Support register as right operand in min/max support.

src/x64/lithium-codegen-x64.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 1403 matching lines @@
     Condition condition = (operation == HMathMinMax::kMathMin)
         ? less_equal
         : greater_equal;
     Register left_reg = ToRegister(left);
     if (right->IsConstantOperand()) {
       Immediate right_imm =
           Immediate(ToInteger32(LConstantOperand::cast(right)));
       __ cmpq(left_reg, right_imm);
       __ j(condition, &return_left, Label::kNear);
       __ movq(left_reg, right_imm);
+    } else if (right->IsRegister()) {
+      Register right_reg = ToRegister(right);
+      __ cmpq(left_reg, right_reg);
+      __ j(condition, &return_left, Label::kNear);
+      __ movq(left_reg, right_reg);
     } else {
       Operand right_op = ToOperand(right);
       __ cmpq(left_reg, right_op);
       __ j(condition, &return_left, Label::kNear);
       __ movq(left_reg, right_op);
     }
     __ bind(&return_left);
   } else {
     ASSERT(instr->hydrogen()->representation().IsDouble());
     Label check_nan_left, check_zero, return_left, return_right;
@@ skipping 3840 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64