$ perl -MDevel::Peek -e 'use utf8; my $s="(\x{5fcd}\x{65e0}\x{53ef}\x{5fcd})"; Dump($s); print length($s), "\n";'
SV = PV(0x8154b00) at 0x8154720
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,POK,pPOK,UTF8)
  PV = 0x816ff80 "(\345\277\215\346\227\240\345\217\257\345\277\215)"\0 [UTF8 "(\x{5fcd}\x{65e0}\x{53ef}\x{5fcd})"]
  CUR = 14
  LEN = 16
6