Is there any function which gives the complete code of the calling routine?

With caveats: yes. See Data::Dump::Streamer and it Deparse() method.

use Data::Dump::Streamer;

## Calling this sub
sub callersCode{ 
    my $d=Data::Dump::Streamer->new; 
    my @i=caller(1); 
    $d->Deparse(1); 
    return scalar $d->Dump( *{$i[3]} )->Out(); 
};;

## from this one
sub fred {
    my( @x ) = @_;
    for ( @x ) {
        m[a] and s[a][A]g;
     }
     print callersCode();
};;

## When called
fred( 1,2,3 );;

## this output is produced
$VAR1 = *::fred;
*::fred = sub {
            BEGIN {
              $^H{'feature_say'} = q(1);
              $^H{'feature_state'} = q(1);
              $^H{'feature_switch'} = q(1);
            }
            my(@x) = @_;
            foreach $_ (@x) {
              s/a/A/g if /a/;
            }
            print callersCode();
          };
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