vm_backtrace       18 vm_eval.c      static inline VALUE vm_backtrace(rb_thread_t *th, int lev);
vm_backtrace      758 vm_eval.c      		    (bt2 = vm_backtrace(th, -2), RARRAY_LEN(bt2) > 0)) {
vm_backtrace     1303 vm_eval.c          return vm_backtrace(GET_THREAD(), lev);
vm_backtrace     1312 vm_eval.c          ary = vm_backtrace(GET_THREAD(), -1);
vm_backtrace     1321 vm_eval.c          return vm_backtrace(GET_THREAD(), -1);