Previously, our handling for contiguity was inconsistent in the following ways:
- is_strides_like 2d/3d and is_non_overlapping_and_dense always were computed
based on sizes_and_strides_, even if you had symbolic ints
- Furthermore, even if you set custom policy for strides, these quantities were
not overridable by subclasses
- Furthermore, we didn't even store these fields on ExtraMeta
- We duplicate implementations of compute_contiguous (plain, channels last,
channels last 3d)
- We inconsistently called refresh_numel()/refresh_contiguous(), versus
recomputing it ourselves
This factor makes a consistent strategy for all of the boolean fields, and
for numel computation. After this refactor:
- All layout boolean fields are interposable via strides policy
and can be overridden from Python; you will never access a garbage field
- All layout boolean fields are on ExtraMeta
- You can always call refresh_numel/contiguous, no matter if your Tensor is
contiguous or not
- The numel/layout boolean fields are always populated consistently with
the sizes strides fields (either on Tensor or ExtraMeta), even if you
have custom policy
- There is only one implementation of the actual computation logic
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Differential Revision: [D39907696](https://our.internmc.facebook.com/intern/diff/D39907696)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/85858
Approved by: https://github.com/albanD
Based on @ezyang's suggestion, mode stack now has "one true mode" which is the _only_ mode that can ever be active at the C++ level. That mode's torch dispatch is just to take the top mode in the stack, reenable itself (if we aren't at the end of the mode stack), and run the top mode's torch_{dispatch|function}
This maintains that in the middle of a mode's torch dispatch, the mode itself will not be active. It changes the function the user has to call to see what the current mode is (no longer queries the C++, it's python only) but allows the user to also see the entire mode stack easily
Removes `enable_torch_dispatch_mode` and `.restore()` since neither makes sense in this new setup
### Background
Why do we want this? Well, a pretty common pattern that was coming up was that users had to do something like
```python
## PRE-PR UX
def f(mode):
with mode.restore(): # user needs to understand this restore thing?
...
with Mode() as m:
pass
f(m)
```
Many users were getting error from forgetting to call `.restore` or from forgetting to add the (tbh weird) "mode instantiation" step where they use the mode as a context manager with an empty body. Really, they wanted to treat modes like context managers and just write
```python
## FROM FEEDBACK, USER DESIRED CODE. POSSIBLE POST-PR
def f(mode):
with mode:
...
f(Mode())
```
** Technical Details **
With the old mode stack, we basically had a linked list so the mode itself could only be used once and had a fixed parent. In this new design, the mode stack is just a python list that we're pushing to and popping from. There's only one mode that's ever active at the C++ level and it runs the next mode in the Python list. The modes don't have state on them anymore
Pull Request resolved: https://github.com/pytorch/pytorch/pull/84774
Approved by: https://github.com/ezyang, https://github.com/zou3519
Signed-off-by: Edward Z. Yang <ezyangfb.com>
From @ezyang's original PR:
There are a number of situations where we have non-backend kernels (e.g., CompositeImplicitAutograd, batching rules) which we would like to port to Python, but we have no way to integrate these ports with the overall system while using preexisting C++ registrations otherwise. This PR changes that by introducing a Python dispatcher (which can have its own kernels directly in Python), which can be interpose over ordinary C++ dispatch. The ingredients:
We introduce a new PythonDispatcher dispatch key, that has the same tenor as FuncTorchDynamicLayerFrontMode: it works by getting triggered before every other dispatch key in the dispatch key, and shunting to a Python implementation
The Python dispatcher is a per-interpreter global object that is enabled/disabled via the guard EnablePythonDispatcher/DisablePythonDispatcher. We don't make it compositional as I have no idea what a compositional version of this feature would look like. Because it is global, we don't need to memory manage it and so I use a simpler SafePyHandle (newly added) to control access to this pointer from non-Python C++. Like __torch_dispatch__, we use PyInterpreter to get to the Python interpreter to handle the dispatch.
I need to reimplement dispatch table computation logic in Python. To do this, I expose a lot more helper functions for doing computations on alias dispatch keys and similar. I also improve the pybind11 handling for DispatchKey so that you can either accept the pybind11 bound enum or a string; this simplifies our binding code. See https://github.com/pybind/pybind11/issues/483#issuecomment-1237418106 for how this works; the technique is generally useful.
I need to be able to call backend fallbacks. I do this by permitting you to call at a dispatch key which doesn't have a kernel for the operator; if the kernel doesn't exist, we check the backend fallback table instead.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/84826
Approved by: https://github.com/ezyang
Make it so that it is valid to set metadata after detach calls, like `x.detach().resize_(...)`.
This technically lifts some restrictions around `.data`. This PR means that you can now technically call `x.data.resize_(...)`, which can now directly resize `x` instead of erroring.
My understanding: Before the tensor-variable merge, when `x` and `x.data` were really different tensors, you could resize `x.data` independently of `x`, and during the merge, this error was added to avoid silent confusing behavior changes.
It was agreed that this error has been around long enough (several years) that it's acceptable to drop. cc @albanD @ezyang.
(Ed already had a prototype PR [here](https://github.com/pytorch/pytorch/pull/83545) - I ended up making one to try to slog through test failures).
Pull Request resolved: https://github.com/pytorch/pytorch/pull/83590
Approved by: https://github.com/ezyang
I noticed I was missing tensor creations with modes when I tried
to delete proxy tensor. This was the cause.
Hypothetically, all PyInterpreter calls could get this treatment.
But I think it only matters for detach; the rest do not return
Tensors and most modes will not be interested in them.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/83372
Approved by: https://github.com/zou3519
This reverts commit a58876ace78df1cfeb136cad592487f34d7e02f1.
Reverted https://github.com/pytorch/pytorch/pull/74727 on behalf of https://github.com/seemethere due to Fails internal use cases, might extend out to external use cases as well. Need to assess overall impact of this change more widely
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
Currently we have 2 ways of doing the same thing for torch dispatch and function modes:
`with push_torch_dispatch_mode(X)` or `with X.push(...)`
is now the equivalent of doing
`with X()`
This removes the first API (which is older and private so we don't need to go through a deprecation cycle)
There is some risk here that this might land race with a PR that uses the old API but in general it seems like most are using the `with X()` API or `enable_torch_dispatch_mode(X())` which isn't getting removed.
EDIT: left the `with X.push(...)` API since there were ~3 land races with that over the past day or so. But made it give a warning and ask users to use the other API
Pull Request resolved: https://github.com/pytorch/pytorch/pull/78215
Approved by: https://github.com/ezyang
This PR is doing a few interrelated things, all of which are necessary to get correctness. Read the comment in torch/fx/experimental/proxy_tensor.py for the high level overview.
Let's break down the parts of this PR:
* Bug fix where `enable_torch_dispatch_mode` with `None` doesn't work. This make `enable_torch_dispatch_mode(current_mode.inner)` work which is the basis for how we temporarily disable fake tensor mode.
* Bug fix for when fake tensor mode is combined with a non-mode tensor subclass. This actually could be ablated from this PR but it affects where the logic for allowing non fake tensor inputs with lift goes, so it's all in here in one go. There are some relevant tests for the fix in fake tensor, but it turns out I didn't need this because I'm always using proxy tensors as a mode (which ensures the ordering is right.)
* New `lift_fresh` view operator. Note that like lift, we have to manually write the functionalize kernel for these functions.
* The actual change, which is to save constants when we see them in the proxy tensor mode, and then propagate them as we go (because otherwise you'll handle mutations on constants incorrectly--see test.)
This is mildly BC-breaking if anyone was previously interposing on
at::lift, but this operator was relatively new and I checked
functorch which has no explicit reference to lift. So I think it
should not be too disruptive.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/81192
Approved by: https://github.com/samdow, https://github.com/bdhirsh
I noticed that in some situations torch dispatch modes were being
invoked with a mode active, which isn't supposed to happen (we
disable modes before calling into the user mode.) I also noticed that
I was getting a warning that I had a deprecated non-static definition of
torch dispatch on an argument even though there wasn't any.
It turns out this is because modes were part of the overloaded arguments
list in the Python fallback kernel for torch dispatch. This is wrong;
instead we should rely on the actual dispatching function to consult
modes. This makes the code simpler.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80992
Approved by: https://github.com/zou3519
