[Interpreter] Reduce temporary register usage in generated bytecode.

src/interpreter/bytecodes.h

Index: src/interpreter/bytecodes.h
diff --git a/src/interpreter/bytecodes.h b/src/interpreter/bytecodes.h
index 8f65c6e438738791df3de2c3bafb2c4b53623153..ee2500626b3988d795961e8bbc059ac836f8315e 100644
--- a/src/interpreter/bytecodes.h
+++ b/src/interpreter/bytecodes.h
@@ -210,8 +210,18 @@ class 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;