OUTER: {
   for (;;) {
      defined( my $_ = <$fh> ) or last OUTER;
      if (/alpha/) {
         f();
         last;
      } else {
         g();
      }
   }

   while (<$fh>) {
      g();
   }
}

##</code><code>##

OUTER: {
   defined( my $_ = <$fh> ) or last OUTER;

   for (;;) {
      if (/alpha/) {
         f();
         last;
      }

      defined( $_ = <$fh> ) or last OUTER;
   }

   for (;;) {
      g();

      defined( $_ = <$fh> ) or last OUTER;
   }
}

##</code><code>##

LOOP: {
   defined( my $_ = <$fh> ) or last;

   if (/alpha/) {
      f();
      redo;
   }

   for (;;) {
      g();
      defined( $_ = <$fh> ) or last;
   }
}