AoC day 14 (pt2), Perl

#!/usr/bin/perl

use strict;
use warnings;
no warnings qw(portable);

use List::AllUtils  qw(sum indexes);

my %mem;
my $or_mask;
my @float;

sub recurse_write {
    my ($loc, $val, @float) = @_;

    if (!@float) {
        $mem{$loc} = $val;
    } else {
        my $bit  = 1 << (shift @float);
        &recurse_write( $loc & ~$bit, $val, @float );
        &recurse_write( $loc |  $bit,  $val, @float );
    }
}

while (<>) {
    if (m#mask = ([10X]+)#) {
        $or_mask  = eval( "0b" . ($1 =~ y/X/0/r) );
        @float = indexes { $_ eq 'X' } reverse split( //, $1 );

    } elsif (m#mem\[(\d+)\] = (\d+)#) {
        &recurse_write( $1 | $or_mask, $2, @float );
    }
}

print "Part 2: ", sum( values %mem ), "\n";