The value register in storefield(smi) is not used as a temp

src/x64/lithium-x64.cc

 // Copyright 2012 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/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/hydrogen-osr.h"
 #include "src/lithium-inl.h"
@@ skipping 2380 matching lines @@
       HConstant::cast(instr->value())->NotInNewSpace() &&
       !instr->field_representation().IsDouble();
 
   LOperand* val;
   if (needs_write_barrier) {
     val = UseTempRegister(instr->value());
   } else if (is_external_location) {
     val = UseFixed(instr->value(), rax);
   } else if (can_be_constant) {
     val = UseRegisterOrConstant(instr->value());
-  } else if (instr->field_representation().IsSmi()) {
-    val = UseRegister(instr->value());
   } else if (instr->field_representation().IsDouble()) {
     val = UseRegisterAtStart(instr->value());
   } else {
     val = UseRegister(instr->value());
   }
 
   // We only need a scratch register if we have a write barrier or we
   // have a store into the properties array (not in-object-property).
   LOperand* temp = (!is_in_object || needs_write_barrier ||
       needs_write_barrier_for_map) ? TempRegister() : NULL;
@@ skipping 279 matching lines @@
   LOperand* function = UseRegisterAtStart(instr->function());
   LAllocateBlockContext* result =
       new(zone()) LAllocateBlockContext(context, function);
   return MarkAsCall(DefineFixed(result, rsi), instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64