LoadUint32() doesn't need a scratch register.

src/x64/lithium-x64.h

 // 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.
 
 #ifndef V8_X64_LITHIUM_X64_H_
 #define V8_X64_LITHIUM_X64_H_
 
 #include "hydrogen.h"
 #include "lithium-allocator.h"
 #include "lithium.h"
@@ skipping 1949 matching lines @@
   explicit LInteger32ToDouble(LOperand* value) {
     inputs_[0] = value;
   }
 
   LOperand* value() { return inputs_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(Integer32ToDouble, "int32-to-double")
 };
 
 
-class LUint32ToDouble V8_FINAL : public LTemplateInstruction<1, 1, 1> {
+class LUint32ToDouble V8_FINAL : public LTemplateInstruction<1, 1, 0> {
  public:
-  explicit LUint32ToDouble(LOperand* value, LOperand* temp) {
+  explicit LUint32ToDouble(LOperand* value) {
     inputs_[0] = value;
-    temps_[0] = temp;
   }
 
   LOperand* value() { return inputs_[0]; }
-  LOperand* temp() { return temps_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(Uint32ToDouble, "uint32-to-double")
 };
 
 
 class LNumberTagI V8_FINAL : public LTemplateInstruction<1, 1, 0> {
  public:
   explicit LNumberTagI(LOperand* value) {
     inputs_[0] = value;
   }
@@ skipping 838 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_