} else if (J->parent == 0 && !bc_isret(bc_op(J->cur.startins))) {
/* Return to lower frame would leave the loop in a root trace. */
lj_trace_err(J, LJ_TRERR_LLEAVE);
+ } else if (J->needsnap) { /* Tailcalled to ff with side-effects. */
+ lj_trace_err(J, LJ_TRERR_NYIRETL); /* No way to insert snapshot here. */
} else { /* Return to lower frame. Guard for the target we return to. */
TRef trpt = lj_ir_kgc(J, obj2gco(pt), IRT_PROTO);
TRef trpc = lj_ir_kptr(J, (void *)frame_pc(frame));