[BC-Breaking] Separate `stream_id`, `device_index`, and `device_type` in `pack` and `unpack` for `Streams` (#81596)
#75854
A naive attempt at working around the limitations of using a single 64-bit integer to pack `stream_id`, `device_index`, and `device_type`.
Stills needs sanity checks, testing, and minimization of BC-breaking changes.
Currently a Holder for the `StreamData3` struct is used for `IValue` compatibility. While doing this seems to work for `ivalue.h` and `ivalue_inl.h`, this doesn't seem to be naively working for the JIT CUDA stream wrapper? (Something about ambiguous calls if an `intrusive_ptr` to `c10::ivalue::StreamData3Holder` is used as the return type for `pack()`. It turns out that the methods required to access the fields for rematerializing a CUDA Stream are basically already present anyway, so `pack` is simply removed in the wrapper for now and the methods to access the required fields are called directly.
CC @ptrblck
Pull Request resolved: https://github.com/pytorch/pytorch/pull/81596
Approved by: https://github.com/ezyang
