pytorch/torch/_export/wrappers.py
Zhengxu Chen 3f62b05d31 [export] Use forward hooks to capture module signatures. (#120468)
Summary:
When we export in on strict mode and turn on preserve_module_call_signature, the following assertion error will occur today:
```
child_split[: len(parent_split)] == parent_split
```
This is due to the fact that we're monkey patching forward call directly, which kinda breaks the attribute propagation in the tracer. It's actually better to implement this by using forward hook because we don't have to alter the original module structure at all during export.

Test Plan: CI

Differential Revision: D54102714

Pull Request resolved: https://github.com/pytorch/pytorch/pull/120468
Approved by: https://github.com/ydwu4
2024-02-27 17:44:06 +00:00

115 lines
3.9 KiB
Python

from contextlib import contextmanager
import torch
import torch._custom_ops
from torch._C import DispatchKey
from torch._higher_order_ops.strict_mode import strict_mode
from torch._higher_order_ops.utils import autograd_not_implemented
from torch._ops import HigherOrderOperator
from torch._subclasses.fake_tensor import FakeTensorMode
from torch.fx.experimental.proxy_tensor import ProxyTorchDispatchMode, track_tensor_tree
from torch.utils import _pytree as pytree
_export_tracepoint = HigherOrderOperator("_export_tracepoint")
@_export_tracepoint.py_impl(ProxyTorchDispatchMode)
def export_tracepoint_dispatch_mode(mode, *args, **kwargs):
if not mode.enable_tracing:
return _export_tracepoint(*args, **kwargs)
p_args, p_kwargs = pytree.tree_map(mode.tracer.unwrap_proxy, (args, kwargs))
proxy = mode.tracer.create_proxy(
"call_function", _export_tracepoint, p_args, p_kwargs
)
return track_tensor_tree(args, proxy, constant=None, tracer=mode.tracer)
@_export_tracepoint.py_impl(FakeTensorMode)
def export_tracepoint_fake_tensor_mode(mode, *args, **kwargs):
with mode:
return args
@_export_tracepoint.py_functionalize_impl
def export_tracepoint_functional(ctx, *args, **kwargs):
unwrapped_args = ctx.unwrap_tensors(args)
unwrapped_kwargs = ctx.unwrap_tensors(kwargs)
with ctx.redispatch_to_next():
out = _export_tracepoint(*unwrapped_args, **unwrapped_kwargs)
return ctx.wrap_tensors(out)
_export_tracepoint.py_impl(DispatchKey.Autograd)(
autograd_not_implemented(_export_tracepoint, deferred_error=True)
)
@_export_tracepoint.py_impl(DispatchKey.CPU)
def export_tracepoint_cpu(*args, **kwargs):
return args
def _wrap_submodule(mod, path, module_call_specs):
assert isinstance(mod, torch.nn.Module)
assert path != ""
submodule = mod
for name in path.split("."):
if not hasattr(submodule, name):
raise RuntimeError(f"Couldn't find submodule at path {path}")
submodule = getattr(submodule, name)
def update_module_call_signatures(path, in_spec, out_spec):
if path in module_call_specs:
assert module_call_specs[path]["in_spec"] == in_spec
assert module_call_specs[path]["out_spec"] == out_spec
module_call_specs[path] = {"in_spec": in_spec, "out_spec": out_spec}
def check_flattened(flat_args):
for a in flat_args:
if not (isinstance(a, (torch.Tensor, str, int, float, bool)) or a is None):
raise AssertionError(
f"Only Tensors or scalars are supported as pytree flattened inputs, got: {a}"
)
def pre_hook(module, args, kwargs):
flat_args, in_spec = pytree.tree_flatten((args, kwargs))
check_flattened(flat_args)
flat_args = _export_tracepoint(*flat_args, kind="module_call_inputs", path=path)
args, kwargs = pytree.tree_unflatten(flat_args, in_spec)
return args, kwargs
def post_hook(module, args, kwargs, res):
_, in_spec = pytree.tree_flatten((args, kwargs))
flat_res, out_spec = pytree.tree_flatten(res)
check_flattened(flat_res)
flat_res = _export_tracepoint(*flat_res, kind="module_call_outputs", path=path)
update_module_call_signatures(path, in_spec, out_spec)
return pytree.tree_unflatten(flat_res, out_spec)
pre_handle = submodule.register_forward_pre_hook(pre_hook, with_kwargs=True)
post_handle = submodule.register_forward_hook(post_hook, with_kwargs=True)
return pre_handle, post_handle
@contextmanager
def _wrap_submodules(f, preserve_signature, module_call_signatures):
handles = []
try:
for path in preserve_signature:
handles.extend(_wrap_submodule(f, path, module_call_signatures))
yield
finally:
for handle in handles:
handle.remove()
def _mark_strict_experimental(cls):
def call(self, *args):
return strict_mode(self, args)
cls.__call__ = call
return cls