Emit slightly more compact code in untag double.

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3271 matching lines @@
 
   // Heap number map check.
   __ cmp(FieldOperand(input_reg, HeapObject::kMapOffset),
          Factory::heap_number_map());
   __ j(equal, &heap_number);
 
   __ cmp(input_reg, Factory::undefined_value());
   DeoptimizeIf(not_equal, env);
 
   // Convert undefined to NaN.
-  __ push(input_reg);
-  __ mov(input_reg, Factory::nan_value());
-  __ movdbl(result_reg, FieldOperand(input_reg, HeapNumber::kValueOffset));
-  __ pop(input_reg);
+  ExternalReference nan = ExternalReference::address_of_nan();
+  __ movdbl(result_reg, Operand::StaticVariable(nan));
   __ jmp(&done);
 
   // Heap number to XMM conversion.
   __ bind(&heap_number);
   __ movdbl(result_reg, FieldOperand(input_reg, HeapNumber::kValueOffset));
   __ jmp(&done);
 
   // Smi to XMM conversion
   __ bind(&load_smi);
   __ SmiUntag(input_reg);  // Untag smi before converting to float.
@@ skipping 693 matching lines @@
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32