Significant bytecode generation API change!
The new suggested convention to generating bytecode to call a function is now to wrap instructions that push a callable to the stack with `add_push_null`, then that callable is called with `create_call_function` with `push_null=False` (see diff for examples).
In Python 3.13, NULL is now expected to be pushed after the callable. In <=3.12, the NULL was pushed before the callable. This change abstracts away the exact placement of the NULL, but the developer must be aware that a NULL may be needed when codegen'ing a callable.
This abstraction also reduces the need for the `push_null=True` option in `create_call_function`, which removes the need to rotate a NULL to the right place on the stack with a sequence of `SWAP` instructions.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/129172
Approved by: https://github.com/jansel
The big idea is that floats are treated as Tensors on input/output to the FX graph, but on the inside, we immediately call item() on the synthetic Tensor and record regular float operations on it. Canonicalization to Tensor operations will happen in a standalone FX pass. This behavior is controlled by `specialize_float` config variable when set to False.
The generated graph looks like this for the test `test_unspec_float_output`:
```
def forward(self, L_x_: "f32[3]", L_y_: "f32[]"):
l_x_ = L_x_
l_y_ = L_y_
# File: /data/users/ezyang/a/pytorch/test/dynamo/test_unspec.py:511 in f, code: return x + 1, y * 2
add: "f32[3]" = l_x_ + 1; l_x_ = None
item: "Sym(zf0)" = l_y_.item(); l_y_ = None
mul: "Sym(2*zf0)" = item * 2; item = None
scalar_tensor: "f32[]" = torch.scalar_tensor(mul); mul = None
return (add, scalar_tensor)
```
The ingredients:
* **torch/_dynamo/variables/builder.py** When `specialize_float` is False, we wrap float literals with `wrap_symfloat`. This is an unholy mashup of `wrap_symint` and `wrap_unspecialized_primitive`. The overall strategy is that we first generate a tensor argument (because that's what we want to show up into the FX graph), but then immediately call item() on the tensor argument to get a SymNodeVariable, which we will do the rest of the tracing with. Importantly, this SymNodeVariable is backed with the source of the original float: this means we can guard on the resulting value (something we could NOT do with UnspecializedPythonVariable). This has to be done manually, because if you literally call item() on the tensor, you will end up with an unbacked float. There is a bit of copy paste from wrap_symint and wrap_unspecialized_primitive which we can try to factor out, but this really is its own thing and you should review every line of code in the function.
* **torch/fx/experimental/symbolic_shapes.py** We now can generate guards on float inputs, and these guards are handled inside of ShapeEnv. So we need to be able to allocate (backed!) float symbols, and produce guards for them. Fairly straightforward generalization.
* **torch/_dynamo/codegen.py** I also need to maintain the invariant that there are no float outputs to the FX graph. I chose to do this at codegen time. When we detect a SymNodeVariable on the return stack for a float, we on the fly convert it (via `as_tensor`) to a TensorVariable, which is the true output. We then special case the output bytecode to call item() on it again. The tensor conversion is memoized on SymNodeVariable since we typically run the code generation process twice.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/125325
Approved by: https://github.com/lezcano, https://github.com/jansel
We split install_global_once into two APIs:
- `install_global_by_id(prefix, value) -> name`: installs a global if it hasn't
been installed yet
- `install_global(prefix, value) -> name`: always installs the global (and
generates a unique name for it)
Then, we refactor most callsites of `install_global_unsafe` to one of
the previous. Some callsites cannot be refactored because we create the
global name first, do a lot of stuff with it, and then install it.
This fixes more test flakiness.
Test Plan:
- Existing tests; I can't reliably repro the flakiness
Pull Request resolved: https://github.com/pytorch/pytorch/pull/118100
Approved by: https://github.com/ezyang, https://github.com/mlazos
Fixes https://github.com/pytorch/pytorch/issues/117851
In tests, we ran into an issue where:
- In frame A, Dynamo would install a global
- We call reset()
- reset() did not delete the installed global due to a refcycle
- In frame B, Dynamo would re-use the same global
- Python gc ran, deleting the installed global, leading to the compiled
version of frame B raising NameNotFound
This PR changes the following:
- module globals are now installed at a per-frame basis.
- renames install_global to install_global_unsafe: if the names are not
unique and end up being re-used across frames, then we've got trouble.
Test Plan:
- I tested that this got rid of the test flakiness locally. I'm not sure
how to easily write a test for this, because I don't actually know
what the refcycle in the above is.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/117998
Approved by: https://github.com/ezyang, https://github.com/anijain2305
This prepares the PR where we implement sets in terms of dicts.
To do so, rather than storing internally a dictionary that maps literals
to VariableTrackers, it stores (pretty much) a dictionary from VTs to VTs.
To do so, keys are wrapped in an opaque internal class _Hashable.
The Hashable class is opaque on purpose so that it fails hard if
if it inadvertently leaks back into user code.
We also found and fixed a number of latent bugs and inconsistencies
in the way dynamo checked what can be a dict key. More generally, we
make much clearer what are the things that need to be modified to add
a new supported key type to Dicts.
Fixes [#107595](https://www.internalfb.com/tasks?t=107595)
Fixes [#111603](https://www.internalfb.com/tasks?t=111603)
Re-PR of https://github.com/pytorch/pytorch/pull/111196 sadly due to reverts, we could not reuse @lezcano's original PR.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/116785
Approved by: https://github.com/mlazos
1. Removes calls to `replace_all` and `clone` and makes VTs mutable.
2. Properly handles Tuple Iterator mutation. Previously TupleIterator variables would only be properly reconstructed if they were advanced at least once in a frame. On calls to `next`, the source information would be lost (due to constructing a new iterator without using builder), which would ensure that during codegen the variable would be reconstructed from scratch. Now that VTs are mutated, the source is never lost, so we need to properly track mutation and handle it by replaying calls to `next` at the end of the modified bytecode.
3. Added test for checking iadd side effects, this was missing in our unit test coverage.
4. Fixed two incorrect sources, DelayGraphBreakVariable, and UserMethodVariable both relied on setting the source to AttrSource(parent, name) at the callsite of `var_getattr`.
5. Fixed a bug in inplace adding for lists, it would set the resulting VariableTracker's source to `None` which would utilize a different reconstruct path in codegen. Now this is handled explicitly by reconstructing vars when allow_cache=`False`, so that during side effect replay, the mutated var is correctly updated.
In subsequent PRs:
* Refactoring side effect tracking to be significantly simpler (I think we only need an `is_modified` flag)
* Refactor `next_variables` iterator to match the signature of `next`
* Remove all references to `options` in the code
* Refactor VTs representing mutable collections to implement their own mutation update handling
* Remove clone and/or make it specific to lists for creating slices
* Add mutation tracking/replay for sets
* Add mutation tracking/replay for iter.py
* Removing setting source in builder (it's set at the top level after a var is returned)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/113725
Approved by: https://github.com/jansel
This prepares the PR where we implement sets in terms of dicts.
To do so, rather than storing internally a dictionary that maps literals
to VariableTrackers, it stores (pretty much) a dictionary from VTs to VTs.
To do so, keys are wrapped in an opaque internal class `_Hashable`.
The Hashable class is opaque on purpose so that it fails hard if
if it inadvertently leaks back into user code.
We also found and fixed a number of latent bugs and inconsistencies
in the way dynamo checked what can be a dict key. More generally, we
make much clearer what are the things that need to be modified to add
a new supported key type to Dicts.
Fixes https://github.com/pytorch/pytorch/issues/107595
Fixes https://github.com/pytorch/pytorch/issues/111603
Pull Request resolved: https://github.com/pytorch/pytorch/pull/111196
Approved by: https://github.com/jansel
As part of this diff, I have upgraded the `python_version` config setting to 3.11. `bytecode_transformation.py` (and a few other files) have functions using APIs only available in Python 3.11+. Those APIs are gated by a sys.version_info check in their typeshed .pyi files. So setting the min version to 3.11 allows those functions to typecheck properly.
An alternative is to make the relevant types Any:
```
if sys.version_info >= (3, 11):
_Positions = dis.Positions
else:
_Positions = Any
```
However, with python_version = 3.8, that means we're not getting any useful typechecking signal when encountering values of type _Position.
Changing the python_version to 3.11 does mean that we will stop typechecking codepaths that run only on lower versions, but that seems a small price to pay. It does also mean that we won't catch code that uses newer APIs without the appropriate version check, but again, not sure this has much of an impact.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/112561
Approved by: https://github.com/ezyang
RFC: https://github.com/pytorch/rfcs/pull/54
First commit is the contents of https://github.com/Quansight-Labs/numpy_pytorch_interop/
We have already been using this in core for the last few months as a external dependency. This PR pulls all these into core.
In the next commits, I do a number of things in this order
- Fix a few small issues
- Make the tests that this PR adds pass
- Bend backwards until lintrunner passes
- Remove the optional dependency on `torch_np` and simply rely on the upstreamed code
- Fix a number dynamo tests that were passing before (they were not tasting anything I think) and are not passing now.
Missing from this PR (but not blocking):
- Have a flag that deactivates tracing NumPy functions and simply breaks. There used to be one but after the merge stopped working and I removed it. @lezcano to investigate.
- https://github.com/pytorch/pytorch/pull/106431#issuecomment-1667079543. @voznesenskym to submit a fix after we merge.
All the tests in `tests/torch_np` take about 75s to run.
This was a work by @ev-br, @rgommers @honno and I. I did not create this PR via ghstack (which would have been convenient) as this is a collaboration, and ghstack doesn't allow for shared contributions.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106211
Approved by: https://github.com/ezyang
Issue: #93684
In previous PRs #95849#99560 we redirect `numpy.*`, `<tensor>.numpy()` calls to `torch_np.*` methods and attributes, by creating `NumpyNdarrayVariable` for those calls.
We need to handle `NumpyNdarrayVariable` when graph break happens.
This PR did 2 things:
1. In `codegen.py` we made sure we can reconstruct the value wrapped by `NumpyNdarrayVariable`, to be `torch_np.ndarray` in the stack whenerver we recompiles the subgraph.
2. In `builder.py` we can wrap the value to be `NumpyNdarrayVariable` and save it as graph input.
-----
Starting from commit 6:
## A new design for supporting numpy in dynamo
In short the core concept doesn't change: we still convert `numpy` API calls to `torch_np` API calls. However, instead of wrapping a `torch_np.ndarray` in `NumpyNdarrayVariable`, the new design wraps a `torch.Tensor`.
The reason for doing this change is because we need to keep `torch.Tensor` everywhere in the captured graph, so that it works well with the backend of dynamo. See discussions in https://github.com/Quansight-Labs/numpy_pytorch_interop/issues/142 for details.
### Flow
This is an example showing how do we think about dynamo working on a simple function:
```python
def f(x: torch.Tensor, y: torch.Tensor):
a, b = x.numpy(), y.numpy()
c = np.add(x, y)
return torch.from_numpy(c)
```
```
+------------+ +------------+
torch.Tensor | |numpy.ndarray| |
-------------- .numpy() --------------| |
| | | | +------------------+
+------------+ | numpy.add |numpy.ndarray| |torch.Tensor
+------------+ | --------------| torch.from_numpy --------------
torch.Tensor | |numpy.ndarray| | | |
-------------- .numpy() --------------| | +------------------+
| | | |
+------------+ +------------+
+------------+ +----------------+
torch.Tensor | |torch.Tensor | |
-------------- .detach() --------------| |
| | | | +----------------+ +------------+
+------------+ | |torch_np.ndarray| |torch.Tensor| |torch.Tensor
| torch_np.add -----------------| util.to_tensor -------------| .detach() --------------
+------------+ | | | | | |
torch.Tensor | |torch.Tensor | | +----------------+ +------------+
-------------- .detach() --------------| |
| | | |
+------------+ | +----------------+ |
| wrapper on torch_np.add |
+--------------------------------------------------------+
```
### Approach
`torch_np` APIs can take both `torch_np.ndarray` as well as `torch.Tensor`. What we need to do is to have a wrapper for these APIs to convert the return value back to `torch.Tensor`. This way only the wrapper is showing up in the captured graph, with `torch.Tensor`s as input and `torch.Tensor` as output.
If we have a graph break or we've traced to the end of the program, we need to inspect all the `NumpyNdarrayVariable` in the stack and convert them back to `numpy.ndarray`, to make sure the compiled version is still behaving the same as the eager version.
### Examples
Here's an example of the graph generated:
```python
def fn(x: np.ndarray, y: np.ndarray):
a = x.real
b = y.real
torch._dynamo.graph_break()
return np.add(a, 1), np.add(b, 1)
```
Graph generated:
```
[2023-05-16 10:31:48,737] torch._dynamo.output_graph.__graph: [DEBUG] TRACED GRAPH
__compiled_fn_0 <eval_with_key>.0 opcode name target args kwargs
------------- -------------- ---------------------------------------------------------- ---------------------- --------
placeholder l_x_ L_x_ () {}
placeholder l_y_ L_y_ () {}
call_function from_numpy <built-in method from_numpy of type object at 0x12b1fdc80> (l_x_,) {}
call_function from_numpy_1 <built-in method from_numpy of type object at 0x12b1fdc80> (l_y_,) {}
call_function attr_wrapper <function attr_wrapper at 0x12e8693a0> (from_numpy, 'real') {}
call_function attr_wrapper_1 <function attr_wrapper at 0x12e8693a0> (from_numpy_1, 'real') {}
output output output ((),) {}
[2023-05-16 10:31:48,908] torch._dynamo.output_graph.__graph: [DEBUG] TRACED GRAPH
__compiled_fn_2 <eval_with_key>.1 opcode name target args kwargs
------------- ------------- ---------------------------------------------------------- ------------------------------- --------
placeholder l_a_ L_a_ () {}
placeholder l_b_ L_b_ () {}
call_function from_numpy <built-in method from_numpy of type object at 0x12b1fdc80> (l_a_,) {}
call_function from_numpy_1 <built-in method from_numpy of type object at 0x12b1fdc80> (l_b_,) {}
call_function wrapped_add <Wrapped function <original add>> (from_numpy, 1) {}
call_function wrapped_add_1 <Wrapped function <original add>> (from_numpy_1, 1) {}
output output output ((wrapped_add, wrapped_add_1),) {}
```
### Changes
* `codegen.py`: reconstruct `numpy.ndarray` from `NumpyNdarrayVariable` by adding bytecode to call `utils.to_numpy_helper()`.
* `output_graph.py`: getting rid of legacy code that does exactly what `codegen.py` does, which only handling return case but not graph break case.
* `utils.py`: added helpers to convert `numpy.ndarray` to `torch.Tensor` and vice versa. Also adding a wrapper class that takes in a function. In `__call__` it calls the function and converts its out to `torch.Tensor` (or a list of it).
* `builder.py`: add method to wrap `numpy.ndarray` graph inputs into `NumpyNdarrayVariable`, by calling `torch.numpy` in the proxy.
* `misc.py`: `numpy` API calls goes into `NumpyVariable` and we find the function with the same name in `torch_np` module, then wrap it with the wrapper defined in `utils.py`.
* `tensor.py`, `torch.py`: proxy `tensor.numpy()` to be `torch.detach()` but wrap it with `NumpyNdarrayVariable`. Similarly, `torch.from_numpy()` -> `torch.detach()` but wrap it with `TensorVariable`. In `NumpyNdarrayVariable`, do the similar `torch_np.ndarray` to `torch.Tensor` wrapping for attributes.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100839
Approved by: https://github.com/ezyang
Issue: #93684
# Problem
Reduce graph breaks when dynamo compiles python functions containing numpy functions and ndarray operations.
# Design (as I know it)
* Use torch_np.ndarray(a wrapper of tensor) to back a `VariableTracker`: `NumpyTensorVariable`.
* Translate all attributes and methods calls, on ndarray, to torch_np.ndarray equivalent.
This PR adds `NumpyTensorVariable` and supports:
1. tensor to ndarray, ndarray to tensor
2. numpy functions such as numpy.meshgrid()
3. ndarray attributes such as `itemsize`, `stride`
Next PR will handle returning `np.ndarray` and add support for ndarray methods
Pull Request resolved: https://github.com/pytorch/pytorch/pull/95849
Approved by: https://github.com/ezyang
