subject: [PATCH] Do not put constants into output_bits

---
 backends/aiger/xaiger.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/backends/aiger/xaiger.cc b/backends/aiger/xaiger.cc
index 99ca4f8d5..7c7697874 100644
--- a/backends/aiger/xaiger.cc
+++ b/backends/aiger/xaiger.cc
@@ -229,9 +229,9 @@ struct XAigerWriter
 							/*if (!output_bits.count(b))*/
 							if (abc_box)
 								co_bits.emplace_back(b, 0);
-							else {
+							else if (b.wire) {
 								output_bits.insert(b);
-								if (b.wire && !b.wire->port_input)
+								if (!b.wire->port_input)
 									unused_bits.erase(b);
 							}
 						}