You could create a LineInfo file during a run of the program by setting the environment variable PERLDB_OPTS to NonStop=1 LineInfo=db.out AutoTrace and run the file with perl -d flag, and then parse the db.out file.
The file will contain all the code you've "touched" plus a line that tells you where perl found it, like

strict::bits(C:/Perl/lib/strict.pm:95):
95:        foreach my $s (@_){ $bits |= $bitmask{$s} || 0; };
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You will know which functions you have used during that run, which may or may not be all the functions that your code can use.

/brother t0mas