use strict;
use File::Basename;

my %count;
my @mask = (
        '/some/path/',
        'some/other/path',
        'another/path',
);

my $regex = join '|', @mask;
# Now you have a list of alternatives $regex = qr<GET (.*\b(?:$regex)\b.*) HTTP/1.1" 200 [0-9].*> 
# now the regex is precompiled
# N.B. I added \b to make the filename only match on word boundaries.
# So some/path won't match anothersome/path
# but it will match another/some/path

open F, "access.log";

while (<F>) {
        if (/$regex/) {
                ++$count{basename($1)};
        }
}

foreach (sort keys %count) {
        print $_," = ",$count{$_},"\n";
}