From 536ec5e179b23451defbbaec3b83f99362d6f952 Mon Sep 17 00:00:00 2001
From: Mathias Soeken <mathias.soeken@epfl.ch>
Date: Mon, 6 Nov 2017 14:33:39 +0100
Subject: [PATCH] XMG Rewrite.

---
 src/classical/xmg/xmg_rewrite.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/classical/xmg/xmg_rewrite.cpp b/src/classical/xmg/xmg_rewrite.cpp
index de1c112f..e52318d2 100644
--- a/src/classical/xmg/xmg_rewrite.cpp
+++ b/src/classical/xmg/xmg_rewrite.cpp
@@ -214,9 +214,12 @@ std::vector<xmg_function> xmg_rewrite_top_down_inplace( xmg_graph& dest,
   std::map<xmg_node, xmg_function> old_to_new;
 
   old_to_new[0] = dest.get_constant( false );
-  for ( const auto& pi : index( xmg.inputs() ) )
+  if ( !pi_mapping.empty() )
   {
-    old_to_new[pi.value.first] = pi_mapping[pi.index];
+    for ( const auto& pi : index( xmg.inputs() ) )
+    {
+      old_to_new[pi.value.first] = pi_mapping[pi.index];
+    }
   }
 
   /* prefill */