Revert of Remove register index/code indirection

src/compiler/graph-visualizer.cc

 // Copyright 2013 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/graph-visualizer.h"
 
 #include <sstream>
 #include <string>
 
 #include "src/code-stubs.h"
@@ skipping 701 matching lines @@
 }
 
 
 void GraphC1Visualizer::PrintLiveRange(LiveRange* range, const char* type,
                                        int vreg) {
   if (range != NULL && !range->IsEmpty()) {
     PrintIndent();
     os_ << vreg << ":" << range->relative_id() << " " << type;
     if (range->HasRegisterAssigned()) {
       AllocatedOperand op = AllocatedOperand::cast(range->GetAssignedOperand());
+      int assigned_reg = op.index();
       if (op.IsDoubleRegister()) {
-        DoubleRegister assigned_reg = op.GetDoubleRegister();
-        os_ << " \"" << assigned_reg.ToString() << "\"";
+        os_ << " \"" << DoubleRegister::AllocationIndexToString(assigned_reg)
+            << "\"";
       } else {
         DCHECK(op.IsRegister());
-        Register assigned_reg = op.GetRegister();
-        os_ << " \"" << assigned_reg.ToString() << "\"";
+        os_ << " \"" << Register::AllocationIndexToString(assigned_reg) << "\"";
       }
     } else if (range->spilled()) {
       auto top = range->TopLevel();
       int index = -1;
       if (top->HasSpillRange()) {
         index = kMaxInt;  // This hasn't been set yet.
       } else if (top->GetSpillOperand()->IsConstant()) {
         os_ << " \"const(nostack):"
             << ConstantOperand::cast(top->GetSpillOperand())->virtual_register()
             << "\"";
@@ skipping 81 matching lines @@
         os << "#" << SafeId(i) << ":" << SafeMnemonic(i);
       }
       os << ")" << std::endl;
     }
   }
   return os;
 }
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8