LoadUint32() doesn't need a scratch register.

src/x64/lithium-codegen-x64.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 "v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "x64/lithium-codegen-x64.h"
 #include "code-stubs.h"
@@ skipping 4513 matching lines @@
     __ Cvtlsi2sd(ToDoubleRegister(output), ToRegister(input));
   } else {
     __ Cvtlsi2sd(ToDoubleRegister(output), ToOperand(input));
   }
 }
 
 
 void LCodeGen::DoUint32ToDouble(LUint32ToDouble* instr) {
   LOperand* input = instr->value();
   LOperand* output = instr->result();
-  LOperand* temp = instr->temp();
 
-  __ LoadUint32(ToDoubleRegister(output),
-                ToRegister(input),
-                ToDoubleRegister(temp));
+  __ LoadUint32(ToDoubleRegister(output), ToRegister(input));
 }
 
 
 void LCodeGen::DoNumberTagI(LNumberTagI* instr) {
   LOperand* input = instr->value();
   ASSERT(input->IsRegister() && input->Equals(instr->result()));
   Register reg = ToRegister(input);
 
   __ Integer32ToSmi(reg, reg);
 }
@@ skipping 26 matching lines @@
 
 void LCodeGen::DoDeferredNumberTagU(LNumberTagU* instr) {
   Label done, slow;
   Register reg = ToRegister(instr->value());
   Register tmp = ToRegister(instr->temp1());
   XMMRegister temp_xmm = ToDoubleRegister(instr->temp2());
 
   // Load value into temp_xmm which will be preserved across potential call to
   // runtime (MacroAssembler::EnterExitFrameEpilogue preserves only allocatable
   // XMM registers on x64).
-  XMMRegister xmm_scratch = double_scratch0();
-  __ LoadUint32(temp_xmm, reg, xmm_scratch);
+  __ LoadUint32(temp_xmm, reg);
 
   if (FLAG_inline_new) {
     __ AllocateHeapNumber(reg, tmp, &slow);
     __ jmp(&done, Label::kNear);
   }
 
   // Slow case: Call the runtime system to do the number allocation.
   __ bind(&slow);
   {
     // Put a valid pointer value in the stack slot where the result
@@ skipping 1103 matching lines @@
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64