[Turbofan] Remove UnallocatedOperand::set_virtual_register.

src/compiler/instruction-selector.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/instruction-selector.h"
 
 #include <limits>
 
 #include "src/assembler-inl.h"
 #include "src/base/adapters.h"
@@ skipping 284 matching lines @@
     if (next == InstructionOperand::kInvalidVirtualRegister) {
       break;
     }
     rename = next;
   }
   return rename;
 }
 
 void InstructionSelector::TryRename(InstructionOperand* op) {
   if (!op->IsUnallocated()) return;
-  int vreg = UnallocatedOperand::cast(op)->virtual_register();
+  UnallocatedOperand* unalloc = UnallocatedOperand::cast(op);
+  int vreg = unalloc->virtual_register();
   int rename = GetRename(vreg);
   if (rename != vreg) {
-    UnallocatedOperand::cast(op)->set_virtual_register(rename);
+    *unalloc = UnallocatedOperand(*unalloc, rename);
   }
 }
 
 void InstructionSelector::SetRename(const Node* node, const Node* rename) {
   int vreg = GetVirtualRegister(node);
   if (static_cast<size_t>(vreg) >= virtual_register_rename_.size()) {
     int invalid = InstructionOperand::kInvalidVirtualRegister;
     virtual_register_rename_.resize(vreg + 1, invalid);
   }
   virtual_register_rename_[vreg] = GetVirtualRegister(rename);
@@ skipping 2535 matching lines @@
   return new (instruction_zone()) FrameStateDescriptor(
       instruction_zone(), state_info.type(), state_info.bailout_id(),
       state_info.state_combine(), parameters, locals, stack,
       state_info.shared_info(), outer_state);
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8