[turbofan] Small fix in live range printer.

src/compiler/register-allocator.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/base/adapters.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/register-allocator.h"
 #include "src/string-stream.h"
 
 namespace v8 {
@@ skipping 1040 matching lines @@
      << " ";
   if (range->TopLevel()->is_phi()) os << "phi ";
   if (range->TopLevel()->is_non_loop_phi()) os << "nlphi ";
 
   os << "{" << std::endl;
   auto interval = range->first_interval();
   auto use_pos = range->first_pos();
   PrintableInstructionOperand pio;
   pio.register_configuration_ = printable_range.register_configuration_;
   while (use_pos != nullptr) {
-    pio.op_ = *use_pos->operand();
-    os << pio << use_pos->pos() << " ";
+    if (use_pos->HasOperand()) {
+      pio.op_ = *use_pos->operand();
+      os << pio << use_pos->pos() << " ";
+    }
     use_pos = use_pos->next();
   }
   os << std::endl;
 
   while (interval != nullptr) {
     os << '[' << interval->start() << ", " << interval->end() << ')'
        << std::endl;
     interval = interval->next();
   }
   os << "}";
@@ skipping 2241 matching lines @@
     auto eliminate = moves->PrepareInsertAfter(move);
     to_insert.push_back(move);
     if (eliminate != nullptr) to_eliminate.push_back(eliminate);
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8