t = t.mul(x0, y1) // update t so we don't lose t's underlying array
		addAt(z, t, k)

		// add xi*y0<<i, xi*y1*b<<(i+k)
		y0 := y0.norm()
		for i := k; i < len(x); i += k {
			xi := x[i:]
			if len(xi) > k {
				xi = xi[:k]
			}
			xi = xi.norm()
			t = t.mul(xi, y0)
			addAt(z, t, i)
			t = t.mul(xi, y1)
			addAt(z, t, i+k)
		}

		putNat(tp)
	}

	return z.norm()
}

			if len(qhatv) > s {
				subVW(qhatv[s:], qhatv[s:], c)
			}
			addAt(uu[s:], v[s:], 0)
		}
		if qhatv.cmp(uu.norm()) > 0 {
			panic("impossible")
		}
		c := subVV(uu[:len(qhatv)], uu[:len(qhatv)], qhatv)
		if c > 0 {
			subVW(uu[len(qhatv):], uu[len(qhatv):], c)
		}
		addAt(z, qhat, j-B)
		j -= B
	}

	// TODO(rsc): Rewrite loop as described above and delete all this code.

		x = 42
		c <- true
	}()
	_ = &x
	<-c
}

type AddrT struct {
	_ [256]byte
	x int
}

type AddrT2 struct {
	_ [512]byte
	p *AddrT
}

func TestRaceAddrExpr(t *testing.T) {
	c := make(chan bool, 1)
	a := AddrT2{p: &AddrT{x: 42}}
	go func() {
		a.p = &AddrT{x: 43}
		c <- true
	}()
	_ = &a.p.x
	<-c
}

// functions, is the atomic equivalent of:
//
//	if *addr == old {
//		*addr = new
//		return true
//	}
//	return false
//
// The add operation, implemented by the AddT functions, is the atomic
// equivalent of:
//
//	*addr += delta
//	return *addr
//
// The load and store operations, implemented by the LoadT and StoreT
// functions, are the atomic equivalents of "return *addr" and