Here's another tybalt89-ish solution:

c:\@Work\Perl\monks>perl -wMstrict -le
"use Test::More 'no_plan';
 use Test::NoWarnings;
 ;;
 use constant W => 0.5;
 ;;
 my @records = (
   'U_TOP_LOGIC/ipre_reg_0/Q,0,0,1,1,0,0,1,1,0,0',
   'U_TOP_LOGIC/ipre_reg_6/Q,1,1,0,0,1,1,0,0,1,1',
   'U_TOP_LOGIC/pre_reck_1/Q,1,1,0,1,1,0,0,1,1,0',
   'U_TOP_LOGIC/pre_reg_10/Q,0,1,0,1,1,0,0,1,1,1',
   'U_TOP_LOGIC/pre_reg_11/Q,0,0,1,0,1,0,0,1,0,1',
   );
 ;;
 my $rx_transition = qr{ (?<= 1) 0 | (?<= 0) 1 }xms;
 ;;
 my @pat = (0);
 for my $record (@records) {
   my (undef, $trans) = split m{ \d/Q, }xms, $record, 2;
   $trans =~ tr/01//cd;
   $pat[ $-[0] ]++ while $trans =~ m{ $rx_transition }xmsg;
   }
 $_ *= W for @pat;
 ;;
 is_deeply \@pat, [ 0, 0.5, 2.5, 1.5, 1.5, 1.5, 1, 1.5, 1.5, 1, ],
           'weighted';
 ;;
 done_testing;
"
ok 1 - weighted
1..1
ok 2 - no warnings
1..2
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Update: You can simplify the code slightly by changing the
    $pat[ $-[0] ]++ while $trans =~ m{ $rx_transition }xmsg;
statement to
    $pat[ $-[0] ] += W while $trans =~ m{ $rx_transition }xmsg;
and getting rid of the
    $_ *= W for @pat;
post-loop weighting fixup statement altogether – but this code might be slightly slower.