Thanks pme another method to solve , following is my code and what I want :

 
#!/usr/bin/perl
use 5.010;
use strict;
use warnings;

my $port_name = 'sdm_yout_i[1]';
$port_name =~ s/\[|\]/\\$&/g; # escaping [ and ]
open my $fh,         "tt.txt"     or die $!;
while (<$fh>)
{
    if  ( /\.([0-9a-z_]+?) \( \{.*?${port_name} .*?,/ ) {
            print '$port_name = ' ; say $port_name;
            print '$cell name = ' ; say $1;
    }
    
}
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Output :

 
$port_name = sdm_yout_i\[1\]
$cell name = sdm_yout_i
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