From my experience with diffing a moved segment will only result in showing two unrelated differences (an insert and a cut) which are not identified as a move.

found this proposing other tools I haven't used yet,

http://stackoverflow.com/questions/12590947/using-git-diff-to-detect-code-movement-how-to-use-diff-options

But these methods are language agnostic and don't use semantic knowledge of Perl.