Vim语法着色:如何仅突出显示长行？

set colorcolumn=80

function! LongLineHighlight()
    let line_length = strlen(getline('.'))
    if line_length > 80
        highlight OverLength ctermbg=red guibg=red
        execute 'match OverLength /\%>80v.\+/'
    else
        match
    endif
endfunction

autocmd CursorMoved * call LongLineHighlight()
autocmd CursorMovedI * call LongLineHighlight()