ARM: Make use of d16-d31 when available.

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 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 3015 matching lines @@
 
   if (elements_kind == EXTERNAL_FLOAT_ELEMENTS ||
       elements_kind == EXTERNAL_DOUBLE_ELEMENTS) {
     CpuFeatures::Scope scope(VFP3);
     DwVfpRegister result = ToDoubleRegister(instr->result());
     Operand operand = key_is_constant
         ? Operand(constant_key << element_size_shift)
         : Operand(key, LSL, shift_size);
     __ add(scratch0(), external_pointer, operand);
     if (elements_kind == EXTERNAL_FLOAT_ELEMENTS) {
-      __ vldr(result.low(), scratch0(), additional_offset);
-      __ vcvt_f64_f32(result, result.low());
+      __ vldr(kScratchDoubleReg.low(), scratch0(), additional_offset);
+      __ vcvt_f64_f32(result, kScratchDoubleReg.low());
     } else  {  // i.e. elements_kind == EXTERNAL_DOUBLE_ELEMENTS
       __ vldr(result, scratch0(), additional_offset);
     }
   } else {
     Register result = ToRegister(instr->result());
     MemOperand mem_operand = PrepareKeyedOperand(
         key, external_pointer, key_is_constant, constant_key,
         element_size_shift, shift_size,
         instr->additional_index(), additional_offset);
     switch (elements_kind) {
@@ skipping 2748 matching lines @@
   __ sub(scratch, result, Operand(index, LSL, kPointerSizeLog2 - kSmiTagSize));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal