OP_BACKREF2      1685 ext/mbstring/oniguruma/regcomp.c 	  case 2:  r = add_opcode(reg, OP_BACKREF2); break;
OP_BACKREF2      5717 ext/mbstring/oniguruma/regcomp.c   { OP_BACKREF2,            "backref2",             ARG_NON },
OP_BACKREF2      2132 ext/mbstring/oniguruma/regexec.c     case OP_BACKREF2:  MOP_IN(OP_BACKREF2);