OP_BACKREF2      1775 regcomp.c      	  case 2:  r = add_opcode(reg, OP_BACKREF2); break;
OP_BACKREF2      6200 regcomp.c        { OP_BACKREF2,            "backref2",             ARG_NON },
OP_BACKREF2      2525 regexec.c          CASE(OP_BACKREF2)  MOP_IN(OP_BACKREF2);