This PR was inspired by internal models that were cache missing due to PGO. At a high level the problem looks as follows
Run 1, Invocation 1: We do static compile, save some example values in PGO/automatic dynamic
Run 1, Invocation 2: We detect varying inputs, do dynamic compile, get a dynamic graph and save to PGO. Crucially what we save to PGO is actually a superset of what is actually dynamic. If we notice an input was varying, we mark it as dynamic in PGO even if later on that value gets specialized. When a value gets specialized, we actually remove the symbol from the graph. This results in an interesting conundrum where although we are producing the same isomorphic graph, PGO makes the second run cache miss. Let's see how....
Run 2, Invocation 1: We fetch the PGO, over-mark things as dynamic, get a fx graph, look it up in the cache and... whoops! cache miss! This is because of the aforementioned behavior where the PGO profile will cause us to over-allocate symbols. In practice this means we end up saving a graph in cache with symbols x:s1, y:s3 and on second attempt we cache miss with x:s1, y:s6 where symbols s3,s4,s5 were all optimistically marked dynamic by PGO and subsequently specialized.
We solve this problem by hashing the source names. This ensures somewhat stable assignment. To prevent catastrophic symbol collisions, we use linear probing to ensure no collisions.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/149665
Approved by: https://github.com/Mingming-Ding, https://github.com/laithsakka
This PR was inspired by internal models that were cache missing due to PGO. At a high level the problem looks as follows
Run 1, Invocation 1: We do static compile, save some example values in PGO/automatic dynamic
Run 1, Invocation 2: We detect varying inputs, do dynamic compile, get a dynamic graph and save to PGO. Crucially what we save to PGO is actually a superset of what is actually dynamic. If we notice an input was varying, we mark it as dynamic in PGO even if later on that value gets specialized. When a value gets specialized, we actually remove the symbol from the graph. This results in an interesting conundrum where although we are producing the same isomorphic graph, PGO makes the second run cache miss. Let's see how....
Run 2, Invocation 1: We fetch the PGO, over-mark things as dynamic, get a fx graph, look it up in the cache and... whoops! cache miss! This is because of the aforementioned behavior where the PGO profile will cause us to over-allocate symbols. In practice this means we end up saving a graph in cache with symbols x:s1, y:s3 and on second attempt we cache miss with x:s1, y:s6 where symbols s3,s4,s5 were all optimistically marked dynamic by PGO and subsequently specialized.
We solve this problem by hashing the source names. This ensures somewhat stable assignment. To prevent catastrophic symbol collisions, we use linear probing to ensure no collisions.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/149665
Approved by: https://github.com/Mingming-Ding, https://github.com/laithsakka
PR does following
* Turns `inference_mode` to False and `no_grad` for `convert_frame`, if the inference_mode is on globally.
* Turns off inference_mode for fake tensor prop. This ensures that converting from real inference tensor to a fake tensor removes the inference-ness.
* Graph breaks on is_inference and is_inference_mode_enabled.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/149321
Approved by: https://github.com/jansel, https://github.com/zou3519
We've root caused this to correctly throwing attribute error on ScriptFunction
when missing attributes are caused. This PR will fix crashes that are showing
up. I'm going to stack a second PR to fix torch._c.ScriptFunction just being a
very badly behaving python object (which should also fix this
Pull Request resolved: https://github.com/pytorch/pytorch/pull/147894
Approved by: https://github.com/jansel
This PR adds support for list subclasses. Among other things are
1) Tracking the mutations on internal vts like `_dict_vt` and `_list_vt` using sources. This helps identify if there was a mutation in the underlying data structures, and we need to reconstruct it.
2) `UserDefinedObjectVariable` now has a new method - `is_modified` which `side_effect` infra relies upon to check mutations in the underlying vts (like `_dict_vt`).
3) `reconstruction` logic ensures that we use `dict.__getitem__` and `list.__getitem__` methods. This is super important because we don't want to call the overridden `__getitem__` methods.
If this PR is hard to review, please let me know. I can break it into several small PRs.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/146819
Approved by: https://github.com/StrongerXi, https://github.com/jansel
Earlier if there were no ops in the graph, fullgraph=True will also fallback to eager. This hides issues in testing, where we silently fallback to eager, and do not test optimized bytecode. As can be seen in the PR, I had to fix several tests when I forced to use the optimized bytecode in the absence of graph. A few failing tests will be fixed in follow up PRs.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/146527
Approved by: https://github.com/zou3519, https://github.com/StrongerXi
This enables a check that which a class which only inherits from immutable classes like str, tuple, and NamedTuple, also defined `__slots__` so they don't allocate memory unnecessarily. This also ensure contributors think about how they define their classes with subclass NamedTuples and str, of which we have many in our codebase
Pull Request resolved: https://github.com/pytorch/pytorch/pull/146276
Approved by: https://github.com/aorenste
Fixes#130559
* Intro
This PR adds support for `@contextmanager` in Dynamo. We chose to limit the
scope of this work to only `@contextmanager` and plan to handle generators fully
in #141055 (still in draft).
* Motivation
Dynamo lacks support for generator functions. When it encounters one, it traces
it as if it were a regular function. This is problematic because it can lead to
incorrect behavior. To illustrate, consider the test case below:
```python
import torch
import contextlib
@contextlib.contextmanager
def set_default_dtype(dtype):
old_dtype = torch.get_default_dtype()
try:
torch.set_default_dtype(dtype)
yield
finally:
torch.set_default_dtype(old_dtype)
@torch.compile(backend="eager", fullgraph=True)
def fn():
with set_default_dtype(torch.float64):
x = torch.tensor([3.0, 3.0 + 5.0j])
return x
```
Before this work, Dynamo would not stop at the `yield`, and the graph produced
would contain both calls to `set_default_dtype` executed one after the other.
This is incorrect because the context manager should execute code before and
after the `yield`.
* List of changes
`YIELD_VALUE` now raises an exception (`YieldValueOp`) to signal that control
flow must be suspended and returned to the caller. Additionally, `RETURN_VALUE`
behaves differently in a generator function. Unlike regular functions, where
`RETURN_VALUE` indicates the final result, in generators it signifies that the
generator is exhausted and implicitly raises `StopIteration`.
A new `VariableTracker` named `FunctionDecoratedByContextlibContextManagerVariable`
was introduced to handle `@contextmanager`. This variable tracker acts not just
as a wrapper for the original function but also maintains an internal `tx`
(InstructionTranslator) object to suspend and return control flow to the parent
tracer when a `yield` is encountered.
* Corner cases
Returning a context manager from a compiled function is not supported. This
would require PyTorch to synchronize the generator state between Dynamo and the
interpreter. Any attempt to return it will result in an `IncorrectUsage`
exception.
Graph breaks require special handling as well. In the event of a graph break,
the frame associated with the context manager is skipped, and the context
manager runs in eager mode.
* This PR is breaking my code
There is a configuration flag (`enable_trace_contextlib`) that can be set to
`False` to disable tracing context managers. If this still causes crashes,
please revert this PR.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/136033
Approved by: https://github.com/zou3519
Previously when Dynamo encounters a `functools.wrap(...)` call, it would
check `VariableTracker.can_reconstruct` and graph break if failed.
That has 2 issues:
1. Implementation of `can_reconstruct` is incorrect, since logic of
reconstructability isn't necessarily encapsulated in
`VariableTracker.reconstruct` -- for some VTs like `CellVariable`,
it's also in `SideEffects.codegen_save_tempvars`. This is exposed by
#134731.
2. We don't always need to reconstruct the result of
`functools.wrap(...)`, for those cases we don't want to give up
tracing by an early `con_reconstruct` check. Instead we could just
let it fall through, and graph break in the actual `reconstruct` call
later, if needed.
This patch removes the `can_reconstruct` check altogether. It was
introduced in #114279, but the added tests pass even without the check
now; this might be because of some recent bug fixing on cells and side
effects.
Fixes#134731, #141514.
D66838708
Pull Request resolved: https://github.com/pytorch/pytorch/pull/142000
Approved by: https://github.com/zou3519
Previously when Dynamo encounters a `functools.wrap(...)` call, it would
check `VariableTracker.can_reconstruct` and graph break if failed.
That has 2 issues:
1. Implementation of `can_reconstruct` is incorrect, since logic of
reconstructability isn't necessarily encapsulated in
`VariableTracker.reconstruct` -- for some VTs like `CellVariable`,
it's also in `SideEffects.codegen_save_tempvars`. This is exposed by
#134731.
2. We don't always need to reconstruct the result of
`functools.wrap(...)`, for those cases we don't want to give up
tracing by an early `con_reconstruct` check. Instead we could just
let it fall through, and graph break in the actual `reconstruct` call
later, if needed.
This patch removes the `can_reconstruct` check altogether. It was
introduced in #114279, but the added tests pass even without the check
now; this might be because of some recent bug fixing on cells and side
effects.
Fixes#134731, #141514.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/142000
Approved by: https://github.com/zou3519
