def bit_length(intval):
    """
    Return the number of bits necessary to represent integer `intval`.
    """
    assert isinstance(intval, int)
    if intval >= 0:
        return len(bin(intval)) - 2
    else:
        return len(bin(-intval - 1)) - 2

    Return the number of bits necessary to represent integer `intval`.
    
numba/core/utils.py