copy(orig[nsends:], orig[len(cases)-nrecvs:])
	}

	order := make([]uint16, 2*(nsends+nrecvs))
	var pc0 *uintptr
	if raceenabled {
		pcs := make([]uintptr, nsends+nrecvs)
		for i := range pcs {
			selectsetpc(&pcs[i])
		}
		pc0 = &pcs[0]
	}

	chosen, recvOK := selectgo(&sel[0], &order[0], pc0, nsends, nrecvs, dflt == -1)

	// Translate chosen back to caller's ordering.
	if chosen < 0 {

func selectnbsend(hchan chan<- any, elem *any) bool
func selectnbrecv(elem *any, hchan <-chan any) (bool, bool)

func selectsetpc(pc *uintptr)
func selectgo(cas0 *byte, order0 *byte, pc0 *uintptr, nsends int, nrecvs int, block bool) (int, bool)
func block()

func makeslice(typ *byte, len int, cap int) unsafe.Pointer
func makeslice64(typ *byte, len int64, cap int64) unsafe.Pointer