#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
Applies so more fixes to headers that may have been missed before for performance optimization.cc @jgong5 @mingfeima @XiaobingSuper @sanchitintel @ashokei @jingxu10 @EikanWang @ezyang since this more in the series of the clang-tidy fixup
This is PR fixes 3 main issues:
1. Use emplacement more in headers
1. Avoid unnecessary copies and use const ref when possible
1. Default any special functions when possible to make them potentially trivial and more readable.
1. There is also one change in this PR that tries to prevent unnecessary math promotion, the rest of these changes are in another PR
Pull Request resolved: https://github.com/pytorch/pytorch/pull/91445
Approved by: https://github.com/ezyang
The big idea is to add `create_unbacked_symfloat` and `create_unbacked_symint` to ShapeEnv, allowing you to allocate symbolic floats/ints corresponding to data you don't know about at compile time. Then, instead of immediately erroring out when you try to call local_scalar_dense on a FakeTensor, we instead create a fresh symint/symfloat and return that.
There a bunch of odds and ends that need to be handled:
* A number of `numel` calls converted to `sym_numel`
* When we finally return from item(), we need to ensure we actually produce a SymInt/SymFloat when appropriate. The previous binding code assumed that you would have to get a normal Python item. I add a pybind11 binding for Scalar (to PyObject only) and refactor the code to use that. There is some trickiness where you are NOT allowed to go through c10::SymInt if there isn't actually any SymInt involved. See comment.
* One of our unit tests tripped an implicit data dependent access which occurs when you pass a Tensor as an argument to a sizes parameter. This is also converted to support symbolic shapes
* We now support tracking bare SymInt/SymFloat returns in proxy tensor mode (this was already in symbolic-shapes branch)
* Whenever we allocate an unbacked symint, we record the stack trace it was allocated at. These get printed when you attempt data dependent access on the symint (e.g., you try to guard on it)
* Subtlety: unbacked symints are not necessarily > 1. I added a test for this.
These unbacked symints are not very useful right now as you will almost always immediately raise an error later when you try to guard on them. The next logical step is adding an assertion refinement system that lets ShapeEnv learn facts about unbacked symints so it can do a better job eliding guards that are unnecessary.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/90624
Approved by: https://github.com/Skylion007, https://github.com/voznesenskym
This refactor was prompted by challenges handling mixed int/float
operations in C++. A previous version of this patch
added overloads for each permutation of int/float and was unwieldy
https://github.com/pytorch/pytorch/pull/87722/ This PR takes a different
approach.
The general outline of the patch is to combine the C++ types SymIntNode
and SymFloatNode into a single type, SymNode. This is type erased; we
no longer know statically at C++ if we have an int/float and have to test
it with the is_int()/is_float() virtual methods. This has a number of
knock on effects.
- We no longer have C++ classes to bind to Python. Instead, we take an
entirely new approach to our Python API, where we have a SymInt/SymFloat
class defined entirely in Python, which hold a SymNode (which corresponds
to the C++ SymNode). However, SymNode is not pybind11-bound; instead,
it lives as-is in Python, and is wrapped into C++ SymNode using PythonSymNode
when it goes into C++. This implies a userland rename.
In principle, it is also possible for the canonical implementation of SymNode
to be written in C++, and then bound to Python with pybind11 (we have
this code, although it is commented out.) However, I did not implement
this as we currently have no C++ implementations of SymNode.
Because we do return SymInt/SymFloat from C++ bindings, the C++ binding
code needs to know how to find these classes. Currently, this is done
just by manually importing torch and getting the attributes.
- Because SymInt/SymFloat are easy Python wrappers, __sym_dispatch__ now
takes SymInt/SymFloat, rather than SymNode, bringing it in line with how
__torch_dispatch__ works.
Some miscellaneous improvements:
- SymInt now has a constructor that takes SymNode. Note that this
constructor is ambiguous if you pass in a subclass of SymNode,
so an explicit downcast is necessary. This means toSymFloat/toSymInt
are no more. This is a mild optimization as it means rvalue reference
works automatically.
- We uniformly use the caster for c10::SymInt/SymFloat, rather than
going the long way via the SymIntNode/SymFloatNode.
- Removed some unnecessary toSymInt/toSymFloat calls in normalize_*
functions, pretty sure this doesn't do anything.
- guard_int is now a free function, since to guard on an int you cannot
assume the method exists. A function can handle both int and SymInt
inputs.
- We clean up the magic method definition code for SymInt/SymFloat/SymNode.
ONLY the user classes (SymInt/SymFloat) get magic methods; SymNode gets
plain methods; this is to help avoid confusion between the two types.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
cc @jansel @mlazos @soumith @voznesenskym @yanboliang @penguinwu @anijain2305
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87817
Approved by: https://github.com/albanD, https://github.com/anjali411
No more "expected tuple but got tuple". We appropriately
grovel in the list/tuple for the element that mismatched
and report what exactly twinged the failure.
invalid_arguments.cpp is a shitshow so I did something
slapdash to get it not completely horrible. See
https://github.com/pytorch/pytorch/issues/87514 for more context.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87601
Approved by: https://github.com/Chillee
- Make toIValue accept SymIntNode and SymFloatNode where number (aka Scalar) is
expected
- Binding for symintlistOptional in python arg parser
- Teach translate to convert from IntArrayRef to ArrayRef<int64_t>
- Don't query _symint function for meta info in LTC unless LTC is
code generating a symint function
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86042
Approved by: https://github.com/Chillee
This is by no means comprehensive, but adds initial support for SymInt as a Scalar.
Things that don't work yet but need to:
- for some reason `torch.add(tensor, sym_int)` got matched to the `add.Tensor(Tensor self, Tensor other, *, Scalar alpha=1) -> Tensor` schema
- `x + sym_int` failed bc we tried to turn `x` into a sym int:
```
"__radd__",
[](c10::SymIntNode a, py::object b) -> c10::SymIntNode {
auto snb = toSymIntNode(a, b);
return a->add(snb);
})
```
- Many more things I'm sure
Pull Request resolved: https://github.com/pytorch/pytorch/pull/84958
Approved by: https://github.com/ezyang
### Description
Adding a custom caster for `c10::SymInt`. This simplifies handling of c10::SymInt on C++/Pytorch boundary. Namely, removing if statements to handle the union nature (e.g. SymIntNode, int) of c10::SymInt.
### Issue
<!-- Link to Issue ticket or RFP -->
### Testing
<!-- How did you test your change? -->
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82692
Approved by: https://github.com/ezyang
Fixes#81774
`TensorOptions` arguments in the JIT schema are optional, but in the Python API these were being translated to non-optional but with a default value. This change makes the arguments accept `None` for consistency with the JIT schema. However, it also means that `dtype=c10::nullopt` was previously completely untested so this also fixes several related bugs.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82241
Approved by: https://github.com/ngimel
Done via
```
git grep -l 'SymbolicIntNode' | xargs sed -i 's/SymbolicIntNode/SymIntNodeImpl/g'
```
Reasoning for the change:
* Sym is shorter than Symbolic, and consistent with SymInt
* You usually will deal in shared_ptr<...>, so we're going to
reserve the shorter name (SymIntNode) for the shared pointer.
But I don't want to update the Python name, so afterwards I ran
```
git grep -l _C.SymIntNodeImpl | xargs sed -i 's/_C.SymIntNodeImpl/_C.SymIntNode/'
```
and manually fixed up the binding code
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82350
Approved by: https://github.com/Krovatkin
This PR adds support for `SymInt`s in python. Namely,
* `THPVariable_size` now returns `sym_sizes()`
* python arg parser is modified to parse PyObjects into ints and `SymbolicIntNode`s
* pybind11 bindings for `SymbolicIntNode` are added, so size expressions can be traced
* a large number of tests added to demonstrate how to implement python symints.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/78135
Approved by: https://github.com/ezyang
Since we plan to have a bunch of code that is sensitive to whether or
not a SymInt contains a symbolic shape or not, it seems like a bad idea
to have an implicit constructor.
For example, code like:
```
sizes_and_strides_.stride_at_unchecked(dim) = 0;
```
would sail through, and the `0` would get implicitly promoted to a
SymInt.
This is a tradeoff though: it makes code that handles `SymInt`s more
clunky as `int64_t`s and integer literals need to be explicitly wrapped
in `SymInt` before being used.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77666
Approved by: https://github.com/ezyang
I figured these out by unconditionally turning on a no-op torch function
mode on the test suite and then fixing errors as they showed up. Here's
what I found:
- _parse_to failed internal assert when __torch_function__'ed because it
claims its name is "to" to the argument parser; added a name override
so we know how to find the correct name
- Infix operator magic methods on Tensor did not uniformly handle
__torch_function__ and TypeError to NotImplemented. Now, we always
do the __torch_function__ handling in
_wrap_type_error_to_not_implemented and your implementation of
__torch_function__ gets its TypeErrors converted to NotImplemented
(for better or for worse; see
https://github.com/pytorch/pytorch/issues/75462 )
- A few cases where code was incorrectly testing if a Tensor was
Tensor-like in the wrong way, now use is_tensor_like (in grad
and in distributions). Also update docs for has_torch_function to
push people to use is_tensor_like.
- is_grads_batched was dropped from grad in handle_torch_function, now
fixed
- Report that you have a torch function even if torch function is
disabled if a mode is enabled. This makes it possible for a mode
to return NotImplemented, pass to a subclass which does some
processing and then pass back to the mode even after the subclass
disables __torch_function__ (so the tensors are treated "as if"
they are regular Tensors). This brings the C++ handling behavior
in line with the Python behavior.
- Make the Python implementation of overloaded types computation match
the C++ version: when torch function is disabled, there are no
overloaded types (because they all report they are not overloaded).
Signed-off-by: Edward Z. Yang <ezyangfb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75484
Approved by: https://github.com/zou3519
Summary:
This PR introduces `SymInt` type to Pytorch which will be used by LTC and AOTAutograd for tracing size arithmetic and tests.
`SymInt` is a C++ union structure [int64_t, SymbolicIntNode*] that wraps around an int64_t field where the value of the field could be an index into a list of `shared_ptr<SymbolicIntNode>` or a real int.
This PR doesn't add any support for actually tracing symbolic ints. i.e. data_ for now can only contain real ints.
```
Goal 1: just to show we can add a type to PyTorch core. (wraps int) LANDEABLE
Finalize the naming - symint
Want the name to be short
Does invoke “size” - NO
SInt/SymInt/SymbolicInt
SInt could mean signed int
sym_int or symint or SymInt (originally it was “int”; capitalized implies object semantics, whereas lowercase implies value semantics)
JIT schema - symint
C++ - symint
```
See more details here: https://docs.google.com/document/d/1iiLNwR5ohAsw_ymfnOpDsyF6L9RTUaHMpD8 (d843f63f2a)YLw-jxEw
Pull Request resolved: https://github.com/pytorch/pytorch/pull/74861
Reviewed By: qihqi, ngimel
Differential Revision: D35226230
Pulled By: Krovatkin
fbshipit-source-id: 34acf342bd50fcaa4d8d5dd49c2fd6a98823a5b3
(cherry picked from commit 218643f63ef181cabb92d13a6e837eb64f2dda3c)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68693
Generation of python bindings for native functions is split over 8
different files. One for each namespace, with the torch namespace
split into 3 shards, and methods in their own file as well. This
change ensures that editing any single (non-method) operator only
causes one of these files to be rebuilt.
Test Plan: Imported from OSS
Reviewed By: jbschlosser
Differential Revision: D32596270
Pulled By: albanD
fbshipit-source-id: 0570ec69e7476b8f1bc21138ba18fe8f95ebbe3f
(cherry picked from commit ba0fc71a3a)
Summary:
Use `Py_ssize_t` when calling Python API
Use `c10::irange` to automatically infer loop type
Use `size_t` or `unsigned` for unsigned type
Partially addresses https://github.com/pytorch/pytorch/issues/69948
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71250
Reviewed By: atalman
Differential Revision: D33569724
Pulled By: malfet
fbshipit-source-id: c9eb75be9859d586c00db2f824c68840488a2822
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66054
I need this function in functorch to support the ability of custom
jitted kernels to invoke torch_function when applicable.
Test Plan: functorch unit tests
Reviewed By: qihqi, ngimel
Differential Revision: D31416599
Pulled By: bertmaher
fbshipit-source-id: 90b57badd6a6b9d505ebfc436869b962b55c66d7
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62030
Remove dtype tracking from Python Storage interface, remove all the different `<type>Storage` classes except for `ByteStorage`, and update serialization accordingly, while maintaining as much FC/BC as possible
Fixes https://github.com/pytorch/pytorch/issues/47442
* **THE SERIALIZATION FORMAT IS FULLY FC/BC.** We worked very hard to make sure this is the case. We will probably want to break FC at some point to make the serialization structure of tensors make more sense, but not today.
* There is now only a single torch.ByteStorage class. Methods like `Tensor.set_` no longer check that the dtype of storage is appropriate.
* As we no longer know what dtype of a storage is, we've **removed** the size method from Storage, replacing it with nbytes. This is to help catch otherwise silent errors where you confuse number of elements with number of bytes.
* `Storage._new_shared` takes a `nbytes` kwarg and will reject previous positional only calls. `Storage._new_with_file` and `_set_from_file` require explicit element size arguments.
* It's no longer possible to convert storages to different types using the float/double/etc methods. Instead, do the conversion using a tensor.
* It's no longer possible to allocate a typed storage directly using FloatStorage/DoubleStorage/etc constructors. Instead, construct a tensor and extract its storage. The classes still exist but they are used purely for unpickling.
* The preexisting serialization format stores dtype with storage, and in fact this dtype is used to determine the dtype of the tensor overall.
To accommodate this case, we introduce a new TypedStorage concept that exists only during unpickling time which is used to temporarily store the dtype so we can construct a tensor. **If you overrode the handling of pickling/unpickling, you MUST add handling for TypedStorage** or your serialization code will degrade to standard file-based serialization.
Original pull request: https://github.com/pytorch/pytorch/pull/59671
Reviewed By: soulitzer, ngimel
Differential Revision: D29466819
Pulled By: ezyang
fbshipit-source-id: 4a14e5d3c2b08e06e558683d97f7378a3180b00e
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64360
This PR adds a (private) enable_python_mode context manager.
(see torch/utils/_python_dispatch.py).
enable_python_mode accepts the type of a __torch_dispatch__ object
as its argument. Whenever an operator gets called inside of the
context manager, it dispatches to the __torch_dispatch__ of
the passed-in type.
Example usage:
```
with enable_python_mode(LoggingTensor):
z = torch.empty([])
assert isinstance(z, LoggingTensor)
```
There are quite a few changes that were made to support this.
First, we added TorchDispatchTypeObject, a C++ struct that represents the
type of a `__torch_dispatch__` object (e.g. LoggingTensor).
It holds both the PyObject* representing the class and a PyInterpreter*
so we know which Python interpreter it came from.
Next, we updated the concrete_dispatch_fn in python_variable.cpp to accept
a `const std::shared_ptr<TorchDispatchTypeObject>&` argument. When this
is null, dispatching happens as usual. When it is non-null, we prepend
the TorchDispatchTypeObject's PyObject* to the overloaded args list so that
it is considered first for dispatch.
To get that to work, we changed how `handle_torch_dispatch_no_python_arg_parser`
works. The "overloaded args list" previously only consisted of Tensor PyObjects,
but now it can have types in addition to Tensors!
- We renamed `append_overloaded_arg` to `append_overloaded_arg`
- We added a new `append_overloaded_type` that appends a type to
overloaded_args
- We added special handling in `handle_torch_dispatch_no_python_arg_parser`
and `append_overloaded_arg` to handle types in addition to Tensors.
Then, there is PythonMode and PythonModeTLS.
- We reuse the DispatchKey::Python dispatch key as a mode key
- We use PythonMode::enter and PythonMode::exit to enable/disable
DispatchKey::Python and set the PythonModeTLS.
- PythonModeTLS stores a TorchDispatchTypeObject as metadata.
- PythonMode is in libtorch_python, and PythonModeTLS is in ATen.
This split is due to the libtorch_python library boundary (because we need
to save TLS in ATen/ThreadLocalState)
- We modify the PythonFallbackKernel to look up
the relevant TorchDispatchTypeObject (if Python Mode is active) and
dispatch using it.
There are two more miscellaneous changes:
- internal_new_from_data (torch/csrc/utils/tensor_new.cpp) gets an
exclude guard. enable_python_mode currently does not handle
torch.tensor and the exclude guard is to prevent a bug.
Future:
- This PR does not allow for the nesting of Python modes. In the future we
should be able to enable this with a more sane no_dispatch API and by changing
the TLS to a stack. For now I did not need this for CompositeImplicitAutograd testing.
Test Plan: - new tests
Reviewed By: ezyang
Differential Revision: D30698082
Pulled By: zou3519
fbshipit-source-id: 7094a90eee6aa51f8b71bc4d91cfb6f49e9691f8
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63496
This PR adds a (private) enable_python_mode context manager.
(see torch/utils/_python_dispatch.py).
enable_python_mode accepts the type of a __torch_dispatch__ object
as its argument. Whenever an operator gets called inside of the
context manager, it dispatches to the __torch_dispatch__ of
the passed-in type.
Example usage:
```
with enable_python_mode(LoggingTensor):
z = torch.empty([])
assert isinstance(z, LoggingTensor)
```
There are quite a few changes that were made to support this.
First, we added TorchDispatchTypeObject, a C++ struct that represents the
type of a `__torch_dispatch__` object (e.g. LoggingTensor).
It holds both the PyObject* representing the class and a PyInterpreter*
so we know which Python interpreter it came from.
Next, we updated the concrete_dispatch_fn in python_variable.cpp to accept
a `const std::shared_ptr<TorchDispatchTypeObject>&` argument. When this
is null, dispatching happens as usual. When it is non-null, we prepend
the TorchDispatchTypeObject's PyObject* to the overloaded args list so that
it is considered first for dispatch.
To get that to work, we changed how `handle_torch_dispatch_no_python_arg_parser`
works. The "overloaded args list" previously only consisted of Tensor PyObjects,
but now it can have types in addition to Tensors!
- We renamed `append_overloaded_arg` to `append_overloaded_arg`
- We added a new `append_overloaded_type` that appends a type to
overloaded_args
- We added special handling in `handle_torch_dispatch_no_python_arg_parser`
and `append_overloaded_arg` to handle types in addition to Tensors.
Then, there is PythonMode and PythonModeTLS.
- We reuse the DispatchKey::Python dispatch key as a mode key
- We use PythonMode::enter and PythonMode::exit to enable/disable
DispatchKey::Python and set the PythonModeTLS.
- PythonModeTLS stores a TorchDispatchTypeObject as metadata.
- PythonMode is in libtorch_python, and PythonModeTLS is in ATen.
This split is due to the libtorch_python library boundary (because we need
to save TLS in ATen/ThreadLocalState)
- We modify the PythonFallbackKernel to look up
the relevant TorchDispatchTypeObject (if Python Mode is active) and
dispatch using it.
There are two more miscellaneous changes:
- internal_new_from_data (torch/csrc/utils/tensor_new.cpp) gets an
exclude guard. enable_python_mode currently does not handle
torch.tensor and the exclude guard is to prevent a bug.
Future:
- This PR does not allow for the nesting of Python modes. In the future we
should be able to enable this with a more sane no_dispatch API and by changing
the TLS to a stack. For now I did not need this for CompositeImplicitAutograd testing.
Test Plan: - new tests
Reviewed By: malfet, albanD
Differential Revision: D30543236
Pulled By: zou3519
fbshipit-source-id: ef5444d96a5a957d1657b7e37dce80f9a497d452
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63411
In order to get this behavior, you have to use append_overloaded,
which I forgot to use in the previous implementation. I exposed
an internal helper function which is more appropriate for dispatch
to Python where we know that an argument is definitely a Tensor (and
this test no longer needs to be done).
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Reviewed By: zou3519
Differential Revision: D30374489
Pulled By: ezyang
fbshipit-source-id: 43b08c00d1958c9b26d82a025d19f0b67bb85590
Summary:
This PR suppresses clang-tidy warnings in the codebase (for now) so that we can re-enable clang-tidy checks on master.
I ran this script to add the `NOLINTNEXTLINE` comments (on a devserver):
```bash
python3 setup.py develop
# Uses same script that's run on CI and adds the -j (parallel), -s (add comments), -k (continue if diagnostic errors are found) options
python3 tools/clang_tidy.py \
-j \
-s \
-k \
-v \
--paths torch/csrc/ \
-g"-torch/csrc/jit/passes/onnx/helper.cpp" \
-g"-torch/csrc/jit/passes/onnx/shape_type_inference.cpp" \
-g"-torch/csrc/jit/serialization/onnx.cpp" \
-g"-torch/csrc/jit/serialization/export.cpp" \
-g"-torch/csrc/jit/serialization/import.cpp" \
-g"-torch/csrc/jit/serialization/import_legacy.cpp" \
-g"-torch/csrc/onnx/init.cpp" \
-g"-torch/csrc/cuda/nccl.*" \
-g"-torch/csrc/cuda/python_nccl.cpp" \
-g"-torch/csrc/autograd/FunctionsManual.cpp" \
-g"-torch/csrc/generic/*.cpp" \
-g"-torch/csrc/jit/codegen/cuda/runtime/*" \
-g"-torch/csrc/deploy/interpreter/interpreter.cpp" \
-g"-torch/csrc/deploy/interpreter/interpreter.h" \
-g"-torch/csrc/deploy/interpreter/interpreter_impl.h" \
-g"-torch/csrc/deploy/interpreter/test_main.cpp"
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60649
Test Plan: Verified changes by re-running the script (without the `-s` option) and seeing no warnings/errors.
Reviewed By: walterddr, janeyx99
Differential Revision: D29504258
Pulled By: 1ntEgr8
fbshipit-source-id: 78310b30ee8213b73ddb4771ad874665323e7a4e
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59760
See https://github.com/pytorch/pytorch/issues/59049
There are some moving parts to this PR, I'll structure this explanation so the straightforward parts go first, and then the less straightforward parts.
**The actual dispatch to Python.** The core logic of dispatch to Python lives in `concrete_dispatch_fn` in `torch/csrc/autograd/python_variable.cpp`. It takes the input IValue stack, scans all the arguments for Tensor arguments, and defers most of the heavy lifting to `handle_torch_function_no_python_arg_parser` which actually does all of the logic for calling out to torch dispatch (in particular, this function handles multiple dispatch situations for you). Because we have a different function name than regular `__torch_function__` handling, `handle_torch_function_no_python_arg_parser` is generalized to accept a magic method name to look for when testing if Tensors have custom handling or not. Unlike `__torch_function__`, by default there is no `__torch_dispatch__` on Tensor classes.
**Maintaining the Python dispatch key.** In order to get to the dispatch to Python logic, we must tag Tensors with the `__torch_dispatch__` magic method with the newly added Python dispatch key (separated from PythonFuncTorch to allow for a transitional period while they migrate to this mechanism). We expose a new private property `_is_python_dispatch` that assists in debugging if a Tensor is participating in Python dispatch or not. We apply the Python dispatch key the first time a PyObject for a Tensor is constructed (THPVariable_NewWithVar), testing if `__torch_dispatch__` exists with then newly added `check_has_torch_dispatch`.
**Shallow copy and detach.** For the simple examples tested in this PR, most creations of Tensor route through the dispatcher. The exception to this is `shallow_copy_and_detach`, which bypasses the dispatcher and is used when saving tensors for backwards. When a Tensor is Python dispatch, we override the behavior of `shallow_copy_and_detach` to instead directly call into `__torch_dispatch__` to perform a `detach` operation (in the same way it would be invoked if you called `detach` directly). Because this Python call is triggered directly from c10::TensorImpl, it must be indirected through `PyInterpreter::detach`, which is the general mechanism for dynamic dispatching to the Python interpreter associated with a TensorImpl.
**torchdeploy compatibility.** The dispatch to Python logic cannot be directly registered to the dispatcher as it is compiled in the Python library, which will get loaded multiple times per torchdeploy interpreter. Thus, we must employ a two phase process. First, we register a fallback inside a non-Python library (aten/src/ATen/core/PythonFallbackKernel.cpp). Its job is to determine the appropriate PyInterpreter to handle the Python dispatch by going through all of the arguments and finding the first argument that has a PyObject/PyInterpreter. With this PyInterpreter, it makes another dynamic dispatch via "dispatch" which will go to the correct torchdeploy interpreter to handle dispatching to actual Python.
**Testing.** We provide a simple example of a LoggingTensor for testing, which can be used to generate TorchScript-like traces to observe what operations are being called when a Tensor is invoked. Although a LoggingTensor would be better implemented via an is-a relationship rather than a has-a relationship (as is done in the test), we've done it this way to show that arbitrarily complex compositions of tensors inside a tensor work properly.
**Known limitations.**
* We haven't adjusted any operator code, so some patterns may not work (as they lose the Python subclass in an unrecoverable way)
* `__torch_function__` must be explicitly disabled with `_disabled_torch_function_impl` otherwise things don't work quite correctly (in particular, what is being disabled is default subclass preservation behavior.)
* We don't ever populate kwargs, even when an argument is kwarg-only
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Differential Revision:
D29017912
D29017912
Test Plan: Imported from OSS
Reviewed By: bdhirsh
Pulled By: ezyang
fbshipit-source-id: a67714d9e541d09203a8cfc85345b8967db86238
