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533 lines
22 KiB
533 lines
22 KiB
from ._ops import OpOverload
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from typing import Any, Optional, Set, List
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import traceback
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import torch
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import weakref
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import functools
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import inspect
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import re
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import contextlib
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import sys
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__all__ = [
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'Library',
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'impl',
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'define',
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'fallthrough_kernel',
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'impl_abstract',
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'get_ctx',
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]
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# Set containing the combination of (namespace, operator, DispatchKey) for which a new kernel has been registered
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# The keys in the set are of the form `namespace + "/" + op_name + "/" + dispatch_key`.
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# This set is maintained to ensure that two libraries don't try to override the exact same functionality to avoid
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# libraries calling into kernels not intended to be called.
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_impls: Set[str] = set()
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_defs: Set[str] = set()
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# prim is reserved by TorchScript interpreter
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_reserved_namespaces = ['prim']
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def fallthrough_kernel():
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"""
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A dummy function to pass to ``Library.impl`` in order to register a fallthrough.
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"""
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raise NotImplementedError("fallthrough_kernel() should never be called.")
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class Library:
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"""
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A class to create libraries that can be used to register new operators or
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override operators in existing libraries from Python.
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A user can optionally pass in a dispatch keyname if they only want to register
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kernels corresponding to only one specific dispatch key.
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To create a library to override operators in an existing library (with name ns), set the kind to "IMPL".
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To create a new library (with name ns) to register new operators, set the kind to "DEF".
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To create a fragment of a possibly existing library to register operators (and bypass
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the limitation that there is only one library for a given namespace), set the kind to
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"FRAGMENT".
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Args:
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ns: library name
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kind: "DEF", "IMPL" (default: "IMPL"), "FRAGMENT"
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dispatch_key: PyTorch dispatch key (default: "")
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"""
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def __init__(self, ns, kind, dispatch_key=""):
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if kind not in ('IMPL', 'DEF', 'FRAGMENT'):
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raise ValueError("Unsupported kind: ", kind)
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if ns in _reserved_namespaces and (kind == "DEF" or kind == 'FRAGMENT'):
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raise ValueError(ns, " is a reserved namespace. Please try creating a library with another name.")
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frame = traceback.extract_stack(limit=3)[0]
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filename, lineno = frame.filename, frame.lineno
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self.m: Optional[Any] = torch._C._dispatch_library(kind, ns, dispatch_key, filename, lineno)
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self.ns = ns
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self._op_defs: Set[str] = set()
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self._op_impls: Set[str] = set()
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self._registration_handles: List["torch._library.utils.RegistrationHandle"] = []
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self.kind = kind
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self.dispatch_key = dispatch_key
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# Use a finalizer to setup the "destructor" instead of __del__.
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# Python __del__ can lead to weird things (globals and locals may already
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# be gone when __del__ actually gets called!). finalizers help the
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# situation because it lets us capture references and keeps them alive
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weakref.finalize(self, _del_library, _impls, self._op_impls, _defs, self._op_defs, self._registration_handles)
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def __repr__(self):
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return f"Library(kind={self.kind}, ns={self.ns}, dispatch_key={self.dispatch_key})>"
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def define(self, schema, alias_analysis="", *, tags=()):
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r'''Defines a new operator and its semantics in the ns namespace.
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Args:
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schema: function schema to define a new operator.
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alias_analysis (optional): Indicates if the aliasing properties of the operator arguments can be
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inferred from the schema (default behavior) or not ("CONSERVATIVE").
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tags (Tag | Sequence[Tag]): one or more torch.Tag to apply to this
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operator. Tagging an operator changes the operator's behavior
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under various PyTorch subsystems; please read the docs for the
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torch.Tag carefully before applying it.
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Returns:
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name of the operator as inferred from the schema.
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Example::
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>>> # xdoctest: +REQUIRES(env:TORCH_DOCTEST_LIBRARY)
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>>> my_lib = Library("foo", "DEF")
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>>> my_lib.define("sum(Tensor self) -> Tensor")
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'''
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# This is added because we also want to disallow PURE_FUNCTION alias analysis which is a valid
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# AliasAnalysis type in C++
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if alias_analysis not in ["", "FROM_SCHEMA", "CONSERVATIVE"]:
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raise RuntimeError(f"Invalid alias_analysis type {alias_analysis}")
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assert self.m is not None
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if isinstance(tags, torch.Tag):
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tags = (tags,)
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result = self.m.define(schema, alias_analysis, tuple(tags))
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qualname = self.ns + "::" + schema.split("(")[0]
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self._op_defs.add(qualname)
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_defs.add(qualname)
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return result
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def impl(self, op_name, fn, dispatch_key=''):
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r'''Registers the function implementation for an operator defined in the library.
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Args:
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op_name: operator name (along with the overload) or OpOverload object.
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fn: function that's the operator implementation for the input dispatch key or :func:`~fallthrough_kernel`
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to register a fallthrough.
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dispatch_key: dispatch key that the input function should be registered for. By default, it uses
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the dispatch key that the library was created with.
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Example::
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>>> my_lib = Library("aten", "IMPL")
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>>> def div_cpu(self, other):
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>>> return self * (1 / other)
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>>> my_lib.impl("div.Tensor", div_cpu, "CPU")
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'''
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if not callable(fn):
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raise TypeError(f"Input function is required to be a callable but found type {type(fn)}")
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if dispatch_key == '':
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dispatch_key = self.dispatch_key
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if isinstance(op_name, str):
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name = op_name
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elif isinstance(op_name, OpOverload):
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name = op_name._schema.name
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overload_name = op_name._schema.overload_name
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if overload_name != '':
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name = name + '.' + overload_name
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else:
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raise RuntimeError("impl should be passed either a name or an OpOverload object as the first argument")
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key = self.ns + "/" + name.split("::")[-1] + "/" + dispatch_key
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if key in _impls:
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# TODO: in future, add more info about where the existing function is registered (this info is
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# today already returned by the C++ warning when impl is called but we error out before that)
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raise RuntimeError("This is not allowed since there's already a kernel registered from python overriding {}"
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"'s behavior for {} dispatch key and {} namespace.".
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format(name.split("::")[-1], dispatch_key, self.ns))
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if dispatch_key == "Meta":
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dispatcher_op_name = name
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if '::' not in dispatcher_op_name:
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dispatcher_op_name = f'{self.ns}::{dispatcher_op_name}'
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# Internally, we shouldn't be registering meta kernels for any operators that
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# have CompositeImplicitAutograd kernels.
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# Instead, we should be letting those decompositions run, and writing meta kernels
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# only for the base operators.
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if torch._C._dispatch_has_kernel_for_dispatch_key(dispatcher_op_name, "CompositeImplicitAutograd"):
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raise RuntimeError(
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f"We should not register a meta kernel directly to the operator '{name}',"
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" because it has a CompositeImplicitAutograd kernel in core."
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" Instead we should let the operator decompose, and ensure that we have meta kernels"
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" for the base ops that it decomposes into.")
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assert self.m is not None
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self.m.impl(name, dispatch_key if dispatch_key != "" else "CompositeImplicitAutograd", fn)
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_impls.add(key)
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self._op_impls.add(key)
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def _destroy(self):
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if self.m is not None:
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self.m.reset()
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self.m = None
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for handle in self._registration_handles:
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handle.destroy()
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self._registration_handles.clear()
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for name in self._op_defs:
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# Delete the cached torch.ops.ns.foo if it was registered.
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# Otherwise, accessing it leads to a segfault.
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# It's possible that we only registered an overload in this Library
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# and another library owns an alive overload.
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# That's OK - the next time torch.ops.ns.foo gets called, it'll be
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# recomputed to point at the right collection of overloads.
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ns, name_with_overload = name.split("::")
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name = name_with_overload.split(".")[0]
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if not hasattr(torch.ops, ns):
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continue
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namespace = getattr(torch.ops, ns)
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if not hasattr(namespace, name):
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continue
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delattr(namespace, name)
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def _del_library(captured_impls, op_impls, captured_defs, op_defs, registration_handles):
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captured_impls -= op_impls
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captured_defs -= op_defs
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for handle in registration_handles:
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handle.destroy()
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@contextlib.contextmanager
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def _scoped_library(*args, **kwargs):
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try:
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lib = Library(*args, **kwargs)
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yield lib
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finally:
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lib._destroy()
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_keep_alive: List[Library] = []
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NAMELESS_SCHEMA = re.compile(r"\(.*\) -> .*")
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@functools.singledispatch
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def define(qualname, schema, *, lib=None, tags=()):
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r"""Defines a new operator.
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In PyTorch, defining an op (short for "operator") is a two step-process:
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- we need to define the op (by providing an operator name and schema)
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- we need to implement behavior for how the operator interacts with
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various PyTorch subsystems, like CPU/CUDA Tensors, Autograd, etc.
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This entrypoint defines the custom operator (the first step)
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you must then perform the second step by calling various
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``impl_*`` APIs, like :func:`torch.library.impl` or
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:func:`torch.library.impl_abstract`.
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Args:
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qualname (str): The qualified name for the operator. Should be
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a string that looks like "namespace::name", e.g. "aten::sin".
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Operators in PyTorch need a namespace to
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avoid name collisions; a given operator may only be created once.
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If you are writing a Python library, we recommend the namespace to
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be the name of your top-level module.
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schema (str): The schema of the operator. E.g. "(Tensor x) -> Tensor"
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for an op that accepts one Tensor and returns one Tensor. It does
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not contain the operator name (that is passed in ``qualname``).
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lib (Optional[Library]): If provided, the lifetime of this operator
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will be tied to the lifetime of the Library object.
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tags (Tag | Sequence[Tag]): one or more torch.Tag to apply to this
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operator. Tagging an operator changes the operator's behavior
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under various PyTorch subsystems; please read the docs for the
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torch.Tag carefully before applying it.
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Example::
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>>> # xdoctest: +REQUIRES(env:TORCH_DOCTEST_LIBRARY)
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>>> import torch
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>>> import numpy as np
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>>>
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>>> # Define the operator
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>>> torch.library.define("mylib::sin", "(Tensor x) -> Tensor")
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>>>
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>>> # Add implementations for the operator
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>>> @torch.library.impl("mylibrary::sin", "cpu")
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>>> def f(x):
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>>> return torch.from_numpy(np.sin(x.numpy()))
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>>>
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>>> # Call the new operator from torch.ops.
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>>> x = torch.randn(3)
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>>> y = torch.ops.mylib.sin(x)
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>>> assert torch.allclose(y, x)
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"""
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if not isinstance(qualname, str):
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raise ValueError(
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f"define(qualname, schema): expected qualname "
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f"to be instance of str, got {type(qualname)}")
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namespace, name = torch._library.utils.parse_namespace(qualname)
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if lib is None:
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lib = Library(namespace, "FRAGMENT")
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_keep_alive.append(lib)
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if not NAMELESS_SCHEMA.fullmatch(schema):
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raise ValueError(
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f"define(qualname, schema, ...): expected schema "
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f"to look like e.g. \"(Tensor x) -> Tensor\" but "
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f"got \"{schema}\"")
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lib.define(name + schema, alias_analysis="", tags=tags)
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@define.register
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def _(lib: Library, schema, alias_analysis=""):
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"""The old torch.library.define.
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We're keeping this around for BC reasons
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"""
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def wrap(f):
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name = lib.define(schema, alias_analysis)
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lib.impl(name, f)
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return f
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return wrap
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@functools.singledispatch
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def impl(qualname, types, func=None, *, lib=None):
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"""Register an implementation for a device type for this operator.
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You may pass "default" for ``types`` to register this implementation as the
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default implementation for ALL device types.
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Please only use this if the implementation truly supports all device types;
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for example, this is true if it is a composition of built-in PyTorch operators.
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Some valid types are: "cpu", "cuda", "xla", "mps", "ipu", "xpu".
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Args:
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qualname (str): Should be a string that looks like "namespace::operator_name".
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types (str | Sequence[str]): The device types to register an impl to.
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lib (Optional[Library]): If provided, the lifetime of this registration
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will be tied to the lifetime of the Library object.
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Examples:
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>>> import torch
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>>> import numpy as np
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>>>
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>>> # Define the operator
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>>> torch.library.define("mylibrary::sin", "(Tensor x) -> Tensor")
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>>>
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>>> # Add implementations for the cpu device
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>>> @torch.library.impl("mylibrary::sin", "cpu")
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>>> def f(x):
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>>> return torch.from_numpy(np.sin(x.numpy()))
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>>>
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>>> x = torch.randn(3)
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>>> y = torch.ops.mylibrary.sin(x)
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>>> assert torch.allclose(y, x.sin())
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"""
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if isinstance(types, str):
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types = (types,)
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keys = set({})
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for typ in types:
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is_dispatch_key = torch._C._parse_dispatch_key(typ)
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if is_dispatch_key:
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# We also support passing a DispatchKey to impl. Please prefer using
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# the higher-level torch.library APIs and only pass DispatchKey to
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# torch.library.impl with caution (or even better, don't use this
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# option and file an issue on GitHub for what you need).
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# We don't advertise this to users because
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# it is very easy to shoot yourself in the foot.
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keys.add(typ)
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else:
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keys.add(_device_type_to_key(typ))
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def register(func):
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namespace, _ = torch._library.utils.parse_namespace(qualname)
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if lib is None:
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use_lib = Library(namespace, "FRAGMENT")
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_keep_alive.append(use_lib)
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else:
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use_lib = lib
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for key in keys:
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use_lib.impl(qualname, func, key)
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if func is None:
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return register
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else:
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register(func)
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def _device_type_to_key(device_type: str) -> str:
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if device_type == "default":
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# This is technically not correct, because although all device_type
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# DispatchKeys are included in CompositeExplicitAutograd,
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# not everything in CompositeExplicitAutograd is associated with a
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# device_type. I don't really care that much about the difference.
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return "CompositeExplicitAutograd"
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return torch._C._dispatch_key_for_device(device_type)
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@impl.register
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def _(lib: Library, name, dispatch_key=""):
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"""Legacy torch.library.impl API. Kept around for BC"""
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def wrap(f):
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lib.impl(name, f, dispatch_key)
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return f
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return wrap
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def impl_abstract(qualname, func=None, *, lib=None, _stacklevel=1):
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r"""Register an abstract implementation for this operator.
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An "abstract implementation" specifies the behavior of this operator on
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Tensors that carry no data. Given some input Tensors with certain properties
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(sizes/strides/storage_offset/device), it specifies what the properties of
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the output Tensors are.
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The abstract implementation has the same signature as the operator.
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It is run for both FakeTensors and meta tensors. To write an abstract
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implementation, assume that all Tensor inputs to the operator are
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regular CPU/CUDA/Meta tensors, but they do not have storage, and
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you are trying to return regular CPU/CUDA/Meta tensor(s) as output.
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The abstract implementation must consist of only PyTorch operations
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(and may not directly access the storage or data of any input or
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intermediate Tensors).
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This API may be used as a decorator (see examples).
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For a detailed guide on custom ops, please see
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https://docs.google.com/document/d/1W--T6wz8IY8fOI0Vm8BF44PdBgs283QvpelJZWieQWQ/edit
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Examples:
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>>> import torch
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>>> import numpy as np
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>>> from torch import Tensor
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>>>
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>>> # Example 1: an operator without data-dependent output shape
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>>> torch.library.define(
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>>> "mylib::custom_linear",
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>>> "(Tensor x, Tensor weight, Tensor bias) -> Tensor")
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>>>
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>>> @torch.library.impl_abstract("mylib::custom_linear")
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>>> def custom_linear_abstract(x, weight):
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>>> assert x.dim() == 2
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>>> assert weight.dim() == 2
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>>> assert bias.dim() == 1
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>>> assert x.shape[1] == weight.shape[1]
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>>> assert weight.shape[0] == bias.shape[0]
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>>> assert x.device == weight.device
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>>>
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>>> return (x @ weight.t()) + bias
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>>>
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>>> # Example 2: an operator with data-dependent output shape
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>>> torch.library.define("mylib::custom_nonzero", "(Tensor x) -> Tensor")
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>>>
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>>> @torch.library.impl_abstract("mylib::custom_nonzero")
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>>> def custom_nonzero_abstract(x):
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>>> # Number of nonzero-elements is data-dependent.
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>>> # Since we cannot peek at the data in an abstract impl,
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>>> # we use the ctx object to construct a new symint that
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>>> # represents the data-dependent size.
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>>> ctx = torch.library.get_ctx()
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>>> nnz = ctx.new_dynamic_size()
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>>> shape = [nnz, x.dim()]
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>>> result = x.new_empty(shape, dtype=torch.int64)
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>>> return result
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>>>
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>>> @torch.library.impl("mylib::custom_nonzero", "cpu")
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>>> def custom_nonzero_cpu(x):
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>>> x_np = x.numpy()
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>>> res = np.stack(np.nonzero(x_np), axis=1)
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>>> return torch.tensor(res, device=x.device)
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"""
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source = torch._library.utils.get_source(_stacklevel + 1)
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frame = sys._getframe(_stacklevel)
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caller_module = inspect.getmodule(frame)
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# Can be none if you call impl_abstract from somewhere there isn't a module
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# (e.g. __main__)
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caller_module_name = None if caller_module is None else caller_module.__name__
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# TODO(rzou): We're gonna need to stage this change with torchvision,
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# since torchvision is github first.
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if caller_module_name is not None and caller_module_name.startswith("torchvision."):
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caller_module_name = None
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def inner(func):
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entry = torch._library.simple_registry.singleton.find(qualname)
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if caller_module_name is not None:
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func_to_register = _check_pystubs_once(func, qualname, caller_module_name)
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else:
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func_to_register = func
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handle = entry.abstract_impl.register(func_to_register, source)
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if lib is not None:
|
|
lib._registration_handles.append(handle)
|
|
return func
|
|
|
|
if func is None:
|
|
return inner
|
|
return inner(func)
|
|
|
|
|
|
# If the op was defined in C++, then we want to make sure there was an
|
|
# m.impl_abstract_pystub(module, ...) call and that the module is the
|
|
# same as the module that called torch.library.impl_abstract.
|
|
def _check_pystubs_once(func, qualname, actual_module_name):
|
|
checked = False
|
|
|
|
def inner(*args, **kwargs):
|
|
nonlocal checked
|
|
if checked:
|
|
return func(*args, **kwargs)
|
|
|
|
op = torch._library.utils.lookup_op(qualname)
|
|
if op._defined_in_python:
|
|
checked = True
|
|
return func(*args, **kwargs)
|
|
|
|
maybe_pystub = torch._C._dispatch_pystub(
|
|
op._schema.name,
|
|
op._schema.overload_name)
|
|
if not maybe_pystub:
|
|
namespace = op.namespace
|
|
cpp_filename = op._handle().debug()
|
|
raise RuntimeError(
|
|
f"Operator '{qualname}' was defined in C++ and has a Python "
|
|
f"abstract impl. In this situation, we require there to also be a "
|
|
f"companion C++ `m.impl_abstract_pystub(\"{actual_module_name}\")` "
|
|
f"call, but we could not find one. Please add that to "
|
|
f"to the top of the C++ TORCH_LIBRARY({namespace}, ...) block the "
|
|
f"operator was registered in ({cpp_filename})")
|
|
pystub_module = maybe_pystub[0]
|
|
if actual_module_name != pystub_module:
|
|
cpp_filename = op._handle().debug()
|
|
raise RuntimeError(
|
|
f"Operator '{qualname}' specified that its python abstract impl "
|
|
f"is in the Python module '{pystub_module}' but it was actually found "
|
|
f"in '{actual_module_name}'. Please either move the abstract impl "
|
|
f"or correct the m.impl_abstract_pystub call ({cpp_filename})")
|
|
checked = True
|
|
return func(*args, **kwargs)
|
|
return inner
|
|
|
|
|
|
# NOTE [ctx inside the fake implementation]
|
|
# If a user has an operator with data-dependent output shape, then when writing
|
|
# a fake implementation they must query the current ctx and use methods on the
|
|
# ctx to construct a new unbacked symint.
|
|
#
|
|
# This is done via us setting the global_ctx_getter function every time a fake
|
|
# implementation is invoked.
|
|
def get_ctx() -> "torch._library.abstract_impl.AbstractImplCtx":
|
|
"""get_ctx() returns the current AbstractImplCtx object.
|
|
|
|
Calling ``get_ctx()`` is only valid inside of an abstract impl
|
|
(see :func:`torch.library.impl_abstract` for more usage details.
|
|
"""
|
|
return torch._library.abstract_impl.global_ctx_getter()
|