paddle1.8.1动态图：
本来想写：index_select(hx[0], permutation, dim=1)，
结果写成：index_select(hx[0], permutation)，索引越界不报错。

hx[0]和permutation如下所示：

hx[0].shape = [6, 27, 400]
permutation.shape = [27]
permutation.numpy() =array([16, 22,  5,  0, 26, 11, 23,  2, 10, 15,  3,  6,  1,  9, 21, 20, 18, 19,  8, 14, 13,  7, 12, 24, 25, 17,  4], dtype=int64)

执行上面的代码前三个batch没报错，第4个batch时core掉。