Find the maximum subarray XOR in a given array

Given an array of integers. find the maximum XOR subarray value in given array.

Examples :

Input: arr[] = {1, 2, 3, 4}
Output: 7
The subarray {3, 4} has maximum XOR value

Input: arr[] = {8, 1, 2, 12, 7, 6}
Output: 15
The subarray {1, 2, 12} has maximum XOR value

Input: arr[] = {4, 6}
Output: 6
The subarray {6} has maximum XOR value