pytorch

ec30d902 - Split libtorch.so back into libtorch_{cpu,cuda,hip} (#29731)

Split libtorch.so back into libtorch_{cpu,cuda,hip} (#29731) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/29731 The new structure is that libtorch_cpu contains the bulk of our code, and libtorch depends on libtorch_cpu and libtorch_cuda. Some subtleties about the patch: - There were a few functions that crossed CPU-CUDA boundary without API macros. I just added them, easy enough. An inverse situation was aten/src/THC/THCTensorRandom.cu where we weren't supposed to put API macros directly in a cpp file. - DispatchStub wasn't getting all of its symbols related to static members on DispatchStub exported properly. I tried a few fixes but in the end I just moved everyone off using DispatchStub to dispatch CUDA/HIP (so they just use normal dispatch for those cases.) Additionally, there were some mistakes where people incorrectly were failing to actually import the declaration of the dispatch stub, so added includes for those cases. - torch/csrc/cuda/nccl.cpp was added to the wrong list of SRCS, now fixed (this didn't matter before because previously they were all in the same library) - The dummy file for libtorch was brought back from the dead; it was previously deleted in #20774 - In an initial version of the patch, I forgot to make torch_cuda explicitly depend on torch_cpu. This lead to some very odd errors, most notably "bin/blob_test: hidden symbol `_ZNK6google8protobuf5Arena17OnArenaAllocationEPKSt9type_infom' in lib/l ibprotobuf.a(arena.cc.o) is referenced by DSO" - A number of places in Android/iOS builds have to add torch_cuda explicitly as a library, as they do not have transitive dependency calculation working correctly. This situation also happens with custom C++ extensions. - There's a ROCm compiler bug where extern "C" on functions is not respected. There's a little workaround to handle this. - Because I was too lazy to check if HIPify was converting TORCH_CUDA_API into TORCH_HIP_API, I just made it so HIP build also triggers the TORCH_CUDA_API macro. Eventually, we should translate and keep the nature of TORCH_CUDA_API constant in all cases. Fixes #27215 (as our libraries are smaller), and executes on part of the plan in #29235. Signed-off-by: Edward Z. Yang <ezyang@fb.com> Test Plan: Imported from OSS Differential Revision: D18632773 Pulled By: ezyang fbshipit-source-id: ea717c81e0d7554ede1dc404108603455a81da82