OP_POP           1382 regcomp.c            r = add_opcode(reg, OP_POP);
OP_POP           6218 regcomp.c        { OP_POP,                 "pop",                  ARG_NON },
OP_POP           2847 regexec.c          CASE(OP_POP)  MOP_IN(OP_POP);