Verifier must ensure that start and end node of graph are set.

src/compiler/verifier.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/verifier.h"
 
 #include "src/compiler/generic-algorithm.h"
 #include "src/compiler/generic-node-inl.h"
 #include "src/compiler/generic-node.h"
 #include "src/compiler/graph-inl.h"
@@ skipping 206 matching lines @@
     reached_from_end.insert(node);
   }
 
   return GenericGraphVisit::CONTINUE;
 }
 
 
 void Verifier::Run(Graph* graph) {
   Visitor visitor(graph->zone());
 
+  CHECK_NE(NULL, graph->start());
   visitor.from_start = true;
   graph->VisitNodeUsesFromStart(&visitor);
+  CHECK_NE(NULL, graph->end());
   visitor.from_start = false;
   graph->VisitNodeInputsFromEnd(&visitor);
 
   // All control nodes reachable from end are reachable from start.
   for (NodeSet::iterator it = visitor.reached_from_end.begin();
        it != visitor.reached_from_end.end(); ++it) {
     CHECK(!NodeProperties::IsControl(*it) ||
           visitor.reached_from_start.count(*it));
   }
 }
 }
 }
 }  // namespace v8::internal::compiler