mark_stack        612 gc/mark.c      mse * GC_mark_from(mark_stack_top, mark_stack, mark_stack_limit)
mark_stack        614 gc/mark.c      mse * mark_stack;
mark_stack        632 gc/mark.c        while (mark_stack_top >= mark_stack && credit >= 0) {
mark_stack        634 gc/mark.c        while ((((ptr_t)mark_stack_top - (ptr_t)mark_stack) | credit)