the specific meaning of keyword opts in res_cand

[summerban]

hi：
I tried to figure out the specific meaning of c[opts] in pick_sig.py
such as:
1:trim_non_tail_roots:
2:frag
3:trim_tail_call_args
4:func_existence_test: represents whether this function can be found in system symbol table?
5:trim_tail_abs_jmp:
6:match_fmt_str：means this patch has format string change?

could you please give me a explaination
thank you very much