Record and replay for ShapeEnv. (#107989)
This PR introduces record and replay functionality for `ShapeEnv` instances. In short,
throughout the execution of a program, we record events (e.g. function calls that modify
its state) so that, in the future, we are able to reproduce any intermediary state of the
instance.
In summary, this PR introduces the following changes (they mostly belong to
_symbolic_shapes.py_ unless otherwise stated):
- Create `ShapeEnvEvent` class for recording function calls + arguments
- Create `record_shapeenv_event` decorator and decorate every function that changes the
state of a `ShapeEnv`: it creates an appropriate event and add it to the available
ShapeEnv instance (sometimes it has to extract from `SymTypes`).
- Create `SymNode.with_shape_env` convenient function for replacing `ShapeEnv` references
- Wraps `ShapeEnv` initialization method: so that we also save the exact way a `ShapeEnv`
was constructed, i.e. arguments
- Introduces a way to compare two `ShapeEnv` instances, defining a concept of state for
that class. In short, the state of `ShapeEnv` is every variable that may change the
execution flow
- Create `check_shape_env_recorded_events` dynamo configuration for enabling the check for
equality the state of `ShapeEnv` with another one that was constructed by replaying all
the recorded events. This check takes place inside `produce_guards`
- Create `replay_shape_env_events` function for replaying given events. It assumes the
first event is `ShapeEnv` initialization function
Pull Request resolved: https://github.com/pytorch/pytorch/pull/107989
Approved by: https://github.com/ezyang
