TLFLAGS_IN_GCLIST
if (((thrd)->tlflags & TLFLAGS_IN_GCLIST) == 0) { \
(thrd)->tlflags |= TLFLAGS_IN_GCLIST; \
if (((thrd)->tlflags & TLFLAGS_IN_GCLIST) != 0) { \
(thrd)->tlflags &= ~TLFLAGS_IN_GCLIST; \