C-h f indent-region

...
  3) Indent each line via ‘indent-according-to-mode’.
...


##</code><code>##

2) If ‘indent-region-function’ is non-nil, call that function
to indent the region.

##</code><code>##

If ‘cperl-indent-region-fix-constructs’, will improve spacing on
conditional/loop constructs.