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pytorch / FBGEMM

FB (Facebook) + GEMM (General Matrix-Matrix Multiplication) - https://code.fb.com/ml-applications/fbgemm/
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Fix torch_dispatch issue in group_index_select_dim0_gpu_backward #2767

Closed egienvalue closed 3 months ago

egienvalue commented 3 months ago

Summary: The group_index_select_dim0_gpu_backward returns tensor list with undefined tensor. It is not compatible to __torch_dispatch__ which call into Python from C++. The undefined tensors in the vector become None in Python. Once it returns to C++ call stack, It can't convert [None,None, Tensor] back to std::vector<at::Tensor>. To solve this problem, the group_index_select_dim0_gpu_backward must return valid tensor list without undefined tensors (the diff used tensor with size {0}). It can set the variable_list to undefined tensor after returned from the pytorch dispatcher, which is a common scenario I have seen in other ops.

Reviewed By: sryap

Differential Revision: D58761943

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facebook-github-bot commented 3 months ago

This pull request was exported from Phabricator. Differential Revision: D58761943

facebook-github-bot commented 3 months ago

This pull request has been merged in pytorch/FBGEMM@b32d59ec6e856c9971c8280463c89cedc1a719f6.