}
	var m uint64 = magic64
	magicptr := uintptr(m)
	x.before = magicptr
	x.after = magicptr
	x.i = ^uintptr(0)
	j := x.i
	for mask := uintptr(1); mask != 0; mask <<= 1 {
		old := x.i
		k := AndUintptr(&x.i, ^mask)
		j &= ^mask
		if x.i != j || k != old {
			t.Fatalf("mask=%d i=%d j=%d k=%d old=%d", mask, x.i, j, k, old)
		}
	}
	if x.before != magicptr || x.after != magicptr {