Code Contribution: 【Lv3】【Operator Development】gather_backward

[StrongSpoon]

Description 任务介绍

Develop backward function for gather operator.
开发gather算子的反向功能。

Requirements 任务要求

Interface 接口
gather_backward(Tensor grad, Tensor self, int dim, Tensor index, bool sparse_grad) -> Tensor
Function reference 功能参考
https://pytorch.org/docs/stable/generated/torch.gather.html#torch-gather
Implementation reference 实现参考
https://github.com/FlagOpen/FlagGems/blob/master/src/flag_gems/ops/gather.py

The operator should support all optional arguments defined in the interface.
算子应支持接口中定义的所有参数选项。

DDL 提交时间

Please submit a Pull Request within 3 weeks after accepting the assignment.
请于接取任务后三周内提交PR。
Please provide both accuracy test and performance test code.
请同时提供实现正确性测试与性能测试代码。