diff --git a/src/compiler/node.cc b/src/compiler/node.cc
index 198c353..f4e7b17 100644
--- a/src/compiler/node.cc
+++ b/src/compiler/node.cc
@@ -193,6 +193,22 @@
   Verify();
 }
 
+void Node::InsertInputs(Zone* zone, int index, int count) {
+  DCHECK_NOT_NULL(zone);
+  DCHECK_LE(0, index);
+  DCHECK_LT(0, count);
+  DCHECK_LT(index, InputCount());
+  for (int i = 0; i < count; i++) {
+    AppendInput(zone, InputAt(Max(InputCount() - count, 0)));
+  }
+  for (int i = InputCount() - count - 1; i >= Max(index, count); --i) {
+    ReplaceInput(i, InputAt(i - count));
+  }
+  for (int i = 0; i < count; i++) {
+    ReplaceInput(index + i, nullptr);
+  }
+  Verify();
+}
 
 void Node::RemoveInput(int index) {
   DCHECK_LE(0, index);
@@ -369,7 +385,11 @@
     os << "(";
     for (int i = 0; i < n.InputCount(); ++i) {
       if (i != 0) os << ", ";
-      os << n.InputAt(i)->id();
+      if (n.InputAt(i)) {
+        os << n.InputAt(i)->id();
+      } else {
+        os << "null";
+      }
     }
     os << ")";
   }