A64: Add and use a double register which holds the 0.0 value.

src/a64/lithium-codegen-a64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
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 //
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@@ skipping 3899 matching lines @@
   //  Math.pow(-0.0, 0.5) == +0.0
 
   // Catch -infinity inputs first.
   // TODO(jbramley): A constant infinity register would be helpful here.
   __ Fmov(double_scratch(), kFP64NegativeInfinity);
   __ Fcmp(double_scratch(), input);
   __ Fabs(result, input);
   __ B(&done, eq);
 
   // Add +0.0 to convert -0.0 to +0.0.
-  // TODO(jbramley): A constant zero register would be helpful here.
-  __ Fmov(double_scratch(), 0.0);
-  __ Fadd(double_scratch(), input, double_scratch());
+  __ Fadd(double_scratch(), input, fp_zero);
   __ Fsqrt(result, double_scratch());
 
   __ Bind(&done);
 }
 
 
 void LCodeGen::DoPower(LPower* instr) {
   Representation exponent_type = instr->hydrogen()->right()->representation();
   // Having marked this as a call, we can use any registers.
   // Just make sure that the input/output registers are the expected ones.
@@ skipping 1808 matching lines @@
   __ Bind(&out_of_object);
   __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
   // Index is equal to negated out of object property index plus 1.
   __ Sub(result, result, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
   __ Ldr(result, FieldMemOperand(result,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ Bind(&done);
 }
 
 } }  // namespace v8::internal