MIPS[64]: Fix `MIPS: Improve Float(32|64)(Max|Min)`.

src/crankshaft/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.7
 // 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 1748 matching lines @@
      __  Movn(result_reg, left_reg, scratch);
      __  Movz(result_reg, right_reg, scratch);
     }
   } else {
     DCHECK(instr->hydrogen()->representation().IsDouble());
     FPURegister left_reg = ToDoubleRegister(left);
     FPURegister right_reg = ToDoubleRegister(right);
     FPURegister result_reg = ToDoubleRegister(instr->result());
 
     Label nan, done;
-    if (operation == HMathMinMax::kMathMax) {
+    if (left_reg.is(right_reg)) {
+      __ Move(result_reg, left_reg);
+    } else if (operation == HMathMinMax::kMathMax) {
       __ Float64Max(result_reg, left_reg, right_reg, &nan);
     } else {
       DCHECK(operation == HMathMinMax::kMathMin);
       __ Float64Min(result_reg, left_reg, right_reg, &nan);
     }
     __ Branch(&done);
 
     __ bind(&nan);
     __ add_d(result_reg, left_reg, right_reg);
 
@@ skipping 3634 matching lines @@
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8