!181 support tensor index data type int64 for tensor get item

Merge pull request !181 from zhangbuxue/support_tensor_index_int64

docs/source_en/constraints_on_network_construction.md

@@ -105,10 +105,11 @@ The index operation includes `tuple` and` Tensor`. The following focuses on the
   - Assignment: Not supported yet.
   
 - Tensor index: index is `Tensor`
-   - Value: `tensor_x [index]`, `index` must be `Tensor` of type `int32`, the element value range is `[0, tensor_x.shape[0])`.
+   - Value: `tensor_x [index]`, `index` must be `Tensor` of data type `int32` or `int64`,
+     the element value range is `[0, tensor_x.shape[0])`.
    - Assignment: `tensor_x [index] = U`.
       - `tensor_x` data type must be one of the following: `float16`, `float32`, `int8`, `uint8`.
-      - `index` must be `Tensor` of type `int32`, the element value range is `[0, tensor_x.shape [0])`.
+      - `index` must be `Tensor` of data type `int32`, the element value range is `[0, tensor_x.shape [0])`.
       - `U` can be `Number`, `Tensor`, `Tuple` only containing `Number`, `Tuple` only containing `Tensor`.
         - Single `Number` or every `Number` in  `Tuple` must be the same type as `tensor_x`, ie
           When the data type of `tensor_x` is `uint8` or `int8`, the `Number` type should be `int`;

docs/source_zh_cn/constraints_on_network_construction.md

@@ -102,7 +102,7 @@
   - 取值：`tensor_x[True]`。
   - 赋值：暂不支持。
 - Tensor索引：index为`Tensor`
-  - 取值：`tensor_x[index]`，`index`必须是`int32`类型的`Tensor`，元素取值范围在`[0, tensor_x.shape[0])`。
+  - 取值：`tensor_x[index]`，`index`必须是`int32`、`int64`类型的`Tensor`，元素取值范围在`[0, tensor_x.shape[0])`。
   - 赋值：`tensor_x[index]=U`。
     - `tensor_x`的数据类型必须是下面一种： `float16`，`float32`，`int8`，`uint8`。
     - `index`必须是`int32`类型的`Tensor`，元素取值范围在`[0, tensor_x.shape[0])`。