Looking for how to do --regex-c ctags equivalent

Hi All,

I am using global to tag the Linux kernel source and some recent
changes made me look for --regex based conversion during tag
generation. exuberant-ctags support --regex option which helps to
achive things like

  --regex-c='/^SYSCALL_DEFINE[[:digit:]]?\(([^,)]*).*/sys_\1/'


That is needed so that if i do a find_tag on sys_open it goes to the
below definition.

SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode)

Is there a way i can do the same using gtags. I don't want to use
ctags mode in gtags-parser.

-aneesh