Files
pytorch/torch/_library/utils.py
Richard Zou ad0883a288 [real_tensor_prop] Infer Fake kernels during real tensor prop (#139213)
This PR changes real_tensor_prop to also infer fake kernels when the
operator doesn't have it.

We infer the fake output to be of the same properties as the real
output, with unbacked symints in the sizes and some stride order.

Test Plan:
- new tests
Pull Request resolved: https://github.com/pytorch/pytorch/pull/139213
Approved by: https://github.com/pianpwk
ghstack dependencies: #139212
2024-10-30 21:29:33 +00:00

455 lines
16 KiB
Python

# mypy: allow-untyped-defs
import dataclasses
import inspect
import sys
from typing import Any, Callable, Dict, Iterable, Iterator, Tuple, Union
import torch
import torch.utils._pytree as pytree
from torch import _C, _utils_internal
from torch._ops import OpOverload
@dataclasses.dataclass
class Kernel:
"""Models a (function, source location)"""
func: Callable
source: str
def __call__(self, *args, **kwargs):
return self.func(*args, **kwargs)
class RegistrationHandle:
"""Does something when someone calls .destroy() on it"""
def __init__(self, on_destroy: Callable):
self._on_destroy = on_destroy
def destroy(self) -> None:
self._on_destroy()
def get_source(stacklevel: int) -> str:
"""Get a string that represents the caller.
Example: "/path/to/foo.py:42"
Use stacklevel=1 to get the caller's source
Use stacklevel=2 to get the caller's caller's source
etc.
"""
frame = inspect.getframeinfo(sys._getframe(stacklevel))
source = f"{frame.filename}:{frame.lineno}"
return source
def parse_namespace(qualname: str) -> Tuple[str, str]:
splits = qualname.split("::")
if len(splits) != 2:
raise ValueError(
f"Expected `qualname` to be of the form "
f'"namespace::name", but got {qualname}. '
f"The qualname passed to the torch.library APIs must consist "
f"of a namespace and a name, e.g. aten::sin"
)
return splits[0], splits[1]
def lookup_op(qualname: str) -> OpOverload:
namespace, name = parse_namespace(qualname)
if "." in name:
name, overload = name.split(".")
else:
overload = "default"
ns = getattr(torch.ops, namespace)
packet = getattr(ns, name)
return getattr(packet, overload)
def is_builtin(op: OpOverload) -> bool:
assert isinstance(op, OpOverload)
return op.namespace in {"aten", "prim", "prims"}
def is_functional_schema(schema: Any) -> bool:
"""Check if the schema is functional.
An operator is functional if:
- it does not mutate any of its inputs
- it does not return a view on any of its inputs
- it has at least one return
"""
def is_functional(schema):
if schema.is_mutable:
return False
rets = schema.returns
is_non_mutating_view = len(rets) > 0 and any(
r.alias_info is not None and not r.alias_info.is_write for r in rets
)
if is_non_mutating_view:
return False
if not schema.returns:
return False
return True
if isinstance(schema, torch._C.FunctionSchema):
return is_functional(schema)
# Lazy import because not all PyTorch builds have torchgen
from torchgen.model import FunctionSchema
if isinstance(schema, str):
schema = FunctionSchema.parse(schema)
assert isinstance(schema, FunctionSchema)
return is_functional(schema)
# should be torch._C.JitType but that annotation is busted
def is_tensorlist_like_type(typ: Any) -> bool:
return (
typ == _C.ListType(_C.TensorType.get())
or typ == _C.ListType(_C.OptionalType(_C.TensorType.get()))
or typ == _C.OptionalType(_C.ListType(_C.TensorType.get()))
or typ == _C.OptionalType(_C.ListType(_C.OptionalType(_C.TensorType.get())))
)
# should be torch._C.JitType but that annotation is busted
def is_tensor_like_type(typ: Any) -> bool:
return typ == _C.TensorType.get() or typ == _C.OptionalType(_C.TensorType.get())
def mutates_and_returns_first_arg(op: OpOverload):
"""Check if an op is an inplace aten op, i.e. it mutates and returns the first arg.
TODO: torchgen/model.py's FunctionSchema.parse is the source of truth for this,
but not all PyTorch builds have torchgen (due to the yaml dependency being weird).
Figure this out.
Example: add_(Tensor(a!) x, Tensor y) -> Tensor(a)
"""
if op.namespace != "aten":
return False
schema = op._schema
if not len(schema.returns) == 1:
return False
if schema.returns[0].alias_info is None:
return False
alias_set = schema.returns[0].alias_info.after_set
if len(alias_set) != 1:
return False
loc = next(iter(alias_set))
if len(schema.arguments) < 1:
return False
first_arg = schema.arguments[0]
if first_arg.alias_info is None:
return False
if not first_arg.alias_info.is_write:
return False
alias_set = first_arg.alias_info.after_set
if len(alias_set) != 1:
return False
if loc != next(iter(alias_set)):
return False
for arg in schema.arguments[1:]:
if arg.alias_info is not None:
return False
return True
def fill_defaults(schema, args, kwargs):
new_args = []
new_kwargs = {}
for i in range(len(schema.arguments)):
info = schema.arguments[i]
if info.kwarg_only:
if info.name in kwargs:
new_kwargs[info.name] = kwargs[info.name]
else:
new_kwargs[info.name] = info.default_value
else:
if i < len(args):
new_args.append(args[i])
else:
new_args.append(info.default_value)
return tuple(new_args), new_kwargs
def zip_schema(
schema: _C.FunctionSchema, args: Tuple[Any, ...], kwargs: Dict[str, Any]
) -> Iterable[Tuple[_C.Argument, Any]]:
"""zips schema.arguments and (args, kwargs) together.
Assumes that (args, kwargs) were the inputs to some torch._ops.OpOverload:
that is, (args, kwargs) must be bindable to the schema (args, kwargs).
"""
assert len(schema.arguments) >= len(args) + len(kwargs)
for i in range(len(schema.arguments)):
info = schema.arguments[i]
if info.kwarg_only:
if info.name in kwargs:
yield info, kwargs[info.name]
continue
if i >= len(args):
if not info.kwarg_only and info.name in kwargs:
yield info, kwargs[info.name]
# args that are equal to their default values are not populated
# if they are followed by args that are equal to their defaults.
# Skip these.
continue
yield info, args[i]
return
def hop_schema_from_fx_node(node):
from torchgen.gen_schema_utils import FunctionSchemaGen
hop = node.target
if not isinstance(hop, torch._ops.HigherOrderOperator):
raise RuntimeError("fx_node's target must be a hop.")
def _collect_example_val(node):
meta_val = node.meta.get("val", None)
if meta_val is None:
assert node.op == "get_attr"
meta_val = getattr(node.graph.owning_module, node.target)
return meta_val
example_inputs = []
for arg in node.args:
if isinstance(arg, (torch.fx.Node, torch.fx.node.Node)):
example_inputs.append(_collect_example_val(arg))
elif isinstance(
arg, (torch.fx.immutable_collections.immutable_list, list, tuple)
):
example_inputs.append([_collect_example_val(x) for x in arg])
else:
raise RuntimeError(f"Unsupported arg type {type(arg)}")
# Bound the arguments to make sure number of inputs are correct
bound_args: inspect.BoundArguments = inspect.signature(hop.__call__).bind(
*example_inputs
)
# We treat example_output as a single value in return. This is to differentiate 1. return a single val
# vs 2. return a tuple with one element.
example_output = _collect_example_val(node)
return FunctionSchemaGen.from_example(
hop._name, tuple(bound_args.arguments.items()), (list(example_output),)
)
def can_generate_trivial_fake_impl(op: OpOverload) -> bool:
assert isinstance(op, OpOverload)
if is_builtin(op):
# We control the built-ins. These may (in rare cases)
# do input metadata mutation (which we have banned on custom ops)
return False
schema = op._schema
# It's suspicious if the op is not mutable but returns nothing, so we return False out of an abundance of caution
if not schema.is_mutable:
return False
if len(schema.returns) > 0:
return False
# If the op returns nothing, then it has a trivial fake impl.
return True
def requires_set_python_module() -> bool:
"""If an op was defined in C++ and extended from Python using the
torch.library APIs, returns if we require that there have been a
m.set_python_module("mylib.ops") call from C++ that associates
the C++ op with a python module.
"""
return getattr(_utils_internal, "REQUIRES_SET_PYTHON_MODULE", True)
def handle_dispatch_mode(curr_mode, op_overload, *args, **kwargs):
assert isinstance(curr_mode, torch.utils._python_dispatch.TorchDispatchMode)
overload_types = []
args_flattened, _ = torch.utils._pytree.tree_flatten((args, kwargs.values()))
for a in args_flattened:
# TODO: need to double check the semantics of the "types" argument to torch_dispatch.
# It's generated in PyInterpreter.cpp, but seems to be generated in two places,
# where in one case we only include tensors with the python key, and in another
# we include **all** tensors.
if isinstance(a, torch.Tensor) and torch._C._dispatch_keys(a).has(
torch._C.DispatchKey.Python
):
overload_types.append(type(a))
# TODO: check that I got these args correct (in C++, we pass in "0000"??)
return curr_mode.__torch_dispatch__(op_overload, overload_types, args, kwargs)
def has_kwarg_only_args(schema: _C.FunctionSchema):
return any(a.kwarg_only for a in schema.arguments)
def has_kwarg_only_tensors(schema: _C.FunctionSchema):
for a in schema.arguments:
if not (is_tensor_like_type(a.type) or is_tensorlist_like_type(a.type)):
continue
if not a.kwarg_only:
continue
return True
return False
def has_tensor_arg(schema: _C.FunctionSchema) -> bool:
"""
Given a schema, returns True if the schema has a Tensor arg.
A Tensor arg is any arg with a type annotation that might involve Tensor.
"""
return any(
(is_tensor_like_type(a.type) or is_tensorlist_like_type(a.type))
for a in schema.arguments
)
def get_device_arg_index(schema: _C.FunctionSchema) -> Union[int, None]:
"""
Given a schema, returns the id of the `device: torch.device` argument.
If it does not exist, returns None.
"""
for index, arg in enumerate(schema.arguments):
if arg.type is _C.DeviceObjType.get() and arg.name == "device":
return index
return None
def iter_tensors(
args: Tuple[Any], kwargs: Dict[str, Any], allowed_nesting: int = 1
) -> Iterator[torch.Tensor]:
def check(arg):
if isinstance(arg, torch.Tensor):
yield arg
elif allowed_nesting > 0 and isinstance(arg, (tuple, list)):
yield from iter_tensors(tuple(arg), {}, allowed_nesting - 1)
for arg in args:
yield from check(arg)
for kwarg in kwargs.values():
yield from check(kwarg)
def check_aliasing_constraint(name, prev, result, get_module=lambda: "???"):
"""
custom operators' outputs must not alias any inputs or other outputs.
"""
storages = {id(t.untyped_storage()) for t in prev if isinstance(t, torch.Tensor)}
tuple_result = result
if not isinstance(result, tuple):
tuple_result = (result,)
for tensor in iter_tensors(tuple_result, {}):
key = id(tensor.untyped_storage())
if id(tensor.untyped_storage()) in storages:
raise RuntimeError(
f"{name} (with implementation in {get_module()}): "
f"The output of this custom operator (1) must not "
f"also be an input to this custom operator and "
f"(2) may not alias any inputs to this custom operator "
f"or other returns. "
f"The most common way to trigger this error is if "
f"we have y = custom_op(x) and y and x are the same Tensor. "
f"Please instead return a clone of the offending output "
f"tensor(s) (e.g. return x.clone()) or refactor the custom "
f"operator to not return y."
)
storages.add(key)
class MutationChecker:
"""
Check if an operator mutated its arguments.
Usage:
checker = MutationChecker(op, flat_args, args_spec)
op(*args, **kwargs)
checker.check()
"""
def __init__(self, op, flat_args, args_spec):
self.op = op
self.args_spec = args_spec
self.flat_args = flat_args
self.real_pre_hashes = [
hash_tensor(a) if isinstance(a, torch.Tensor) else None for a in flat_args
]
def check(self):
real_post_hashes = [
hash_tensor(a) if isinstance(a, torch.Tensor) else None
for a in self.flat_args
]
was_mutated = [
not torch.equal(pre, post)
if isinstance(pre, torch.Tensor) and isinstance(post, torch.Tensor)
else None
for pre, post in zip(self.real_pre_hashes, real_post_hashes)
]
was_mutated_args, was_mutated_kwargs = pytree.tree_unflatten(
was_mutated, self.args_spec
)
for info, was_mutated in zip_schema(
self.op._schema, was_mutated_args, was_mutated_kwargs
):
def check_one(info, was_mutated):
if info.is_write == was_mutated:
return
raise RuntimeError(
f"{self.op._name}: for argument '{info.name}': the operator's schema "
f"{self.op._schema} specified that "
f"the operator {'mutates' if info.is_write else 'does not mutate'} "
f"the argument, but this seems to be emperically wrong. "
f"Please make the schema and operator behavior consistent. "
f"You can specify that an operator mutates a Tensor by "
f"e.g. changing its schema type from 'Tensor name' to 'Tensor(a!) name'"
f"(use different identifiers (a, b, c, ...) for different Tensors)"
)
if is_tensor_like_type(info.type):
check_one(info, was_mutated)
elif is_tensorlist_like_type(info.type):
was_any_mutated = False if was_mutated is None else any(was_mutated)
check_one(info, was_any_mutated)
def hash_tensor(t: torch.Tensor) -> torch.Tensor:
"""Some inexpensive hash. Used as a quick and dirty indicator for tensor mutation"""
return t.detach().float().mean()
def has_fake_kernel(op: torch._ops.OpOverload) -> bool:
"""If an operator (that stays alive until FakeTensorMode) has a Fake kernel.
Don't use this if the operator decomposes before FakeTensorMode.
"""
if can_generate_trivial_fake_impl(op):
return True
name = op._name
if torch._C._dispatch_has_kernel_for_dispatch_key(
name, "CompositeImplicitAutograd"
):
return True
opdef = torch._library.custom_ops._maybe_get_opdef(name)
if opdef is None:
# the non-torch.library.custom_op path
if torch._C._dispatch_has_kernel_for_dispatch_key(
name, "CompositeExplicitAutograd"
):
return True
entry = torch._library.simple_registry.singleton.find(name)
if entry.fake_impl.kernel is not None:
return True
if torch._C._dispatch_has_kernel_for_dispatch_key(name, "Meta"):
return True
else:
# the torch.library.custom_op path
if opdef._abstract_fn is not None:
return True
return False