From 13e233217cd0caceeb5d30d2eefa5238ffc5bfc9 Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Tue, 28 May 2019 11:29:59 -0700
Subject: [PATCH] Small improvement

---
 backends/aiger/xaiger.cc | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/backends/aiger/xaiger.cc b/backends/aiger/xaiger.cc
index 2bc059dc5..5919b2302 100644
--- a/backends/aiger/xaiger.cc
+++ b/backends/aiger/xaiger.cc
@@ -328,6 +328,7 @@ struct XAigerWriter
 							if (I != b)
 								alias_map[b] = I;
 							co_bits.emplace_back(b, cell, port_name, offset++, 0);
+							unused_bits.erase(b);
 						}
 					}
 					if (w->port_output) {
@@ -347,6 +348,7 @@ struct XAigerWriter
 						for (const auto &b : rhs.bits()) {
 							SigBit O = sigmap(b);
 							ci_bits.emplace_back(O, cell, port_name, offset++);
+							undriven_bits.erase(O);
 						}
 					}
 				}
@@ -383,10 +385,6 @@ struct XAigerWriter
 			}
 		}
 
-		// Do some CI/CO post-processing:
-		// CIs cannot be undriven
-		for (const auto &c : ci_bits)
-			undriven_bits.erase(std::get<0>(c));
 		// Erase all POs that are undriven
 		if (!holes_mode)
 			for (auto bit : undriven_bits)