pytorch/torch/_dynamo/variables/torch.py
Edward Z. Yang fa4c77e39b Rename PyOperator to HigherOrderOperator (#97493)
Twice this week I have had people confuse "operator defined with Python
operator registration aka torch.library" and "PyOperator which is used
to define control flow operators and other operators that cannot be
represented in JIT schema."  Renaming PyOperator for clarity.

Signed-off-by: Edward Z. Yang <ezyang@meta.com>

Pull Request resolved: https://github.com/pytorch/pytorch/pull/97493
Approved by: https://github.com/SherlockNoMad
2023-03-24 05:04:02 +00:00

1038 lines
39 KiB
Python

import logging
import math
import re
import types
from typing import Dict, List
import torch._C
import torch.fx
import torch.nn
import torch.onnx.operators
from torch._dynamo.utils import get_fake_value
from torch._dynamo.variables import SymNodeVariable
from torch._guards import GuardsCheckpointState
from .. import config, variables
from ..allowed_functions import torch_get_name
from ..exc import unimplemented
from ..source import GetItemSource, NNModuleSource
from ..utils import (
check_constant_args,
check_unspec_python_args,
HAS_NUMPY,
istype,
np,
product,
proxy_args_kwargs,
specialize_args_kwargs,
tensortype_to_dtype,
)
from .base import VariableTracker
from .lists import ListVariable, TupleVariable
from .misc import AutocastModeVariable, NullContextVariable
from .tensor import TensorWithTFOverrideVariable
log = logging.getLogger(__name__)
# TODO(voz): Maybe rename these later
tensor_dunder_fns = [
torch.Tensor.__rmatmul__,
torch.Tensor.__rmod__,
torch.Tensor.__rpow__,
torch.Tensor.__rsub__,
torch._C._TensorBase.__radd__,
torch._C._TensorBase.__rmul__,
torch._C._TensorBase.__ror__,
torch._C._TensorBase.__rxor__,
torch._C._TensorBase.__rand__,
]
torch_special_class_types = (torch._C.Generator,)
REWRITE_OPS_TO_TENSOR_SIZE_METHOD = [
torch.onnx.operators.shape_as_tensor,
torch._shape_as_tensor,
]
constant_fold_functions = [
torch._assert,
torch._utils._get_device_index,
torch.cuda.is_available,
torch.device,
torch.distributed.is_available,
torch.finfo,
torch.get_default_dtype,
torch.iinfo,
torch.is_autocast_cache_enabled,
torch.is_autocast_cpu_enabled,
torch.is_autocast_enabled,
torch.is_floating_point,
torch.nn.functional._Reduction.get_enum,
]
if torch.distributed.is_available():
constant_fold_functions.append(torch.distributed.is_initialized)
# TODO(voz): perhaps a decorator? This is rather readable for now tho, and not a public API.
def remap_as_fn___radd__(*args):
return torch._C._TensorBase.__radd__(*args)
def remap_as_fn___rmul__(*args):
return torch._C._TensorBase.__rmul__(*args)
def remap_as_fn___ror__(*args):
return torch._C._TensorBase.__ror__(*args)
def remap_as_fn___rxor__(*args):
return torch._C._TensorBase.__rxor__(*args)
def remap_as_fn___rand__(*args):
return torch._C._TensorBase.__rand__(*args)
tensor_dunder_fns_remap = {
torch._C._TensorBase.__radd__: remap_as_fn___radd__,
torch._C._TensorBase.__rmul__: remap_as_fn___rmul__,
torch._C._TensorBase.__ror__: remap_as_fn___ror__,
torch._C._TensorBase.__rxor__: remap_as_fn___rxor__,
torch._C._TensorBase.__rand__: remap_as_fn___rand__,
}
try:
# Wed need to monkeypatch transformers here, sadly.
# TODO(voz): Upstream to transformers lib
import transformers
def _dynamo_overriden_transformers_eq(self, other):
if not hasattr(other, "__dict__"):
return False
return self.__dict__ == other.__dict__
transformers.configuration_utils.PretrainedConfig.__eq__ = (
_dynamo_overriden_transformers_eq
)
except ImportError:
pass
class TorchVariable(VariableTracker):
"""Points to a module or method in torch.*"""
def __init__(self, value, **kwargs):
super().__init__(**kwargs)
if value in tensor_dunder_fns_remap:
value = tensor_dunder_fns_remap[value]
self.value = value
# the remainder of this is just optional debug checks
try:
self_should_be_none = getattr(self.value, "__self__", None)
except RuntimeError as e:
assert "No such operator" in str(e), str(e)
self_should_be_none = None
# assert "_ntuple.<locals>.parse" not in str(value)
if self_should_be_none is None:
pass
elif isinstance(self_should_be_none, types.ModuleType):
# weird ones like torch.nn.functional.avg_pool2d have __self__
name = self_should_be_none.__name__
assert re.match(r"^(torch|math)([.]|$)", name), f"__self__ set to {name}"
elif isinstance(
self_should_be_none, type(torch._C._get_tracing_state.__self__)
):
# some _C functions have __self__ as a null capsule
pass
elif isinstance(self_should_be_none, torch_special_class_types):
pass
else:
raise AssertionError(f"{value} found with __self__ set")
def __repr__(self):
return f"TorchVariable({self.value})"
def unique_var_name(self):
name = torch_get_name(self.value, f"allowed_fn_{id(self.value)}")
return "__" + re.sub(r"[^a-zA-Z0-9_]+", "_", name)
def reconstruct(self, codegen):
return codegen.setup_globally_cached(self.unique_var_name(), self.value, False)
def as_proxy(self):
return self.value
def python_type(self):
if isinstance(self.value, (torch.Tensor, torch.nn.Module)):
return type(self.value)
return super().python_type()
def as_python_constant(self):
return self.value
def can_constant_fold_through(self):
if self.value in constant_fold_functions:
return True
return getattr(self.value, "__module__", None) == "math"
def call_function(
self, tx, args: "List[VariableTracker]", kwargs: "Dict[str, VariableTracker]"
) -> "VariableTracker":
from . import (
ConstantVariable,
CUDAStreamContextVariable,
CUDAStreamVariable,
GradModeVariable,
SymNodeVariable,
TensorVariable,
UserDefinedObjectVariable,
)
from .builder import wrap_fx_proxy, wrap_fx_proxy_cls
constant_args = check_constant_args(args, kwargs)
unspec_python_args = check_unspec_python_args(args, kwargs)
options = VariableTracker.propagate(self, args, kwargs.values())
if self.value in config.constant_functions:
assert not args and not kwargs
return ConstantVariable(config.constant_functions[self.value], **options)
elif self.can_constant_fold_through() and (constant_args or unspec_python_args):
args, kwargs = specialize_args_kwargs(tx, args, kwargs)
# constant fold
return ConstantVariable(
self.as_python_constant()(
*[x.as_python_constant() for x in args],
**{k: v.as_python_constant() for k, v in kwargs.items()},
),
**options,
)
elif istype(self.value, type) and issubclass(self.value, torch.nn.Module):
if self.value is torch.nn.Softmax:
return self._call_softmax(tx, args, kwargs, options)
if self.value is torch.nn.CrossEntropyLoss:
return self._call_cross_entropy_loss(tx, args, kwargs, options)
else:
unimplemented(f"construct nn.Module: {self.value.__name__}")
elif self.value in (torch.is_tensor, torch.overrides.is_tensor_like):
assert len(args) == 1
if isinstance(args[0], TensorVariable) or (
self.value is torch.overrides.is_tensor_like
and isinstance(args[0], UserDefinedObjectVariable)
and hasattr(args[0].value, "__torch_function__")
):
return ConstantVariable(True, **options)
else:
return ConstantVariable(False, **options)
elif (
self.value
in (
torch.is_floating_point,
torch.is_complex,
)
and isinstance(args[0], TensorVariable)
and args[0].dtype is not None
):
if self.value is torch.is_floating_point:
return ConstantVariable(args[0].dtype.is_floating_point, **options)
elif self.value is torch.is_complex:
return ConstantVariable(args[0].dtype.is_complex, **options)
else:
raise AssertionError()
elif (
self.value is torch.numel
and isinstance(args[0], TensorVariable)
and args[0].size is not None
):
return ConstantVariable(product(args[0].size), **options)
elif self.value in REWRITE_OPS_TO_TENSOR_SIZE_METHOD:
assert len(args) == 1
assert isinstance(args[0], TensorVariable)
return args[0].call_method(tx, "size", [], {})
elif self.value in (
torch.nn.modules.utils._single,
torch.nn.modules.utils._pair,
torch.nn.modules.utils._triple,
torch.nn.modules.utils._quadruple,
torch.nn.modules.utils._ntuple,
):
return self._call_ntuple(tx, args, kwargs, options)
elif self.value is torch.no_grad:
return GradModeVariable.create(tx, False, **options)
elif self.value is torch.enable_grad:
return GradModeVariable.create(tx, True, **options)
elif self.value is torch.set_grad_enabled and len(args) == 1:
return GradModeVariable.create(tx, args[0].as_python_constant(), **options)
elif self.value is torch.is_grad_enabled:
assert not (args or kwargs)
return ConstantVariable(torch.is_grad_enabled(), **options).add_guards(
GradModeVariable._guards_singleton
)
elif self.value is torch.cuda.stream:
log.warning(
"torch.cuda.stream() not fully supported, streams may be ignored"
)
assert len(args) == 1
return CUDAStreamContextVariable.create(tx, args[0], **options)
elif self.value is torch.cuda.streams.Stream:
return wrap_fx_proxy_cls(
CUDAStreamVariable,
tx,
tx.output.create_proxy(
"call_function",
torch.cuda.streams.Stream,
(),
{},
),
**options,
)
elif not config.dynamic_shapes and self.is_dynamic_shapes(args, kwargs):
unimplemented(f"dynamic shapes: {self.value.__name__}")
elif len(args) > 0 and isinstance(args[0], TensorWithTFOverrideVariable):
# This code block implements inlining the __torch_function__
# override of a tensor.
tensor_with_tf_override = args[0]
# TODO(future PR): make this implement the full __torch_function__ API
# instead of assuming the relevant override is in the first argument.
args[0] = args[0].tensor_variable
unwrapped = TensorWithTFOverrideVariable.inline_torch_function_unwrapped(
tx,
self,
tensor_with_tf_override.orig_tensor_variable_source,
tensor_with_tf_override.subclass_torch_function__func,
tensor_with_tf_override.subclass_type,
options,
args,
kwargs,
)
# The wrapping here follows the logic in
# `torch.Tensor.__torch_function__`.
if self.value in torch.overrides.get_default_nowrap_functions():
return unwrapped
return TensorWithTFOverrideVariable(
unwrapped,
tensor_with_tf_override.orig_tensor_variable_source,
tensor_with_tf_override.subclass_torch_function__func,
tensor_with_tf_override.subclass_type,
)
elif self.value is torch.amp.autocast_mode.autocast:
return AutocastModeVariable.create(target_values=args, kwargs=kwargs)
elif self.value in [torch.cuda.amp.autocast, torch.cpu.amp.autocast]:
assert "device_type" not in kwargs
if self.value is torch.cuda.amp.autocast:
kwargs.update({"device_type": ConstantVariable("cuda")})
else:
kwargs.update({"device_type": ConstantVariable("cpu")})
return AutocastModeVariable.create(target_values=args, kwargs=kwargs)
elif self.value in (
torch.profiler.profile,
torch.profiler.record_function,
torch.autograd.profiler.profile,
torch.autograd.profiler.record_function,
):
log.warning("Profiler will be ignored")
return NullContextVariable(**options)
elif self.value is torch.autograd._profiler_enabled:
unimplemented("torch.autograd._profiler_enabled not supported yet")
elif self.value is torch.jit.annotate:
assert len(args) == 2
return args[1]
elif self.value is torch.backends.cudnn.is_acceptable:
# is_acceptable(tensor) returns true if
# (a) tensor dtype/device are supported by cudnn
# (b) cudnn is available
# (c) some initialization has completed
# technically, it depends on some global state from (c) (torch.backends.cudnn.__cudnn_version)
assert (
len(args) == 1 or "tensor" in kwargs
), "Expect 1 input to cudnn.is_acceptable"
tensor_variable = args[0] if len(args) > 0 else kwargs["tensor"]
assert isinstance(
tensor_variable, TensorVariable
), "Expect input to cudnn.is_acceptable to be a tensor"
tensor_inp = torch.tensor(
0, dtype=tensor_variable.dtype, device=tensor_variable.device
)
return ConstantVariable(
torch.backends.cudnn.is_acceptable(tensor_inp), **options
)
if (
self.value.__name__ == "get_state"
and hasattr(self.value, "__self__")
and isinstance(self.value.__self__, torch._C.Generator)
):
def get_state_from_generator():
return self.value()
return wrap_fx_proxy(
tx=tx,
proxy=tx.output.create_proxy(
"call_function",
get_state_from_generator,
*proxy_args_kwargs(args, kwargs),
),
example_value=self.value(),
**options,
)
if (
self.value.__name__ == "set_state"
and hasattr(self.value, "__self__")
and isinstance(self.value.__self__, torch._C.Generator)
) or self.value == torch.random.set_rng_state:
assert len(args) == 1
assert isinstance(args[0], TensorVariable)
unimplemented(
"TODO: make torch.random.set_rng_state work with FakeTensor/aot_autograd"
)
# In fake tensor case, this state doesn't matter, but
# it needs to be valid to not segfault. Pull a real tensor out.
# The value won't matter since we are running with fake tensors anyway, so rng doesn't matter.
# However, it is imperative to record the call_function in the graph with the true args
# (Not the fake example_value) - for the sake of graph correctness.
if self.value == torch.random.set_rng_state:
example_value = torch.random.get_rng_state()
else:
example_value = self.value.__self__.get_state()
self.value.__module__ = self.__module__
return wrap_fx_proxy(
tx=tx,
proxy=tx.output.create_proxy(
"call_function",
self.value,
*proxy_args_kwargs(args, kwargs),
),
example_value=example_value,
**options,
)
elif (
self.value == torch.numel
and len(args) == 1
and isinstance(args[0], TensorVariable)
and len(kwargs) == 0
):
# TODO(voz): This is rewritten as a call_method because
# torch.numel(x) w/ sym shapes raises a RuntimeError and x.numel() does not
return wrap_fx_proxy(
tx=tx,
proxy=tx.output.create_proxy(
"call_method",
"numel",
*proxy_args_kwargs(args, kwargs),
),
**options,
)
elif (
self.value == torch.addcdiv
and len(args) == 3
and "value" in kwargs
and len(kwargs) == 1
):
# decompose addcdiv into constituent ops, prevents a graph break due to converting
# value to a scalar
result = TorchVariable(torch.div, **options).call_function(tx, args[1:], {})
result = TorchVariable(torch.mul, **options).call_function(
tx, [result, kwargs["value"]], {}
)
return TorchVariable(torch.add, **options).call_function(
tx, [args[0], result], {}
)
else:
any_symints_or_symfloats = any(
[isinstance(x, SymNodeVariable) for x in args]
)
all_ints_or_floats = all(
[
isinstance(
x, (variables.ConstantVariable, variables.SymNodeVariable)
)
for x in args
]
)
bin_ops = {"add", "sub", "mul", "div", "sqrt"}
if (
getattr(self.value, "__module__", "") == "torch"
and self.value.__name__ in bin_ops
and any_symints_or_symfloats
and all_ints_or_floats
):
msg = f"""\
Calling {str(self.value)} on only torch.SymInt arguments is not yet supported.
To support this behavior, we need to allow const-propping tensors that store symint data.
For now, dynamo will explicitly graph break when it encounters user code with this behavior.
"""
log.warning(msg)
raise unimplemented(msg)
# Handle sth like torch.LongTensor(list(np.int64, np.int64, ...)),
# as FX symbolic trace doesn't support numpy int/float as base types.
if (
HAS_NUMPY
and self.value in tensortype_to_dtype
and len(args) == 1
and isinstance(args[0], ListVariable)
and args[0].is_python_constant()
):
for x in args[0].items:
if isinstance(x.value, np.generic):
x.value = x.value.item()
if self.value == torch._C._nn.scaled_dot_product_attention:
# See:[Note] SDPA_flash's meta function returns incorrect Philox seed and offset
# in pytorch/torch/_meta_registrations.py
all_kwargs = kwargs.copy()
all_kwargs.update(
dict(
zip(
(
"query",
"key",
"value",
"attn_mask",
"dropout_p",
"is_causal",
),
args,
)
)
)
fake_query = all_kwargs["query"].as_proxy().node.meta["example_value"]
fake_key = all_kwargs["key"].as_proxy().node.meta["example_value"]
fake_value = all_kwargs["value"].as_proxy().node.meta["example_value"]
fake_mask = all_kwargs.get("attn_mask")
if isinstance(fake_mask, TensorVariable):
fake_mask = fake_mask.as_proxy().node.meta["example_value"]
else:
fake_mask = None
dropout_p = kwargs.get("dropout_p")
dropout_p = dropout_p.value if dropout_p is not None else 0.0
is_causal = kwargs.get("is_causal")
is_causal = is_causal.value if is_causal is not None else False
# We look through the stack to find a cuda autocast context
# If we do we will convert the fake tensors to torch.float16
is_cuda_autocast_context = False
for block in tx.block_stack:
if (
isinstance(block.with_context, AutocastModeVariable)
and block.with_context.target_values[0] == "cuda"
):
is_cuda_autocast_context = True
break
if is_cuda_autocast_context and fake_query.device.type == "cuda":
amp_dtype = torch.float16
fake_query = fake_query.clone().to(amp_dtype)
fake_key = fake_key.clone().to(amp_dtype)
fake_value = fake_value.clone().to(amp_dtype)
backend_choice = torch._fused_sdp_choice(
fake_query, fake_key, fake_value, fake_mask, dropout_p, is_causal
)
if backend_choice == torch.backends.cuda.SDPBackend.FLASH_ATTENTION:
if dropout_p is not None and dropout_p != 0.0:
unimplemented(
"FlashAttention with dropout is not supported in cuda graphs"
)
# TODO(voz): Replace w/ dynamic shape rewrite table.
# Ideally, we would be able to do this at ctor time, but alas we need a combination
# of value + args to determine this.
fn_ = self.value
if any([isinstance(x, SymNodeVariable) for x in args]):
if self.value == math.sqrt:
from torch.fx.experimental.symbolic_shapes import sym_sqrt
fn_ = sym_sqrt
if fn_ is torch.tensor:
def check_any_unspec(x):
# NB: This includes UnspecializedPythonVariable
if isinstance(x, (TensorVariable, SymNodeVariable)):
return True
elif isinstance(x, ListVariable):
return any(check_any_unspec(y) for y in x.items)
# TODO: there maybe other recursive structures you need to
# check
else:
return False
# NB: OK to pass torch.tensor(tensor), this will trace fine
# TODO: But torch.tensor(unspec) would not trace fine. Not
# handled right now.
data_arg = None
if args:
data_arg = args[0]
elif "data" in kwargs:
data_arg = kwargs["data"]
if isinstance(data_arg, ListVariable) and check_any_unspec(data_arg):
unimplemented("torch.tensor call with list of unspec")
tensor_variable = wrap_fx_proxy(
tx=tx,
proxy=tx.output.create_proxy(
"call_function",
fn_,
*proxy_args_kwargs(args, kwargs),
),
**options,
)
if "out" in kwargs and not (
isinstance(kwargs["out"], variables.ConstantVariable)
and kwargs["out"].as_python_constant() is None
):
# out variants of torch operators like torch.sort and
# torch.sigmoid mutate the tensors in the out field. Track such
# tensors and rewrite the symbolic locals.
if isinstance(tensor_variable, TupleVariable):
assert isinstance(kwargs["out"], TupleVariable)
output_tensor_names = [
tx.find_symbolic_locals_name(x) for x in kwargs["out"].items
]
for idx, name in enumerate(output_tensor_names):
if name in tx.symbolic_locals:
tx.symbolic_locals[name] = tensor_variable.items[idx]
elif isinstance(tensor_variable, TensorVariable):
assert isinstance(kwargs["out"], TensorVariable)
name = tx.find_symbolic_locals_name(kwargs["out"])
if name in tx.symbolic_locals:
tx.symbolic_locals[name] = tensor_variable
else:
unimplemented(f"out variant of {type(kwargs['out'])}")
return tensor_variable
def is_dynamic_shapes(self, args, kwargs):
"""Check for dynamic shapes when shape specialization is enabled"""
# TODO(jansel): need to get a complete list
if self.value in (
torch.nonzero,
torch.unique,
torch.unique_consecutive,
) or self.value.__name__ in ("nms",):
return True
if self.value is torch.where and len(args) + len(kwargs) == 1:
return True
if self.value in (
torch.arange,
torch.repeat_interleave,
):
none = variables.ConstantVariable(None)
def has_non_const(it):
return not all(x.is_python_constant() for x in it)
def arange(start=none, end=none, step=none, **kwargs):
return has_non_const([start, end, step])
def repeat_interleave(input, repeats, dim=none, **kwargs):
return has_non_const([repeats])
return locals()[self.value.__name__](*args, **kwargs)
return False
def _call_softmax(self, tx, args, kwargs, options):
"""rewrite the pattern nn.Softmax(dim=-1)(x) to F.softmax(x, -1)"""
dim = args[0] if args else kwargs.get("dim", variables.ConstantVariable(None))
def fake_softmax(input):
from .builder import wrap_fx_proxy
return wrap_fx_proxy(
tx=tx,
proxy=tx.output.create_proxy(
"call_function",
torch.nn.functional.softmax,
*proxy_args_kwargs([input, dim], {}),
),
**VariableTracker.propagate([self, dim, input]),
)
return variables.LambdaVariable(fake_softmax, **options)
def _call_cross_entropy_loss(self, tx, args, kwargs, options):
"""
functional: input, target, weight=None, size_average=None, ignore_index=- 100, reduce=None, reduction='mean',
label_smoothing=0.0
non functional ctor: weight=None, size_average=None, ignore_index=- 100, reduce=None, reduction='mean',
label_smoothing=0.0
non functional loss call: input, target, optional_output
"""
from . import ConstantVariable
def normalize_args(
weight=ConstantVariable(None),
size_average=ConstantVariable(None),
ignore_index=ConstantVariable(-100),
reduce=ConstantVariable(None),
reduction=ConstantVariable("mean"),
label_smoothing=ConstantVariable(0.0),
):
return (
weight,
size_average,
ignore_index,
reduce,
reduction,
label_smoothing,
)
(
weight,
size_average,
ignore_index,
reduce_arg,
reduction,
label_smoothing,
) = normalize_args(*args, **kwargs)
def fake_cross_entropy_loss(input, target):
from .builder import wrap_fx_proxy
return wrap_fx_proxy(
tx=tx,
proxy=tx.output.create_proxy(
"call_function",
torch.nn.functional.cross_entropy,
*proxy_args_kwargs(
[
input,
target,
weight,
size_average,
ignore_index,
reduce_arg,
reduction,
label_smoothing,
],
{},
),
),
**VariableTracker.propagate(
[
self,
weight,
size_average,
ignore_index,
reduce_arg,
reduction,
label_smoothing,
input,
target,
]
),
)
return variables.LambdaVariable(fake_cross_entropy_loss, **options)
def _call_ntuple(self, tx, args, kwargs, options):
"""inline behavior of torch.nn.modules.utils._ntuple"""
if self.value is torch.nn.modules.utils._ntuple:
count = args[0].as_python_constant()
else:
count = self.value.__closure__[0].cell_contents
assert isinstance(count, int)
def handle_ntuple(value):
if value.has_unpack_var_sequence(tx):
return variables.TupleVariable(
list(value.unpack_var_sequence(tx)),
**VariableTracker.propagate(self, value, args, kwargs.values()),
)
elif value.is_python_constant():
# constant prop through it
return variables.ConstantVariable(
torch.nn.modules.utils._ntuple(count)(value.as_python_constant()),
**VariableTracker.propagate(self, value, args, kwargs.values()),
)
else:
unimplemented(f"torch.nn.modules.utils._ntuple({value})")
if self.value is torch.nn.modules.utils._ntuple:
return variables.LambdaVariable(handle_ntuple, **options)
else:
return handle_ntuple(args[0])
class TorchHigherOrderOperator(VariableTracker):
def __init__(self, value, **kwargs):
super().__init__(**kwargs)
self.value = value
def call_function(
self, tx, args: "List[VariableTracker]", kwargs: "Dict[str, VariableTracker]"
) -> "VariableTracker":
from . import (
ListVariable,
NestedUserFunctionVariable,
TensorVariable,
UserFunctionVariable,
)
from .builder import wrap_fx_proxy
assert kwargs is None or len(kwargs) == 0, "kwargs are not supported, yet"
def make_attr(name):
node = tx.output.create_proxy(
"get_attr",
name,
(),
{},
)
return node
def add_subgraph(name, gm):
next_name = None
i = 0
while not next_name:
candidate = f"cond_{name}_{i}"
if candidate in tx.output.nn_modules:
i += 1
else:
next_name = candidate
gm.__name__ = next_name
src = NNModuleSource(GetItemSource(self.source, next_name))
gm.torchdynamo_force_dynamic = False
tx.output.register_attr_or_module(gm, next_name, source=src)
return next_name
def get_comparable_state(state):
# Nub out bits of state that we don't require to be
# equal
return state._replace(
output=state.output._replace(
guard_state=GuardsCheckpointState(set()),
nn_modules=None,
param_name_to_source=None,
# Timestamp is monotonically increasing so we don't
# care about divergence
timestamp=0,
# Unused in branches
graphargs=[],
)
)
def speculate_subgraph(f, sub_args, graph_checkpoint, checkpoint):
# Setup the subgraph we're going to capture into
tx.output.graph = torch.fx.Graph()
tx.output.graphargs = []
tx.output.name_to_input.clear()
args = []
# One argument to graph per sub_args
for a in sub_args:
if isinstance(a, TensorVariable):
tx.output.create_graph_input(a.as_proxy().node.name)
args.append(a)
else:
# call_function() needs a TensorVariable, therefore we construct
# one with inner graph proxy.
assert isinstance(a, torch.Tensor)
proxy = tx.output.create_graph_input("arg")
args.append(wrap_fx_proxy(tx=tx, proxy=proxy, example_value=a))
# NB: we don't bother populating graphargs, as
# they won't actually get used by anything
output = f.call_function(tx, args, {})
# Register output to graph
# Modeled off of compile_and_call_fx_graph
# TODO: support non single Tensor output
assert isinstance(output, TensorVariable)
tx.output.guards.update(output.guards)
tx.output.create_node(
"output", "output", (tx.output.create_arg((output.as_proxy(),))), {}
)
tx.output.side_effects.prune_dead_object_new(tx)
state = tx.copy_graphstate()
guards = state.output.guards
nn_modules = state.output.nn_modules
comparable_state = get_comparable_state(state)
graph = tx.output.graph
tx.output.graph = graph_checkpoint
tx.restore_graphstate(checkpoint)
return (
output,
graph,
guards,
nn_modules,
comparable_state,
)
if self.value.__name__ == "cond":
# TODO(voz): Support fake tensor dispatch for recursive
# ops - see torch/dispatch/_dispatcher.py
assert len(args) == 4
assert type(args[0]) in (TensorVariable, SymNodeVariable), str(
type(args[0])
) # predicate
assert isinstance(
args[1], (UserFunctionVariable, NestedUserFunctionVariable)
), str(
type(args[1])
) # true_fn
assert isinstance(
args[2], (UserFunctionVariable, NestedUserFunctionVariable)
), str(
type(args[2])
) # false_fn
assert type(args[3]) is ListVariable, str(type(args[3])) # args
# Our strategy for tracing the true/false branches of cond
# are to checkpoint our graphstate, run the true branch,
# roll it back to the checkpoint, and run the false
# branch, and then merge the graphstates. Well, perhaps
# "merge" is too strong a word: we mostly assert that
# the resulting graphstates have to be the same.
#
# We only permit guards to diverge (we union the guards from
# both branches). In particular, this means that side
# effects are NOT permitted inside true/false branches; this
# would be difficult to implement, because of the path
# explosion problem.
graph_checkpoint, checkpoint = tx.output.graph, tx.copy_graphstate()
sub_args = args[3].unpack_var_sequence(tx)
def speculate_branch(branch):
# NB: 0 is predicate
ix = 1 if branch else 2
return speculate_subgraph(
args[ix], sub_args, graph_checkpoint, checkpoint
)
(
true_r,
true_graph,
true_guards,
true_nn_modules,
true_cmp,
) = speculate_branch(True)
(
false_r,
false_graph,
false_guards,
false_nn_modules,
false_cmp,
) = speculate_branch(False)
true_tracked_fakes = true_cmp.output.tracked_fakes
false_tracked_fakes = false_cmp.output.tracked_fakes
tx.output.tracked_fakes = list({*false_tracked_fakes, *true_tracked_fakes})
# Add guards
tx.output.tracing_context.guards_context.dynamo_guards |= false_guards
tx.output.tracing_context.guards_context.dynamo_guards |= true_guards
true_name = add_subgraph(
"true", torch.fx.GraphModule(true_nn_modules, true_graph)
)
false_name = add_subgraph(
"false", torch.fx.GraphModule(false_nn_modules, false_graph)
)
# Apply side effects (guaranteed to be equal)
tx.output.side_effects = true_cmp.output.side_effects
true_node = make_attr(true_name)
false_node = make_attr(false_name)
p_args = (
args[0].as_proxy(),
true_node,
false_node,
[a.as_proxy() for a in sub_args],
)
# TODO: assert that the true/false return values are
# consistent
example_value = true_r.as_proxy().node.meta["example_value"]
elif self.value.__name__ == "map":
assert type(args[0]) in (UserFunctionVariable, NestedUserFunctionVariable)
assert type(args[1]) is TensorVariable
sample_shape = args[1].get_real_value().size()
if len(sample_shape) < 1 or sample_shape[0] == 0:
unimplemented(
"map() operator doesn't support scalar or zero-sized tensors during tracing."
)
checkpoint = tx.copy_graphstate()
# To get the example output from map() we will need to prodive at least one sample to
# the loop body. In our case we will always use xs[0], and our map() won't support zero
# sized tensor during tracing.
(
body_r,
body_graph,
body_guards,
body_nn_modules,
body_cmp,
) = speculate_subgraph(
args[0],
[
get_fake_value(args[1].as_proxy().node, tx)[0],
*args[2:],
],
tx.output.graph,
checkpoint,
)
# We don't support side effects inside a map loop body for simplicity.
parent_cmp = get_comparable_state(checkpoint)
parent_tracked_fakes = parent_cmp.output.tracked_fakes
body_tracked_fakes = body_cmp.output.tracked_fakes
tx.output.tracked_fakes = list({*parent_tracked_fakes, *body_tracked_fakes})
# Add guards
tx.output.tracing_context.guards_context.dynamo_guards |= body_guards
body_name = add_subgraph(
"body", torch.fx.GraphModule(body_nn_modules, body_graph)
)
body_node = make_attr(body_name)
p_args = (body_node, *(arg.as_proxy() for arg in args[1:]))
r = body_r.as_proxy().node.meta["example_value"]
example_value = r.new_empty(
[get_fake_value(args[1].as_proxy().node, tx).shape[0], *r.shape]
)
else:
unimplemented(f"HigherOrderOperator {self.value.__name__}")
# Store the invocation as a call
return wrap_fx_proxy(
tx=tx,
proxy=tx.output.create_proxy(
"call_function",
self.value,
args=tuple(p_args),
kwargs={},
),
example_value=example_value,
)