Sometimes, it could be difficult to write a fake class e.g. when the original implementation is using some third-party libraries or users are certain that the class is safe to trace with the real object.
This PR allows user to specify their intention by implementing a "safe_to_trace_with_real_obj" method on their script class.
Test Plan:
`pytest test/export/test_torchbind.py -k safe`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/129586
Approved by: https://github.com/zou3519
Fixes#129601
Background: it's possible that a traceable wrapper subclass will have an optional inner tensor constituent (e.g. NJT's cached min / max sequence lengths). To specify this, the subclass's `__tensor_flatten__()` impl should leave out any unspecified optional inner tensors in the returned list of `attrs`.
This PR guards on the list of inner tensor `attrs` returned in `subclass.__tensor_flatten__()[0]`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/129618
Approved by: https://github.com/anijain2305
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
Adds support for `Variable._execution_engine.queue_callback()`, which is used in FSDP2.
Important tests:
- `pytest -rA test/inductor/test_compiled_autograd.py::TestCompiledAutograd::test_callback_graph_break_throws_error`
- `pytest -rA test/inductor/test_compiled_autograd.py::TestAutogradWithCompiledAutograd::test_callback_adds_callback`
- `PYTORCH_TEST_WITH_DYNAMO=1 python test/test_autograd.py -k TestAutograd.test_callback_adds_callback`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/126366
Approved by: https://github.com/xmfan
Fixes https://github.com/pytorch/pytorch/issues/125720
I was earlier worried that DELETE_* or STORE_* on referent values should result in a graph break, because they could invalidate the weak ref. But then @zou3519 pointed out that weakref invalidation will happen EVENTUALLY, CPython provides no guarantees when the weakref will be invalidated (even when the user calls del x and x is the last reference).
So any code that relies on del x to invalidate the weakref of x right away is BAD code. CPython provide no guarantees. Therefore we can (ab)use this nuance, and can just ignore DELETE_* or STORE_* on the referent objects.
The only corner case is when Dynamo is reconstructing the weakref object. Dynamo will have a hard time being correct here, so just SKIP_FRAME on such a case. This is rare.
Cpython notes
1) https://docs.python.org/3/library/weakref.html
2) https://docs.python.org/3/reference/datamodel.html#index-2
Pull Request resolved: https://github.com/pytorch/pytorch/pull/128533
Approved by: https://github.com/jansel
FIXES#113263. Same idea as in https://github.com/pytorch/pytorch/pull/113417, but we need a more intrusive C API to silently nop default saved tensor hooks, in order to support user-code that use torch.autograd.disable_saved_tensors_hooks (see test_unpack_hooks_can_be_disabled). We mock the output of get_hooks while leaving push/pop untouched.
For compiled autograd, we're firing pack hooks once and unpack hooks twice right now, I'll look into this separately from this issue.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/123196
Approved by: https://github.com/soulitzer
Today inlining builtin nn modules is not compatible with parameter freezing. Freezing parameters and then constant folding them through the graph relies on the assumption that they will not be inputs and will be static across calls to the same graph. When inlining builtin nn modules this assumption is broken and we reuse the same graph for different instances of the same nn module. There are three options 1) abandon constant folding, 2) create a dispatcher layer (like cudagraphs) which will dispatch to the correct constant-folded graph for each distinct set of parameters or 3) recompile
This PR implements 3 by introducing guards on the parameter pointers. This was due to freezing being relatively rare and performance sensistive. 2 Had many more unknowns and 1 is not a viable option due to the drop in performance.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/128355
Approved by: https://github.com/anijain2305
This PR requires a little justification, but let's start with what it does first:
1. When you have a 0d CPU scalar int64/float64 tensor input to a graph, we will preallocate a backed SymInt/SymFloat corresponding to what you would get if you call item() on this tensor. This means you can freely change your input to be a Python int/float or a Tensor with an item() call and end up with exactly the same level of expressivity (specifically, you can guard on the internal SymInt/SymFloat no matter what). By default, the source of the backed SymInt/SymFloat is `L['tensor'].item()`, but if you have promoted a float input into a Tensor, we will cancel out `torch.as_tensor(L['float']).item()` into just `L['float']`.
2. We switch wrap_symfloat to use this, instead of hand crafting the new SymNodeVariable. Everything works out, except that we carefully pass the item() result to tracked fakes (and not the fake Tensor argument)
OK, so why do this at all? There is some marginal benefit where now some item() calls on scalar inputs can be guarded on, but IMO this is a pretty marginal benefit, and if it was the only reason, I wouldn't do this. The real reason for this is that I need to be able to propagate fake tensors through the graphs that are produced by Dynamo, and if I am doing the old custom wrap_symfloat logic, there's no way I can do this, because ordinarily an item() call will cause an unbacked SymInt when I reallocate.
The other obvious way to solve the problem above is to make a HOP alternative that item() that "bakes in" the backed SymInt its supposed to return. But this strategy seems more parsimonious, and it does have the marginal benefit I mentioned above. The main downside is that what I have to do next, is make it so that when I run tensor computation, I also apply the equivalent operations to the SymInt/SymFloat as well. That's next PR.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/126245
Approved by: https://github.com/eellison
ghstack dependencies: #126637
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
- `FakeContext` hides all fields other than ctx.saved_tensors, this dynamo errors when the autograd.Function.backward uses other attrs on ctx and it also doesn't allow fallback to eager.
- If we remove it, we still can't fallback to eager: node variables are already freed (ctx.saved_tensors throws)
- However, we can fallback to "pseudo-eager" by using a duck-typed ctx and routing the ctx.saved_tensors to lifted tensors
- Dynamo tries to inline external_utils.call_backward, treats BackwardCFunction as a AutogradFunctionContextVariable (only used up until we create the fake context: FakeBackwardCFunction)
- we call_function backward from the forward class AutogradFunctionVariable, and we still pass in the fake context as a UserDefinedObjectVariable (can later use AutogradFunctionContextVariable + HOO graph speculate)
Fixes#125489#124827
Pull Request resolved: https://github.com/pytorch/pytorch/pull/125661
Approved by: https://github.com/jansel
While there are some similarities, they are also quite different (one
handles Numpy numbers while the other handles ints. I am also going to
add a wrap_symfloat soon which will do even more different behavior.
So split these out for clarity.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/125483
Approved by: https://github.com/lezcano
ghstack dependencies: #125395, #125419
We guard on key order
1) When a key is a non-constant object
2) When we actually need key order - like .values, .items etc
For dicts/OrderedDicts that do not require key order guarding, we just rely on usual `GuardManger + DictGetItemGuardAccessor`. This is faster than going through the `list(d.keys())` based design for OrderedDicts.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/124779
Approved by: https://github.com/jansel
Update ruff to 0.4.1 .
This version fixes a lot false negatives/false positives, is 20-40% faster, and has various other bug fixes.
Below is a before and after table showing the execution time of ruff lint and ruff format in milliseconds courtesy of https://astral.sh/blog/ruff-v0.4.0
| Repository | Linter (v0.3) | Linter (v0.4) | Formatter (v0.3) | Formatter (v0.4) |
|----------------------------------------------------|---------------|---------------|------------------|------------------|
| [pytorch/pytorch](https://github.com/pytorch/pytorch) | 328.7 | 251.8 | 351.1 | 274.9 |
Pull Request resolved: https://github.com/pytorch/pytorch/pull/124549
Approved by: https://github.com/ezyang
