ai-content-maker/.venv/Lib/site-packages/torch/export/dynamic_shapes.py

877 lines
34 KiB
Python

import builtins
import dataclasses
import inspect
import math
import sys
import weakref
from collections import defaultdict
from typing import Any, Callable, Dict, List, Optional, Set, Tuple, TYPE_CHECKING, Union
import torch
from torch._subclasses.fake_tensor import FakeTensor
from torch.utils._pytree import SUPPORTED_NODES
from .exported_program import ExportedProgram
if TYPE_CHECKING:
from sympy import Symbol
from torch._guards import Source
from ..fx.experimental.symbolic_shapes import ShapeEnv, StrictMinMaxConstraint
__all__ = ["Constraint", "Dim", "dims", "dynamic_dim"]
class _Dim(type):
"""
Metaclass for :func:`Dim` types.
"""
@staticmethod
def readable(name, min_, max_):
if min_ == 2:
min_ = None
if max_ == sys.maxsize - 1:
max_ = None
if min_ is None and max_ is None:
return f"Dim('{name}')"
if min_ is None:
return f"Dim('{name}', max={max_})"
if max_ is None:
return f"Dim('{name}', min={min_})"
return f"Dim('{name}', min={min_}, max={max_})"
def __add__(cls, other):
# e.g., dim + 1
if type(other) is not int:
raise NotImplementedError(
f"Attempted to add {other} to {cls.__name__}, where an integer was expected. "
"(Only increasing linear operations with integer coefficients are supported.)"
)
return cls._derive(lambda x: x + other)
def __radd__(cls, other):
return cls + other
def __sub__(cls, other):
# e.g., dim - 1
if type(other) is not int:
raise NotImplementedError(
f"Attempted to subtract {other} from {cls.__name__}, where an integer was expected. "
"(Only increasing linear operations with integer coefficients are supported.)"
)
return cls._derive(lambda x: x - other)
def __rsub__(cls, other):
raise NotImplementedError(
f"Attempted to negate {cls.__name__}. "
"(Only increasing linear operations with integer coefficients are supported.)"
)
def __mul__(cls, other):
# e.g., dim * 2
if type(other) is not int or other <= 0:
raise NotImplementedError(
f"Attempted to multiply {other} with {cls.__name__}, where a positive integer was expected. "
"(Only increasing linear operations with integer coefficients are supported.)"
)
return cls._derive(lambda x: x * other)
def __rmul__(cls, other):
return cls * other
def _derived_name(cls, fn):
from sympy import sympify
return str(fn(sympify(cls.__name__)))
def _derive(cls, fn):
return _DerivedDim(cls._derived_name(fn), (int,), {"root": cls, "fn": fn})
class _DerivedDim(_Dim):
"""
Metaclass for derived :func:`Dim` types.
Currently we only support increasing linear expressions with integer coefficients.
In other words, a derived Dim can always be written in the form Ax + B, where
x is a regular Dim (i.e., non-derived Dim), A and B are integers, and A is positive.
(In particular, the latter ensures that x < y => Ax + B < Ay + B.)
These restrictions on the form of derived Dims makes the metatheory simpler: e.g.,
it simplifies computing ranges for derived Dims, solving for underlying regular Dims,
deciding equalities between derived Dims, and so on.
The function lambda x: Ax + B is expressed by `fn`, where x is a normal Dim, `root`.
The range of a derived Dim is computed by mapping `fn` over the range of its `root`.
"""
@property
def min(self):
# assume that self.fn is an increasing function
# TODO(avik): use sympy value range analysis instead?
from sympy import Integer
_min_symint = self.fn(Integer(self.root.min)) # type: ignore[attr-defined]
assert _min_symint >= 2, (
f"Expected derived min value of {self.__name__} to be >= 2. "
f"Please specify an appropriate min value for {self.root.__name__} " # type: ignore[attr-defined]
f"(currently {self.root.min})." # type: ignore[attr-defined]
)
return int(_min_symint)
@property
def max(self):
# assume that self.fn is an increasing function
# TODO(avik): use sympy value range analysis instead?
from sympy import Integer
_max_symint = self.fn(Integer(self.root.max)) # type: ignore[attr-defined]
assert _max_symint <= sys.maxsize - 1, (
f"Expected derived max value of {self.__name__} to be <= {sys.maxsize - 1}. "
f"Please specify an appropriate max value for {self.root.__name__} " # type: ignore[attr-defined]
f"(currently {self.root.max})." # type: ignore[attr-defined]
)
return int(_max_symint)
def _derive(self, fn):
# We support nesting, e.g., 2*dim + 1.
# This is implemented by composing operations on the same root.
# As a consequence, roots are always regular Dims (i.e., not derived Dims).
return _DerivedDim(
self._derived_name(fn),
(int,),
{"root": self.root, "fn": lambda x: fn(self.fn(x))}, # type: ignore[attr-defined]
)
def Dim(name: str, *, min: Optional[int] = None, max: Optional[int] = None):
"""
:func:`Dim` constructs a type analogous to a named symbolic integer with a range.
It can be used to describe multiple possible values of a dynamic tensor dimension.
Note that different dynamic dimensions of the same tensor, or of different tensors,
can be described by the same type.
Args:
name (str): Human-readable name for debugging.
min (Optional[int]): Minimum possible value of given symbol (inclusive)
max (Optional[int]): Maximum possible value of given symbol (inclusive)
Returns:
A type that can be used in dynamic shape specifications for tensors.
"""
_min = 2 if min is None else builtins.max(min, 2)
_max = sys.maxsize - 1 if max is None else builtins.min(max, sys.maxsize - 1)
assert _max > _min, f"Cannot create Dim with inconsistent min={min}, max={max}"
dim = _Dim(name, (int,), {"min": _min, "max": _max})
dim.__module__ = getattr(
inspect.getmodule(inspect.stack()[1][0]), "__name__", "__main__"
)
return dim
def dims(*names: str, min: Optional[int] = None, max: Optional[int] = None):
"""
Util to create multiple :func:`Dim` types.
"""
return tuple(Dim(name, min=min, max=max) for name in names)
@dataclasses.dataclass
class _ConstraintTarget:
"""
This represents input tensor dimensions. Don't create this
class directly; instead, use :func:`dynamic_dim`.
"""
w_tensor: Any # weakref to torch.Tensor
# TODO: We don't need t_id; we can get it off of w_tensor
t_id: int
dim: int
class _ConstraintFactory(type):
"""
Metaclass that ensures a private constructor for :class:`_Constraint`
"""
def __call__(cls, *args, **kwargs):
raise TypeError(
f"{cls.__module__}.{cls.__qualname__} has no public constructor. "
f"Please use torch.export.dynamic_dim() to create one"
)
def _create(
cls, w_tensor, t_id, dim, constraint_range, shared=None, debug_name=None
):
return super().__call__(
w_tensor, t_id, dim, constraint_range, shared, debug_name
)
def _create_constraint(
w_tensor, t_id, dim, constraint_range, shared=None, debug_name=None
):
return _Constraint._create(
w_tensor, t_id, dim, constraint_range, shared, debug_name
)
@dataclasses.dataclass
class _Constraint(_ConstraintTarget, metaclass=_ConstraintFactory):
"""
.. warning::
Do not construct :class:`_Constraint` directly, use :func:`dynamic_dim` instead.
This represents constraints on input tensor dimensions, e.g., requiring
them to be fully polymorphic or within some range.
"""
# NOTE(avik): In the future, this could be Union[StrictMinMaxConstraint, <other kinds>]
constraint_range: "StrictMinMaxConstraint"
# Represent that `constraint_range` is shared with another _ConstraintTarget, which
# typically arises because of a specified equality with another dynamic dimension.
shared: Optional[_ConstraintTarget] = None
debug_name: Optional[str] = None
def _clone_with_range(self, lower=2, upper=math.inf):
# Import sympy locally
from torch.fx.experimental.symbolic_shapes import StrictMinMaxConstraint
from torch.utils._sympy.value_ranges import ValueRanges
constraint_range = StrictMinMaxConstraint(
vr=self.constraint_range.vr & ValueRanges(lower=lower, upper=upper),
warn_only=False,
)
return _create_constraint(
self.w_tensor,
self.t_id,
self.dim,
constraint_range,
self.shared,
self.debug_name,
)
def __ge__(self, lower):
return self._clone_with_range(lower=lower)
def __gt__(self, lower):
return self._clone_with_range(lower=lower + 1)
def __le__(self, upper):
return self._clone_with_range(upper=upper)
def __lt__(self, upper):
return self._clone_with_range(upper=upper - 1)
def __bool__(self):
# NOTE(avik): We do not support compound expressions like a <= x <= b.
# This is because Python implicitly desugars them into bool(a <= x) and bool(x <= b),
# and moreover, enforces that any overload of __bool__ must return True or False.
# FWIW, sympy also raises TypeError in this case.
raise TypeError(
"Cannot determine truth value of _Constraint. "
"If you are trying to combine _Constraint's with logical connectives, "
"you can specify them separately instead."
)
@property
def serializable_spec(self):
# We need a serialization compatible format of the constraint so that it
# can be savedin the graph module w/o breaking the module serialization.
# The saved constraints will be used directly for the post-exporting pass
# that converts constraints to runtime assertion. The saved constraints
# will not be saved in the serialized module.
# TODO: A better way is needed. Currently we use 't_id' to map the constraint,
# which is not reliable
return {
"t_id": self.t_id,
"dim": self.dim,
"min": self.constraint_range.vr.lower,
"max": self.constraint_range.vr.upper,
}
def __eq__(self, other):
if not isinstance(other, _Constraint):
raise TypeError(
"A dynamic dim can be specified equal only to another dynamic dim. "
f"Equality with {type(other)} is not supported."
)
# import sympy locally
from torch.fx.experimental.symbolic_shapes import StrictMinMaxConstraint
constraint_range = StrictMinMaxConstraint(
vr=self.constraint_range.vr & other.constraint_range.vr,
warn_only=False,
)
if self.debug_name is None:
debug_name = other.debug_name
else:
assert other.debug_name is None or self.debug_name == other.debug_name
debug_name = self.debug_name
return _create_constraint(
self.w_tensor,
self.t_id,
self.dim,
constraint_range,
shared=_ConstraintTarget(other.w_tensor, other.t_id, other.dim),
debug_name=debug_name,
)
@dataclasses.dataclass
class _PhantomRoot:
"""
This represents the root of a derived Dim where the root does not directly
specify the shape of any input dimension, but the derived Dim does.
e.g., the input shapes 2*dim and dim + 1 are related via a "phantom" dim.
The fields `name`, `constraint_range`, and `val` carried by a phantom root
help create a symbol for it. Any derived dims with this phantom root are
backed by expressions over this symbol.
"""
name: str
constraint_range: "StrictMinMaxConstraint"
val: int
@dataclasses.dataclass
class _DerivedConstraint(_ConstraintTarget):
"""
This represents a derived Dim, whose root is either a regular constraint target
(which directly specifies the shape of some input dimension) or a phantom root
(which does so indirectly).
"""
# NOTE: This is not currently a subclass of _Constraint because we do not support
# `shared` for derived `Dim`s. Indeed, sharing is a necessary concept only for
# legacy constraints based on `dynamic_dim`: equality can be expressed simply by
# reusing the same (derived or normal) `Dim`.
root: Union[_ConstraintTarget, _PhantomRoot]
fn: Callable
constraint_range: "StrictMinMaxConstraint"
debug_name: Optional[str] = None
@property
def shared(self):
# Some code paths expect a union of _Constraint and _DerivedConstraint.
# Thus we expose a `shared` field that is always None.
# TODO(avik): clean this up
return None
@property
def serializable_spec(self):
# same as _Constraint.serializable_spec
return {
"t_id": self.t_id,
"dim": self.dim,
"min": self.constraint_range.vr.lower,
"max": self.constraint_range.vr.upper,
}
Constraint = Union[_Constraint, _DerivedConstraint]
def dynamic_dim(t: torch.Tensor, index: int, debug_name: Optional[str] = None):
"""
.. warning::
(This feature is DEPRECATED. See :func:`Dim` instead.)
:func:`dynamic_dim` constructs a :class:`_Constraint` object that describes the dynamism of
a dimension ``index`` of tensor ``t``. :class:`_Constraint` objects should be passed to
``constraints`` argument of :func:`export`.
Args:
t (torch.Tensor): Example input tensor that have dynamic dimension size(s)
index (int): Index of dynamic dimension
Returns:
A :class:`_Constraint` object that describes shape dynamism. It can be passed to :func:`export` so
that :func:`export` does not assume static size of specified tensor, i.e. keeping it dynamic
as a symbolic size rather than specializing according to size of example tracing input.
Specifically :func:`dynamic_dim` can be used to express following types of dynamism.
- Size of a dimension is dynamic and unbounded::
t0 = torch.rand(2, 3)
t1 = torch.rand(3, 4)
# First dimension of t0 can be dynamic size rather than always being static size 2
constraints = [dynamic_dim(t0, 0)]
ep = export(fn, (t0, t1), constraints=constraints)
- Size of a dimension is dynamic with a lower bound::
t0 = torch.rand(10, 3)
t1 = torch.rand(3, 4)
# First dimension of t0 can be dynamic size with a lower bound of 5 (inclusive)
# Second dimension of t1 can be dynamic size with a lower bound of 2 (exclusive)
constraints = [
dynamic_dim(t0, 0) >= 5,
dynamic_dim(t1, 1) > 2,
]
ep = export(fn, (t0, t1), constraints=constraints)
- Size of a dimension is dynamic with an upper bound::
t0 = torch.rand(10, 3)
t1 = torch.rand(3, 4)
# First dimension of t0 can be dynamic size with a upper bound of 16 (inclusive)
# Second dimension of t1 can be dynamic size with a upper bound of 8 (exclusive)
constraints = [
dynamic_dim(t0, 0) <= 16,
dynamic_dim(t1, 1) < 8,
]
ep = export(fn, (t0, t1), constraints=constraints)
- Size of a dimension is dynamic and it is always equal to size of another dynamic dimension::
t0 = torch.rand(10, 3)
t1 = torch.rand(3, 4)
# Sizes of second dimension of t0 and first dimension are always equal
constraints = [
dynamic_dim(t0, 1) == dynamic_dim(t1, 0),
]
ep = export(fn, (t0, t1), constraints=constraints)
- Mix and match all types above as long as they do not express conflicting requirements
"""
from torch._dynamo.exc import UserError, UserErrorType
if not isinstance(t, torch.Tensor):
raise UserError(
UserErrorType.DYNAMIC_DIM,
f"Expected tensor as input to dynamic_dim but got {type(t)}",
)
if t.dim() < 1:
raise UserError(
UserErrorType.DYNAMIC_DIM, "Cannot mark 0-dimension tensors to be dynamic"
)
if index >= t.dim():
raise UserError(
UserErrorType.DYNAMIC_DIM,
f"Expected the dimension passed to dynamic_dim to be in the range [0:{t.dim()-1}]"
f" but got {index}, which is out of bounds for the given tensor.",
)
# Import sympy locally
import sympy
from torch.fx.experimental.symbolic_shapes import StrictMinMaxConstraint
from torch.utils._sympy.value_ranges import ValueRanges
return _create_constraint(
weakref.ref(t),
id(t),
index,
StrictMinMaxConstraint(
vr=ValueRanges(lower=2, upper=sympy.oo), warn_only=False
),
debug_name=debug_name,
)
def _process_equalities(
constraint: Constraint,
get_sources: Callable[[int, int], List["Source"]],
shape_env: "ShapeEnv",
source_pairs: List[Tuple["Source", "Source"]],
derived_equalities: List[Tuple["Source", Union["Source", "Symbol"], Callable]],
phantom_symbols: Dict[str, "Symbol"],
):
"""
Updates `source_pairs`, `derived_equalities`, and `phantom_symbols` (which become
fields of `EqualityConstraint`) based on a given input `constraint`.
"""
source, *other_sources = get_sources(constraint.t_id, constraint.dim)
# When t.size()[dim] maps to src0, src1, ..., srcN, we add
# constraints that make src0 "equal" to src1, ..., srcN.
source_pairs.extend((source, other_source) for other_source in other_sources)
if not isinstance(constraint, _DerivedConstraint):
if constraint.shared is not None:
# Moreover, when t.size()[dim] is specified equal to t'.size()[dim']
# and t'.size()[dim'] maps to src1', ..., srcN', we add
# constraints that also make src0 "equal" to src1', ..., srcN'.
other_sources = get_sources(constraint.shared.t_id, constraint.shared.dim)
source_pairs.extend(
(source, other_source) for other_source in other_sources
)
else:
# branch based on the root of the _DerivedConstraint
if not isinstance(constraint.root, _PhantomRoot):
# either root points to an input source
root = get_sources(constraint.root.t_id, constraint.root.dim)[0] # type: ignore[assignment]
else:
# or root points to a phantom symbol
if constraint.root.name in phantom_symbols:
root = phantom_symbols[constraint.root.name] # type: ignore[assignment]
else:
# create a phantom symbol in the shape env based on the _PhantomRoot
root = shape_env.create_symbol(
val=constraint.root.val,
source=torch._dynamo.source.ConstantSource(constraint.root.name),
dynamic_dim=torch.fx.experimental.symbolic_shapes.DimDynamic.DYNAMIC,
constraint_dim=constraint.root.constraint_range,
)
phantom_symbols[constraint.root.name] = root # type: ignore[assignment]
fn = constraint.fn
# A derived equality (source, root, fn) informally corresponds to source = fn(root).
# Here source describes an input and root might describe another input or a phantom symbol.
derived_equalities.append((source, root, fn))
def _process_dynamic_shapes(
f: Callable,
args: Tuple[Any, ...],
kwargs: Optional[Dict[str, Any]] = None,
dynamic_shapes: Optional[Union[Dict[str, Any], Tuple[Any], List[Any]]] = None,
) -> Optional[List[Constraint]]:
from collections import defaultdict
from collections.abc import Mapping, Sequence
from torch._dynamo.exc import UserError, UserErrorType
if dynamic_shapes is None or len(dynamic_shapes) == 0:
return None
kwargs = kwargs if kwargs is not None else {}
def tree_zip(combined_args, dynamic_shapes):
if isinstance(combined_args, (tuple, list)):
if not isinstance(dynamic_shapes, Sequence):
raise UserError(
UserErrorType.INVALID_INPUT,
f"Expected dynamic_shapes of a {type(combined_args)} to be a Sequence, "
f"got {dynamic_shapes} instead",
)
if len(combined_args) != len(dynamic_shapes):
raise UserError(
UserErrorType.INVALID_INPUT,
f"Expected {dynamic_shapes} to have {len(combined_args)} items",
)
for i, shape in enumerate(dynamic_shapes):
yield from tree_zip(combined_args[i], shape)
elif isinstance(combined_args, dict):
if not isinstance(dynamic_shapes, Mapping):
raise UserError(
UserErrorType.INVALID_INPUT,
f"Expected dynamic_shapes of a {type(combined_args)} to be a Mapping, "
f"got {dynamic_shapes} instead",
)
if len(combined_args) != len(dynamic_shapes):
raise UserError(
UserErrorType.INVALID_INPUT,
f"Expected {dynamic_shapes} to have {len(combined_args)} items",
)
for k, shape in dynamic_shapes.items():
yield from tree_zip(combined_args[k], shape)
elif type(combined_args) in SUPPORTED_NODES:
if not isinstance(dynamic_shapes, Sequence):
raise UserError(
UserErrorType.INVALID_INPUT,
f"Expected dynamic_shapes of a user-registered class (e.g., "
f"{type(combined_args)}) to be a Sequence that matches the "
f"flattened structure, but got {dynamic_shapes} instead",
)
yield from tree_zip(
SUPPORTED_NODES[type(combined_args)].flatten_fn(combined_args)[0],
dynamic_shapes,
)
elif isinstance(combined_args, torch.Tensor):
yield (combined_args, dynamic_shapes)
else:
if dynamic_shapes is not None:
raise UserError(
UserErrorType.INVALID_INPUT,
f"Expected dynamic_shapes of a {type(combined_args)} to be None, "
f"got {dynamic_shapes} instead",
)
# map of Dim names representing input shape dimensions to constraints on them
symbols: Dict[str, List[Constraint]] = defaultdict(list)
# track roots that do not directly represent input shape dimensions
phantom_roots: Dict[str, _PhantomRoot] = {}
derived_constraints_with_phantom_root: List[_DerivedConstraint] = []
def to_constraint(dim, tensor, i):
import sympy
from torch.fx.experimental.symbolic_shapes import StrictMinMaxConstraint
from torch.utils._sympy.solve import try_solve
from torch.utils._sympy.value_ranges import ValueRanges
def root_value():
# given tensor.shape[i] is the value of dim = fn(root),
# find the value of root
symbol = sympy.Symbol(dim.root.__name__, integer=True)
expr = dim.fn(symbol)
solution = try_solve(sympy.Eq(expr, tensor.shape[i]), symbol)
if solution is not None:
return int(solution[1]) # type: ignore[call-overload]
else:
raise UserError( # noqa: TRY200
UserErrorType.CONSTRAINT_VIOLATION,
f"Expected shape[{i}] = {tensor.shape[i]} of input Tensor to be "
f"of the form {expr}, where {symbol} is an integer",
)
if isinstance(dim, _DerivedDim):
# generate a _DerivedConstraint where the root is:
# - either a _ConstraintTarget (if dim.root directly describes an input shape)
# - or a _PhantomRoot (otherwise)
dim_root = dim.root # type: ignore[attr-defined]
if dim_root.__name__ in symbols:
# root represents an input shape dimension
root_constraint = symbols[dim_root.__name__][0]
root = _ConstraintTarget(
root_constraint.w_tensor,
root_constraint.t_id,
root_constraint.dim,
)
elif dim_root.__name__ not in phantom_roots:
# create a phantom root
root = _PhantomRoot( # type: ignore[assignment]
name=dim_root.__name__,
constraint_range=StrictMinMaxConstraint(
vr=ValueRanges(lower=dim_root.min, upper=dim_root.max),
warn_only=False,
),
val=root_value(),
)
phantom_roots[dim_root.__name__] = root # type: ignore[assignment]
else:
root = phantom_roots[dim_root.__name__] # type: ignore[assignment]
constraint = _DerivedConstraint(
weakref.ref(tensor),
id(tensor),
i,
root,
dim.fn, # type: ignore[attr-defined]
StrictMinMaxConstraint(
vr=ValueRanges(lower=dim.min, upper=dim.max),
warn_only=False,
),
debug_name=dim.__name__,
)
if isinstance(root, _PhantomRoot):
# NOTE(avik): since we have not processed all inputs yet, we may replace this
# with a root that does represent an input shape dimension later (see below)
derived_constraints_with_phantom_root.append(constraint)
else:
constraint = dynamic_dim(tensor, i, debug_name=dim.__name__)
if dim.min != 2:
constraint = constraint >= dim.min
if dim.max != sys.maxsize - 1:
constraint = constraint <= dim.max
return constraint
bounds: Dict[str, Tuple[int, int]] = {}
def check_same_bounds(dim):
if dim.__name__ in symbols:
min_, max_ = bounds[dim.__name__]
if dim.min != min_ or dim.max != max_:
this_ = _Dim.readable(dim.__name__, min_, max_)
that_ = _Dim.readable(dim.__name__, dim.min, dim.max)
raise UserError(
UserErrorType.INVALID_INPUT,
f"Found different definitions {this_} and {that_} "
f"for the same symbolic dimension {dim}!",
)
else:
bounds[dim.__name__] = (dim.min, dim.max)
def update_symbols(tensor, shape):
if isinstance(shape, dict):
for i, dim in shape.items():
if isinstance(dim, _Dim):
check_same_bounds(dim)
constraint = to_constraint(dim, tensor, i)
symbols[dim.__name__].append(constraint)
else:
if dim is not None:
raise UserError(
UserErrorType.INVALID_INPUT,
f"Unexpected item #{i} ({dim}) in dynamic_shape {shape} of Tensor, "
"try None instead",
)
elif isinstance(shape, (tuple, list)):
for i, dim in enumerate(shape):
if isinstance(dim, _Dim):
check_same_bounds(dim)
constraint = to_constraint(dim, tensor, i)
symbols[dim.__name__].append(constraint)
else:
if dim is not None:
raise UserError(
UserErrorType.INVALID_INPUT,
f"Unexpected item #{i} ({dim}) in dynamic_shape {shape} of Tensor, "
"try None instead",
)
else:
if shape is not None:
raise UserError(
UserErrorType.INVALID_INPUT,
f"Unexpected dynamic_shape {shape} of Tensor, " "try None instead",
)
import inspect
if isinstance(f, ExportedProgram):
f = f.module()
signature = (
inspect.signature(f.forward)
if isinstance(f, torch.nn.Module)
else inspect.signature(f)
)
combined_args = signature.bind(*args, **kwargs).arguments
# This means user didn't specify dynamic shapes with argument names.
combined_args = combined_args if isinstance(dynamic_shapes, Mapping) else list(combined_args.values()) # type: ignore[assignment]
for tensor, shape in tree_zip(combined_args, dynamic_shapes):
update_symbols(tensor, shape)
constraints = []
for derived_constraint_with_phantom_root in derived_constraints_with_phantom_root:
phantom_root_name = derived_constraint_with_phantom_root.root.name # type: ignore[union-attr]
if phantom_root_name in symbols:
# We found an input shape dimension corresponding to this name, so we
# do not need a phantom symbol for it after all.
# NOTE(avik): Overall we want to maintain the invariant that roots that
# are phantom symbols are really "phantom," i.e., they cannot be represented
# by any input source. This is important when we are deciding derived equalities,
# since we can focus our attention exclusively on input sources: deciding
# derived equalities involving phantom symbols are, in comparison, trivial.
derived_constraint_with_phantom_root.root = symbols[phantom_root_name][0]
for dynamic_dims in symbols.values():
if all(
isinstance(dynamic_dim, _DerivedConstraint) for dynamic_dim in dynamic_dims
):
constraints.extend(dynamic_dims)
else:
primary, *others = dynamic_dims
if others:
for other in others:
constraints.append(primary == other) # type: ignore[arg-type]
else:
constraints.append(primary)
return constraints # type: ignore[return-value]
def _process_constraints(
fake_mode,
graph_module: torch.fx.GraphModule,
num_lifted_params_buffers: int,
example_inputs: List[torch.Tensor],
) -> Dict:
"""
Process the constraints stored in the graph module to return something more readable.
Args:
graph_module (torch.fx.GraphModule): GraphModule returned from
dynamo.export, which contains the "input_shape_constraints" and
"inline_constraints" metadata
example_inputs: Flattened list of example inputs used to export the graph module
Returns:
range_constraints (Dict[sympy.Symbol, ValueRanges]): Mapping of
symbols (from SymInts) appearing in the fake tensors in
node.meta["val"] to their range constraints, which are a tuple
containing (lower, upper) constraints.
"""
from torch._export.passes.add_runtime_assertions_for_constraints_pass import (
InputDim,
)
# Import sympy locally
from torch.fx.experimental.symbolic_shapes import SymInt
from torch.utils._sympy.value_ranges import ValueRanges
input_shape_constraints = graph_module.meta.get("input_shape_constraints", [])
inline_constraints = graph_module.meta.get("inline_constraints", [])
# Create dict mapping tensor_id to node names
tensor_id_to_nodes: Dict[int, List[str]] = defaultdict(list)
# Create dict mapping placeholder node names to their nodes
placeholder_nodes: Dict[str, torch.fx.Node] = {}
for i, node in enumerate(graph_module.graph.nodes):
if node.op != "placeholder":
# All placeholder nodes should be together in the beginning of the
# graph
break
if i >= num_lifted_params_buffers:
example_input = example_inputs[i - num_lifted_params_buffers]
tensor_id_to_nodes[id(example_input)].append(node.name)
placeholder_nodes[node.name] = node
# Create dict mapping (node name, dim) a list of range (lower, upper)
# constraints
multi_range_constraints: Dict[InputDim, List[ValueRanges]] = defaultdict(list)
for constraint in input_shape_constraints:
for node in tensor_id_to_nodes[constraint["t_id"]]:
node_dim = InputDim(node, constraint["dim"])
# Accumulate range constraints
multi_range_constraints[node_dim].append(
ValueRanges(constraint["min"], constraint["max"])
)
# Create dict mapping symbol to a singular range (lower, upper)
range_constraints: Dict[Any, ValueRanges] = {}
# Add inline constraints to range_constraints
range_constraints = {
symbol: inline_constraints[symbol] for symbol in inline_constraints
}
free_symbols: Set["Symbol"] = set()
# Add input range constraints to range_constraints
for input_dim, multi_range_constraint in multi_range_constraints.items(): # type: ignore[assignment]
# Simplify the range constraints into a single range constraint
# Ex. ranges [2, 10] and [3, 11] would get merged to [3, 10]
min_vals = [rc.lower for rc in multi_range_constraint]
max_vals = [rc.upper for rc in multi_range_constraint]
min_val = max(min_vals) # type: ignore[type-var]
max_val = min(max_vals) # type: ignore[type-var]
assert min_val <= max_val # type: ignore[operator]
# Add input node range constraints
val = placeholder_nodes[input_dim.input_name].meta["val"]
assert isinstance(val, FakeTensor)
symint = val.shape[input_dim.dim]
assert isinstance(
symint, SymInt
), f"Expected SymInt but got {symint}: {type(symint)}"
symbol = symint.node.expr
range_constraints[symbol] = ValueRanges(min_val, max_val)
free_symbols.update(symbol.free_symbols)
for symbol in free_symbols:
if symbol not in range_constraints:
# Placeholders can have symbolic shapes that are derived expressions.
# The above code will record direct range constraints for them
# so that we can do runtime assertions. In addition, for serde checks
# we want to record range constraints for their root symbols.
range_constraints[symbol] = fake_mode.shape_env.var_to_range[symbol]
return range_constraints