[Interpreter] Reduce temporary register usage in generated bytecode.

src/interpreter/bytecodes.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_INTERPRETER_BYTECODES_H_
 #define V8_INTERPRETER_BYTECODES_H_
 
 #include <iosfwd>
 
 // Clients of this interface shouldn't depend on lots of interpreter internals.
@@ skipping 193 matching lines @@
   bool is_function_context() const;
 
   static Register FromOperand(uint8_t operand);
   uint8_t ToOperand() const;
 
   static bool AreContiguous(Register reg1, Register reg2,
                             Register reg3 = Register(),
                             Register reg4 = Register(),
                             Register reg5 = Register());
 
-  bool operator==(const Register& o) const { return o.index() == index(); }
-  bool operator!=(const Register& o) const { return o.index() != index(); }
+  bool operator==(const Register& other) const {
+    return index() == other.index();
+  }
+  bool operator!=(const Register& other) const {
+    return index() != other.index();
+  }
+  bool operator<(const Register& other) const {
+    return index() < other.index();
+  }
+  bool operator<=(const Register& other) const {
+    return index() <= other.index();
+  }
 
  private:
   static const int kIllegalIndex = kMaxInt;
 
   void* operator new(size_t size);
   void operator delete(void* p);
 
   int index_;
 };
 
@@ skipping 58 matching lines @@
 
 std::ostream& operator<<(std::ostream& os, const Bytecode& bytecode);
 std::ostream& operator<<(std::ostream& os, const OperandType& operand_type);
 std::ostream& operator<<(std::ostream& os, const OperandSize& operand_type);
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_BYTECODES_H_