OP_POP_STOP_BT   1392 regcomp.c            r = add_opcode(reg, OP_POP_STOP_BT);
OP_POP_STOP_BT   6236 regcomp.c        { OP_POP_STOP_BT,          "pop-stop-bt",          ARG_NON },
OP_POP_STOP_BT   3001 regexec.c          CASE(OP_POP_STOP_BT)  MOP_IN(OP_POP_STOP_BT);