Add files using upload-large-folder tool

vllm/lib/python3.10/site-packages/decorator-5.1.1.dist-info/INSTALLER

@@ -0,0 +1 @@
+pip

vllm/lib/python3.10/site-packages/decorator-5.1.1.dist-info/LICENSE.txt

@@ -0,0 +1,26 @@
+Copyright (c) 2005-2018, Michele Simionato
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+  Redistributions of source code must retain the above copyright
+  notice, this list of conditions and the following disclaimer.
+  Redistributions in bytecode form must reproduce the above copyright
+  notice, this list of conditions and the following disclaimer in
+  the documentation and/or other materials provided with the
+  distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
+TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.

vllm/lib/python3.10/site-packages/decorator-5.1.1.dist-info/RECORD

@@ -0,0 +1,10 @@
+__pycache__/decorator.cpython-310.pyc,,
+decorator-5.1.1.dist-info/INSTALLER,sha256=zuuue4knoyJ-UwPPXg8fezS7VCrXJQrAP7zeNuwvFQg,4
+decorator-5.1.1.dist-info/LICENSE.txt,sha256=_RFmDKvwUyCCxFcGhi-vwpSQfsf44heBgkCkmZgGeC4,1309
+decorator-5.1.1.dist-info/METADATA,sha256=XAr2zbYpRxCkcPbsmg1oaiS5ea7mhTq-j-wb0XjuVho,3955
+decorator-5.1.1.dist-info/RECORD,,
+decorator-5.1.1.dist-info/REQUESTED,sha256=47DEQpj8HBSa-_TImW-5JCeuQeRkm5NMpJWZG3hSuFU,0
+decorator-5.1.1.dist-info/WHEEL,sha256=ewwEueio1C2XeHTvT17n8dZUJgOvyCWCt0WVNLClP9o,92
+decorator-5.1.1.dist-info/pbr.json,sha256=AL84oUUWQHwkd8OCPhLRo2NJjU5MDdmXMqRHv-posqs,47
+decorator-5.1.1.dist-info/top_level.txt,sha256=Kn6eQjo83ctWxXVyBMOYt0_YpjRjBznKYVuNyuC_DSI,10
+decorator.py,sha256=el5cAEgoTEpRQN65tOxGhElue-CccMv0xol-J2MwOc0,16752

vllm/lib/python3.10/site-packages/decorator-5.1.1.dist-info/WHEEL

@@ -0,0 +1,5 @@
+Wheel-Version: 1.0
+Generator: bdist_wheel (0.37.0)
+Root-Is-Purelib: true
+Tag: py3-none-any
+

vllm/lib/python3.10/site-packages/decorator-5.1.1.dist-info/pbr.json

@@ -0,0 +1 @@
+{"is_release": false, "git_version": "8608a46"}

vllm/lib/python3.10/site-packages/decorator-5.1.1.dist-info/top_level.txt

@@ -0,0 +1 @@
+decorator

vllm/lib/python3.10/site-packages/torchgen/__init__.py

@@ -0,0 +1,10 @@
+"""torchgen
+
+This module contains codegeneration utilities for PyTorch. It is used to
+build PyTorch from source, but may also be used for out-of-tree projects
+that extend PyTorch.
+
+Note well that we provide no BC guarantees for torchgen. If you're interested
+in using torchgen and want the PyTorch team to be aware, please reach out
+on GitHub.
+"""

vllm/lib/python3.10/site-packages/torchgen/code_template.py

@@ -0,0 +1,99 @@
+from __future__ import annotations
+
+import re
+from typing import Mapping, Sequence
+
+
+# match $identifier or ${identifier} and replace with value in env
+# If this identifier is at the beginning of whitespace on a line
+# and its value is a list then it is treated as
+# block substitution by indenting to that depth and putting each element
+# of the list on its own line
+# if the identifier is on a line starting with non-whitespace and a list
+# then it is comma separated ${,foo} will insert a comma before the list
+# if this list is not empty and ${foo,} will insert one after.
+
+
+class CodeTemplate:
+    substitution_str = r"(^[^\n\S]*)?\$([^\d\W]\w*|\{,?[^\d\W]\w*\,?})"
+    substitution = re.compile(substitution_str, re.MULTILINE)
+
+    pattern: str
+    filename: str
+
+    @staticmethod
+    def from_file(filename: str) -> CodeTemplate:
+        with open(filename) as f:
+            return CodeTemplate(f.read(), filename)
+
+    def __init__(self, pattern: str, filename: str = "") -> None:
+        self.pattern = pattern
+        self.filename = filename
+
+    def substitute(
+        self, env: Mapping[str, object] | None = None, **kwargs: object
+    ) -> str:
+        if env is None:
+            env = {}
+
+        def lookup(v: str) -> object:
+            assert env is not None
+            return kwargs[v] if v in kwargs else env[v]
+
+        def indent_lines(indent: str, v: Sequence[object]) -> str:
+            return "".join(
+                [indent + l + "\n" for e in v for l in str(e).splitlines()]
+            ).rstrip()
+
+        def replace(match: re.Match[str]) -> str:
+            indent = match.group(1)
+            key = match.group(2)
+            comma_before = ""
+            comma_after = ""
+            if key[0] == "{":
+                key = key[1:-1]
+                if key[0] == ",":
+                    comma_before = ", "
+                    key = key[1:]
+                if key[-1] == ",":
+                    comma_after = ", "
+                    key = key[:-1]
+            v = lookup(key)
+            if indent is not None:
+                if not isinstance(v, list):
+                    v = [v]
+                return indent_lines(indent, v)
+            elif isinstance(v, list):
+                middle = ", ".join([str(x) for x in v])
+                if len(v) == 0:
+                    return middle
+                return comma_before + middle + comma_after
+            else:
+                return str(v)
+
+        return self.substitution.sub(replace, self.pattern)
+
+
+if __name__ == "__main__":
+    c = CodeTemplate(
+        """\
+    int foo($args) {
+
+        $bar
+            $bar
+        $a+$b
+    }
+    int commatest(int a${,stuff})
+    int notest(int a${,empty,})
+    """
+    )
+    print(
+        c.substitute(
+            args=["hi", 8],
+            bar=["what", 7],
+            a=3,
+            b=4,
+            stuff=["things...", "others"],
+            empty=[],
+        )
+    )

vllm/lib/python3.10/site-packages/torchgen/context.py

@@ -0,0 +1,130 @@
+from __future__ import annotations
+
+import contextlib
+import functools
+from typing import Any, Callable, Iterator, List, Optional, Tuple, TypeVar, Union
+
+import torchgen.local as local
+from torchgen.model import (
+    BackendIndex,
+    DispatchKey,
+    NativeFunction,
+    NativeFunctionsGroup,
+    NativeFunctionsViewGroup,
+)
+from torchgen.utils import context, S, T
+
+
+# Helper functions for defining generators on things in the model
+
+F = TypeVar(
+    "F",
+    NativeFunction,
+    NativeFunctionsGroup,
+    NativeFunctionsViewGroup,
+    Union[NativeFunction, NativeFunctionsGroup],
+    Union[NativeFunction, NativeFunctionsViewGroup],
+)
+
+F2 = TypeVar(
+    "F2",
+    NativeFunction,
+    NativeFunctionsGroup,
+    Optional[NativeFunction],
+    bool,
+    str,
+)
+
+F3 = TypeVar("F3", Tuple[NativeFunction, Any], List[NativeFunction])
+
+
+@contextlib.contextmanager
+def native_function_manager(
+    g: NativeFunctionsGroup | NativeFunctionsViewGroup | NativeFunction,
+) -> Iterator[None]:
+    if isinstance(g, NativeFunctionsGroup):
+        # By default, we associate all errors with structured native functions
+        # with the out variant.  In some cases, it might be better to have
+        # a more specific place to hang things; if so, use
+        # native_function_manager again on the inside
+        f = g.out
+    elif isinstance(g, NativeFunctionsViewGroup):
+        # We associate errors with the view operator
+        f = g.view
+    else:
+        f = g
+    with context(lambda: f"in native_functions.yaml line {f.loc}:\n  {f.func}"):
+        with local.parametrize(
+            use_const_ref_for_mutable_tensors=f.use_const_ref_for_mutable_tensors,
+            use_ilistref_for_tensor_lists=f.part_of_structured_group,
+        ):
+            yield
+
+
+# Given a function that operates on NativeFunction, wrap it into a new function
+# that sets some appropriate context managers for that native function.
+# YOU MUST WRAP FUNCTIONS IN THIS for calls to api modules to be sound
+# (you will get an error if we try to access the local variables without having
+# set them).
+def with_native_function(func: Callable[[F], T]) -> Callable[[F], T]:
+    @functools.wraps(func)
+    def wrapper(f: F) -> T:
+        with native_function_manager(f):
+            return func(f)
+
+    return wrapper
+
+
+def with_native_function_and(func: Callable[[F, F2], T]) -> Callable[[F, F2], T]:
+    @functools.wraps(func)
+    def wrapper(f: F, f2: F2) -> T:
+        # The first native_function is assumed to be the one with the appropriate context.
+        with native_function_manager(f):
+            return func(f, f2)
+
+    return wrapper
+
+
+def method_with_native_function(func: Callable[[S, F], T]) -> Callable[[S, F], T]:
+    @functools.wraps(func)
+    def wrapper(slf: S, f: F) -> T:
+        with native_function_manager(f):
+            return func(slf, f)
+
+    return wrapper
+
+
+def method_with_nested_native_function(
+    func: Callable[[S, F3], T]
+) -> Callable[[S, F3], T]:
+    @functools.wraps(func)
+    def wrapper(slf: S, f: F3) -> T:
+        with native_function_manager(f[0]):
+            return func(slf, f)
+
+    return wrapper
+
+
+# Convenience decorator for functions that explicitly take in a BackendIndex,
+# instead of indirectly taking one in as a closure
+def with_native_function_and_index(
+    func: Callable[[F, BackendIndex], T]
+) -> Callable[[F, BackendIndex], T]:
+    @functools.wraps(func)
+    def wrapper(f: F, backend_index: BackendIndex) -> T:
+        with native_function_manager(f):
+            return func(f, backend_index)
+
+    return wrapper
+
+
+# Convenience decorator for functions that explicitly take in a Dict of BackendIndices
+def with_native_function_and_indices(
+    func: Callable[[F, dict[DispatchKey, BackendIndex]], T]
+) -> Callable[[F, dict[DispatchKey, BackendIndex]], T]:
+    @functools.wraps(func)
+    def wrapper(f: F, backend_indices: dict[DispatchKey, BackendIndex]) -> T:
+        with native_function_manager(f):
+            return func(f, backend_indices)
+
+    return wrapper

vllm/lib/python3.10/site-packages/torchgen/executorch/api/custom_ops.py

@@ -0,0 +1,149 @@
+from __future__ import annotations
+
+from collections import defaultdict
+from dataclasses import dataclass
+from typing import Sequence, TYPE_CHECKING
+
+from torchgen import dest
+
+
+# disable import sorting to avoid circular dependency.
+from torchgen.api.types import DispatcherSignature  # usort: skip
+from torchgen.context import method_with_native_function
+from torchgen.model import BaseTy, BaseType, DispatchKey, NativeFunction, Variant
+from torchgen.utils import concatMap, Target
+
+
+if TYPE_CHECKING:
+    from torchgen.executorch.model import ETKernelIndex
+    from torchgen.selective_build.selector import SelectiveBuilder
+
+
+# Generates RegisterKernelStub.cpp, which provides placeholder kernels for custom operators. This will be used at
+# model authoring side.
+@dataclass(frozen=True)
+class ComputeNativeFunctionStub:
+    @method_with_native_function
+    def __call__(self, f: NativeFunction) -> str | None:
+        if Variant.function not in f.variants:
+            return None
+
+        sig = DispatcherSignature.from_schema(
+            f.func, prefix=f"wrapper_CPU_{f.func.name.overload_name}_", symint=False
+        )
+        assert sig is not None
+        if len(f.func.returns) == 0:
+            ret_name = ""
+        elif len(f.func.returns) == 1:
+            if f.func.arguments.out:
+                ret_name = f.func.arguments.out[0].name
+            else:
+                ret_name = next(
+                    (
+                        a.name
+                        for a in f.func.arguments.flat_non_out
+                        if a.type == f.func.returns[0].type
+                    ),
+                    "",
+                )
+            if not ret_name:
+                # if return type is tensor
+                if f.func.returns[0].type == BaseType(BaseTy.Tensor):
+                    # Returns an empty tensor
+                    ret_name = "at::Tensor()"
+                else:
+                    raise Exception(  # noqa: TRY002
+                        f"Can't handle this return type {f.func}"
+                    )  # noqa: TRY002
+        elif len(f.func.arguments.out) == len(f.func.returns):
+            # Returns a tuple of out arguments
+            tensor_type = "at::Tensor &"
+            comma = ", "
+            ret_name = f"""::std::tuple<{comma.join([tensor_type] * len(f.func.returns))}>(
+                {comma.join([r.name for r in f.func.arguments.out])}
+            )"""
+        else:
+            assert all(
+                a.type == BaseType(BaseTy.Tensor) for a in f.func.returns
+            ), f"Only support tensor returns but got {f.func.returns}"
+            # Returns a tuple of empty tensors
+            tensor_type = "at::Tensor"
+            comma = ", "
+            ret_name = f"""::std::tuple<{comma.join([tensor_type] * len(f.func.returns))}>(
+                {comma.join(["at::Tensor()" for _ in f.func.returns])}
+            )"""
+        ret_str = f"return {ret_name};" if len(f.func.returns) > 0 else ""
+        return f"""
+{sig.defn()} {{
+    {ret_str}
+}}
+    """
+
+
+def gen_custom_ops_registration(
+    *,
+    native_functions: Sequence[NativeFunction],
+    selector: SelectiveBuilder,
+    kernel_index: ETKernelIndex,
+    rocm: bool,
+) -> tuple[str, str]:
+    """
+    Generate custom ops registration code for dest.RegisterDispatchKey.
+
+    :param native_functions: a sequence of `NativeFunction`
+    :param selector: for selective build.
+    :param kernel_index: kernels for all the ops.
+    :param rocm: bool for dest.RegisterDispatchKey.
+    :return: generated C++ code to register custom operators into PyTorch
+    """
+
+    # convert kernel index to BackendIndex. This is because we can't handle ETKernelIndex yet.
+    # TODO larryliu: evaluate if this code is still needed. If yes let it handle ETKernelIndex.
+
+    dispatch_key = DispatchKey.CPU
+    backend_index = kernel_index._to_backend_index()
+    static_init_dispatch_registrations = ""
+    ns_grouped_native_functions: dict[str, list[NativeFunction]] = defaultdict(list)
+    for native_function in native_functions:
+        ns_grouped_native_functions[native_function.namespace].append(native_function)
+
+    for namespace, functions in ns_grouped_native_functions.items():
+        if len(functions) == 0:
+            continue
+        dispatch_registrations_body = "\n".join(
+            list(
+                concatMap(
+                    dest.RegisterDispatchKey(
+                        backend_index,
+                        Target.REGISTRATION,
+                        selector,
+                        rocm=rocm,
+                        symint=False,
+                        class_method_name=None,
+                        skip_dispatcher_op_registration=False,
+                    ),
+                    functions,
+                )
+            )
+        )
+        static_init_dispatch_registrations += f"""
+TORCH_LIBRARY_IMPL({namespace}, {dispatch_key}, m) {{
+{dispatch_registrations_body}
+}};"""
+    anonymous_definition = "\n".join(
+        list(
+            concatMap(
+                dest.RegisterDispatchKey(
+                    backend_index,
+                    Target.ANONYMOUS_DEFINITION,
+                    selector,
+                    rocm=rocm,
+                    symint=False,
+                    class_method_name=None,
+                    skip_dispatcher_op_registration=False,
+                ),
+                native_functions,
+            )
+        )
+    )
+    return anonymous_definition, static_init_dispatch_registrations

vllm/lib/python3.10/site-packages/torchgen/executorch/api/unboxing.py

@@ -0,0 +1,230 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Callable, Sequence, TYPE_CHECKING
+
+from torchgen.model import (
+    Argument,
+    BaseTy,
+    BaseType,
+    ListType,
+    NativeFunction,
+    OptionalType,
+    Type,
+)
+
+
+if TYPE_CHECKING:
+    from torchgen.api.types import Binding, CType, NamedCType
+
+
+connector = "\n\t"
+
+
+# Return unboxing function name for a NativeFunction
+def name(f: NativeFunction) -> str:
+    return f.func.name.unambiguous_name()
+
+
+@dataclass(frozen=True)
+class Unboxing:
+    """
+    Takes a sequence of Bindings and unbox EValues to these Bindings. Return generated code that performs correct unboxing.
+    A sample generated code:
+    // aten::mul.out(Tensor self, Tensor other, *, Tensor(a!) out) -> Tensor(a!)
+    void mul_out(EValue** stack) {
+        EValue& self = *stack[0];
+        EValue& other = *stack[1];
+        EValue& out = *stack[2];
+        const torch::executor::Tensor & self_base = self.to<torch::executor::Tensor>();
+        const torch::executor::Tensor & other_base = other.to<torch::executor::Tensor>();
+        torch::executor::Tensor & out_base = out.to<torch::executor::Tensor>();
+
+        EXECUTORCH_SCOPE_PROF("native_call_mul.out");
+        torch::executor::mul_outf(self_base, other_base, out_base);
+
+
+    }
+    """
+
+    # this is a callable that converts a JIT argument, into its C++ type.
+    # Translates (type, mutability, binds) to NamedCType. E.g., torchgen.api.cpp.argumenttype_type.
+    argument_type_gen: Callable[
+        ...,
+        NamedCType,
+    ]
+
+    # Convert all the arguments in a NativeFunction to C++ code
+    def convert_arguments(
+        self, args: Sequence[Binding]
+    ) -> tuple[list[Binding], list[str]]:
+        code_list = [f"EValue& {args[i].name} = *stack[{i}];" for i in range(len(args))]
+        binding_list = []
+        for arg in args:
+            # expecting only Argument
+            if not isinstance(arg.argument, Argument):
+                raise Exception(  # noqa: TRY002
+                    f"Unexpected argument type, expecting `Argument` but got {arg}"
+                )
+            argument: Argument = arg.argument
+            unboxed_name, _, code, decl = self.argumenttype_evalue_convert(
+                argument.type, argument.name, mutable=argument.is_write
+            )
+            code_list.extend(decl)
+            code_list.extend(code)
+            binding_list.append(arg.with_name(unboxed_name))
+        return binding_list, code_list
+
+    def argumenttype_evalue_convert(
+        self, t: Type, arg_name: str, *, mutable: bool = False
+    ) -> tuple[str, CType, list[str], list[str]]:
+        """
+        Takes in the type, name and mutability corresponding to an argument, and generates a tuple of:
+        (1) the C++ code necessary to unbox the argument
+        (2) A Binding corresponding to the newly created unboxed variable, including variable name and its CType
+        :param t: a `Type` of an argument
+        :param arg_name: argument name
+        :param mutable: boolean for whether this argument type is mutable
+        :return: unboxed result
+        """
+        ctype = self.argument_type_gen(t, mutable=mutable, binds=arg_name).type
+
+        if isinstance(t, BaseType):
+            out_name = f"{arg_name}_base"
+            code, decl = self._gen_code_base_type(
+                arg_name=arg_name, out_name=out_name, ctype=ctype
+            )
+        elif isinstance(t, OptionalType):
+            out_name = f"{arg_name}_opt_out"
+            code, decl = self._gen_code_optional_type(
+                arg_name=arg_name, out_name=out_name, t=t, ctype=ctype
+            )
+        elif isinstance(t, ListType):
+            out_name = f"{arg_name}_list_out"
+            code, decl = self._gen_code_list_type(
+                arg_name=arg_name, out_name=out_name, t=t, ctype=ctype
+            )
+        else:
+            raise Exception(  # noqa: TRY002
+                f"Cannot handle type {t}. arg_name: {arg_name}"
+            )  # noqa: TRY002
+        return out_name, ctype, code, decl
+
+    def _gen_code_base_type(
+        self, arg_name: str, out_name: str, ctype: CType
+    ) -> tuple[list[str], list[str]]:
+        return [
+            f"{ctype.cpp_type()} {out_name} = {arg_name}.to<{ctype.cpp_type(strip_ref=True)}>();"
+        ], []
+
+    def _gen_code_optional_type(
+        self, arg_name: str, out_name: str, t: OptionalType, ctype: CType
+    ) -> tuple[list[str], list[str]]:
+        in_name = f"{arg_name}_opt_in"
+        res_name, base_type, res_code, decl = self.argumenttype_evalue_convert(
+            t.elem, in_name
+        )
+        return (
+            f"""
+    auto {out_name} = {arg_name}.toOptional<{base_type.cpp_type(strip_ref=True)}>();
+            """.split(
+                "\n"
+            ),
+            decl,
+        )
+
+    def _gen_code_list_type(
+        self, arg_name: str, out_name: str, t: ListType, ctype: CType
+    ) -> tuple[list[str], list[str]]:
+        in_name = f"{arg_name}_list_in"
+        elem_name = f"{arg_name}_elem"
+        code = []
+        res_name, res_ctype, res_code, decl = self.argumenttype_evalue_convert(
+            t.elem, elem_name
+        )
+
+        if isinstance(t.elem, BaseType) and t.elem.name == BaseTy.Tensor:
+            code.extend(
+                f"""
+    auto {out_name} = {arg_name}.toTensorList();
+                """.split(
+                    "\n"
+                )
+            )
+        elif isinstance(t.elem, BaseType) and (
+            t.elem.name == BaseTy.int or t.elem.name == BaseTy.SymInt
+        ):
+            code.extend(
+                f"""
+    auto {out_name} = {arg_name}.toIntList();
+                """.split(
+                    "\n"
+                )
+            )
+        elif isinstance(t.elem, BaseType) and t.elem.name == BaseTy.float:
+            code.extend(
+                f"""
+    auto {out_name} = {arg_name}.toDoubleList();
+                """.split(
+                    "\n"
+                )
+            )
+        elif isinstance(t.elem, BaseType) and t.elem.name == BaseTy.bool:
+            # handle list type with size, e.g., bool[4]
+            code.extend(
+                f"""
+#ifdef USE_ATEN_LIB
+std::array<bool, {t.size}> {out_name};
+auto {in_name} = {arg_name}.toBoolList();
+size_t _i = 0;
+for (auto {elem_name}: {in_name}) {{
+    {out_name}[_i++] = {elem_name};
+}}
+#else
+auto {out_name} = {arg_name}.toBoolList();
+#endif
+                """.split(
+                    "\n"
+                )
+            )
+        # pytorch codegen:
+        # we have to use c10::List for optional element. e.g., Tensor?[] -> c10::List<::std::optional<at::Tensor>>
+        elif (
+            isinstance(t.elem, OptionalType)
+            and isinstance(t.elem.elem, BaseType)
+            and t.elem.elem.name == BaseTy.Tensor
+        ):
+            code.extend(
+                f"""
+#ifdef USE_ATEN_LIB
+auto {in_name} = {arg_name}.toListOptionalTensor();
+c10::List<::std::optional<at::Tensor>> {out_name};
+for (auto {elem_name}: {in_name}) {{
+    {out_name}.push_back({elem_name});
+}}
+#else
+auto {out_name} = {arg_name}.toListOptionalTensor();
+#endif
+                """.split(
+                    "\n"
+                )
+            )
+        else:
+            # use ArrayRef as default.
+            vec_name = arg_name + "_vec"
+            # need to bring vector instantiation out of scope so that ArrayRef has valid data
+            decl.append(
+                f"std::vector<{res_ctype.cpp_type(strip_ref=True)}> {vec_name};"
+            )
+            code.extend(
+                f"""
+    for (EValue {elem_name}: {in_name}) {{
+        {connector.join(res_code)}
+        {vec_name}.push_back({res_name});
+    }}
+    {ctype.cpp_type(strip_ref=True)} {out_name}({vec_name});
+                """.split(
+                    "\n"
+                )
+            )
+        return code, decl

vllm/lib/python3.10/site-packages/torchgen/executorch/model.py

@@ -0,0 +1,220 @@
+# Represents all kernels used by an Executorch model.
+# It maintains a Dict[OperatorName, Dict[ETKernelKey, BackendMetadata]] structure.
+
+from __future__ import annotations
+
+import itertools
+from collections import defaultdict, namedtuple
+from dataclasses import dataclass
+from enum import IntEnum
+
+from torchgen.model import (
+    BackendIndex,
+    BackendMetadata,
+    DispatchKey,
+    NativeFunction,
+    NativeFunctionsGroup,
+    OperatorName,
+)
+from torchgen.utils import assert_never
+
+
+KERNEL_KEY_VERSION = 1
+
+
+# TODO: Duplicated Subset from codegen.tool.gen_oplist, remove declaration in codegen
+class ScalarType(IntEnum):
+    Byte = 0
+    Char = 1
+    Short = 2
+    Int = 3
+    Long = 4
+    Float = 6
+    Double = 7
+    Bool = 11
+
+
+ETParsedYaml = namedtuple("ETParsedYaml", ["native_functions", "kernel_index"])
+
+
+@dataclass(frozen=True)
+class ETKernelKeyOpArgMeta:
+    arg_name: str
+    dtype: str
+    # The order of the dimensions if entry is a Tensor
+    dim_order: tuple[int, ...]
+
+    def to_native_string(self) -> str:
+        dtype_str = ScalarType[self.dtype].value
+        dim_str = str(self.dim_order)[1:-1].replace(" ", "")
+        return f"{dtype_str};{dim_str}"
+
+
+@dataclass(frozen=True)
+class ETKernelKey:
+    # Field undefined is default = True
+    arg_meta: tuple[ETKernelKeyOpArgMeta, ...] = ()
+
+    # Indicator for this kernel being used as a catch all
+    default: bool = False
+
+    version: int = KERNEL_KEY_VERSION
+
+    @staticmethod
+    def gen_from_yaml(
+        args: dict[str, tuple[str, str]],
+        type_alias_map: dict[str, list[str]],  # TODO: Support unwrapped str val
+        dim_order_alias_map: dict[str, list[int]],
+    ) -> list[ETKernelKey]:
+        """Generate ETKernelKeys from arg kernel specs
+        Multiple ETKernelKeys are returned due to dtype permutations from utilizing
+        type_alias_map (actualizing each potential type permutation as a KernelKey)
+
+        Args:
+            args: Mapping from argument name to kernel specs
+                Kernel specs are a tuple of (dtype, dim_order).
+                Currently tuple entries must be aliased via the alias map arguments
+            type_alias_map: Mapping from type alias to potential type enums
+                i.e { T0 : [Double, Int] } means T0 can be either Double or Int
+                Used for lookup by args
+            dim_order_alias_map: Mapping from alias to a list of dimension orders
+                Used for lookup by args
+        """
+        # Cast to dim order to int
+        dim_order_alias_map = {
+            k: [int(alias) for alias in v] for k, v in dim_order_alias_map.items()
+        }
+        kernel_keys = []
+
+        # Get all used Dtype Alias
+        dtype_alias_used = set()
+        for type_alias, dim_order in args.values():
+            # Enforce usage of alias initially
+            # TODO: Support inlined arguments
+            assert type_alias in type_alias_map, "Undefined type alias: " + str(
+                type_alias
+            )
+            assert (
+                dim_order in dim_order_alias_map
+            ), "Undefined dim_order alias: " + str(dim_order)
+            dtype_alias_used.add(type_alias)
+
+        # Generate all permutations of dtype alias values
+        alias_dtypes = [
+            [(alias, dtype) for dtype in type_alias_map[alias]]
+            for alias in dtype_alias_used
+        ]
+        alias_permutations = [
+            dict(permutation) for permutation in list(itertools.product(*alias_dtypes))
+        ]
+
+        # Using each alias value permutation, generate kernel keys
+        op_arg_cache = {}
+        for permutation in alias_permutations:
+            arg_list = []
+            for arg_name, arg_spec in args.items():
+                dtype = permutation[arg_spec[0]]
+                dim_order = dim_order_alias_map[arg_spec[1]]  # type: ignore[assignment]
+                if (
+                    cache_key := (arg_name, dtype, tuple(dim_order))
+                ) not in op_arg_cache:
+                    op_arg_cache[cache_key] = ETKernelKeyOpArgMeta(*cache_key)  # type: ignore[arg-type]
+
+                arg_list.append(op_arg_cache[cache_key])
+            kernel_keys.append(ETKernelKey(tuple(arg_list)))
+
+        return kernel_keys
+
+    def to_native_string(self) -> str:
+        if self.default:
+            return "default"
+        return (
+            "v"
+            + str(KERNEL_KEY_VERSION)
+            + "/"
+            + "|".join([arg.to_native_string() for arg in self.arg_meta])
+        )
+
+
+@dataclass(frozen=True)
+class ETKernelIndex:
+    index: dict[OperatorName, dict[ETKernelKey, BackendMetadata]]
+
+    def has_kernels(self, g: NativeFunction | NativeFunctionsGroup) -> bool:
+        m = self.get_kernels(g)
+        return m is not None
+
+    def get_kernels(
+        self, g: NativeFunction | NativeFunctionsGroup
+    ) -> dict[ETKernelKey, BackendMetadata]:
+        if isinstance(g, NativeFunction):
+            f = g
+        elif isinstance(g, NativeFunctionsGroup):
+            f = g.functional
+        else:
+            assert_never(g)
+        if f.func.name not in self.index:
+            return {}
+        return self.index[f.func.name]
+
+    @staticmethod
+    def grow_from_backend_indices(
+        kernel_index: dict[OperatorName, dict[ETKernelKey, BackendMetadata]],
+        backend_indices: dict[DispatchKey, dict[OperatorName, BackendMetadata]],
+    ) -> None:
+        for dk in backend_indices:
+            index = backend_indices[dk]
+            for op, backend_metadata in index.items():
+                if op in kernel_index:
+                    kernel_index[op][ETKernelKey(default=True)] = backend_metadata
+                else:
+                    kernel_index[op] = {ETKernelKey(default=True): backend_metadata}
+
+    @staticmethod
+    def from_backend_indices(
+        backend_indices: dict[DispatchKey, dict[OperatorName, BackendMetadata]]
+    ) -> ETKernelIndex:
+        kernel_index: dict[
+            OperatorName, dict[ETKernelKey, BackendMetadata]
+        ] = defaultdict(dict)
+        ETKernelIndex.grow_from_backend_indices(kernel_index, backend_indices)
+        return ETKernelIndex(kernel_index)
+
+    def grow(
+        self, backend_indices: dict[DispatchKey, dict[OperatorName, BackendMetadata]]
+    ) -> ETKernelIndex:
+        ETKernelIndex.grow_from_backend_indices(self.index, backend_indices)
+        return self
+
+    def _to_backend_index(self) -> BackendIndex:
+        """
+        WARNING: this will be deprecated once all the codegen places know how to handle ETKernelIndex.
+        """
+        index: dict[OperatorName, BackendMetadata] = {}
+        for op in self.index:
+            kernel_dict = self.index[op]
+            assert (
+                len(kernel_dict.values()) == 1
+            ), f"Can't convert ETKernelIndex to BackendIndex because {op} has more than one kernels. Got {kernel_dict}"
+            index[op] = kernel_dict.get(
+                ETKernelKey(default=True),
+                BackendMetadata(kernel="", structured=False, cpp_namespace=""),
+            )
+        return BackendIndex(
+            dispatch_key=DispatchKey.CPU,
+            use_out_as_primary=False,
+            device_guard=False,
+            external=False,
+            index=index,
+        )
+
+    # Note duplicate ETKernelKey from index_b will clobber the metadata from index_a
+    @staticmethod
+    def merge_indices(index_a: ETKernelIndex, index_b: ETKernelIndex) -> ETKernelIndex:
+        combined = defaultdict(dict, index_a.index.copy())
+
+        for op, entry in index_b.index.items():
+            for key, metadata in entry.items():
+                combined[op][key] = metadata
+
+        return ETKernelIndex(combined)

vllm/lib/python3.10/site-packages/torchgen/executorch/parse.py

@@ -0,0 +1,153 @@
+from __future__ import annotations
+
+from collections import defaultdict, namedtuple
+from typing import Any
+
+import yaml
+
+from torchgen.executorch.model import ETKernelIndex, ETKernelKey
+from torchgen.gen import LineLoader, parse_native_yaml
+from torchgen.model import (
+    BackendMetadata,
+    DispatchKey,
+    FunctionSchema,
+    NativeFunction,
+    OperatorName,
+)
+from torchgen.utils import NamespaceHelper
+
+
+# Parse native_functions.yaml into a sequence of NativeFunctions and ET Backend Indices.
+ETParsedYaml = namedtuple("ETParsedYaml", ["native_functions", "et_kernel_indices"])
+
+# Fields in native_functions.yaml used to determine which kernels should be used
+ET_FIELDS = ["kernels", "type_alias", "dim_order_alias"]
+
+
+def parse_from_yaml(ei: dict[str, object]) -> dict[ETKernelKey, BackendMetadata]:
+    """Given a loaded yaml representing kernel assignment information, extract the
+    mapping from `kernel keys` to `BackendMetadata` (the latter representing the kernel instance)
+
+    Args:
+        ei: Dict keys {kernels, type_alias, dim_order_alias}
+            See ETKernelKey for description of arguments
+    """
+    e = ei.copy()
+    if (kernels := e.pop("kernels", None)) is None:
+        return {}
+
+    type_alias: dict[str, list[str]] = e.pop("type_alias", {})  # type: ignore[assignment]
+    dim_order_alias: dict[str, list[str]] = e.pop("dim_order_alias", {})  # type: ignore[assignment]
+    dim_order_alias.pop("__line__", None)
+
+    kernel_mapping: dict[ETKernelKey, BackendMetadata] = {}
+
+    for entry in kernels:  # type: ignore[attr-defined]
+        arg_meta = entry.get("arg_meta")
+        if arg_meta is not None:
+            arg_meta.pop("__line__")
+
+        kernel_name = entry.get("kernel_name")
+        namespace_helper = NamespaceHelper.from_namespaced_entity(
+            kernel_name, max_level=3
+        )
+        kernel_namespace = namespace_helper.get_cpp_namespace(default="at")
+        backend_metadata = BackendMetadata(
+            kernel=namespace_helper.entity_name,
+            structured=False,
+            cpp_namespace=(kernel_namespace + "::native"),
+        )
+
+        kernel_keys = (
+            [ETKernelKey((), default=True)]
+            if arg_meta is None
+            else ETKernelKey.gen_from_yaml(arg_meta, type_alias, dim_order_alias)  # type: ignore[arg-type]
+        )
+
+        for kernel_key in kernel_keys:
+            assert kernel_key not in kernel_mapping, (
+                "Duplicate kernel key: " + str(kernel_key) + " " + str(e)
+            )
+            kernel_mapping[kernel_key] = backend_metadata
+
+    return kernel_mapping
+
+
+def parse_et_yaml_struct(es: object) -> ETKernelIndex:
+    """Given a loaded yaml representing a list of operators, for each op extract the mapping
+    of `kernel keys` to `BackendMetadata` (the latter representing the kernel instance
+    that should be used by the kernel key).
+    """
+    indices: dict[OperatorName, dict[ETKernelKey, BackendMetadata]] = {}
+    for ei in es:  # type: ignore[attr-defined]
+        e = ei.copy()
+
+        funcs = e.pop("func")
+        assert isinstance(funcs, str), f"not a str: {funcs}"
+        namespace_helper = NamespaceHelper.from_namespaced_entity(
+            namespaced_entity=funcs, max_level=1
+        )
+        opname = FunctionSchema.parse(namespace_helper.entity_name).name
+
+        assert opname not in indices, f"Duplicate func found in yaml: {opname} already"
+
+        if len(index := parse_from_yaml(e)) != 0:
+            indices[opname] = index
+
+    return ETKernelIndex(indices)
+
+
+def extract_kernel_fields(es: object) -> dict[OperatorName, dict[str, Any]]:
+    """Given a loaded yaml representing a list of operators, extract the
+    kernel key related fields indexed by the operator name.
+    """
+    fields: dict[OperatorName, dict[str, Any]] = defaultdict(dict)
+    for ei in es:  # type: ignore[attr-defined]
+        funcs = ei.get("func")
+        assert isinstance(funcs, str), f"not a str: {funcs}"
+        namespace_helper = NamespaceHelper.from_namespaced_entity(
+            namespaced_entity=funcs, max_level=1
+        )
+        opname = FunctionSchema.parse(namespace_helper.entity_name).name
+
+        for field in ET_FIELDS:
+            if (value := ei.get(field)) is not None:
+                fields[opname][field] = value
+
+    return fields
+
+
+def parse_et_yaml(
+    path: str,
+    tags_yaml_path: str,
+    ignore_keys: set[DispatchKey] | None = None,
+    skip_native_fns_gen: bool = False,
+) -> tuple[list[NativeFunction], dict[OperatorName, dict[str, Any]]]:
+    """Parse native_functions.yaml into NativeFunctions and an Operator Indexed Dict
+    of fields to persist from native_functions.yaml to functions.yaml
+    """
+    with open(path) as f:
+        es = yaml.load(f, Loader=LineLoader)
+
+    et_kernel = extract_kernel_fields(es)
+
+    # Remove ET specific fields from entries for BC compatibility
+    strip_et_fields(es)
+
+    native_yaml = parse_native_yaml(
+        path,
+        tags_yaml_path,
+        ignore_keys,
+        skip_native_fns_gen=skip_native_fns_gen,
+        loaded_yaml=es,
+    )
+    return native_yaml.native_functions, et_kernel
+
+
+def strip_et_fields(es: object) -> None:
+    """Given a loaded yaml representing a list of operators,
+    remove ET specific fields from every entries for BC compatibility
+    """
+    for entry in es:  # type: ignore[attr-defined]
+        for field in ET_FIELDS:
+            entry.pop(field, None)

vllm/lib/python3.10/site-packages/torchgen/gen_aoti_c_shim.py

@@ -0,0 +1,486 @@
+from __future__ import annotations
+
+import textwrap
+from dataclasses import dataclass
+from typing import Sequence
+
+from torchgen.api.types import DispatcherSignature
+from torchgen.api.types.signatures import CppSignature, CppSignatureGroup
+from torchgen.context import method_with_native_function
+from torchgen.model import (
+    Argument,
+    BackendIndex,
+    BaseTy,
+    BaseType,
+    DispatchKey,
+    FunctionSchema,
+    ListType,
+    NativeFunction,
+    NativeFunctionsGroup,
+    OperatorName,
+    OptionalType,
+    Type,
+)
+from torchgen.utils import mapMaybe
+
+
+base_type_to_c_type = {
+    BaseTy.Tensor: "AtenTensorHandle",
+    BaseTy.bool: "int32_t",  # Use int to pass bool
+    BaseTy.int: "int64_t",
+    BaseTy.SymInt: "int64_t",  # Inductor-generated code won't see a SymInt
+    BaseTy.Scalar: "double",  # Use double to pass both integer and floating point
+    BaseTy.float: "double",  # TODO: how about other floating point types?
+    BaseTy.str: "const char*",
+    BaseTy.DeviceIndex: "int32_t",
+    BaseTy.Layout: "int32_t",  # Represent enum as int
+    BaseTy.MemoryFormat: "int32_t",  # Represent enum as int
+    BaseTy.ScalarType: "int32_t",  # Represent enum as int
+    BaseTy.Generator: "AtenGeneratorHandle",
+}
+
+base_type_to_aten_type = {
+    BaseTy.Tensor: "at::Tensor",
+    BaseTy.bool: "bool",
+    BaseTy.int: "int64_t",
+    BaseTy.SymInt: "c10::SymInt",
+    BaseTy.Scalar: "c10::Scalar",
+    BaseTy.float: "double",
+    BaseTy.str: "c10::string_view",
+    BaseTy.DeviceIndex: "c10::DeviceIndex",
+    BaseTy.Layout: "c10::Layout",
+    BaseTy.MemoryFormat: "c10::MemoryFormat",
+    BaseTy.ScalarType: "c10::ScalarType",
+    BaseTy.Generator: "at::Generator",
+}
+
+base_type_to_callsite_expr = {
+    BaseTy.Tensor: "*tensor_handle_to_tensor_pointer",
+    BaseTy.bool: "",
+    BaseTy.int: "",
+    BaseTy.SymInt: "",
+    BaseTy.Scalar: "",
+    BaseTy.float: "",
+    BaseTy.str: "",
+    BaseTy.DeviceIndex: "static_cast<c10::DeviceIndex>",
+    BaseTy.Layout: "static_cast<c10::Layout>",
+    BaseTy.MemoryFormat: "static_cast<c10::MemoryFormat>",
+    BaseTy.ScalarType: "static_cast<c10::ScalarType>",
+    BaseTy.Generator: "*generator_handle_to_generator_pointer",
+}
+
+
+# convert args to C types, names in declarations, and expressions in function bodies
+def convert_arg_type_and_name(typ: Type, name: str) -> tuple[list[str], list[str], list[str], list[str]]:  # type: ignore[return]
+    if isinstance(typ, BaseType):
+        if typ.name in base_type_to_c_type:
+            return (
+                [base_type_to_c_type[typ.name]],
+                [name],
+                [base_type_to_aten_type[typ.name]],
+                [
+                    f"{base_type_to_callsite_expr[typ.name]}({name})"
+                    if base_type_to_callsite_expr[typ.name]
+                    else name
+                ],
+            )
+        elif typ.name == BaseTy.Device:
+            return (
+                ["int32_t", "int32_t"],
+                [name, name + "_index_"],
+                ["c10::Device"],
+                [
+                    f"c10::Device(static_cast<c10::DeviceType>({name}), static_cast<c10::DeviceIndex>({name}_index_))"
+                ],
+            )
+        else:
+            # TODO: BaseTy.Dimname, etc.
+            raise NotImplementedError(f"TODO: add support for arg type {repr(typ)}")
+    elif isinstance(typ, OptionalType):
+        c_types, names, aten_types, callsite_exprs = convert_arg_type_and_name(
+            typ.elem, name
+        )
+        j = 0  # index for names
+        new_aten_types = []
+        new_callsite_exprs = []
+        for aten_type in aten_types:
+            # Use pointer to denote optional type
+            c_types[j] = c_types[j] + "*"
+            if aten_type.startswith("c10::ArrayRef<"):
+                # ArrayRef is passed as pointer + size, but no need to add "*" to the size argument
+                new_aten_types.append(f"::std::optional<{aten_type}>")
+                base_type = aten_type[len("c10::ArrayRef<") : -1]
+                new_callsite_exprs.append(
+                    f"pointer_to_optional_list<{base_type}>({names[j]}, {names[j+1]})"
+                )
+                j += 2
+            elif aten_type == "c10::Device":
+                # Device is passed as device_type + device_index
+                new_aten_types.append("::std::optional<c10::Device>")
+                new_callsite_exprs.append(
+                    f"pointer_to_optional_device({names[j]}, {names[j+1]})"
+                )
+                j += 2
+            else:
+                new_aten_types.append(f"::std::optional<{aten_type}>")
+                new_callsite_exprs.append(
+                    f"pointer_to_optional<{aten_type}>({names[j]})"
+                )
+                j += 1
+
+        return (
+            c_types,
+            names,
+            new_aten_types,
+            new_callsite_exprs,
+        )
+    elif isinstance(typ, ListType):
+        # Need to explictly pass the list as pointer + length
+        c_types, names, aten_types, _ = convert_arg_type_and_name(typ.elem, name)
+        assert len(c_types) == 1, "ListType with unsupported element type " + repr(typ)
+
+        # The list content should never be modified
+        c_types[0] = f"const {c_types[0]}*"
+        c_types.append("int64_t")
+        name = names[0]
+        names.append(name + "_len_")
+
+        atype = aten_types[0]
+        callsite_exprs = []
+        if atype == "bool":
+            # no converter from std::vector<bool> to c10::ArrayRef<bool>
+            # construct std::array<bool, N> instead
+            assert typ.size is not None
+            callsite_exprs.append(f"pointer_to_list<{typ.size}>({name})")
+        elif atype == "::std::optional<at::Tensor>":
+            # convert from std::vector<::std::optional<at::Tensor>> to c10::List<::std::optional<at::Tensor>>
+            callsite_exprs.append(
+                f"c10::List<{atype}>(c10::ArrayRef<{atype}>(pointer_to_list<{atype}>({name}, {name}_len_)))"
+            )
+        else:
+            callsite_exprs.append(f"pointer_to_list<{atype}>({name}, {name}_len_)")
+
+        aten_types = [f"c10::ArrayRef<{t}>" for t in aten_types]
+        return (
+            c_types,
+            names,
+            aten_types,
+            callsite_exprs,
+        )
+
+
+def zip_type_and_name(types: list[str], names: list[str]) -> list[str]:
+    return [typ + " " + name for typ, name in zip(types, names)]
+
+
+# Generate argument declarations and callsite expressions
+def gen_arguments(flat_arguments: Sequence[Argument]) -> tuple[list[str], list[str]]:
+    types = []
+    new_names = []
+    callsite_exprs = []
+    for arg in flat_arguments:
+        new_types, names, _, new_callsite_exprs = convert_arg_type_and_name(
+            arg.type, arg.name
+        )
+        types.extend(new_types)
+        new_names.extend(names)
+        callsite_exprs.extend(new_callsite_exprs)
+    return zip_type_and_name(types, new_names), callsite_exprs
+
+
+# Return values are passed out as pointer arguments because all the C shim functions
+# are expected to return AOTITorchError.
+# Generate returns as declarations and callsite expressions
+def gen_returns(schema: FunctionSchema) -> tuple[list[str], list[str]]:
+    types = []
+    names = []
+    for idx, ret in enumerate(schema.returns):
+        names.append(f"ret{idx}")
+        if isinstance(ret.type, BaseType) and ret.type.name in base_type_to_c_type:
+            types.append(base_type_to_c_type[ret.type.name] + "*")
+        else:
+            raise NotImplementedError(
+                f"TODO: add support for return type {repr(ret.type)}"
+            )
+
+    def convert_return(typ: BaseType, val: str) -> str:
+        if typ.name == BaseTy.Tensor:
+            return f"new_tensor_handle(std::move({val}));"
+        elif typ.name == BaseTy.SymInt:
+            return f"{val}.expect_int()"
+        elif typ.name == BaseTy.Scalar:
+            return f"{val}.toDouble()"
+        else:
+            return val
+
+    ret_pointer_can_be_null = False
+    unambiguous_name = schema.name.unambiguous_name()
+    for name in [
+        "_scaled_dot_product_flash_attention",
+        "_scaled_dot_product_efficient_attention",
+        "_scaled_dot_product_cudnn_attention",
+        "convolution_backward",
+    ]:
+        if name in unambiguous_name:
+            ret_pointer_can_be_null = True
+            break
+
+    callsite_exprs: list[str] = []
+    for idx, ret in enumerate(schema.returns):
+        tmp = "tmp_result" if len(names) == 1 else f"std::get<{idx}>(tmp_result)"
+        assert isinstance(ret.type, BaseType)
+        rval = convert_return(ret.type, tmp)
+        if ret_pointer_can_be_null:
+            callsite_exprs.append(f"if ({names[idx]}) {{ *{names[idx]} = {rval}; }}")
+        else:
+            callsite_exprs.append(f"*{names[idx]} = {rval};")
+
+    return zip_type_and_name(types, names), callsite_exprs
+
+
+# gen.py generates header first and then src, so caching the result here to avoid duplicate work
+declaration_definition_cache: dict[tuple[str, str, str], tuple[str, str]] = {}
+
+
+def gen_declaration_and_definition(
+    schema: FunctionSchema, device: str, backend_call: str
+) -> tuple[str, str]:
+    func_name = schema.name.unambiguous_name()
+
+    global declaration_definition_cache
+    if (func_name, device, backend_call) in declaration_definition_cache:
+        return declaration_definition_cache[(func_name, device, backend_call)]
+
+    if schema.is_out_fn():
+        # out_variant has out arguments in the front, and it's ok to ignore return values
+        # because C shim functions only return AOTITorchError
+        args, callsite_exprs = gen_arguments(
+            [*schema.arguments.out, *schema.arguments.flat_non_out]
+        )
+        ret_assignments: list[str] = []
+    else:
+        args, callsite_exprs = gen_arguments(schema.arguments.flat_all)
+        # ignore return values for inplace ops
+        ret_declarations, ret_assignments = (
+            ([], []) if schema.name.name.inplace else gen_returns(schema)
+        )
+        args.extend(ret_declarations)
+
+    declaration = f"AOTITorchError aoti_torch_{device}_{func_name}({', '.join(args)})"
+
+    tmp_result = "auto tmp_result = " if ret_assignments else ""
+    ret_assignments_str = "\n" + "\n".join(ret_assignments) if ret_assignments else ""
+    definition = f"""
+{declaration} {{
+    AOTI_TORCH_CONVERT_EXCEPTION_TO_ERROR_CODE({{
+        {tmp_result}{backend_call}(
+{textwrap.indent(', '.join(callsite_exprs), "            ")}
+        );{textwrap.indent(ret_assignments_str, "        ")}
+    }});
+}}
+"""
+    declaration_definition_cache[(func_name, device, backend_call)] = (
+        declaration,
+        definition,
+    )
+    return declaration, definition
+
+
+def gen_static_dispatch_backend_call_signature(
+    sig: CppSignature | DispatcherSignature,
+    f: NativeFunction,
+) -> CppSignature:
+    sig = DispatcherSignature.from_schema(f.func)
+    cpp_sigs = CppSignatureGroup.from_native_function(
+        f, method=False, fallback_binding=False
+    )
+    if sig.symint and f.func.has_symint():
+        cpp_sig = cpp_sigs.symint_signature
+    else:
+        cpp_sig = cpp_sigs.signature
+    assert cpp_sig is not None
+    return cpp_sig
+
+
+def gen_static_dispatch_backend_call(
+    f: NativeFunction,
+    backend_index: BackendIndex,
+) -> str:
+    sig = DispatcherSignature.from_schema(f.func)
+    cpp_sig = gen_static_dispatch_backend_call_signature(sig, f)
+    return f"at::{backend_index.dispatch_key.lower()}::{cpp_sig.name()}"
+
+
+def get_backend_index_for_aoti(
+    func: NativeFunction,
+    func_group_mapping: dict[OperatorName, NativeFunctionsGroup],
+    dispatch_key: DispatchKey,
+    backend_indices: dict[DispatchKey, BackendIndex],
+) -> BackendIndex | None:
+    backend_index = None
+    if backend_indices[dispatch_key].has_kernel(func) or (
+        func.structured_delegate is not None
+        and func.structured_delegate in func_group_mapping
+        and backend_indices[dispatch_key].has_kernel(
+            func_group_mapping[func.structured_delegate]
+        )
+    ):
+        backend_index = backend_indices[dispatch_key]
+    elif backend_indices[DispatchKey.CompositeExplicitAutograd].has_kernel(func):
+        # We need to create C shim wrappers for CompositeExplicitAutograd kernels
+        backend_index = backend_indices[DispatchKey.CompositeExplicitAutograd]
+    elif backend_indices[DispatchKey.CompositeExplicitAutogradNonFunctional].has_kernel(
+        func
+    ):
+        # We need to create C shim wrappers for CompositeExplicitAutogradNonFunctional kernels
+        backend_index = backend_indices[
+            DispatchKey.CompositeExplicitAutogradNonFunctional
+        ]
+    elif backend_indices[DispatchKey.CompositeImplicitAutograd].has_kernel(func):
+        backend_index = backend_indices[DispatchKey.CompositeImplicitAutograd]
+
+    return backend_index
+
+
+def get_header_for_aoti(
+    func: NativeFunction,
+    func_group_mapping: dict[OperatorName, NativeFunctionsGroup],
+    dispatch_key: DispatchKey,
+    backend_indices: dict[DispatchKey, BackendIndex],
+) -> str | None:
+    backend_index = get_backend_index_for_aoti(
+        func, func_group_mapping, dispatch_key, backend_indices
+    )
+    return (
+        None
+        if backend_index is None
+        else f"#include <ATen/ops/{func.root_name}_{backend_index.dispatch_key.lower()}_dispatch.h>"
+    )
+
+
+def get_fallback_op_name(func: NativeFunction) -> str:
+    return (
+        f"{func.namespace}.{func.func.name.name}.{func.func.name.overload_name}"
+        if func.func.name.overload_name
+        else f"{func.namespace}.{func.func.name.name}.default"
+    )
+
+
+def gen_c_shim(
+    func: NativeFunction,
+    func_group_mapping: dict[OperatorName, NativeFunctionsGroup],
+    dispatch_key: DispatchKey,
+    backend_indices: dict[DispatchKey, BackendIndex],
+    header: bool,
+) -> str | None:
+    backend_index = get_backend_index_for_aoti(
+        func, func_group_mapping, dispatch_key, backend_indices
+    )
+    if backend_index is None:
+        return None
+
+    schema = func.func
+    device = dispatch_key.lower()
+    backend_call = gen_static_dispatch_backend_call(
+        func,
+        backend_index,
+    )
+
+    try:
+        if header:
+            declaration, _ = gen_declaration_and_definition(
+                schema, device, backend_call
+            )
+            return f"AOTI_TORCH_EXPORT {declaration};"
+        else:
+            _, definition = gen_declaration_and_definition(schema, device, backend_call)
+            return definition
+
+    except NotImplementedError:
+        return None
+
+
+@dataclass(frozen=True)
+class ShimGenerator:
+    func_group_mapping: dict[OperatorName, NativeFunctionsGroup]
+    dispatch_key: DispatchKey
+    backend_indices: dict[DispatchKey, BackendIndex]
+    header: bool  # True to generate .h and False to generate .cpp
+
+    @method_with_native_function
+    def __call__(
+        self,
+        func: NativeFunction,
+    ) -> str | None:
+        result = gen_c_shim(
+            func,
+            self.func_group_mapping,
+            self.dispatch_key,
+            self.backend_indices,
+            self.header,
+        )
+        return result
+
+
+def gen_aoti_c_shim(
+    native_functions: Sequence[NativeFunction],
+    func_group_mapping: dict[OperatorName, NativeFunctionsGroup],
+    dispatch_key: DispatchKey,
+    backend_indices: dict[DispatchKey, BackendIndex],
+    header: bool,
+    includes: str = "",
+) -> str:
+    body = "\n".join(
+        list(
+            mapMaybe(
+                ShimGenerator(
+                    func_group_mapping, dispatch_key, backend_indices, header
+                ),
+                native_functions,
+            )
+        )
+    )
+    device = dispatch_key.lower()
+
+    warning = """
+// WARNING: THIS FILE IS AUTOGENERATED BY torchgen. DO NOT MODIFY BY HAND.
+// See https://github.com/pytorch/pytorch/blob/7e86a7c0155295539996e0cf422883571126073e/torchgen/gen.py#L2424-L2436 for details"""
+
+    if header:
+        return f"""
+{warning}
+
+#pragma once
+
+#include <torch/csrc/inductor/aoti_torch/c/shim.h>
+
+#ifdef __cplusplus
+extern "C" {{
+#endif
+
+{body}
+
+#ifdef __cplusplus
+}} // extern "C"
+#endif
+"""
+
+    else:
+        return f"""
+{warning}
+
+#include <torch/csrc/inductor/aoti_torch/generated/c_shim_{device}.h>
+#include <torch/csrc/inductor/aoti_torch/utils.h>
+
+#ifndef AT_PER_OPERATOR_HEADERS
+#include <ATen/{str(dispatch_key)}Functions.h>
+#include <ATen/CompositeExplicitAutogradFunctions.h>
+#include <ATen/CompositeExplicitAutogradNonFunctionalFunctions.h>
+#include <ATen/CompositeImplicitAutogradFunctions.h>
+#else
+{includes}
+#endif
+
+using namespace torch::aot_inductor;
+
+{body}"""

vllm/lib/python3.10/site-packages/torchgen/gen_backend_stubs.py

@@ -0,0 +1,611 @@
+from __future__ import annotations
+
+import argparse
+import os
+import re
+from collections import Counter, defaultdict, namedtuple
+from pathlib import Path
+from typing import Sequence
+
+import yaml
+
+import torchgen.api.dispatcher as dispatcher
+import torchgen.dest as dest
+from torchgen.api.types import DispatcherSignature
+from torchgen.code_template import CodeTemplate
+from torchgen.context import native_function_manager
+from torchgen.gen import get_grouped_native_functions, parse_native_yaml
+from torchgen.model import (
+    BackendIndex,
+    BackendMetadata,
+    DispatchKey,
+    NativeFunction,
+    NativeFunctionsGroup,
+    OperatorName,
+)
+from torchgen.selective_build.selector import SelectiveBuilder
+from torchgen.utils import concatMap, context, FileManager, NamespaceHelper, Target
+from torchgen.yaml_utils import YamlLoader
+
+
+# Parses the external backend's yaml, and adds a new BackendIndex for the backend's dispatch key.
+# Returns a Tuple of (backend_key, autograd_key, cpp_namespace, updated BackendIndex mapping)
+ParsedExternalYaml = namedtuple(
+    "ParsedExternalYaml",
+    ["backend_key", "autograd_key", "class_name", "cpp_namespace", "backend_indices"],
+)
+
+
+def parse_backend_yaml(
+    backend_yaml_path: str,
+    grouped_native_functions: Sequence[NativeFunction | NativeFunctionsGroup],
+    backend_indices: dict[DispatchKey, BackendIndex],
+) -> ParsedExternalYaml:
+    native_functions_map: dict[OperatorName, NativeFunction] = {
+        f.func.name: f
+        for f in concatMap(
+            lambda f: [f] if isinstance(f, NativeFunction) else list(f.functions()),
+            grouped_native_functions,
+        )
+    }
+
+    with open(backend_yaml_path) as f:
+        yaml_values = yaml.load(f, Loader=YamlLoader)
+    assert isinstance(yaml_values, dict)
+
+    valid_keys = [
+        "backend",
+        "class_name",
+        "cpp_namespace",
+        "extra_headers",
+        "supported",
+        "autograd",
+        "full_codegen",
+        "non_native",
+        "ir_gen",
+        "symint",
+    ]
+
+    backend = yaml_values.pop("backend", None)
+    assert backend is not None, 'You must provide a value for "backend"'
+
+    class_name = yaml_values.pop("class_name", None)
+
+    cpp_namespace = yaml_values.pop("cpp_namespace", None)
+    assert cpp_namespace is not None, 'You must provide a value for "cpp_namespace"'
+
+    # Mostly just defaulting to false to stick with LazyTensor convention.
+    use_out_as_primary = yaml_values.pop("use_out_as_primary", False)
+    assert isinstance(
+        use_out_as_primary, bool
+    ), f"You must provide either True or False for use_out_as_primary. Provided: {use_out_as_primary}"
+
+    use_device_guard = yaml_values.pop("device_guard", False)
+    assert isinstance(
+        use_device_guard, bool
+    ), f"You must provide either True or False for device_guard. Provided: {use_device_guard}"
+
+    supported = yaml_values.pop("supported", [])
+    if supported is None:
+        supported = []  # Allow an empty list of supported ops
+    assert isinstance(
+        supported, list
+    ), f'expected "supported" to be a list, but got: {supported} (of type {type(supported)})'
+
+    symint = yaml_values.pop("symint", [])
+    if symint is None:
+        symint = []  # Allow an empty list of symint ops
+    assert isinstance(
+        symint, list
+    ), f'expected "symint" to be a list, but got: {supported} (of type {type(supported)})'
+    symint_set = set(symint)
+
+    supported_autograd = yaml_values.pop("autograd", [])
+    assert isinstance(
+        supported_autograd, list
+    ), f'expected "autograd" to be a list, but got: {supported_autograd}'
+
+    # full_codegen is ignored by parse_backend_yaml, and re-parsed in gen_lazy_tensor.py
+    full_codegen = yaml_values.pop("full_codegen", [])
+    supported.extend(full_codegen)
+
+    # non_native is ignored by parse_backend_yaml, and re-parsed in gen_lazy_tensor.py
+    yaml_values.pop("non_native", {})
+
+    # ir_gen is ignored by parse_backend_yaml, and re-parsed in gen_lazy_tensor.py
+    yaml_values.pop("ir_gen", {})
+
+    assert (
+        len(yaml_values.keys()) == 0
+    ), f'{backend_yaml_path} contains unexpected keys: {", ".join(yaml_values.keys())}. \
+Only the following keys are supported: {", ".join(valid_keys)}'
+
+    def create_backend_index(
+        backend_ops: list[str],
+        symint_ops: set[str],
+        dispatch_key: DispatchKey,
+        *,
+        use_out_as_primary: bool,
+        use_device_guard: bool,
+    ) -> BackendIndex:
+        metadata: dict[OperatorName, BackendMetadata] = {}
+        for op in backend_ops:
+            op_name = OperatorName.parse(op)
+            assert (
+                op_name in native_functions_map
+            ), f"Found an invalid operator name: {op_name}"
+            # See Note [External Backends Follow Dispatcher API]
+            kernel_name = dispatcher.name(native_functions_map[op_name].func)
+            if op in symint_ops:
+                kernel_name += "_symint"
+            # TODO: allow structured external backends later.
+            m = BackendMetadata(
+                kernel=kernel_name, structured=False, cpp_namespace=cpp_namespace
+            )
+            metadata[op_name] = m
+        return BackendIndex(
+            dispatch_key=dispatch_key,
+            use_out_as_primary=use_out_as_primary,
+            external=True,
+            device_guard=use_device_guard,
+            index=metadata,
+        )
+
+    backend_key: DispatchKey | None = None
+    if len(supported) > 0:
+        with context(
+            lambda: f'The provided value for "backend" must be a valid DispatchKey, but got {backend}.'
+        ):
+            backend_key = DispatchKey.parse(backend)
+
+        backend_idx = create_backend_index(
+            supported,
+            symint_set,
+            backend_key,
+            use_out_as_primary=use_out_as_primary,
+            use_device_guard=use_device_guard,
+        )
+        assert backend_key not in backend_indices
+        backend_indices[backend_key] = backend_idx
+
+    autograd_key: DispatchKey | None = None
+    if len(supported_autograd) > 0:
+        with context(
+            lambda: f'The "autograd" key was specified, which indicates that you would like to override \
+the behavior of autograd for some operators on your backend. However "Autograd{backend}" is not a valid DispatchKey.'
+        ):
+            autograd_key = DispatchKey.parse(f"Autograd{backend}")
+
+        autograd_idx = create_backend_index(
+            supported_autograd,
+            symint_set,
+            autograd_key,
+            use_out_as_primary=use_out_as_primary,
+            use_device_guard=use_device_guard,
+        )
+        assert autograd_key not in backend_indices
+        backend_indices[autograd_key] = autograd_idx
+
+    for g in grouped_native_functions:
+        if isinstance(g, NativeFunction):
+            forward_kernels = (
+                []
+                if backend_key is None
+                else [
+                    m
+                    for m in [backend_indices[backend_key].get_kernel(g)]
+                    if m is not None
+                ]
+            )
+            backward_kernels = (
+                []
+                if autograd_key is None
+                else [
+                    m
+                    for m in [backend_indices[autograd_key].get_kernel(g)]
+                    if m is not None
+                ]
+            )
+        else:
+            forward_kernels = (
+                []
+                if backend_key is None
+                else [
+                    m
+                    for m in [
+                        backend_indices[backend_key].get_kernel(f)
+                        for f in g.functions()
+                    ]
+                    if m is not None
+                ]
+            )
+            backward_kernels = (
+                []
+                if autograd_key is None
+                else [
+                    m
+                    for m in [
+                        backend_indices[autograd_key].get_kernel(f)
+                        for f in g.functions()
+                    ]
+                    if m is not None
+                ]
+            )
+
+        forward_kernels = [f for f in forward_kernels if f is not None]
+        backward_kernels = [f for f in backward_kernels if f is not None]
+        assert (
+            len(forward_kernels) == 0 or len(backward_kernels) == 0
+        ), f'Currently, all variants of an op must either be registered to a backend key, or to a backend\'s \
+autograd key. They cannot be mix and matched. If this is something you need, feel free to create an issue! \
+{forward_kernels[0].kernel} is listed under "supported", but {backward_kernels[0].kernel} is listed under "autograd".'
+
+    return ParsedExternalYaml(
+        backend_key, autograd_key, class_name, cpp_namespace, backend_indices
+    )
+
+
+def error_on_missing_kernels(
+    native_functions: Sequence[NativeFunction],
+    backend_indices: dict[DispatchKey, BackendIndex],
+    backend_key: DispatchKey,
+    autograd_key: DispatchKey | None,
+    class_name: str,
+    kernel_defn_file_path: str,
+    full_codegen: list[OperatorName] | None = None,
+) -> None:
+    try:
+        with open(kernel_defn_file_path) as f:
+            backend_defns = f.read()
+    except OSError as e:
+        raise AssertionError(
+            f"Unable to read from the specified impl_path file: {kernel_defn_file_path}"
+        ) from e
+
+    if full_codegen is None:
+        full_codegen = []
+
+    indices = [backend_indices[backend_key].index] + (
+        [] if autograd_key is None else [backend_indices[autograd_key].index]
+    )
+    # Quick mapping from each OperatorName used by the external backend
+    # to its backend kernel name
+    expected_backend_op_names: dict[OperatorName, str] = dict(
+        list(
+            concatMap(
+                lambda index: [
+                    (op_name, metadata.kernel) for op_name, metadata in index.items()
+                ],
+                indices,
+            )
+        )
+    )
+    expected_backend_native_funcs: list[NativeFunction] = [
+        f
+        for f in native_functions
+        if f.func.name in expected_backend_op_names.keys()
+        and f.func.name not in full_codegen
+    ]
+    expected_backend_kernel_name_counts: dict[str, list[NativeFunction]] = defaultdict(
+        list
+    )
+    for native_f in expected_backend_native_funcs:
+        expected_backend_kernel_name_counts[
+            expected_backend_op_names[native_f.func.name]
+        ].append(native_f)
+
+    # This just looks for lines containing "foo(", and assumes that the kernel foo has been implemented.
+    # It might cause false negatives (we won't catch all cases), but that's ok - if we catch a missing kernel
+    # here, then we get a nicer error message. If we miss it, you get a linker error.
+    kernel_defn_regex = rf"(.*){class_name}::\s*([\w\d]*)\("
+    actual_backend_kernel_name_counts = Counter(
+        # A bit unwieldy (this could probably be moved into regex),
+        # but we don't want to include kernel names that come from function calls,
+        # like "return torch_xla::XLANativeFunctions::empty_strided_symint(...)".
+        # Easy check is to ignore any lines with colons before the class name.
+        [
+            y
+            for (x, y) in re.findall(kernel_defn_regex, backend_defns)
+            if not x.endswith(":")
+        ]
+    )
+
+    missing_kernels_err_msg = ""
+    for expected_name, funcs in expected_backend_kernel_name_counts.items():
+        expected_overload_count = len(funcs)
+        actual_overload_count = actual_backend_kernel_name_counts[expected_name]
+        if expected_overload_count != actual_overload_count:
+
+            def create_decl(f: NativeFunction) -> str:
+                with native_function_manager(f):
+                    return DispatcherSignature.from_schema(f.func).decl()
+
+            expected_schemas_str = "\n".join([create_decl(f) for f in funcs])
+            missing_kernels_err_msg += f"""
+{class_name} is missing a kernel definition for {expected_name}. We found {actual_overload_count} kernel(s) with that name,
+but expected {expected_overload_count} kernel(s). The expected function schemas for the missing operator are:
+{expected_schemas_str}
+
+"""
+    assert missing_kernels_err_msg == "", missing_kernels_err_msg
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Generate backend stub files")
+    parser.add_argument(
+        "-s",
+        "--source-yaml",
+        "--source_yaml",
+        help="path to source yaml file containing operator external definitions",
+    )
+    parser.add_argument("-o", "--output-dir", "--output_dir", help="output directory")
+    parser.add_argument(
+        "--dry-run", "--dry_run", type=bool, default=False, help="output directory"
+    )
+    parser.add_argument(
+        "--impl-path",
+        "--impl_path",
+        type=str,
+        default=None,
+        help="path to the source C++ file containing kernel definitions",
+    )
+    options = parser.parse_args()
+
+    run(options.source_yaml, options.output_dir, options.dry_run, options.impl_path)
+
+
+def gen_dispatchkey_nativefunc_headers(
+    fm: FileManager,
+    class_name: str,
+    cpp_namespace: str,
+    backend_indices: dict[DispatchKey, BackendIndex],
+    grouped_native_functions: Sequence[NativeFunction | NativeFunctionsGroup],
+    backend_dispatch_key: DispatchKey,
+    autograd_dispatch_key: DispatchKey | None,
+    backend_name: str = "",
+) -> None:
+    assert class_name is not None
+    generated_comment = (
+        "Autogenerated file by gen_backend_stubs.py. Do not edit directly!"
+    )
+
+    # Convert to a set first to remove duplicate kernel names.
+    # Backends are allowed to repeat kernel names; only generate the declaration once!
+    # Sort for deterministic output.
+    backend_declarations = sorted(
+        set(
+            concatMap(
+                lambda f: dest.compute_native_function_declaration(
+                    f, backend_indices[backend_dispatch_key]
+                ),
+                grouped_native_functions,
+            )
+        )
+    )
+    autograd_declarations = sorted(
+        set(
+            concatMap(
+                lambda f: []
+                if autograd_dispatch_key is None
+                else dest.compute_native_function_declaration(
+                    f, backend_indices[autograd_dispatch_key]
+                ),
+                grouped_native_functions,
+            )
+        )
+    )
+
+    ns_helper = NamespaceHelper(cpp_namespace)
+    fm.write_with_template(
+        f"{backend_dispatch_key}NativeFunctions.h",
+        "DispatchKeyNativeFunctions.h",
+        lambda: {
+            "generated_comment": generated_comment,
+            "namespace_prologue": ns_helper.prologue,
+            "class_name": class_name,
+            "namespace_epilogue": ns_helper.epilogue,
+            "dispatch_declarations": backend_declarations + autograd_declarations,
+            "BackendName": backend_name,
+            "DispatchKey": backend_dispatch_key,
+        },
+    )
+
+
+def gen_dispatcher_registrations(
+    fm: FileManager,
+    output_dir: str,
+    class_name: str,
+    backend_indices: dict[DispatchKey, BackendIndex],
+    grouped_native_functions: Sequence[NativeFunction | NativeFunctionsGroup],
+    backend_dispatch_key: DispatchKey,
+    dispatch_key: DispatchKey,
+    selector: SelectiveBuilder,
+    # build_in_tree is true for lazy TS backend and affects include paths, not used for external backends
+    build_in_tree: bool = False,
+    per_operator_headers: bool = False,
+    backend_name: str = "",
+    eager_registration: bool = True,
+) -> None:
+    headers = [
+        f"{output_dir}/{backend_dispatch_key}NativeFunctions.h",
+    ]
+    if build_in_tree:
+        external_backend_headers_str = "\n".join(f"#include <{h}>" for h in headers)
+    else:
+        external_backend_headers_str = "\n".join(f'#include "{h}"' for h in headers)
+
+    assert class_name is not None
+    backend_index = backend_indices[dispatch_key]
+
+    dispatch_registrations_body = list(
+        concatMap(
+            dest.RegisterDispatchKey(
+                backend_index,
+                Target.REGISTRATION,
+                selector,
+                rocm=False,
+                symint=True,
+                class_method_name=f"{class_name}",
+                skip_dispatcher_op_registration=False,
+            ),
+            grouped_native_functions,
+        )
+    )
+    newline = "\n"
+    ns_helper = NamespaceHelper(namespace_str="at")
+    deferred_dispatch_registrations = ""
+    static_init_dispatch_registrations = ""
+    if eager_registration:
+        static_template = CodeTemplate(
+            """\
+TORCH_LIBRARY_IMPL(aten, $dispatch_key, m) {
+    $dispatch_registrations_body
+};"""
+        )
+        static_init_dispatch_registrations = static_template.substitute(
+            dispatch_key=dispatch_key,
+            dispatch_registrations_body=dispatch_registrations_body,
+        )
+    else:
+        deferred_template = CodeTemplate(
+            """\
+TORCH_API void Register${backend_name}${dispatch_key}NativeFunctions();
+TORCH_API void Register${backend_name}${dispatch_key}NativeFunctions() {
+    static auto m = MAKE_TORCH_LIBRARY_IMPL(aten, $dispatch_key);
+    $dispatch_registrations_body
+}"""
+        )
+        deferred_dispatch_registrations = deferred_template.substitute(
+            backend_name=backend_name,
+            dispatch_key=dispatch_key,
+            dispatch_registrations_body=dispatch_registrations_body,
+        )
+
+    fm.write_with_template(
+        f"Register{dispatch_key}.cpp",
+        "RegisterDispatchKey.cpp",
+        lambda: {
+            "extra_cuda_headers": "",
+            "external_backend_headers": external_backend_headers_str,
+            "ops_headers": "#include <ATen/Functions.h>"
+            if not per_operator_headers
+            else "",
+            "DispatchKey": dispatch_key,
+            "dispatch_namespace": dispatch_key.lower(),
+            "dispatch_headers": dest.gen_registration_headers(
+                backend_index, per_operator_headers=per_operator_headers, rocm=False
+            ),
+            "dispatch_definitions": fm.substitute_with_template(
+                "RegisterDispatchDefinitions.ini",
+                lambda: {
+                    "ns_prologue": ns_helper.prologue,
+                    "ns_epilogue": ns_helper.epilogue,
+                    "static_init_dispatch_registrations": static_init_dispatch_registrations,
+                    "deferred_dispatch_registrations": deferred_dispatch_registrations,
+                    "dispatch_helpers": dest.gen_registration_helpers(backend_index),
+                    "dispatch_namespace": dispatch_key.lower(),
+                    "dispatch_namespaced_definitions": "",
+                    "dispatch_anonymous_definitions": list(
+                        concatMap(
+                            dest.RegisterDispatchKey(
+                                backend_index,
+                                Target.ANONYMOUS_DEFINITION,
+                                selector,
+                                rocm=False,
+                                symint=True,
+                                class_method_name=f"{class_name}",
+                                skip_dispatcher_op_registration=False,
+                            ),
+                            grouped_native_functions,
+                        )
+                    ),
+                },
+            ).split(newline),
+        },
+    )
+
+
+def run(
+    source_yaml: str, output_dir: str, dry_run: bool, impl_path: str | None = None
+) -> None:
+    # Assumes that this file lives at PYTORCH_ROOT/torchgen/gen_backend_stubs.py
+    pytorch_root = Path(__file__).parent.parent.absolute()
+    template_dir = os.path.join(pytorch_root, "aten/src/ATen/templates")
+
+    def make_file_manager(install_dir: str) -> FileManager:
+        return FileManager(
+            install_dir=install_dir, template_dir=template_dir, dry_run=dry_run
+        )
+
+    fm = make_file_manager(output_dir)
+
+    native_yaml_path = os.path.join(
+        pytorch_root, "aten/src/ATen/native/native_functions.yaml"
+    )
+    tags_yaml_path = os.path.join(pytorch_root, "aten/src/ATen/native/tags.yaml")
+    parsed_yaml = parse_native_yaml(native_yaml_path, tags_yaml_path)
+    native_functions, backend_indices = (
+        parsed_yaml.native_functions,
+        parsed_yaml.backend_indices,
+    )
+    grouped_native_functions = get_grouped_native_functions(native_functions)
+    parsed_backend_yaml = parse_backend_yaml(
+        source_yaml, grouped_native_functions, backend_indices
+    )
+    backend_key = parsed_backend_yaml.backend_key
+    autograd_key = parsed_backend_yaml.autograd_key
+    cpp_namespace = parsed_backend_yaml.cpp_namespace
+    class_name = parsed_backend_yaml.class_name
+    backend_indices = parsed_backend_yaml.backend_indices
+
+    selector = SelectiveBuilder.get_nop_selector()
+
+    if backend_key is None:
+        # This could be useful if a backend wants to quickly set up a noop yaml file but doesn't have any kernels ready yet.
+        return
+
+    if class_name is None:
+        # class_name is an optional argument to backend yaml file.
+        # if specified it allows an external backend to override
+        # the name of the class that all generated kernel definitions live under.
+        # if not specified, its value is given as native_function_class_name.
+        class_name = backend_indices[backend_key].native_function_class_name()
+    assert class_name is not None
+
+    if impl_path is not None:
+        error_on_missing_kernels(
+            native_functions,
+            backend_indices,
+            backend_key,
+            autograd_key,
+            class_name,
+            impl_path,
+        )
+
+    gen_dispatchkey_nativefunc_headers(
+        fm,
+        class_name,
+        cpp_namespace,
+        backend_indices,
+        grouped_native_functions,
+        backend_key,
+        autograd_key,
+    )
+
+    for dispatch_key in (
+        [backend_key] if autograd_key is None else [backend_key, autograd_key]
+    ):
+        gen_dispatcher_registrations(
+            fm,
+            output_dir,
+            class_name,
+            backend_indices,
+            grouped_native_functions,
+            backend_key,
+            dispatch_key,
+            selector,
+        )
+
+
+if __name__ == "__main__":
+    main()

vllm/lib/python3.10/site-packages/torchgen/gen_executorch.py

@@ -0,0 +1,998 @@
+from __future__ import annotations
+
+import argparse
+import os
+from collections import defaultdict
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Any, Callable, Sequence, TextIO, TYPE_CHECKING
+
+import yaml
+
+# Parse native_functions.yaml into a sequence of NativeFunctions and Backend Indices.
+from torchgen import dest
+from torchgen.api import cpp as aten_cpp
+from torchgen.api.types import CppSignature, CppSignatureGroup, CType, NamedCType
+from torchgen.context import (
+    method_with_native_function,
+    method_with_nested_native_function,
+    with_native_function_and_index,
+)
+from torchgen.executorch.api import et_cpp
+from torchgen.executorch.api.custom_ops import (
+    ComputeNativeFunctionStub,
+    gen_custom_ops_registration,
+)
+from torchgen.executorch.api.types import contextArg, ExecutorchCppSignature
+from torchgen.executorch.api.unboxing import Unboxing
+from torchgen.executorch.model import ETKernelIndex, ETKernelKey, ETParsedYaml
+from torchgen.executorch.parse import ET_FIELDS, parse_et_yaml, parse_et_yaml_struct
+from torchgen.gen import (
+    get_custom_build_selector,
+    get_native_function_declarations,
+    get_native_function_declarations_from_ns_grouped_kernels,
+    get_native_function_schema_registrations,
+    LineLoader,
+    parse_native_yaml,
+)
+from torchgen.model import (
+    BackendIndex,
+    BackendMetadata,
+    DEFAULT_KERNEL_NAMESPACE,
+    DispatchKey,
+    FunctionSchema,
+    Location,
+    NativeFunction,
+    NativeFunctionsGroup,
+    OperatorName,
+    Variant,
+)
+from torchgen.utils import (
+    context,
+    FileManager,
+    make_file_manager,
+    mapMaybe,
+    NamespaceHelper,
+)
+
+
+if TYPE_CHECKING:
+    from torchgen.selective_build.selector import SelectiveBuilder
+
+
+def _sig_decl_wrapper(sig: CppSignature | ExecutorchCppSignature) -> str:
+    """
+    A wrapper function to basically get `sig.decl(include_context=True)`.
+    For ATen kernel, the codegen has no idea about ET contextArg, so we
+    use this wrapper to add it.
+    """
+    if isinstance(sig, ExecutorchCppSignature):
+        return sig.decl()
+
+    returns_type = aten_cpp.returns_type(sig.func.returns).cpp_type()
+    cpp_args = [a.decl() for a in sig.arguments()]
+    cpp_args_str = ", ".join([contextArg.decl()] + cpp_args)
+    sig_decl = f"{returns_type} {sig.name()}({cpp_args_str})"
+    return sig_decl
+
+
+def static_dispatch(
+    sig: CppSignature | ExecutorchCppSignature,
+    f: NativeFunction,
+    backend_indices: list[BackendIndex],
+) -> str:
+    """
+    For a given `NativeFunction`, find out the corresponding native function and dispatch to it. If zero or more than one
+    native function exists, error out. A simplified version of register_dispatch_key.py
+    Arguments:
+        sig: A CppSignature for this native function we want to use.
+        f: NativeFunction to generate static dispatch.
+        backend_indices: All available backends.
+    Return:
+        C++ code to call backend-specific functions, e.g., "return at::native::add(self, other, scale);"
+    """
+    if len(backend_indices) == 0 or f.manual_kernel_registration:
+        return ""
+
+    backends = [b for b in backend_indices if b.has_kernel(f)]
+    static_block = None
+    if len(backends) == 1:
+        backend_metadata = backends[0].get_kernel(f)
+        if backend_metadata:
+            args = ", ".join(a.name for a in sig.arguments())
+            # Here we are assuming there's no difference between CppSignature and NativeSignature for Executorch.
+            static_block = f"return ::{backend_metadata.cpp_namespace}::{backend_metadata.kernel}({args});"
+    else:
+        static_block = f"""
+ET_ASSERT_UNREACHABLE_MSG("The number of native function(s) binding to {f.func.name} is {len(backends)}.");
+    """
+    return f"""
+// {f.namespace}::{f.func}
+TORCH_API inline {_sig_decl_wrapper(sig)} {{
+    {static_block}
+}}
+"""
+
+
+# Generates Functions.h, which provides the functional public C++ API,
+# and the scaffolding to call into the dispatcher from these functions.
+@dataclass(frozen=True)
+class ComputeFunction:
+    static_dispatch_backend_indices: list[BackendIndex]
+
+    selector: SelectiveBuilder
+
+    use_aten_lib: bool
+
+    is_custom_op: Callable[[NativeFunction], bool]
+
+    @method_with_native_function
+    def __call__(self, f: NativeFunction) -> str | None:
+        is_method_variant = False
+        if not self.selector.is_root_operator(f"{f.namespace}::{f.func.name}"):
+            return None
+
+        if Variant.function not in f.variants and Variant.method in f.variants:
+            is_method_variant = True
+
+        # only valid remaining case is only function is in f.variants
+        elif not (Variant.function in f.variants and Variant.method not in f.variants):
+            raise Exception(  # noqa: TRY002
+                f"Can't handle native function {f.func} with the following variant specification {f.variants}."
+            )
+
+        sig: CppSignature | ExecutorchCppSignature = (
+            CppSignatureGroup.from_native_function(
+                f, method=False, fallback_binding=f.manual_cpp_binding
+            ).most_faithful_signature()
+            if self.use_aten_lib
+            else ExecutorchCppSignature.from_native_function(f)
+        )
+        if self.use_aten_lib and not self.is_custom_op(f):
+            comma = ", "
+
+            if is_method_variant:
+                return f"""
+// {f.namespace}::{f.func}
+TORCH_API inline {_sig_decl_wrapper(sig)} {{
+    return {sig.arguments()[0].name}.{sig.name()}({comma.join(e.name for e in sig.arguments()[1:])});
+}}
+"""
+            else:
+                return f"""
+// {f.namespace}::{f.func}
+TORCH_API inline {_sig_decl_wrapper(sig)} {{
+    return at::{sig.name()}({comma.join(e.name for e in sig.arguments())});
+}}
+"""
+
+        else:
+            return static_dispatch(
+                sig,
+                f,
+                backend_indices=self.static_dispatch_backend_indices,
+            )
+
+
+# Generates RegisterCodegenUnboxedKernels.cpp.
+@dataclass(frozen=True)
+class ComputeCodegenUnboxedKernels:
+    selector: SelectiveBuilder
+
+    use_aten_lib: bool
+
+    @method_with_nested_native_function
+    def __call__(
+        self,
+        unbox_kernel_entry: tuple[NativeFunction, tuple[ETKernelKey, BackendMetadata]],
+    ) -> str:
+        f: NativeFunction = unbox_kernel_entry[0]
+        kernel_key: ETKernelKey | list[ETKernelKey] = unbox_kernel_entry[1][0]
+        kernel_meta: BackendMetadata = unbox_kernel_entry[1][1]
+
+        op_name = f"{f.namespace}::{f.func.name}"
+        if not self.selector.is_root_operator(op_name):
+            return ""
+
+        if not isinstance(kernel_key, list):
+            kernel_key = [kernel_key]
+        used_kernel_keys = self.selector.et_get_selected_kernels(
+            op_name, [k.to_native_string() for k in kernel_key]
+        )
+        if not used_kernel_keys:
+            return ""
+        sig: CppSignature | ExecutorchCppSignature
+        argument_type_gen: Callable[..., NamedCType]
+        return_type_gen: Callable[..., CType]
+        if self.use_aten_lib:
+            sig = CppSignatureGroup.from_native_function(
+                f, method=False, fallback_binding=f.manual_cpp_binding
+            ).most_faithful_signature()
+            argument_type_gen = aten_cpp.argumenttype_type
+            return_type_gen = aten_cpp.returns_type
+            arguments = sig.arguments()
+            kernel_call = f"torch::executor::{f.namespace}::{sig.name()}"
+        else:
+            sig = ExecutorchCppSignature.from_native_function(f)
+            argument_type_gen = et_cpp.argumenttype_type
+            return_type_gen = et_cpp.returns_type
+            arguments = sig.arguments(include_context=False)
+            kernel_call = f"{kernel_meta.cpp_namespace}::{kernel_meta.kernel}"
+        # parse arguments into C++ code
+        binding_list, code_list = Unboxing(
+            argument_type_gen=argument_type_gen
+        ).convert_arguments(arguments)
+
+        # for each C++ argument, generate the conversion code
+        code_connector = "\n\t"
+        arg_connector = ", "
+
+        args_str = f"{arg_connector.join(e.name for e in binding_list)}"
+        event_tracer_output_logging = ""
+        output_ids = []
+
+        if len(f.func.returns) == 0:
+            if len(f.func.arguments.out) == 0:
+                raise Exception(  # noqa: TRY002
+                    f"Can't handle native function {f.func} with no returns and no out yet."
+                )
+            out = f.func.arguments.out[0]
+            return_assignment = f"""stack[{len(binding_list)}] = &{out.name};"""
+            ret_prefix = ""
+            output_ids = [len(binding_list)]
+        else:
+            if len(f.func.arguments.out) == 0:
+                return_assignment = (
+                    f"""*stack[{len(binding_list)}] = EValue(result_);"""
+                )
+                ret_prefix = return_type_gen(f.func.returns).cpp_type() + " result_ = "
+                output_ids = [len(binding_list)]
+            else:
+                return_assignment = ""
+                ret_prefix = ""
+                output_ids = [
+                    len(binding_list) - (i + 1)
+                    for i in reversed(range(len(f.func.arguments.out)))
+                ]
+
+        for output_id in output_ids:
+            event_tracer_output_logging += (
+                f"internal::event_tracer_log_evalue("
+                f"context.internal_event_tracer(), "
+                f"*stack[{output_id}]);\n"
+            )
+
+        newline = "\n    "
+        return "\n".join(
+            [
+                f"""
+Kernel(
+    "{f.namespace}::{f.func.name}",{newline + '"' + (k + '",') if k != 'default' else ''}
+    []({contextArg.defn()}, EValue** stack) {{
+        {code_connector.join(code_list)}
+
+        internal::EventTracerProfileScope event_tracer_scope(context.internal_event_tracer(), "native_call_{f.func.name}");
+        EXECUTORCH_SCOPE_PROF("native_call_{f.func.name}");
+        {ret_prefix}{kernel_call}(context, {args_str});
+        {event_tracer_output_logging}
+        {return_assignment}
+    }}
+),
+"""
+                for k in used_kernel_keys
+            ]
+        )
+
+
+def gen_unboxing(
+    *,
+    native_functions: Sequence[NativeFunction],
+    cpu_fm: FileManager,
+    selector: SelectiveBuilder,
+    use_aten_lib: bool,
+    kernel_index: ETKernelIndex,
+    manual_registration: bool,
+) -> None:
+    # Iterable type for write_sharded is a Tuple of (native_function, (kernel_key, metadata))
+    def key_func(
+        item: tuple[NativeFunction, tuple[ETKernelKey, BackendMetadata]]
+    ) -> str:
+        return item[0].root_name + ":" + item[1][0].to_native_string()
+
+    items: list[tuple[NativeFunction, tuple[ETKernelKey, BackendMetadata]]] = [
+        (native_function, (kernel_key, metadata))
+        for native_function in native_functions
+        for kernel_key, metadata in kernel_index.get_kernels(native_function).items()
+    ]
+
+    header = ["Functions.h" if use_aten_lib else "NativeFunctions.h"]
+    filename = (
+        "RegisterKernels.cpp"
+        if manual_registration
+        else "RegisterCodegenUnboxedKernels.cpp"
+    )
+    cpu_fm.write_sharded(
+        filename,
+        items,
+        key_fn=key_func,
+        env_callable=lambda unbox_kernel_entry: {
+            "unboxed_kernels": [
+                ComputeCodegenUnboxedKernels(selector, use_aten_lib)(unbox_kernel_entry)
+            ],
+            "fn_header": header
+            if unbox_kernel_entry == items[0]
+            else [],  # Only write header once
+        },
+        num_shards=1,
+        sharded_keys={"unboxed_kernels", "fn_header"},
+    )
+
+
+@with_native_function_and_index  # type: ignore[arg-type]
+def compute_native_function_declaration(
+    g: NativeFunctionsGroup | NativeFunction, kernel_index: ETKernelIndex
+) -> list[str]:
+    assert isinstance(g, NativeFunction)
+    sig = ExecutorchCppSignature.from_native_function(f=g)
+    metadata_list = kernel_index.get_kernels(g).values()
+    if metadata_list is None:
+        return []
+
+    # for kernels in lean mode, we declare two versions, one with context and one without.
+    # In the end we will cleanup the unused one.
+    def gen_decl(metadata: BackendMetadata, include_context: bool) -> str:
+        return f"{sig.decl(name=metadata.kernel, include_context=include_context)};"
+
+    return [
+        gen_decl(metadata, include_context)
+        for include_context in [False, True]
+        for metadata in metadata_list
+    ]
+
+
+def gen_functions_declarations(
+    *,
+    native_functions: Sequence[NativeFunction],
+    kernel_index: ETKernelIndex,
+    selector: SelectiveBuilder,
+    use_aten_lib: bool,
+    custom_ops_native_functions: Sequence[NativeFunction] | None = None,
+) -> str:
+    """
+    Generates namespace separated C++ function API inline declaration/definitions.
+    Native functions are grouped by namespaces and the generated code is wrapped inside
+    namespace blocks.
+
+    E.g., for `custom_1::foo.out` in yaml file we will generate a C++ API as a symbol
+    in `torch::executor::custom_1::foo_out`. This way we avoid symbol conflict when
+    the other `custom_2::foo.out` is available.
+    """
+
+    # convert kernel index to BackendIndex. This is because we can't handle ETKernelIndex yet.
+    # TODO larryliu: evaluate if this code is still needed. If yes let it handle ETKernelIndex.
+
+    backend_index = kernel_index._to_backend_index()
+
+    ns_grouped_functions = defaultdict(list)
+    for native_function in native_functions:
+        ns_grouped_functions[native_function.namespace].append(native_function)
+    functions_declarations = ""
+    newline = "\n"
+    for namespace in ns_grouped_functions:
+        ns_helper = NamespaceHelper(
+            namespace_str=namespace,
+            entity_name="",
+            max_level=3,
+        )
+        declarations = list(
+            mapMaybe(
+                ComputeFunction(
+                    static_dispatch_backend_indices=[backend_index],
+                    selector=selector,
+                    use_aten_lib=use_aten_lib,
+                    is_custom_op=lambda f: custom_ops_native_functions is not None
+                    and f in custom_ops_native_functions,
+                ),
+                ns_grouped_functions[namespace],
+            )
+        )
+        functions_declarations += f"""
+{ns_helper.prologue}
+{newline.join(declarations)}
+{ns_helper.epilogue}
+        """
+    return functions_declarations
+
+
+def get_ns_grouped_kernels(
+    *,
+    native_functions: Sequence[NativeFunction],
+    kernel_index: ETKernelIndex,
+    native_function_decl_gen: Callable[
+        [
+            NativeFunctionsGroup | NativeFunction,
+            ETKernelIndex,
+        ],
+        list[str],
+    ],
+) -> dict[str, list[str]]:
+    ns_grouped_kernels: dict[str, list[str]] = defaultdict(list)
+    for f in native_functions:
+        native_function_namespaces = set()
+        op_kernels = kernel_index.get_kernels(f)
+        for backend_metadata in op_kernels.values():
+            if backend_metadata:
+                namespace = backend_metadata.cpp_namespace
+                native_function_namespaces.add(namespace)
+            else:
+                namespace = DEFAULT_KERNEL_NAMESPACE
+            assert (
+                len(native_function_namespaces) <= 1
+            ), f"Codegen only supports one namespace per operator, got {native_function_namespaces}"
+            ns_grouped_kernels[namespace].extend(
+                native_function_decl_gen(f, kernel_index)
+            )
+    return ns_grouped_kernels
+
+
+def gen_headers(
+    *,
+    native_functions: Sequence[NativeFunction],
+    gen_custom_ops_header: bool,
+    custom_ops_native_functions: Sequence[NativeFunction],
+    selector: SelectiveBuilder,
+    kernel_index: ETKernelIndex,
+    cpu_fm: FileManager,
+    use_aten_lib: bool,
+) -> None:
+    """Generate headers.
+
+    Args:
+        native_functions (Sequence[NativeFunction]): a collection of NativeFunction for ATen ops.
+        gen_custom_ops_header (bool): whether we should generate CustomOpsNativeFunctions.h
+        custom_ops_native_functions (Sequence[NativeFunction]): a collection of NativeFunction for custom ops.
+        kernel_index (ETKernelIndex): kernel collection
+        cpu_fm (FileManager): file manager manages output stream
+        use_aten_lib (bool): whether we are generating for PyTorch types or Executorch types.
+    """
+    aten_headers = ["#include <ATen/Functions.h>"]
+    backend_indices = {DispatchKey.CPU: kernel_index._to_backend_index()}
+    if gen_custom_ops_header:
+        cpu_fm.write_with_template(
+            "CustomOpsNativeFunctions.h",
+            "NativeFunctions.h",
+            lambda: {
+                "nativeFunctions_declarations": get_native_function_declarations(
+                    grouped_native_functions=custom_ops_native_functions,
+                    backend_indices=backend_indices,
+                    native_function_decl_gen=dest.compute_native_function_declaration,
+                ),
+                "headers": [
+                    "#include <ATen/ATen.h>",
+                    "#include <torch/torch.h>",
+                ],
+            },
+        )
+        aten_headers.append('#include "CustomOpsNativeFunctions.h"')
+    cpu_fm.write(
+        "Functions.h",
+        lambda: {
+            "static_dispatch_extra_headers": aten_headers
+            if use_aten_lib
+            else ['#include "NativeFunctions.h"'],
+            "Functions_declarations": gen_functions_declarations(
+                native_functions=native_functions,
+                kernel_index=kernel_index,
+                selector=selector,
+                use_aten_lib=use_aten_lib,
+                custom_ops_native_functions=custom_ops_native_functions,
+            ),
+        },
+    )
+    cpu_fm.write(
+        "RegisterKernels.h",
+        lambda: {
+            "generated_comment": "@" + "generated by torchgen/gen_executorch.py",
+        },
+    )
+    headers = {
+        "headers": [
+            "#include <executorch/runtime/core/exec_aten/exec_aten.h> // at::Tensor etc.",
+            "#include <executorch/runtime/kernel/kernel_runtime_context.h>",
+        ],
+    }
+    if use_aten_lib:
+        headers["headers"].append("#include <executorch/codegen/macros.h> // TORCH_API")
+        cpu_fm.write(
+            "NativeFunctions.h",
+            lambda: dict(
+                {
+                    "nativeFunctions_declarations": get_native_function_declarations(
+                        grouped_native_functions=native_functions,
+                        backend_indices=backend_indices,
+                        native_function_decl_gen=dest.compute_native_function_declaration,
+                    ),
+                },
+                **headers,
+            ),
+        )
+    else:
+        ns_grouped_kernels = get_ns_grouped_kernels(
+            native_functions=native_functions,
+            kernel_index=kernel_index,
+            native_function_decl_gen=compute_native_function_declaration,  # type: ignore[arg-type]
+        )
+        cpu_fm.write(
+            "NativeFunctions.h",
+            lambda: dict(
+                {
+                    "nativeFunctions_declarations": get_native_function_declarations_from_ns_grouped_kernels(
+                        ns_grouped_kernels=ns_grouped_kernels,
+                    ),
+                },
+                **headers,
+            ),
+        )
+
+
+def gen_custom_ops(
+    *,
+    native_functions: Sequence[NativeFunction],
+    selector: SelectiveBuilder,
+    kernel_index: ETKernelIndex,
+    cpu_fm: FileManager,
+    rocm: bool,
+) -> None:
+    dispatch_key = DispatchKey.CPU
+    (
+        anonymous_definition,
+        static_init_dispatch_registrations,
+    ) = gen_custom_ops_registration(
+        native_functions=native_functions,
+        selector=selector,
+        kernel_index=kernel_index,
+        rocm=rocm,
+    )
+    cpu_fm.write_with_template(
+        f"Register{dispatch_key}CustomOps.cpp",
+        "RegisterDispatchKeyCustomOps.cpp",
+        lambda: {
+            "ops_headers": '#include "CustomOpsNativeFunctions.h"',
+            "DispatchKey": dispatch_key,
+            "dispatch_namespace": dispatch_key.lower(),
+            "dispatch_namespaced_definitions": "",
+            "dispatch_anonymous_definitions": anonymous_definition,
+            "static_init_dispatch_registrations": static_init_dispatch_registrations,
+        },
+    )
+    cpu_fm.write_with_template(
+        f"Register{dispatch_key}Stub.cpp",
+        "RegisterDispatchKeyCustomOps.cpp",
+        lambda: {
+            "ops_headers": "",
+            "DispatchKey": dispatch_key,
+            "dispatch_namespace": dispatch_key.lower(),
+            "dispatch_namespaced_definitions": "",
+            "dispatch_anonymous_definitions": list(
+                mapMaybe(ComputeNativeFunctionStub(), native_functions)
+            ),
+            "static_init_dispatch_registrations": static_init_dispatch_registrations,
+        },
+    )
+
+    (
+        aten_schema_registrations,
+        schema_registrations,
+    ) = get_native_function_schema_registrations(
+        native_functions=native_functions,
+        schema_selector=selector,
+    )
+    cpu_fm.write(
+        "RegisterSchema.cpp",
+        lambda: {
+            "schema_registrations": schema_registrations,
+            "aten_schema_registrations": aten_schema_registrations,
+        },
+    )
+
+
+def translate_native_yaml(
+    tags_yaml_path: str,
+    aten_yaml_path: str,
+    native_yaml_path: str | None,
+    use_aten_lib: bool,
+    out_file: TextIO,
+) -> None:
+    """Translates Executorch DSL dialect to use the same syntax as
+    native_functions.yaml. The major difference is that Executorch DSL dialect
+    supports "op" key, where it refers to the operator name in native_functions.yaml.
+
+    For example, a functions.yaml may have the following entry:
+
+    - op: add.out
+      ...
+
+    It needs to be translated to the following:
+
+    - func: add.out(Tensor self, Tensor other, *, Scalar alpha=1, Tensor(a!) out) -> Tensor(a!)
+      ...
+
+    We go in aten_yaml_path and find the operator schema for "add.out" and add it
+    to the original functions.yaml. We also add required field "variants", where for
+    Executorch it will always be "function".
+
+    For ATen mode we don't have to do the translation because native_yaml_path is
+    the same as native_functions.yaml.
+
+    Args:
+        tags_yaml_path: Path to a tags.yaml file to satisfy codegen parsing.
+            It is not optional.
+        aten_yaml_path: Path to ATen operator yaml file native_functions.yaml.
+        native_yaml_path: Path to a functions.yaml file to parse.
+            If the path does not exist in the filesystem, it is treated as an
+            empty file. If `custom_ops_yaml_path` exists, the contents of that
+            file are appended to the yaml input to be parsed.
+        use_aten_lib: We use this flag to determine if we want to generate native
+            functions. In ATen mode we should generate out= variants.
+        out_file: The IO object that we are writing into.
+    Returns:
+        None
+    """
+    if use_aten_lib:
+        with open(aten_yaml_path) as aten_yaml:
+            out_file.writelines(aten_yaml.readlines())
+        return
+
+    native_functions, persisted_fields = parse_et_yaml(
+        aten_yaml_path,
+        tags_yaml_path,
+        None,
+        skip_native_fns_gen=False,
+    )
+
+    func_to_scoped_name: dict[FunctionSchema, str] = {
+        f.func: f"{f.namespace}::{f.func.name}" for f in native_functions
+    }
+    op_to_scoped_name: dict[OperatorName, str] = {
+        func.name: name for func, name in func_to_scoped_name.items()
+    }
+
+    schema_dict = {name: str(func) for func, name in func_to_scoped_name.items()}
+    kernel_persist_dict: dict[str, dict[str, Any]] = {
+        op_to_scoped_name[op]: v for op, v in persisted_fields.items()
+    }
+
+    if (
+        not native_yaml_path
+        or not os.path.exists(native_yaml_path)
+        or os.stat(native_yaml_path).st_size == 0
+    ):
+        return
+    with open(native_yaml_path) as native_yaml:
+        native_es = yaml.load(native_yaml, Loader=LineLoader)
+        if not native_es:
+            return
+        for e in native_es:
+            assert isinstance(e.get("__line__"), int), e
+            loc = Location(native_yaml_path, e.pop("__line__"))
+            with context(lambda: f"in {loc}:\n  "):
+                if "variants" not in e:
+                    e["variants"] = "function"
+                if "func" in e:
+                    continue
+                assert isinstance(e.get("op"), str), e
+                opname = e.pop("op")
+                if "::" not in opname:
+                    opname = "aten::" + opname
+                assert opname in schema_dict
+                e["func"] = schema_dict.get(opname)
+
+                # Write out persisted kernel information
+                if opname in kernel_persist_dict:
+                    for k, v in kernel_persist_dict[opname].items():
+                        e[k] = v
+
+        yaml.dump(native_es, out_file, width=1000)
+
+
+def parse_yaml(
+    path: str | None,
+    tags_yaml_path: str,
+    function_filter: Callable[[NativeFunction], bool],
+    skip_native_fns_gen: bool = False,
+) -> tuple[
+    list[NativeFunction],
+    dict[DispatchKey, dict[OperatorName, BackendMetadata]] | ETKernelIndex,
+]:
+    if path and os.path.exists(path) and os.stat(path).st_size > 0:
+        with open(path) as f:
+            es = yaml.load(f, Loader=LineLoader)
+
+        # Check for kernel index structure
+        kernel_index = (
+            parse_et_yaml_struct(es) if any("kernels" in e for e in es) else None
+        )
+
+        # Remove ET specific fields from entries for BC compatibility
+        for entry in es:
+            for field in ET_FIELDS:
+                entry.pop(field, None)
+
+        parsed_yaml = parse_native_yaml(
+            path,
+            tags_yaml_path,
+            None,
+            skip_native_fns_gen=skip_native_fns_gen,
+            loaded_yaml=es,
+        )
+        native_functions = list(filter(function_filter, parsed_yaml.native_functions))
+        op_names = [f.func.name for f in native_functions]
+
+        # (1) Return ETKernelIndex if kernel index is present
+        if kernel_index is not None:
+            filtered_index = {
+                op_name: kernel_mapping
+                for op_name, kernel_mapping in kernel_index.index.items()
+                if op_name in op_names
+            }
+            return native_functions, ETKernelIndex(index=filtered_index)
+
+        # (2) Return BackendIndices if kernel index is absent
+        def map_index(
+            m: dict[OperatorName, BackendMetadata]
+        ) -> dict[OperatorName, BackendMetadata]:
+            return {op: m[op] for op in m if op in op_names}
+
+        backend_indices = {
+            k: map_index(b.index) for (k, b) in parsed_yaml.backend_indices.items()
+        }
+
+        return native_functions, backend_indices
+    else:
+        return [], {}
+
+
+def parse_yaml_files(
+    tags_yaml_path: str,
+    aten_yaml_path: str,
+    native_yaml_path: str | None,
+    custom_ops_yaml_path: str | None,
+    selector: SelectiveBuilder,
+    use_aten_lib: bool,
+) -> tuple[ETParsedYaml, ETParsedYaml | None]:
+    """Parses functions.yaml and custom_ops.yaml files.
+
+    Args:
+        tags_yaml_path: Path to a tags.yaml file to satisfy codegen parsing.
+            It is not optional.
+        aten_yaml_path: Path to ATen operator yaml file native_functions.yaml.
+        native_yaml_path: Path to a functions.yaml file to parse.
+            If the path does not exist in the filesystem, it is treated as an
+            empty file. If `custom_ops_yaml_path` exists, the contents of that
+            file are appended to the yaml input to be parsed.
+        custom_ops_yaml_path: Path to a custom_ops.yaml file to parse. If
+            the path does not exist in the filesystem, it is ignored.
+        selector: For selective build.
+        use_aten_lib: We use this flag to determine if we want to generate native
+            functions. In ATen mode we should generate out= variants.
+    Returns:
+        A tuple with two elements:
+        [0]: The parsed results of concatenating the contents of
+             `native_yaml_path` and `custom_ops_yaml_path`.
+        [1]: The parsed results of the contents of `custom_ops_yaml_path`, if
+             present. If not present, None.
+    """
+    import tempfile
+
+    # only include selected ops, this is because we want to avoid
+    def function_filter(f: NativeFunction) -> bool:
+        return selector.is_native_function_selected(f)
+
+    with tempfile.TemporaryDirectory() as tmpdirname:
+        translated_yaml_path = os.path.join(tmpdirname, "translated.yaml")
+        with open(translated_yaml_path, "w") as translated:
+            translate_native_yaml(
+                tags_yaml_path,
+                aten_yaml_path,
+                native_yaml_path,
+                use_aten_lib,
+                translated,
+            )
+
+        translated_functions, translated_indices = parse_yaml(
+            translated_yaml_path, tags_yaml_path, function_filter, not use_aten_lib
+        )
+        custom_ops_functions, custom_ops_indices = parse_yaml(
+            custom_ops_yaml_path, tags_yaml_path, function_filter, True
+        )
+
+        # Convert BackendIndices to ETKernelIndex
+        if not isinstance(translated_indices, ETKernelIndex):
+            translated_indices = ETKernelIndex.from_backend_indices(translated_indices)
+        if not isinstance(custom_ops_indices, ETKernelIndex):
+            custom_ops_indices = ETKernelIndex.from_backend_indices(custom_ops_indices)
+
+        combined_functions = translated_functions + custom_ops_functions
+        combined_kernel_index = ETKernelIndex.merge_indices(
+            translated_indices, custom_ops_indices
+        )
+        combined_yaml = ETParsedYaml(combined_functions, combined_kernel_index)
+        custom_ops_parsed_yaml = ETParsedYaml(custom_ops_functions, custom_ops_indices)
+
+    return combined_yaml, custom_ops_parsed_yaml
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Generate operator source files")
+    # Although we don't refer to --source-path directly, make_file_manager()
+    # expects it to point to a directory that contains a templates/ subdirectory
+    # containing the file templates.
+    parser.add_argument(
+        "-s",
+        "--source-path",
+        help="path to source directory for kernel templates",
+    )
+    parser.add_argument(
+        "--functions-yaml-path",
+        "--functions_yaml_path",
+        help="path to the functions.yaml file to use. Optional, but at least "
+        "one of --functions-yaml-path and --custom-ops-yaml-path must be "
+        "specified.",
+    )
+    parser.add_argument(
+        "--custom-ops-yaml-path",
+        "--custom_ops_yaml_path",
+        help="path to the custom_ops.yaml file to use. Optional, but at least "
+        "one of --functions-yaml-path and --custom-ops-yaml-path must be "
+        "specified.",
+    )
+    parser.add_argument(
+        "--aten-yaml-path",
+        "--aten_yaml_path",
+        help="path to native_functions.yaml file.",
+    )
+    # Note that make_file_manager() also looks at --install-dir.
+    parser.add_argument(
+        "-d",
+        "--install-dir",
+        "--install_dir",
+        help="output directory",
+        default="build/generated",
+    )
+    parser.add_argument(
+        "-o",
+        "--output-dependencies",
+        help="output a list of dependencies into the given file and exit",
+    )
+    # Although we don't refer to --dry-run directly, make_file_manager() looks
+    # for it.
+    parser.add_argument(
+        "--dry-run",
+        action="store_true",
+        help="run without writing any files (still updates outputs)",
+    )
+    parser.add_argument(
+        "--static-dispatch-backend",
+        "--static_dispatch_backend",
+        nargs="*",
+        help="generate static dispatch code for the specific backend (if set)",
+    )
+    parser.add_argument(
+        "--op-registration-whitelist",
+        "--op_registration_whitelist",
+        nargs="*",
+        help="filter op registrations by the whitelist (if set); "
+        "each item is `namespace`::`operator name` without overload name; "
+        "e.g.: aten::empty aten::conv2d ...",
+    )
+    parser.add_argument(
+        "--op-selection-yaml-path",
+        "--op_selection_yaml_path",
+        help="Provide a path to the operator selection (for custom build) YAML "
+        "that contains the information about the set of selected operators "
+        "and their categories (training, ...). Each operator is either a "
+        "full operator name with overload or just a bare operator name. "
+        "The operator names also contain the namespace prefix (e.g. aten::)",
+    )
+    parser.add_argument(
+        "--tags-path",
+        help="Path to tags.yaml. Required by yaml parsing in codegen system.",
+    )
+    parser.add_argument(
+        "--rocm",
+        action="store_true",
+        help="reinterpret CUDA as ROCm/HIP and adjust filepaths accordingly",
+    )
+    parser.add_argument(
+        "--use-aten-lib",
+        "--use_aten_lib",
+        action="store_true",
+        help="a boolean flag to indicate whether we use ATen kernels or not, in the future this flag will be per "
+        "operator",
+    )
+    parser.add_argument(
+        "--manual_registration",
+        "--manual-registration",
+        action="store_true",
+        help="a boolean flag to indicate whether we want to manually call"
+        "register_kernels() or rely on static init. ",
+    )
+    parser.add_argument(
+        "--generate",
+        type=str,
+        nargs="*",
+        choices=["headers", "sources"],
+        default=["headers", "sources"],
+        help="Generate only a subset of files",
+    )
+    options = parser.parse_args()
+    assert options.tags_path, "tags.yaml is required by codegen yaml parsing."
+
+    selector = get_custom_build_selector(
+        options.op_registration_whitelist,
+        options.op_selection_yaml_path,
+    )
+
+    parsed_yaml, custom_ops_parsed_yaml = parse_yaml_files(
+        aten_yaml_path=options.aten_yaml_path,
+        tags_yaml_path=options.tags_path,
+        native_yaml_path=options.functions_yaml_path,
+        custom_ops_yaml_path=options.custom_ops_yaml_path,
+        selector=selector,
+        use_aten_lib=options.use_aten_lib,
+    )
+    native_functions, kernel_index = (
+        parsed_yaml.native_functions,
+        parsed_yaml.kernel_index,
+    )
+    custom_ops_native_functions = (
+        custom_ops_parsed_yaml.native_functions if custom_ops_parsed_yaml else []
+    )
+
+    cpu_fm = make_file_manager(options=options)
+
+    if "headers" in options.generate:
+        # generate CustomOpsNativeFunctions.h when custom_ops.yaml is present, to match the build system.
+        gen_headers(
+            native_functions=native_functions,
+            gen_custom_ops_header=options.custom_ops_yaml_path,
+            custom_ops_native_functions=custom_ops_native_functions,
+            selector=selector,
+            kernel_index=kernel_index,
+            cpu_fm=cpu_fm,
+            use_aten_lib=options.use_aten_lib,
+        )
+
+    if "sources" in options.generate:
+        gen_unboxing(
+            native_functions=native_functions,
+            cpu_fm=cpu_fm,
+            selector=selector,
+            use_aten_lib=options.use_aten_lib,
+            kernel_index=kernel_index,
+            manual_registration=options.manual_registration,
+        )
+        if custom_ops_native_functions:
+            gen_custom_ops(
+                native_functions=custom_ops_native_functions,
+                selector=selector,
+                kernel_index=kernel_index,
+                cpu_fm=cpu_fm,
+                rocm=options.rocm,
+            )
+
+    if options.output_dependencies:
+        depfile_path = Path(options.output_dependencies).resolve()
+        depfile_name = depfile_path.name
+        depfile_stem = depfile_path.stem
+
+        for fm, prefix in [
+            (cpu_fm, ""),
+        ]:
+            varname = prefix + depfile_stem
+            path = depfile_path.parent / (prefix + depfile_name)
+            fm.write_outputs(varname, str(path))
+
+
+if __name__ == "__main__":
+    main()

vllm/lib/python3.10/site-packages/torchgen/gen_functionalization_type.py

@@ -0,0 +1,882 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Callable, TYPE_CHECKING
+
+from torchgen.api import cpp, dispatcher
+from torchgen.api.translate import translate
+from torchgen.api.types import (
+    BaseCType,
+    Binding,
+    CType,
+    DispatcherSignature,
+    FunctionalizationLambda,
+    iTensorListRefT,
+    NativeSignature,
+    OptionalCType,
+    optionalSymIntArrayRefT,
+    symIntArrayRefT,
+    SymIntT,
+    tensorListT,
+    tensorT,
+    VectorCType,
+    ViewInverseSignature,
+)
+from torchgen.context import (
+    method_with_native_function,
+    native_function_manager,
+    with_native_function,
+    with_native_function_and,
+)
+from torchgen.model import (
+    Argument,
+    BackendIndex,
+    BaseTy,
+    BaseType,
+    FunctionSchema,
+    ListType,
+    NativeFunction,
+    NativeFunctionsGroup,
+    NativeFunctionsViewGroup,
+    Return,
+    SchemaKind,
+    SelfArgument,
+    TensorOptionsArguments,
+)
+from torchgen.native_function_generation import (
+    INPLACE_OPS_THAT_DONT_GET_GROUPED_PROPERLY,
+    MUTABLE_OPS_THAT_CANNOT_GET_AN_OUT_VARIANT,
+    OUT_OPS_THAT_DONT_GET_GROUPED_PROPERLY,
+)
+from torchgen.utils import dataclass_repr
+
+
+if TYPE_CHECKING:
+    from torchgen.selective_build.selector import SelectiveBuilder
+
+
+# Note: [Mutable Ops Not Using Functionalization]
+# Ops in this list currently do not work with functionalization and should be fixed.
+MUTABLE_OPS_NOT_USING_FUNCTIONALIZATION = (
+    OUT_OPS_THAT_DONT_GET_GROUPED_PROPERLY
+    + MUTABLE_OPS_THAT_CANNOT_GET_AN_OUT_VARIANT
+    + INPLACE_OPS_THAT_DONT_GET_GROUPED_PROPERLY
+    + [
+        # It will be BC-breaking, but we should fix their schemas.
+        # should be inplace?
+        "record_stream",
+        # See Note [resize_ in Functionalization]
+        "resize_",
+        "resize_as_",
+        # This function is used as for testing purposes only.
+        "_fill_mem_eff_dropout_mask_",
+    ]
+)
+
+# This file contains codegen that relates to the functionalization pass.
+# It includes:
+# - gen_functionalization_definition
+#     Generates dispatcher kernel definitions for the functionalization pass.
+# - gen_functionalization_registration
+#     Generates dispatcher kernel registrations for the functionalization pass.
+# - gen_functionalization_view_inverse_declaration
+#     Generates a declaration for an "inverse view", for every view op
+#     that is needed in functionalization. We manually implement their definitions.
+# - gen_composite_view_copy_kernel
+#     Generates view_copy() composite kernels for all view_copy operators.
+
+
+# Generates the body of the default composite C++ kernel for a {view}_copy NativeFunction
+# See Note [view_copy NativeFunctions]
+@dataclass(frozen=True)
+class GenCompositeViewCopyKernel:
+    backend_index: BackendIndex
+
+    @method_with_native_function
+    def __call__(self, g: NativeFunctionsViewGroup) -> str | None:
+        if g.view_copy is None:
+            return None
+        elif g.view_copy.func.name.name.base != f"{g.view.func.name.name}_copy":
+            # If the view_copy doesn't match the standard naming scheme of <op>_copy,
+            # assume it already exists and doesn't need to be generated.
+            # Example: slice_inverse() with the copy variant named slice_scatter()
+            # instead of slice_inverse_copy()
+            return None
+
+        metadata = self.backend_index.get_kernel(g.view_copy)
+        assert metadata is not None
+
+        # We can make view_copy work in more cases by using reshape()
+        # when a normal view call would ordinarily fail.
+        # This also makes LTC more efficient, because they don't need to include
+        # clone() calls in their graph (which is normally needed by reshape).
+        if str(g.view_copy.func.name) == "view_copy":
+            assert metadata.kernel == "view_copy_symint"
+            return """\
+at::Tensor view_copy_symint(const at::Tensor & self, at::SymIntArrayRef size) {
+  c10::SymDimVector shape = infer_size_dv(size, self.sym_numel());
+  if (!at::detail::computeStride(self.sym_sizes(), self.sym_strides(), shape).has_value()) {
+    return self.reshape_symint(size);
+  } else {
+    auto output = at::_ops::view::call(self, size);
+    return output.clone(/*memory_format=*/at::MemoryFormat::Contiguous);
+  }
+}
+"""
+        # view_copy is a native signature, since we're generating an at::native:: kernel
+        # Functionalization always operates on symints though
+        view_copy_sig = NativeSignature(
+            g.view_copy.func, symint=metadata.supports_symint()
+        )
+
+        # view is a dispatcher signature, since we're calling into the at::_ops API
+        view_sig = DispatcherSignature(g.view.func)
+
+        view_api_name = g.view.func.name.unambiguous_name()
+        exprs = ", ".join(
+            [e.expr for e in translate(view_copy_sig.arguments(), view_sig.arguments())]
+        )
+
+        # view ops today always return either a Tensor or a list of Tensors
+        assert len(g.view.func.returns) == 1
+        assert g.view.func.returns[0].type == BaseType(
+            BaseTy.Tensor
+        ) or g.view.func.returns[0].type == ListType(BaseType(BaseTy.Tensor), None)
+
+        if g.view.func.returns[0].type == BaseType(BaseTy.Tensor):
+            return_cloned_output = """\
+  return output.clone(/*memory_format=*/at::MemoryFormat::Contiguous);"""
+        else:
+            # If the return type is a list, we need to clone each tensor in the list.
+            return_cloned_output = f"""\
+  {view_copy_sig.returns_type().cpp_type()} out_clone;
+  for (const auto i : c10::irange(output.size())) {{
+    out_clone.push_back(output[i].clone(/*memory_format=*/at::MemoryFormat::Contiguous));
+  }}
+  return out_clone;"""
+
+        # The default generated composite kernel for {view}_copy() operators just clones
+        # the input tensor, and runs the underlying view on the clone.
+        return f"""
+{view_copy_sig.defn(name=metadata.kernel)} {{
+  auto output = at::_ops::{view_api_name}::call({exprs});
+  {return_cloned_output}
+}}
+"""
+
+
+def return_str(rets: tuple[Return, ...], names: list[str]) -> str:
+    assert len(rets) == len(names)
+    if len(rets) == 0:
+        return ""
+    elif len(rets) == 1:
+        return f"return {names[0]};"
+    else:
+        return f"return {dispatcher.returns_type(rets).cpp_type()}({', '.join(names)});"
+
+
+def modifies_arguments(f: NativeFunction) -> bool:
+    return any(
+        a.annotation is not None and a.annotation.is_write
+        for a in f.func.arguments.flat_all
+    )
+
+
+def wrapper_name(func: FunctionSchema) -> str:
+    if func.name.overload_name:
+        return f"{cpp.name(func)}_{func.name.overload_name}"
+    else:
+        return cpp.name(func)
+
+
+def is_tensor_like(a: Argument | TensorOptionsArguments | SelfArgument) -> bool:
+    return isinstance(a, SelfArgument) or (
+        isinstance(a, Argument) and a.type.is_tensor_like()
+    )
+
+
+# We need to wrap / unwrap various arguments from the op in the functionalization kernels.
+# Some op schemas include non-owning types though (like TensorList),
+# and when we unwrap them we expect to get out an owning type!.
+# We also return a lambda that tells you how to conver the non-owning type argument into the owning type.
+def get_owning_type(t: CType) -> tuple[CType, Callable[[str], str]]:
+    if t == BaseCType(tensorListT):
+        return VectorCType(BaseCType(tensorT)), lambda x: f"{x}.vec()"
+    if t == BaseCType(iTensorListRefT):
+        return VectorCType(BaseCType(tensorT)), lambda x: f"{{{x}.begin(), {x}.end()}}"
+    # There are technically other non-owning types out there (like IntArrayRef),
+    # but functionalization only actually cares about the ones involving tensors.
+    return t, lambda x: x
+
+
+# unwraps all tensor-like arguments, returning:
+# (1) a string containing all of the logic that does the unwrapping
+# (2) a context, to be used by translate(), with all of the relevant bindings.
+def unwrap_tensor_args(
+    sig: DispatcherSignature, *, is_view_op: bool
+) -> tuple[str, list[Binding]]:
+    context: list[Binding] = []
+    unwrapped_tensor_args: list[str] = []
+    for arg in sig.arguments():
+        if is_tensor_like(arg.argument):
+            # for tensor inputs, we want to unwrap them before passing them into the redispatch calls.
+            unwrapped_name = f"{arg.name}_"
+            # For most ops, the functionalization needs to sync any pending updates on the input tensors
+            # before calling the operator, since otherwise the operator will act on stale data.
+            # For view ops though, we can continue to defer syncing until the tensor is used by
+            # a non-view operator.
+            maybe_sync_input = (
+                "" if is_view_op else f"at::functionalization::impl::sync({arg.name});"
+            )
+            unwrapped_type, conversion_fn = get_owning_type(
+                arg.nctype.remove_const_ref().type
+            )
+            unwrapped_tensor_args.append(
+                f"""
+      {unwrapped_type.cpp_type()} {unwrapped_name};
+      if (at::functionalization::impl::isFunctionalTensor({arg.name})) {{
+        {maybe_sync_input}
+        {unwrapped_name} = at::functionalization::impl::from_functional_tensor({arg.name});
+      }} else {{
+        {unwrapped_name} = {conversion_fn(arg.name)};
+      }}"""
+            )
+            context.append(arg.with_name(unwrapped_name))
+        else:
+            # for non-tensor inputs, we want to pass them directly into the redispatch calls.
+            context.append(arg)
+    unwrap_tensor_args_str = "\n      ".join(unwrapped_tensor_args)
+    return unwrap_tensor_args_str, context
+
+
+# converts  all tensor-like arguments to meta tensors, which are used to compute stride info. Returns:
+# (1) a string containing all of the logic that does the conversions.
+# (2) a context, to be used by translate(), with all of the relevant bindings.
+def convert_to_meta_tensors(sig: DispatcherSignature) -> tuple[str, list[Binding]]:
+    context: list[Binding] = []
+    unwrapped_tensor_args: list[str] = []
+    for arg in sig.arguments():
+        if is_tensor_like(arg.argument):
+            # for tensor inputs, we want to unwrap them before passing them into the redispatch calls.
+            a_ = arg.name
+            unwrapped_name = f"{arg.name}_meta"
+            unwrapped_tensor_args.append(f"auto {unwrapped_name} = to_meta({a_});")
+            context.append(arg.with_name(unwrapped_name))
+        else:
+            # for non-tensor inputs, we want to pass them directly into the redispatch calls.
+            context.append(arg)
+    unwrap_tensor_args_str = "\n        ".join(unwrapped_tensor_args)
+    return unwrap_tensor_args_str, context
+
+
+# The functionalization codegen currently expects view op schemas to have this form:
+# foo(Tensor(a), ...) -> Tensor(a) (e.g. transpose)
+# foo(Tensor(a!), ...) -> Tensor(a!) (e.g. transpose_)
+def assert_view_op_properties(func: FunctionSchema) -> None:
+    def is_alias(a: Argument) -> bool:
+        return a.annotation is not None
+
+    args = func.arguments.flat_non_out
+    # The first argument is a tensor with an alias semantics (annotations)
+    assert len(args) > 0 and args[0].type == BaseType(
+        BaseTy.Tensor
+    ), f"""In the functionalization codegen, we expect the first argument of every view operator to be a tensor,
+but found an argument of type {str(args[0].type)} for operator: {str(func.name)}."""
+    # No other arguments have aliasing semantics
+    assert is_alias(args[0]) and not any(
+        is_alias(a) for a in args[1:]
+    ), """In the functionalization codegen, we expect the first argument of every view operator to alias the output.
+View operators with multiple aliasing inputs aren't supported yet. Found an operator that doesn't satisfy this constraint"""
+
+
+# One-liner expression for checking if an expression expr of type type has any
+# symbolic values.
+def emit_expr_has_symbolic_values(expr: str, type: CType) -> str:
+    if type == BaseCType(SymIntT):
+        return f"{expr}.is_symbolic()"
+
+    if isinstance(type, OptionalCType):
+        innerexpr = f"(*{expr})"
+        return f"{expr}.has_value() ? {emit_expr_has_symbolic_values(innerexpr, type.elem)} : false"
+
+    if type == BaseCType(optionalSymIntArrayRefT):
+        return emit_expr_has_symbolic_values(
+            expr, OptionalCType(BaseCType(symIntArrayRefT))
+        )
+
+    if type in (BaseCType(symIntArrayRefT), VectorCType(BaseCType(SymIntT))):
+        argname = "arg"
+        lambda_check = emit_expr_has_symbolic_values(argname, BaseCType(SymIntT))
+        return (
+            "std::any_of("
+            f"{expr}.begin(), {expr}.end(), "
+            f"[=](auto& {argname}) {{ return {lambda_check}; }})"
+        )
+
+    raise ValueError(
+        "unsupported type for has_symbolic_values check. "
+        "It should be a SymInt or a collection of those. "
+        f"Got: {type.cpp_type()}"
+    )
+
+
+# Detects whether any of the SymInt arguments are, in fact, symbolic values.
+# This is used in the constructor of ViewMeta.
+def emit_has_symbolic_inputs(sig: DispatcherSignature) -> tuple[str, str]:
+    name = "has_symbolic_inputs"
+    statements = [
+        f"{name} = {name} | ({emit_expr_has_symbolic_values(binding.name, binding.nctype.type)});"
+        for binding in sig.arguments()
+        if (
+            isinstance(binding.argument, Argument)
+            and binding.argument.type.is_symint_like()
+        )
+    ]
+    body = "\n      ".join(statements)
+    return (
+        name,
+        f"""
+      bool {name} = false;
+      {body}""",
+    )
+
+
+# Generates the Functionalization kernel for:
+# - ops that create aliases (e.g. transpose())
+# - ops that are views AND mutations (e.g. transpose_())
+def emit_view_functionalization_body(
+    g: NativeFunctionsViewGroup, *, view_inplace: bool
+) -> str:
+    if view_inplace:
+        # This op is both an inplace op AND a view op.
+        # See Note [Functionalization Pass - Inplace View Ops] for details.
+        # I currently have the view meta call into the out-of-place variant of the view, to avoid
+        # having to define an extra ~20 inplace {view}_inverse_ functions.
+        # Most view ops don't have NativeFunctionGroup's both, because we don't define out= variants for view ops.
+        # I'm assuming that every inplace-view op has a corresponding out-of-place view op,
+        # with the same name but the trailing underscore removed.
+        # This is currently asserted at parse time in gen.py (see error_check_native_functions).
+        assert g.view_inplace is not None
+        f = g.view_inplace
+    else:
+        f = g.view
+
+    assert g.view_copy is not None
+    with native_function_manager(f):
+        call_sig = DispatcherSignature.from_schema(g.view_copy.func)
+
+        # the "view_copy" op name that the functionalization kernels need to call
+        api_name = g.view_copy.func.name.unambiguous_name()
+        # Sometimes the functionalization pass needs to no-op (e.g. if it was passed non-functional tensors)
+        # "no-op"ing in this context is just redispatching to the original op.
+        noop_api_name = f.func.name.unambiguous_name()
+
+        dispatcher_sig = DispatcherSignature.from_schema(f.func)
+        assert_view_op_properties(f.func)
+        view_tensor_name = dispatcher_sig.arguments()[0].name
+
+        return_type = dispatcher_sig.returns_type().remove_const_ref().cpp_type()
+
+        unwrap_tensor_args_str, unwrapped_args_ctx = unwrap_tensor_args(
+            dispatcher_sig, is_view_op=True
+        )
+        view_redispatch_args = [
+            e.expr
+            for e in translate(unwrapped_args_ctx, call_sig.arguments(), method=False)
+        ]
+
+        forward_lambda = FunctionalizationLambda.from_func(g, is_reverse=False)
+        reverse_lambda = FunctionalizationLambda.from_func(g, is_reverse=True)
+
+        # The meta API call should use the same arguments, but convert all tensors to meta tensors first.
+        meta_conversion_str, meta_call_ctx = convert_to_meta_tensors(dispatcher_sig)
+        meta_call_args = [
+            e.expr for e in translate(meta_call_ctx, call_sig.arguments(), method=False)
+        ]
+
+        (
+            symbolic_inputs_varname,
+            symbolic_inputs_check,
+        ) = emit_has_symbolic_inputs(call_sig)
+
+        if "inplace_view" in f.tags:
+            # See Note [Functionalization Pass - Inplace View Ops] for more details
+            return f"""
+    {dispatcher_sig.defn(name=wrapper_name(f.func), is_redispatching_fn=True)} {{
+      if (!at::functionalization::impl::isFunctionalTensor({view_tensor_name})) {{
+        // functionalization is re-entrant, but will no-op if it wasn't passed a FunctionalTensorWrapper.
+        {unwrap_tensor_args_str}
+        at::AutoDispatchSkipFunctionalize guard;
+        return at::_ops::{noop_api_name}::call({', '.join(view_redispatch_args)});
+      }}
+      auto reapply_views = at::functionalization::impl::getFunctionalizationReapplyViewsTLS();
+      auto inverse_return_mode = (
+          reapply_views ? at::functionalization::InverseReturnMode::ViewOrScatterInverse
+            : at::functionalization::InverseReturnMode::NeverView
+      );
+      {symbolic_inputs_check}
+      at::functionalization::ViewMeta view_meta = at::functionalization::ViewMeta(
+        {forward_lambda.decl()} {{
+          if (reapply_views) {{
+            return {forward_lambda.inner_call(reapply_views=True)}
+          }} else {{
+            return {forward_lambda.inner_call(reapply_views=False)}
+          }}
+        }},
+        {reverse_lambda.decl()} {{
+          return {reverse_lambda.inner_call()}
+        }},
+        /*has_symbolic_inputs=*/{symbolic_inputs_varname}
+      );
+      auto compute_reference_meta =
+        {view_tensor_name}.key_set().has_backend(c10::BackendComponent::XLABit) ||
+        {view_tensor_name}.key_set().has_backend(c10::BackendComponent::LazyBit);
+      {return_type} reference_tensor_output;
+      if (compute_reference_meta) {{
+        {meta_conversion_str}
+        at::AutoDispatchSkipFunctionalize func_guard;
+        c10::impl::ExcludeDispatchKeyGuard guard(exclude_keys_for_meta_dispatch);
+        reference_tensor_output = at::_ops::{noop_api_name}::call({', '.join(meta_call_args)});
+      }}
+      // This function adds the above view meta to the current tensor and replays them off the base,
+      // mutating the size/stride info of the current FunctionalTensorWrapper.
+      // Because of this, we need to make sure to run the reference shape function above,
+      // BEFORE doing this (otherwise we'll end up runnin the reference function using the wrong sizes/strides)
+      at::functionalization::impl::mutate_view_meta({view_tensor_name}, view_meta);
+      // See  Note [Propagating strides in the functionalization pass]
+      // XLA/LTC don't implement the logic to propagate strides correctly, so we need to rely
+      // on a reference implementation here (instead of relying on the output from the forward lambda
+      // having the correct stride info)
+      if (compute_reference_meta) {{
+        at::functionalization::impl::set_sizes_strides_offset({view_tensor_name}, reference_tensor_output);
+      }}
+      return {view_tensor_name};
+    }}
+"""
+
+        else:
+            is_multi_output_view = isinstance(f.func.returns[0].type, ListType)
+            return f"""
+    {dispatcher_sig.defn(name=wrapper_name(f.func), is_redispatching_fn=True)} {{
+      {unwrap_tensor_args_str}
+      if (!at::functionalization::impl::isFunctionalTensor({view_tensor_name})) {{
+        // functionalization is re-entrant, but will no-op if it wasn't passed a FunctionalTensorWrapper.
+        at::AutoDispatchSkipFunctionalize guard;
+        return at::_ops::{noop_api_name}::call({', '.join(view_redispatch_args)});
+      }}
+      auto reapply_views = at::functionalization::impl::getFunctionalizationReapplyViewsTLS();
+      auto inverse_return_mode = (
+          reapply_views ? at::functionalization::InverseReturnMode::ViewOrScatterInverse
+            : at::functionalization::InverseReturnMode::NeverView
+      );
+      auto compute_reference_meta =
+        {view_tensor_name}.key_set().has_backend(c10::BackendComponent::XLABit) ||
+        {view_tensor_name}.key_set().has_backend(c10::BackendComponent::LazyBit);
+      {return_type} reference_tensor_output;
+      if (compute_reference_meta) {{
+        {meta_conversion_str}
+        at::AutoDispatchSkipFunctionalize func_guard;
+        c10::impl::ExcludeDispatchKeyGuard guard(exclude_keys_for_meta_dispatch);
+        reference_tensor_output = at::_ops::{noop_api_name}::call({', '.join(meta_call_args)});
+      }}
+      {return_type} tmp_output;
+      {{
+        at::AutoDispatchSkipFunctionalize guard;
+        if (reapply_views) {{
+          tmp_output = at::_ops::{noop_api_name}::call({', '.join(view_redispatch_args)});
+        }} else {{
+          tmp_output = at::_ops::{api_name}::call({', '.join(view_redispatch_args)});
+        }}
+      }}
+      {symbolic_inputs_check}
+      at::functionalization::ViewMeta view_meta = at::functionalization::ViewMeta(
+        {forward_lambda.decl()} {{
+          if (reapply_views) {{
+            return {forward_lambda.inner_call(reapply_views=True)}
+          }} else {{
+            return {forward_lambda.inner_call(reapply_views=False)}
+          }}
+        }},
+        {reverse_lambda.decl()} {{
+          return {reverse_lambda.inner_call()}
+        }},
+        /*has_symbolic_inputs=*/{symbolic_inputs_varname},
+        /*is_multi_output=*/{str(is_multi_output_view).lower()},
+        /*is_as_strided=*/{str(str(f.func.name) == 'as_strided').lower()}
+      );
+      auto out = at::functionalization::impl::create_functional_tensor_with_view_meta(tmp_output, {view_tensor_name}, view_meta);
+      // See  Note [Propagating strides in the functionalization pass]
+      if (compute_reference_meta) {{
+        at::functionalization::impl::set_sizes_strides_offset(out, reference_tensor_output);
+      }}
+      return out;
+    }}
+"""
+
+
+def maybe_create_output(f: NativeFunction, var_name: str) -> str:
+    if len(f.func.returns) == 0:
+        return ""
+    return_type = dispatcher.returns_type(f.func.returns).remove_const_ref().cpp_type()
+    return f"{return_type} {var_name} = "
+
+
+# Given a NativeFunction, and a variable name corresponding to the output of redispatching on the function,
+# this returns two lists of names, consisting of:
+# - the names of returns corresponding to the original (mutable) inputs of the outer function
+# - the names of returns corresponding to the (immutable) outputs of the inner redispatched function
+def get_mutable_redispatch_return_names(
+    f: NativeFunction, inner_return_var: str
+) -> tuple[list[str], list[str]]:
+    aliased_returns = []
+    non_aliased_returns = []
+    for i, name in enumerate(f.func.aliased_return_names()):
+        if name is not None:
+            aliased_returns.append(name)
+        else:
+            non_aliased_returns.append(
+                inner_return_var
+                if len(f.func.returns) == 1
+                else f"std::get<{i}>({inner_return_var})"
+            )
+    return aliased_returns, non_aliased_returns
+
+
+# When functionalization "no-op's" and redispatches on a mutable operator, we need to take care so that:
+#  - For fresh outputs, we return the result of the redispatch (without wrapping outputs)
+#  - For outputs that were aliased to inputs, we return the inputs directly (since some of them might have been wrapped)
+def return_from_mutable_noop_redispatch(
+    f: NativeFunction, inner_return_var: str
+) -> str:
+    aliased, non_aliased = get_mutable_redispatch_return_names(f, inner_return_var)
+    # Just get all of the return names, and immediately return them
+    return return_str(f.func.returns, aliased + non_aliased)
+
+
+def wrap_propagate_mutations_and_return(
+    f: NativeFunction, functional_op: NativeFunction, inner_return_var: str
+) -> str:
+    mutable_arg_names = f.func.arguments.mutable_arg_names()
+    (
+        aliased_outer_rets,
+        non_aliased_outer_rets,
+    ) = get_mutable_redispatch_return_names(f, inner_return_var)
+    _, non_aliased_inner_rets = get_mutable_redispatch_return_names(
+        functional_op, inner_return_var
+    )
+    # The outer function may have a mix of aliased and non-aliased outputs,
+    # But the inner functional op that we're transforming to should only have non-aliased outputs
+    assert len(mutable_arg_names) + len(non_aliased_outer_rets) == len(
+        non_aliased_inner_rets
+    )
+
+    # First, take all of the newly created outputs from the inner call and wrap them into functional tensors
+    updates = []
+    non_aliased_wrapped_ret_names = []
+    for i, inner_ret in enumerate(
+        non_aliased_inner_rets[: len(non_aliased_outer_rets)]
+    ):
+        ret_name = f"output_{i}"
+        updates.append(
+            f"""\
+  auto output_{i} = at::functionalization::impl::to_functional_tensor({inner_ret});"""
+        )
+        non_aliased_wrapped_ret_names.append(ret_name)
+
+    # Next, take all of the mutated outputs from the inner call corresponding to mutated inputs,
+    # and propagate the mutations
+    for outer_arg, inner_ret in zip(
+        mutable_arg_names, non_aliased_inner_rets[len(non_aliased_outer_rets) :]
+    ):
+        updates.append(
+            f"""\
+  auto {outer_arg}_inner = at::functionalization::impl::from_functional_tensor({outer_arg});
+  at::functionalization::impl::replace_({outer_arg}, {inner_ret});
+  at::functionalization::impl::commit_update({outer_arg});
+  at::functionalization::impl::sync({outer_arg});
+  auto {outer_arg}_inner_updated = at::functionalization::impl::from_functional_tensor({outer_arg});
+  at::functionalization::impl::propagate_xla_data_direct({outer_arg}_inner, {outer_arg}_inner_updated);"""
+        )
+
+    # Finally, we return:
+    # - Any mutable arguments that also returns
+    # - Any immutable returns that were created wrapping the output from the inner call
+    returns_str = return_str(
+        f.func.returns, aliased_outer_rets + non_aliased_wrapped_ret_names
+    )
+    updates_str = "\n".join(updates)
+    return f"""\
+{updates_str}
+    {returns_str}"""
+
+
+# Generates the Functionalization kernel for:
+# - mutation ops (inplace and out= ops)
+@with_native_function_and
+def emit_inplace_functionalization_body(
+    f: NativeFunction, g: NativeFunctionsGroup
+) -> str:
+    # mutation case
+    assert modifies_arguments(f)
+
+    dispatcher_sig = DispatcherSignature.from_schema(f.func)
+
+    unwrap_tensor_args_str, unwrapped_args_ctx = unwrap_tensor_args(
+        dispatcher_sig, is_view_op=False
+    )
+
+    mutated_names = [
+        a.name
+        for a in f.func.arguments.flat_all
+        if a.type.is_tensor_like() and a.annotation is not None
+    ]
+    non_mutated_names = [
+        a.name
+        for a in f.func.arguments.flat_all
+        if a.type.is_tensor_like() and a.annotation is None
+    ]
+    non_mutated_tensor_names = [
+        a.name
+        for a in f.func.arguments.flat_all
+        if a.type == BaseType(BaseTy.Tensor) and a.annotation is None
+    ]
+    # all mutable inputs must be functional tensors in order to participate in functionalization
+    check_all_mutated_args_are_functional = " && ".join(
+        ["true"]
+        + [
+            f"at::functionalization::impl::isFunctionalTensor({a})"
+            for a in mutated_names
+        ]
+    )
+    check_any_non_mutated_args_are_functional = " || ".join(
+        ["false"]
+        + [
+            f"at::functionalization::impl::isFunctionalTensor({a})"
+            for a in non_mutated_names
+        ]
+    )
+
+    check_any_non_mutated_tensors_are_xla = " || ".join(
+        ["false"]
+        + [
+            f"{a}.device().type() == c10::DeviceType::XLA"
+            for a in non_mutated_tensor_names
+        ]
+    )
+    # These are used in the cases where we don't functionalize and redispatch to the inplace op
+    # case 1: we hit an inplace op that doesn't have an out-of-place equivalent
+    # case 2: we hit an inplace ops but our inputs are not functional tensors (in which case our kernel just no-ops)
+    inplace_exprs = [
+        e.expr
+        for e in translate(unwrapped_args_ctx, dispatcher_sig.arguments(), method=False)
+    ]
+
+    # call the out-of-place variant of the op
+    return_type = (
+        dispatcher.returns_type(g.functional.func.returns).remove_const_ref().cpp_type()
+    )
+    functional_sig = DispatcherSignature.from_schema(g.functional.func)
+    functional_exprs = [
+        e.expr
+        for e in translate(unwrapped_args_ctx, functional_sig.arguments(), method=False)
+    ]
+
+    if f.func.is_out_fn():
+        mutable_input_post_processing = "\n".join(
+            [
+                f"""
+      at::functionalization::impl::replace_(
+        {a.name}, {'std::get<' + str(i) + '>(tmp_output)' if len(f.func.returns) > 1 else 'tmp_output'});
+      at::functionalization::impl::commit_update({a.name});"""
+                for (i, a) in enumerate(f.func.arguments.out)
+                if a.annotation and a.annotation.is_write and a.type.is_tensor_like()
+            ]
+        )
+    else:
+        mutable_input_post_processing = "\n".join(
+            [
+                f"""
+      at::functionalization::impl::replace_({a.name}, tmp_output);
+      at::functionalization::impl::commit_update({a.name});"""
+                for a in f.func.arguments.flat_all
+                if a.annotation and a.annotation.is_write and a.type.is_tensor_like()
+            ]
+        )
+
+    meta_conversion_str, meta_call_ctx = convert_to_meta_tensors(dispatcher_sig)
+    # We don't want to run the inplace meta func for ops like .set_(), because:
+    # (1) they're unnecessary: inplace meta checks are only useful for ops like add_(),
+    #     where broadcasting will work for the out-of-place case but should fail on the inplace call
+    # (2) They'll also fail without adding extra infra: we'd need to convert the input storage argument
+    #     into a meta storage
+    any_storage_args = any(
+        a.type == BaseType(BaseTy.Storage) for a in f.func.arguments.flat_all
+    )
+
+    return f"""
+    {dispatcher_sig.defn(name=wrapper_name(f.func), is_redispatching_fn=True)} {{
+      if ({str(not any_storage_args and f.func.kind() == SchemaKind.inplace).lower()}) {{
+        // Before converting the mutable op to its functional variant, run meta tensors through the original op.
+        // This will help us catch shape errors that apply to inplace ops that wouldn't apply to their functional variants.
+        // (We can only do this for inplace ops today though, because they technically all support meta tensors).
+        {meta_conversion_str}
+        at::AutoDispatchSkipFunctionalize func_guard;
+        c10::impl::ExcludeDispatchKeyGuard guard(exclude_keys_for_meta_dispatch);
+        at::_ops::{f.func.name.unambiguous_name()}::call({', '.join(a.name for a in meta_call_ctx)});
+      }}
+      {unwrap_tensor_args_str}
+      if (!({check_all_mutated_args_are_functional})) {{
+        // We want to disable this check if there are any XLA tensors.
+        // cpu_tensor.copy_(xla_tensor) is valid code.
+        if (!({check_any_non_mutated_tensors_are_xla}) && ({check_any_non_mutated_args_are_functional})) {{
+         // case 1: trying to mutate a non functional tensor with a functional tensor is an error
+         TORCH_INTERNAL_ASSERT(false,
+           "mutating a non-functional tensor with a functional tensor is not allowed.",
+           " Please ensure that all of your inputs are wrapped inside of a functionalize() call.");
+        }} else {{
+         // case 2: arguments are not functional tensors, so we no-op and redispatch.
+         at::AutoDispatchSkipFunctionalize guard;
+         {maybe_create_output(f, 'tmp_output')}at::_ops::{f.func.name.unambiguous_name()}::call({', '.join(inplace_exprs)});
+         {return_from_mutable_noop_redispatch(f, 'tmp_output')}
+        }}
+      }} else {{
+        {return_type} tmp_output;
+        {{
+          at::AutoDispatchSkipFunctionalize guard;
+          tmp_output = at::_ops::{g.functional.func.name.unambiguous_name()}::call({', '.join(functional_exprs)});
+        }}
+        {wrap_propagate_mutations_and_return(f, g.functional, 'tmp_output')}
+      }}
+    }}"""
+
+
+# The below functions generate RegisterFunctionalization.cpp
+# These files provide the kernels that run the functionalization pass, which can be opted into
+# per backend (e.g. XLA or Vulkan), or as a composable transform (functionalize() in functorch).
+
+
+# See Note [Functionalization Pass: View Inverses].
+def gen_functionalization_view_inverse_declaration(
+    selector: SelectiveBuilder, g: NativeFunctionsViewGroup
+) -> str | None:
+    # For every (non-composite) view op, we need a corresponding "inverse view" function.
+    # This generates the declarations so we get a good compiler error when someone adds a new view.
+    @with_native_function
+    def emit_decl_helper(g: NativeFunctionsViewGroup) -> str | None:
+        if g.view.has_composite_implicit_autograd_kernel:
+            return None
+        view_inverse_sig = ViewInverseSignature(g)
+        return view_inverse_sig.decl()
+
+    return emit_decl_helper(g)
+
+
+def gen_functionalization_registration(
+    selector: SelectiveBuilder,
+    g: NativeFunction | NativeFunctionsGroup | NativeFunctionsViewGroup,
+    composite_implicit_autograd_index: BackendIndex,
+) -> list[str]:
+    @with_native_function
+    def emit_registration_helper(f: NativeFunction) -> str:
+        assert not f.has_composite_implicit_autograd_kernel
+        registration_str = f"TORCH_FN(functionalization::{wrapper_name(f.func)})"
+        return f'm.impl("{f.func.name}", {registration_str});'
+
+    # Don't generate kernels in mobile build
+    if not selector.include_all_operators:
+        return []
+
+    if isinstance(g, NativeFunctionsViewGroup):
+        # functionalization needs to register kernels for view + view_inplace ops
+        # See Note [Functionalization <> torch.Tensor constructor]
+        if str(g.view.func.name) == "lift_fresh":
+            return []
+        view_str = []
+        if not g.view.has_composite_implicit_autograd_kernel:
+            view_str.append(emit_registration_helper(g.view))
+        if (
+            g.view_inplace is not None
+            and not g.view_inplace.has_composite_implicit_autograd_kernel
+        ):
+            assert g.view_inplace.is_view_op
+            view_str.append(emit_registration_helper(g.view_inplace))
+        return view_str
+
+    elif isinstance(g, NativeFunctionsGroup):
+        # Gets a hand-written functionalization kernel
+        if g.inplace is not None and str(g.inplace.func.name) == "set_.source_Tensor":
+            fns = []
+        else:
+            fns = list(g.functions())
+    else:
+        if str(g.func.name) in MUTABLE_OPS_NOT_USING_FUNCTIONALIZATION:
+            return []
+        fns = [g]
+
+    registrations = []
+    for f in fns:
+        if f.has_composite_implicit_autograd_kernel:
+            continue
+        if str(f.func.name) == "lift":
+            # See Note [Functionalization <> torch.Tensor constructor]
+            return []
+        if str(f.func.name) == "resize_":
+            # See Note [resize_ in Functionalization]
+            return []
+        if str(f.func.name.name) != "set_":
+            assert not f.is_view_op
+        # functionalization needs to generate and register kernels for inplace ops.
+        # We *also* need to directly register CompositeImplicitAUtograd kernels
+        # so that they decompose properly before functioanlization.
+        if modifies_arguments(f):
+            registrations.append(emit_registration_helper(f))
+    return registrations
+
+
+def gen_functionalization_definition(
+    selector: SelectiveBuilder,
+    # Note: Ideally this code should never have to look at NativeFunction
+    # (and instead only need to operate on grouped NativeFunctions).
+    # The only reason currently is because we need to emit direct dispatch registrations
+    # For CompositeImplicitAutograd operators, which are potentially ungrouped.
+    g: NativeFunction | NativeFunctionsGroup | NativeFunctionsViewGroup,
+) -> list[str]:
+    # Don't generate kernels in mobile build
+    if not selector.include_all_operators:
+        return []
+
+    if isinstance(g, NativeFunctionsViewGroup):
+        # Case 1: emit view -> view_copy kernels for the functionalization pass
+        view_defs = []
+        if not g.composite:
+            # invariant: NativeFunctionsViewGroup's always have a view_copy operator
+            # if the view is not composite (implicit autograd)
+            assert g.view_copy is not None, dataclass_repr(g, indent=1)
+            view_defs.append(emit_view_functionalization_body(g, view_inplace=False))
+            if g.view_inplace is not None:
+                view_defs.append(emit_view_functionalization_body(g, view_inplace=True))
+        return view_defs
+    elif isinstance(g, NativeFunction):
+        # Invariant: all mutable operators that we need to handle in functionalization
+        # should have been properly grouped up.
+        # TODO: The below ops all have "problematic" schemas that prevent them from
+        # getting functionalized. Instead of bending over backwards to get things to work,
+        # I think we should either:
+        # (1) fix their schemas (BC-breaking)
+        # (2) hand-write their functionalization kernels
+        if (
+            str(g.func.name) not in MUTABLE_OPS_NOT_USING_FUNCTIONALIZATION
+            and str(g.func.name.name) not in MUTABLE_OPS_NOT_USING_FUNCTIONALIZATION
+        ):
+            assert g.has_composite_implicit_autograd_kernel or not modifies_arguments(g)
+        return []
+    else:
+        # Case 2: emit inplace -> out-of-place kernels for the functionalization pass
+        mutation_defs = []
+        mutation_defs.append(emit_inplace_functionalization_body(g.out, g))
+        if g.inplace is not None:
+            mutation_defs.append(emit_inplace_functionalization_body(g.inplace, g))
+        if g.mutable is not None:
+            mutation_defs.append(emit_inplace_functionalization_body(g.mutable, g))
+        return mutation_defs
+    return []

vllm/lib/python3.10/site-packages/torchgen/gen_lazy_tensor.py

@@ -0,0 +1,581 @@
+from __future__ import annotations
+
+import argparse
+import os
+from collections import namedtuple
+from pathlib import Path
+from typing import Any, Callable, Iterable, Iterator, Sequence
+
+import yaml
+
+import torchgen.dest as dest
+from torchgen.api.lazy import setValueT
+from torchgen.api.types import BaseCppType
+from torchgen.dest.lazy_ir import GenLazyIR, GenLazyNativeFuncDefinition, GenTSLazyIR
+from torchgen.gen import get_grouped_native_functions, parse_native_yaml
+from torchgen.gen_backend_stubs import (
+    error_on_missing_kernels,
+    gen_dispatcher_registrations,
+    gen_dispatchkey_nativefunc_headers,
+    parse_backend_yaml,
+)
+from torchgen.model import NativeFunction, NativeFunctionsGroup, OperatorName
+from torchgen.selective_build.selector import SelectiveBuilder
+from torchgen.utils import FileManager, NamespaceHelper
+from torchgen.yaml_utils import YamlLoader
+
+
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #
+#
+#                        Lazy Tensor Codegen
+#
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #
+# Overview
+# ~~~~~~~~
+#
+# This codegen script builds on existing data models and helpers used
+# by all ATen backends, and adds new functionality specific to lazy
+# tensor backends.
+#
+# Inputs:
+# - <backend>_native_functions.yaml: controls which operators are
+#   supported by the backend.
+#
+# Outputs:
+# (for all backends)
+# <DispatchKey>Ir.h defines Lazy IR classes to be constructed during tracing
+# - opt-in: also generate 'lowering' methods for the TorchScript backend only
+# <DispatchKey>NativeFunctions.cpp defines implementations of native functions which perform lazy tracing
+# - opt-in: 'full_codegen' section of backend yaml; 'supported' section omits these implementations
+# <DispatchKey>NativeFunctions.h declares implementations of native functions for both 'supported' and 'full_codegen'
+# ops
+#
+# Register<DispatchKey>.cpp registers all op implementations with the dispatcher
+# RegisterAutograd<DispatchKey>.cpp registers all autograd implementations with the dispatcher
+#
+# Validation Helpers:
+# - Shape Inference: errs if any ops in backend yaml require shape inference not provided by meta kernels or
+#   implementations in torch/csrc/lazy/core/shape_inference.*
+# - native function impls: errs if any 'supported' ops do not have an implementation defined in the backend
+#   (non-codegen) implementation file
+#
+#
+# About the Data Model
+# ~~~~~~~~~~~~~~~~~~~~
+#
+# Modeled after ATen codegen, the first step is to parse yaml and build a data model for the operators
+# we care about.  In this case, the <backend>_native_functions yaml defines a subset of the core operators
+# (defined in more detail in the main native_functions.yaml), which will be supported by your backend.
+# Backends can list ops in two categories:
+#  - `supported` ops require hand-implementations but still get codegenned declarations and registrations
+#  - `full_codegen` ops get implementations (and IR classes) generated too
+#
+# Each native function is modeled as an object with a schema, and each schema has objects representing their
+# arguments.  Much of the codegen is manipulation of the arguments and their types.  For example, lazy tensor
+# backends need to transform 'at::Tensor' arguments into 'lazy::Value' objects, as well as replacing reference
+# types (stringref) with actual string objects, and this is done by manipulating the data model objects.
+# - see api/lazy.py for the lazy data model
+#
+# Once the data model is set up, the rest of this script processes a number of templates for output CPP file
+# and fills in the template values using helpers in `dest/lazy_ir.py` and `dest/lazy_ts_lowering.py`.  These
+# helpers mostly iterate over functions and their arguments, outputting different c++ snippets.
+#
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #
+
+
+# Parses the external backend's yaml, and adds a new BackendIndex for the backend's dispatch key.
+# Returns a Tuple of (backend_key, autograd_key, cpp_namespace, updated BackendIndex mapping, full_codegen)
+ParsedExternalYaml = namedtuple(
+    "ParsedExternalYaml",
+    ["backend_key", "autograd_key", "cpp_namespace", "backend_indices", "full_codegen"],
+)
+
+
+def parse_native_functions_keys(
+    backend_yaml_path: str,
+    grouped_native_functions: Sequence[NativeFunction | NativeFunctionsGroup],
+) -> tuple[list[OperatorName], list[Any], list[OperatorName]]:
+    with open(backend_yaml_path) as f:
+        yaml_values = yaml.load(f, Loader=YamlLoader)
+    assert isinstance(yaml_values, dict)
+
+    full_codegen = yaml_values.pop("full_codegen", [])
+    non_native = yaml_values.pop("non_native", [])
+    ir_gen = yaml_values.pop("ir_gen", [])
+    assert isinstance(full_codegen, list)
+    assert isinstance(non_native, list)
+    assert isinstance(ir_gen, list)
+    full_codegen_opnames = [OperatorName.parse(name) for name in full_codegen]
+    ir_gen_opnames = [OperatorName.parse(name) for name in ir_gen]
+    return full_codegen_opnames, non_native, ir_gen_opnames
+
+
+def validate_shape_inference_header(
+    shape_inference_hdr: str, expected_shape_infr_decls: list[str]
+) -> None:
+    try:
+        with open(shape_inference_hdr) as f:
+            shape_infr_decls = f.read()
+            shape_infr_decl_lines = set(shape_infr_decls.split("\n"))
+    except OSError as e:
+        raise AssertionError(
+            f"Unable to read from the specified shape_inference_hdr file: {shape_inference_hdr}"
+        ) from e
+
+    # TODO(whc) add a check for shape inference functions that have meta kernels implement and should be retired.
+
+    missing_decls = [
+        decl for decl in expected_shape_infr_decls if decl not in shape_infr_decl_lines
+    ]
+    if missing_decls:
+        raise Exception(  # noqa: TRY002
+            f"""Missing shape inference function.\n
+Please add declare this function in {shape_inference_hdr}:\n
+and implement it in the corresponding shape_inference.cpp file.\n
+{os.linesep.join(missing_decls)}"""
+        )
+
+
+# Some helper functions for the codegen.
+def get_ltc_helper_fns() -> str:
+    return """\
+at::Tensor to_meta(const at::Tensor& tensor) {
+  // undefined tensors can't be converted to the meta device, since they don't have sizes/strides
+  if (!tensor.defined()) return tensor;
+  auto out = at::native::empty_strided_meta_symint(tensor.sym_sizes(), tensor.sym_strides(), \
+/*dtype=*/std::make_optional(tensor.scalar_type()), /*layout=*/std::make_optional(tensor.layout()), \
+/*device=*/std::make_optional(c10::Device(c10::kMeta)), /*pin_memory=*/std::nullopt);
+  // needs to handle wrapped numbers, so dtype promotion works properly.
+  if (tensor.unsafeGetTensorImpl()->is_wrapped_number()) {
+    out.unsafeGetTensorImpl()->set_wrapped_number(true);
+  }
+  return out;
+}
+std::optional<at::Tensor> to_meta(const std::optional<at::Tensor>& tensor) {
+  if (tensor.has_value()) {
+    return to_meta(*tensor);
+  }
+  return std::nullopt;
+}
+
+std::vector<at::Tensor> to_meta(at::ITensorListRef t_list) {
+  std::vector<at::Tensor> outs;
+  outs.reserve(t_list.size());
+  for (const auto& tensor : t_list) {
+    outs.push_back(to_meta(tensor));
+  }
+  return outs;
+}
+"""
+
+
+class default_args:
+    node_base: str = "Node"
+    node_base_hdr: str | None = None
+    shape_inference_hdr: str = "torch/csrc/lazy/core/shape_inference.h"
+    tensor_class: str = "torch::lazy::LazyTensor"
+    tensor_class_hdr: str = "torch/csrc/lazy/core/tensor.h"
+    lazy_ir_generator: type[GenLazyIR] = GenLazyIR
+    native_func_definition_generator: type[
+        GenLazyNativeFuncDefinition
+    ] = GenLazyNativeFuncDefinition
+    backend_name: str = "TorchScript"
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Generate Lazy Tensor backend files")
+    parser.add_argument(
+        "-s",
+        "--source-yaml",
+        "--source_yaml",
+        help="path to source yaml file containing operator external definitions",
+    )
+    parser.add_argument("-o", "--output-dir", "--output_dir", help="output directory")
+    parser.add_argument(
+        "--dry-run", "--dry_run", type=bool, default=False, help="output directory"
+    )
+    parser.add_argument(
+        "--impl-path",
+        "--impl_path",
+        type=str,
+        default=None,
+        help="path to the source C++ file containing kernel definitions",
+    )
+    parser.add_argument(
+        "--gen-ts-lowerings",
+        "--gen_ts_lowerings",
+        action="store_true",
+        help="Generate TorchScript lowerings in addition to Lazy IR and NativeFunctions",
+    )
+    parser.add_argument(
+        "--node-base",
+        "--node_base",
+        type=str,
+        default=default_args.node_base,
+        help="Name of backend specific custom Lazy IR Node base class",
+    )
+    parser.add_argument(
+        "--node-base-hdr",
+        "--node_base_hdr",
+        type=str,
+        default=default_args.node_base_hdr,
+        help="Path to header file defining custom Lazy IR Node base class",
+    )
+    parser.add_argument(
+        "--shape-inference-hdr",
+        "--shape_inference_hdr",
+        type=str,
+        default=default_args.shape_inference_hdr,
+        help="Path to header file defining custom Lazy shape inference functions",
+    )
+    parser.add_argument(
+        "--tensor-class",
+        "--tensor_class",
+        type=str,
+        default=default_args.tensor_class,
+        help="Name of backend specific custom Lazy Tensor class",
+    )
+    parser.add_argument(
+        "--tensor-class-hdr",
+        "--tensor_class_hdr",
+        type=str,
+        default=default_args.tensor_class_hdr,
+        help="Path to header file defining custom Lazy Tensor class",
+    )
+    parser.add_argument(
+        "--backend-name",
+        "--backend_name",
+        type=str,
+        default=default_args.backend_name,
+        help="Name of the backend to generate",
+    )
+    options = parser.parse_args()
+
+    # Assumes that this file lives at PYTORCH_ROOT/torchgen/gen_backend_stubs.py
+    torch_root = Path(__file__).parent.parent.parent.absolute()
+    aten_path = str(torch_root / "aten" / "src" / "ATen")
+    lazy_ir_generator: type[GenLazyIR] = default_args.lazy_ir_generator
+    if options.gen_ts_lowerings:
+        lazy_ir_generator = GenTSLazyIR
+    native_func_definition_generator: type[
+        GenLazyNativeFuncDefinition
+    ] = default_args.native_func_definition_generator
+
+    run_gen_lazy_tensor(
+        aten_path,
+        options.source_yaml,
+        options.output_dir,
+        options.dry_run,
+        options.impl_path,
+        options.node_base,
+        options.node_base_hdr,
+        options.tensor_class,
+        options.tensor_class_hdr,
+        options.shape_inference_hdr,
+        lazy_ir_generator,
+        native_func_definition_generator,
+        options.backend_name,
+    )
+
+
+def run_gen_lazy_tensor(
+    aten_path: str,
+    source_yaml: str,
+    output_dir: str,
+    dry_run: bool,
+    impl_path: str | None,
+    node_base: str = default_args.node_base,
+    node_base_hdr: str | None = default_args.node_base_hdr,
+    tensor_class: str = default_args.tensor_class,
+    tensor_class_hdr: str = default_args.tensor_class_hdr,
+    shape_inference_hdr: str = default_args.shape_inference_hdr,
+    lazy_ir_generator: type[GenLazyIR] = default_args.lazy_ir_generator,
+    native_func_definition_generator: type[
+        GenLazyNativeFuncDefinition
+    ] = default_args.native_func_definition_generator,
+    # build_in_tree is true for TS backend and affects include paths
+    build_in_tree: bool = False,
+    # per_operator_headers changes whether ATen/Functions.h or individual operator headers are used
+    # it must match how ATen was built
+    per_operator_headers: bool = False,
+    backend_name: str = default_args.backend_name,
+    gen_forced_fallback_code: bool = False,
+    use_lazy_shape: bool = True,
+    # the following arguments are temporary customization points for xla backend migration.
+    # do not rely on them otherwise, they should be removed once migration is complete
+    backend_namespace: str = "torch::lazy",
+    get_tensorlist: str = "GetTensorList",
+    get_tensor_or_wrap_number: str = "GetLtcTensorOrCreateForWrappedNumber",
+    try_get_tensor: str = "TryGetLtcTensor",
+    metrics_counter: str = 'TORCH_LAZY_FN_COUNTER("lazy::")',
+    create_tensor: str = "LazyTensor::Create",
+    create_from_first_tensor: bool = False,
+    create_aten_from_ltc_tensor: str = "torch::lazy::CreateAtenFromLtcTensor",
+    tuple_aten_from_ltc_tensors: str = "torch::lazy::TupleAtenFromLtcTensors",
+    lazy_value_class: str = "torch::lazy::Value",
+    lazy_tensor_ptr: str = "LazyTensorPtr",
+    get_device_fn: str = "torch::lazy::GetBackendDevice",
+) -> None:
+    lv_tokens = lazy_value_class.split("::")
+    lv_class = lv_tokens[-1]
+    lv_ns = "::".join(lv_tokens[:-1])
+    setValueT(BaseCppType(lv_ns, lv_class))
+    template_dir = os.path.join(aten_path, "templates")
+
+    def make_file_manager(install_dir: str) -> FileManager:
+        return FileManager(
+            install_dir=install_dir, template_dir=template_dir, dry_run=dry_run
+        )
+
+    fm = make_file_manager(output_dir)
+
+    native_yaml_path = os.path.join(aten_path, "native/native_functions.yaml")
+    tags_yaml_path = os.path.join(aten_path, "native/tags.yaml")
+    parsed_yaml = parse_native_yaml(native_yaml_path, tags_yaml_path)
+    native_functions, backend_indices = (
+        parsed_yaml.native_functions,
+        parsed_yaml.backend_indices,
+    )
+    grouped_native_functions = get_grouped_native_functions(native_functions)
+
+    def sort_native_function(f: NativeFunctionsGroup | NativeFunction) -> str:
+        """
+        We sort the native function because of the note in concat_map_codegen.
+        TODO(alanwaketan): Remove this sorting hack once all ops are grouped properly.
+        """
+        func = f.functional.func if isinstance(f, NativeFunctionsGroup) else f.func
+        return str(func.name.name)
+
+    grouped_native_functions = sorted(
+        grouped_native_functions, key=sort_native_function
+    )
+
+    parsed_backend_yaml = parse_backend_yaml(
+        source_yaml, grouped_native_functions, backend_indices
+    )
+    backend_key = parsed_backend_yaml.backend_key
+    autograd_key = parsed_backend_yaml.autograd_key
+    cpp_namespace = parsed_backend_yaml.cpp_namespace
+    backend_indices = parsed_backend_yaml.backend_indices
+    # the following 3 keys are all processed differently
+    # for full_codegen, we generate IR, kernels, etc
+    # for ir_gen, we generate only IR
+    # non_native is used to register kernels not declared in
+    # native_functions.yaml
+    full_codegen, non_native, ir_gen = parse_native_functions_keys(
+        source_yaml, grouped_native_functions
+    )
+
+    def concat_map_codegen(
+        func: Callable[[NativeFunction], Sequence[str]],
+        xs: Iterable[NativeFunctionsGroup | NativeFunction],
+        ops_list: list[OperatorName] = full_codegen,
+    ) -> Iterator[str]:
+        """
+        We code-gen for the functional variant, which is all we need for IR classes/lowerings/shape inferences, but we
+        only code-gen additional entries for the inplace variant for the native functions.
+        """
+
+        for x in xs:
+            fs = list(x.functions()) if isinstance(x, NativeFunctionsGroup) else [x]
+            for f in fs:
+                if f.func.name in ops_list:
+                    yield from func(f)
+
+    selector = SelectiveBuilder.get_nop_selector()
+
+    assert backend_key is not None
+    class_name = backend_indices[backend_key].native_function_class_name()
+
+    if impl_path is not None:
+        error_on_missing_kernels(
+            native_functions,
+            backend_indices,
+            backend_key,
+            autograd_key,
+            class_name,
+            impl_path,
+            full_codegen,
+        )
+
+    """ Validate Shape Inference Definitions
+
+    Generated lazy native functions all perform shape inference, by first using a meta:: kernel
+    if available for that op, and otherwise using a 'compute_shape_{op}' function instead.  The generator
+    knows the call signature for compute_shape_{op} because it matches the nativefunction (and meta::) signature,
+    so it just has to check whether the op is structured and generate a call for one or the other.  It's up to the dev
+    to supply the missing compute_shape_{op} function, but the codegen at least warns you about this and provides
+    the expected signature which can be copy-pasted into shape_inference.h.
+
+    compute_shape_{op} functions are handwritten and should be replaced over time as ops get ported
+    to structured kernels.
+
+    See torch/csrc/lazy/core/shape_inference.cpp #READ THIS! for more information.
+    """
+    if shape_inference_hdr is not None:
+        expected_shape_infr_decls = list(
+            concat_map_codegen(
+                dest.GenLazyShapeInferenceDefinition(
+                    backend_indices[backend_key], tensor_class
+                ),
+                grouped_native_functions,
+            )
+        )
+
+        validate_shape_inference_header(shape_inference_hdr, expected_shape_infr_decls)
+    assert class_name is not None
+
+    # Generate nativefunction declarations
+    # Note, eager registrations is set to False for the lazy TS backend as another LTC backend
+    # may want to register their own lazy kernels instead of registering the TS ones.
+    # The registration will lazily happen when init_ts_backend is called.
+    gen_dispatchkey_nativefunc_headers(
+        fm,
+        class_name,
+        cpp_namespace,
+        backend_indices,
+        grouped_native_functions,
+        backend_key,
+        autograd_key,
+        backend_name,
+    )
+
+    # Generate Dispatcher registrations which hook up the nativefunctions
+    for dispatch_key in (
+        [backend_key] if autograd_key is None else [backend_key, autograd_key]
+    ):
+        gen_dispatcher_registrations(
+            fm,
+            output_dir,
+            class_name,
+            backend_indices,
+            grouped_native_functions,
+            backend_key,
+            dispatch_key,
+            selector,
+            build_in_tree=build_in_tree,
+            per_operator_headers=per_operator_headers,
+            backend_name=backend_name,
+            eager_registration=False,
+        )
+
+    # Generate native function impls that build IR nodes
+    ns_helper = NamespaceHelper(cpp_namespace)
+    fm.write_with_template(
+        f"{backend_key}NativeFunctions.cpp",
+        "DispatchKeyNativeFunctions.cpp",
+        lambda: {
+            "includes": [
+                f"#include <{path}>"
+                for path in [
+                    tensor_class_hdr,
+                    shape_inference_hdr,
+                    "ATen/Functions.h",
+                    "ATen/native/TensorConversions.h",
+                    "ATen/NativeFunctions.h",
+                    "ATen/CompositeExplicitAutogradNonFunctionalFunctions.h",
+                    "ATen/MetaFunctions.h",
+                    "ATen/Operators.h",
+                    "ATen/native/CPUFallback.h",
+                    "torch/csrc/lazy/core/ir_builder.h",
+                    "torch/csrc/lazy/core/lazy_graph_executor.h",
+                    "torch/csrc/lazy/core/metrics.h",
+                    "torch/csrc/lazy/core/shape.h",
+                    f"{output_dir}/{backend_key}NativeFunctions.h",
+                    f"{output_dir}/LazyIr.h",
+                ]
+                + (
+                    ["torch/csrc/lazy/ts_backend/ts_eager_fallback.h"]
+                    if gen_forced_fallback_code
+                    else []
+                )
+            ],
+            "helper_fns": get_ltc_helper_fns(),
+            "native_functions_include": "",
+            "namespace_prologue": ns_helper.prologue,
+            "namespace_epilogue": ns_helper.epilogue,
+            "native_function_definitions": list(
+                concat_map_codegen(
+                    native_func_definition_generator(
+                        f"{backend_key}NativeFunctions",
+                        backend_indices[backend_key],
+                        tensor_class,
+                        gen_forced_fallback_code,
+                        backend_namespace,
+                        get_tensorlist,
+                        get_tensor_or_wrap_number,
+                        try_get_tensor,
+                        metrics_counter,
+                        create_tensor,
+                        create_from_first_tensor,
+                        create_aten_from_ltc_tensor,
+                        tuple_aten_from_ltc_tensors,
+                        lazy_tensor_ptr,
+                        get_device_fn,
+                    ),
+                    grouped_native_functions,
+                )
+            ),
+        },
+    )
+    # Generate IR node classes
+    lazy_ir_obj = lazy_ir_generator(
+        backend_indices[backend_key], backend_name, node_base, use_lazy_shape
+    )
+
+    fm.write_with_template(
+        "LazyIr.h",
+        "LazyIr.h",
+        lambda: {
+            "lazy_ir_sysinc": [
+                f"#include <{path}>"
+                for path in [
+                    "ATen/core/Formatting.h",
+                    "c10/core/ScalarType.h",
+                    "torch/csrc/lazy/core/hash.h",
+                    "torch/csrc/lazy/core/ir.h",
+                    "torch/csrc/lazy/core/shape.h",
+                    "optional",
+                    "vector",
+                ]
+            ],
+            "lazy_ir_inc": [f'#include "{node_base_hdr}"']
+            if node_base_hdr is not None
+            else [],
+            "ir_declarations": list(
+                concat_map_codegen(
+                    lazy_ir_obj, grouped_native_functions, full_codegen + ir_gen
+                )
+            ),
+            "namespace_prologue": ns_helper.prologue,
+            "namespace_epilogue": ns_helper.epilogue,
+        },
+    )
+
+    # Generate Non Native IR Node classes
+    fm.write_with_template(
+        "LazyNonNativeIr.h",
+        "LazyNonNativeIr.h",
+        lambda: {
+            "lazy_non_native_ir_inc": [
+                f"#include <{path}>"
+                for path in [
+                    "torch/csrc/lazy/core/ir.h",
+                    "torch/csrc/lazy/core/ir_builder.h",
+                    "torch/csrc/lazy/core/internal_ops/ltc_ops.h",
+                    "torch/csrc/lazy/core/shape_inference.h",
+                ]
+                + ([node_base_hdr] if node_base_hdr else [])
+                if path
+            ],
+            "non_native_ir_nodes": dest.generate_non_native_lazy_ir_nodes(
+                non_native, lazy_ir_obj
+            ),
+            "namespace_prologue": ns_helper.prologue,
+            "namespace_epilogue": ns_helper.epilogue,
+        },
+    )
+
+
+if __name__ == "__main__":
+    main()

vllm/lib/python3.10/site-packages/torchgen/gen_schema_utils.py

@@ -0,0 +1,97 @@
+from typing import Any, Optional, Tuple, Union
+
+from torchgen.model import (
+    Annotation,
+    Argument,
+    Arguments,
+    BaseOperatorName,
+    BaseTy,
+    BaseType,
+    CustomClassType,
+    FunctionSchema,
+    ListType,
+    OperatorName,
+    Return,
+)
+
+
+# Note: These aren't actually used in torchgen, they're some utilities for generating a schema
+# from real arguments. For example, this is used to generate HigherOrderOperators' schema since
+# their schemas can vary for different instances of the same HOP.
+
+
+class TypeGen:
+    convert_to_base_ty = {
+        int: BaseTy.int,
+        float: BaseTy.float,
+        str: BaseTy.str,
+        bool: BaseTy.bool,
+    }
+
+    @staticmethod
+    def from_example(obj: Any) -> Union[BaseType, ListType, CustomClassType]:
+        import torch
+
+        if isinstance(obj, torch.fx.GraphModule):
+            return BaseType(BaseTy.GraphModule)
+        elif isinstance(obj, torch.Tensor):
+            return BaseType(BaseTy.Tensor)
+        elif isinstance(obj, torch.SymInt):
+            return BaseType(BaseTy.SymInt)
+        elif isinstance(obj, torch.SymBool):
+            return BaseType(BaseTy.SymBool)
+        elif isinstance(obj, torch.ScriptObject):
+            return CustomClassType(obj._type().name())  # type: ignore[attr-defined]
+        elif isinstance(obj, (list, tuple)):
+            assert len(obj) > 0
+            all_base_tys = [TypeGen.from_example(x) for x in obj]
+            if len(set(all_base_tys)) > 1:
+                raise RuntimeError(
+                    f"Cannot generate schema for a seqeunce of args of heterogeneous types: {all_base_tys}. "
+                    "Consider unpacking the argument and give proper names to them if possible "
+                    "instead of using *args."
+                )
+            return ListType(all_base_tys[0], len(obj))
+        tp = type(obj)
+        if tp not in TypeGen.convert_to_base_ty:
+            raise RuntimeError(f"unsupported type {tp}")
+        return BaseType(TypeGen.convert_to_base_ty[tp])
+
+
+class ReturnGen:
+    @staticmethod
+    def from_example(
+        name: Optional[str], obj: Any, annotation: Optional[Annotation]
+    ) -> Return:
+        return Return(name, TypeGen.from_example(obj), annotation)
+
+
+class ArgumentGen:
+    @staticmethod
+    def from_example(
+        name: str, obj: Any, default: Optional[str], annotation: Optional[Annotation]
+    ) -> Argument:
+        return Argument(
+            name, TypeGen.from_example(obj), default=default, annotation=annotation
+        )
+
+
+class FunctionSchemaGen:
+    @staticmethod
+    def from_example(
+        op_name: str,
+        example_inputs: Tuple[Tuple[str, Any], ...],
+        example_outputs: Tuple[Any, ...],
+    ) -> FunctionSchema:
+        args = []
+        for name, inp in example_inputs:
+            args.append(ArgumentGen.from_example(name, inp, None, None))
+        # ignore the annotations and other attributes for now, we could add more when needed.
+        arguments = Arguments(
+            tuple(), None, tuple(args), tuple(), None, tuple(), tuple()
+        )
+        returns = tuple(
+            ReturnGen.from_example(None, out, None) for out in example_outputs
+        )
+        op_name = OperatorName(BaseOperatorName(op_name, False, False, False), "")
+        return FunctionSchema(op_name, arguments, returns)

vllm/lib/python3.10/site-packages/torchgen/gen_vmap_plumbing.py

@@ -0,0 +1,271 @@
+from __future__ import annotations
+
+import textwrap
+from dataclasses import dataclass
+from typing import Sequence
+
+from torchgen.api.translate import translate
+from torchgen.api.types import DispatcherSignature
+from torchgen.context import method_with_native_function
+from torchgen.model import (
+    Argument,
+    BaseTy,
+    BaseType,
+    FunctionSchema,
+    ListType,
+    NativeFunction,
+    OptionalType,
+    Return,
+    SchemaKind,
+    Type,
+)
+from torchgen.utils import mapMaybe
+
+
+def is_tensor(typ: Type) -> bool:
+    return isinstance(typ, BaseType) and typ.name == BaseTy.Tensor
+
+
+def is_optional_tensor(typ: Type) -> bool:
+    return isinstance(typ, OptionalType) and is_tensor(typ.elem)
+
+
+def is_tensor_list(typ: Type) -> bool:
+    return isinstance(typ, ListType) and is_tensor(typ.elem)
+
+
+def unwrap_tensor(name: str, cur_level_var: str) -> list[str]:
+    result = f"""\
+    auto [{name}_value, {name}_bdim] = unwrapTensorAtLevel({name}, {cur_level_var});"""
+    return textwrap.dedent(result).split("\n")
+
+
+def unwrap_optional_tensor(name: str, cur_level_var: str) -> list[str]:
+    result = f"""\
+    std::optional<Tensor> {name}_value;
+    std::optional<int64_t> {name}_bdim;
+    if ({name}) {{
+        std::tie({name}_value, {name}_bdim) = unwrapTensorAtLevel({name}.value(), {cur_level_var});
+    }}"""
+    return textwrap.dedent(result).split("\n")
+
+
+def gen_unwraps(
+    flat_arguments: Sequence[Argument], cur_level_var: str
+) -> tuple[str, list[str]]:
+    arg_names = [a.name for a in flat_arguments]
+    arg_types = [a.type for a in flat_arguments]
+
+    tensors = [name for typ, name in zip(arg_types, arg_names) if is_tensor(typ)]
+    optional_tensors = [
+        name for typ, name in zip(arg_types, arg_names) if is_optional_tensor(typ)
+    ]
+
+    unwraps = []
+    for tensor in tensors:
+        unwraps += unwrap_tensor(tensor, cur_level_var)
+
+    for opt_tensor in optional_tensors:
+        unwraps += unwrap_optional_tensor(opt_tensor, cur_level_var)
+    unwrap_code = "\n".join(unwraps)
+
+    unwrapped_arg_list = []
+    for arg in arg_names:
+        if arg in tensors or arg in optional_tensors:
+            unwrapped_arg_list += [f"{arg}_value", f"{arg}_bdim"]
+        else:
+            unwrapped_arg_list.append(arg)
+    return unwrap_code, unwrapped_arg_list
+
+
+def gen_case_where_all_bdims_are_none(
+    outer_sig: DispatcherSignature, schema: FunctionSchema, cur_level_var: str
+) -> str:
+    conditions = []
+    flat_args = schema.arguments.flat_all
+    for arg in flat_args:
+        if not arg.type.is_tensor_like():
+            continue
+        conditions.append(f"!isBatchedAtLevel({arg.name}, {cur_level_var})")
+
+    sig = DispatcherSignature.from_schema(schema)
+    translated_args = ", ".join(
+        e.expr for e in translate(outer_sig.arguments(), sig.arguments())
+    )
+    return f"""\
+if ({' && '.join(conditions)}) {{
+  return at::_ops::{sig.func.name.unambiguous_name()}::call({translated_args});
+}}"""
+
+
+def gen_returns(
+    returns: tuple[Return, ...], cur_level_var: str, results_var: str
+) -> str:
+    idx = 0
+    wrapped_returns = []
+    for ret in returns:
+        if is_tensor(ret.type):
+            wrapped_returns.append(
+                f"makeBatched(std::get<{idx}>({results_var}), std::get<{idx + 1}>({results_var}), {cur_level_var})"
+            )
+            idx += 2
+        elif is_tensor_list(ret.type):
+            wrapped_returns.append(
+                f"makeBatchedVector(std::get<{idx}>({results_var}), std::get<{idx+1}>({results_var}), {cur_level_var})"
+            )
+            idx += 2
+        else:
+            wrapped_returns.append(f"std::get<{idx}>({results_var})")
+            idx += 1
+    if len(wrapped_returns) == 1:
+        result = f"return {wrapped_returns[0]};"
+    else:
+        result = f'return std::make_tuple({", ".join(wrapped_returns)});'
+    return result
+
+
+def accepts_at_least_one_tensor_input(schema: FunctionSchema) -> bool:
+    return any(a.type.is_tensor_like() for a in schema.arguments.flat_all)
+
+
+def is_mutated_arg(argument: Argument) -> bool:
+    return argument.annotation is not None and argument.annotation.is_write
+
+
+def gen_vmap_inplace_plumbing(native_function: NativeFunction) -> str | None:
+    # Assumptions:
+    # - only one argument is being modified in-place
+    # - the argument that is being modified in-place is the first argument
+    # - all returns are either Tensor, tuple of Tensor, or TensorList
+    schema = native_function.func
+    sig = DispatcherSignature.from_schema(schema)
+    returns = schema.returns
+
+    # Check assumptions. If these are invalid we return None
+    # and punt the work to handle them to the future.
+    assert schema.kind() == SchemaKind.inplace
+    if not is_mutated_arg(schema.arguments.flat_all[0]):
+        return None
+    if not len([arg for arg in schema.arguments.flat_all if is_mutated_arg(arg)]) == 1:
+        return None
+
+    # Only support cases where all returns are Tensors or vector<Tensor>
+    if len(returns) == 0:
+        return None
+    if not all(is_tensor(ret.type) or is_tensor_list(ret.type) for ret in returns):
+        return None
+    if not accepts_at_least_one_tensor_input(schema):
+        return None
+
+    cur_level_var = "cur_level"
+
+    unwraps, unwrapped_arg_list = gen_unwraps(schema.arguments.flat_all, cur_level_var)
+    bdims_all_none_case = gen_case_where_all_bdims_are_none(sig, schema, cur_level_var)
+
+    return f"""\
+template <typename batch_rule_t, batch_rule_t batch_rule>
+{sig.decl(name=schema.name.unambiguous_name() + '_generated_plumbing')} {{
+  c10::impl::ExcludeDispatchKeyGuard guard(DispatchKey::FuncTorchBatched);
+  auto maybe_layer = maybeCurrentDynamicLayer();
+  vmap_check_escaped(maybe_layer, "gen_vmap_inplace_plumbing");
+  int64_t {cur_level_var} = maybe_layer->layerId();
+{textwrap.indent(bdims_all_none_case, "  ")}
+{textwrap.indent(unwraps, "  ")}
+  batch_rule({', '.join(unwrapped_arg_list)});
+  return {schema.arguments.flat_all[0].name};
+}}"""
+
+
+def gen_vmap_plumbing_no_returns(native_function: NativeFunction) -> str:
+    schema = native_function.func
+    sig = DispatcherSignature.from_schema(schema)
+    cur_level_var = "cur_level"
+
+    unwraps, unwrapped_arg_list = gen_unwraps(schema.arguments.flat_all, cur_level_var)
+    bdims_all_none_case = gen_case_where_all_bdims_are_none(sig, schema, cur_level_var)
+
+    return f"""\
+template <typename batch_rule_t, batch_rule_t batch_rule>
+{sig.decl(name=schema.name.unambiguous_name() + '_generated_plumbing')} {{
+  c10::impl::ExcludeDispatchKeyGuard guard(DispatchKey::FuncTorchBatched);
+  auto maybe_layer = maybeCurrentDynamicLayer();
+  vmap_check_escaped(maybe_layer, "gen_vmap_plumbing_no_returns");
+  int64_t {cur_level_var} = maybe_layer->layerId();
+{textwrap.indent(bdims_all_none_case, "  ")}
+{textwrap.indent(unwraps, "  ")}
+  batch_rule({', '.join(unwrapped_arg_list)});
+}}"""
+
+
+def gen_vmap_plumbing(native_function: NativeFunction) -> str | None:
+    schema = native_function.func
+    sig = DispatcherSignature.from_schema(schema)
+    returns = schema.returns
+
+    # Only support cases where all returns are Tensors or vector<Tensor>
+    if not accepts_at_least_one_tensor_input(schema):
+        return None
+    if len(returns) == 0:
+        return gen_vmap_plumbing_no_returns(native_function)
+    return_symint_overrides = [
+        "_scaled_dot_product_flash_attention",
+        "_scaled_dot_product_cudnn_attention",
+    ]
+    if (
+        not all(ret.type.is_tensor_like() for ret in returns)
+        and schema.name.unambiguous_name() not in return_symint_overrides
+    ):
+        return None
+    # in-place views need special handling
+    if "inplace_view" in native_function.tags:
+        return None
+
+    if schema.kind() == SchemaKind.inplace:
+        return gen_vmap_inplace_plumbing(native_function)
+
+    # Don't support these (mutable, out, scratch)
+    if schema.kind() != SchemaKind.functional:
+        return None
+
+    results_var = "results"
+    cur_level_var = "cur_level"
+
+    unwraps, unwrapped_arg_list = gen_unwraps(schema.arguments.flat_all, cur_level_var)
+    bdims_all_none_case = gen_case_where_all_bdims_are_none(sig, schema, cur_level_var)
+
+    wrapped_returns = gen_returns(returns, cur_level_var, results_var)
+    return f"""\
+template <typename batch_rule_t, batch_rule_t batch_rule>
+{sig.decl(name=schema.name.unambiguous_name() + '_generated_plumbing')} {{
+  c10::impl::ExcludeDispatchKeyGuard guard(DispatchKey::FuncTorchBatched);
+  auto maybe_layer = maybeCurrentDynamicLayer();
+  vmap_check_escaped(maybe_layer, "gen_vmap_plumbing");
+  int64_t {cur_level_var} = maybe_layer->layerId();
+{textwrap.indent(bdims_all_none_case, "  ")}
+{textwrap.indent(unwraps, "  ")}
+  auto {results_var} = batch_rule({', '.join(unwrapped_arg_list)});
+  {wrapped_returns}
+}}"""
+
+
+@dataclass(frozen=True)
+class ComputeBatchRulePlumbing:
+    @method_with_native_function
+    def __call__(self, f: NativeFunction) -> str | None:
+        result = gen_vmap_plumbing(f)
+        return result
+
+
+def gen_all_vmap_plumbing(native_functions: Sequence[NativeFunction]) -> str:
+    body = "\n".join(list(mapMaybe(ComputeBatchRulePlumbing(), native_functions)))
+    return f"""
+#pragma once
+#include <ATen/Operators.h>
+#include <ATen/functorch/PlumbingHelper.h>
+
+namespace at {{ namespace functorch {{
+
+{body}
+
+}}}} // namespace at::functorch
+"""

vllm/lib/python3.10/site-packages/torchgen/local.py

@@ -0,0 +1,59 @@
+from __future__ import annotations
+
+import threading
+from contextlib import contextmanager
+from typing import Iterator
+
+
+# Simple dynamic scoping implementation.  The name "parametrize" comes
+# from Racket.
+#
+# WARNING WARNING: LOOKING TO EDIT THIS FILE?  Think carefully about
+# why you need to add a toggle to the global behavior of code
+# generation.  The parameters here should really only be used
+# for "temporary" situations, where we need to temporarily change
+# the codegen in some cases because we cannot conveniently update
+# all call sites, and are slated to be eliminated once all call
+# sites are eliminated.  If you don't have a plan for how to get there,
+# DON'T add a new entry here.
+
+
+class Locals(threading.local):
+    use_const_ref_for_mutable_tensors: bool | None = None
+    use_ilistref_for_tensor_lists: bool | None = None
+
+
+_locals = Locals()
+
+
+def use_const_ref_for_mutable_tensors() -> bool:
+    assert _locals.use_const_ref_for_mutable_tensors is not None, (
+        "need to initialize local.use_const_ref_for_mutable_tensors with "
+        "local.parametrize"
+    )
+    return _locals.use_const_ref_for_mutable_tensors
+
+
+def use_ilistref_for_tensor_lists() -> bool:
+    assert _locals.use_ilistref_for_tensor_lists is not None, (
+        "need to initialize local.use_ilistref_for_tensor_lists with "
+        "local.parametrize"
+    )
+    return _locals.use_ilistref_for_tensor_lists
+
+
+@contextmanager
+def parametrize(
+    *, use_const_ref_for_mutable_tensors: bool, use_ilistref_for_tensor_lists: bool
+) -> Iterator[None]:
+    old_use_const_ref_for_mutable_tensors = _locals.use_const_ref_for_mutable_tensors
+    old_use_ilistref_for_tensor_lists = _locals.use_ilistref_for_tensor_lists
+    try:
+        _locals.use_const_ref_for_mutable_tensors = use_const_ref_for_mutable_tensors
+        _locals.use_ilistref_for_tensor_lists = use_ilistref_for_tensor_lists
+        yield
+    finally:
+        _locals.use_const_ref_for_mutable_tensors = (
+            old_use_const_ref_for_mutable_tensors
+        )
+        _locals.use_ilistref_for_tensor_lists = old_use_ilistref_for_tensor_lists

vllm/lib/python3.10/site-packages/torchgen/native_function_generation.py

@@ -0,0 +1,646 @@
+from __future__ import annotations
+
+from collections import defaultdict
+from typing import Sequence
+
+import torchgen.api.dispatcher as dispatcher
+from torchgen.api.translate import translate
+from torchgen.api.types import Binding, DispatcherSignature, Expr
+from torchgen.context import with_native_function
+from torchgen.model import (
+    Annotation,
+    Argument,
+    BackendIndex,
+    BackendMetadata,
+    BaseOperatorName,
+    BaseTy,
+    BaseType,
+    DEFAULT_KERNEL_NAMESPACE,
+    DeviceCheckType,
+    DispatchKey,
+    FunctionSchema,
+    NativeFunction,
+    NativeFunctionsGroup,
+    OperatorName,
+    Return,
+    SchemaKind,
+    Variant,
+)
+from torchgen.utils import concatMap
+
+
+# See Note: [Out ops with functional variants that don't get grouped properly]
+OUT_OPS_THAT_DONT_GET_GROUPED_PROPERLY = [
+    # This has a functional variant, but it's currently marked private.
+    # This function should be marked private as well (*_backward ops aren't exposed to python anyway).
+    "adaptive_avg_pool3d_backward.grad_input",
+    # There's a functional variant, _slow_conv2d_backward.output_mask, that isn't grouped properly.
+    # Maybe we can kill this operator in favor of convolution_backward?
+    "_slow_conv2d_backward.grad_input",
+]
+
+
+# See Note: [Mutable ops that cannot get an out variant]
+MUTABLE_OPS_THAT_CANNOT_GET_AN_OUT_VARIANT = [
+    # should be out=?
+    "_cummax_helper",
+    # should be out=?
+    "_cummin_helper",
+]
+
+# All of these operators don't have any tensor like returns
+FUNCTIONAL_OPS_THAT_CANNOT_GET_AN_OUT_VARIANT = [
+    "_assert_async",  # no return
+    "_assert_async.msg",  # no return
+    "_cslt_sparse_mm_search",  # returns an int
+    "_assert_scalar",  # no return
+    "_dimI",  # returns an int
+    "_dimV",  # returns an int
+    "_has_same_storage_numel",  # returns a boolean
+    "_linalg_check_errors",  # no return
+    "_local_scalar_dense",  # returns a Scalar
+    "_nested_tensor_from_mask_left_aligned",  # returns a boolean
+    "_nnz",  # returns an int
+    "_use_cudnn_ctc_loss",  # returns a boolean
+    "_use_cudnn_ctc_loss.Tensor",  # returns a boolean
+    "_validate_compressed_sparse_indices",  # no return
+    "allclose",  # returns a boolean
+    "dense_dim",  # returns an int
+    "equal",  # returns a boolean
+    "is_coalesced",  # returns an boolean
+    "is_pinned",  # returns a boolean
+    "is_same_size",  # returns a boolean
+    "is_set_to",  # returns a boolean
+    "q_per_channel_axis",  # returns an int
+    "q_scale",  # returns a float
+    "q_zero_point",  # returns an int
+    "qscheme",  # returns a QScheme
+    "record_stream",  # no return
+    "sparse_dim",  # returns an int
+    "sym_constrain_range",  # no return
+    "sym_constrain_range_for_size",  # no return
+    "_nested_tensor_storage_offsets",  # returns a vector of ints
+    "_chunk_grad_outputs_efficient_attention",  # returns a bool
+    "_fused_sdp_choice",  # returns an int
+    "_print",  # no return
+    "_sink_tokens",  # no return
+    "_nested_get_ragged_idx",  # returns an int
+]
+
+INPLACE_OPS_THAT_DONT_GET_GROUPED_PROPERLY = [
+    # polygamma and polygamma.out both exist, but have a
+    # pre-self arg (while polygamma_ does not)
+    # We should either fix this schema so it can be grouped properly,
+    # or allow the codegen to generate new functional/out= NativeFunctions for this op
+    # (which would require changing its overload name to prevent overload ambiguity).
+    "polygamma_"
+]
+
+
+# Groups "similar" NativeFunctions together
+# example add.Tensor, add_.Tensor, add.out
+# "similar" NativeFunctions are all expected to have an identical `signature()`,
+# But have differing SchemaKinds.
+def pre_group_native_functions(
+    native_functions: Sequence[NativeFunction],
+) -> dict[FunctionSchema, dict[SchemaKind, NativeFunction]]:
+    pre_grouped_native_functions: dict[
+        FunctionSchema, dict[SchemaKind, NativeFunction]
+    ] = defaultdict(dict)
+    for f in native_functions:
+        d = pre_grouped_native_functions[f.func.signature()]
+        assert f.func.kind() not in d
+        d[f.func.kind()] = f
+    return pre_grouped_native_functions
+
+
+# Returns the out variant overload name given a base function overload name
+def get_expected_out_variant_overload_name(overload_name: str | None) -> str:
+    return "out" if not overload_name else f"{overload_name}_out"
+
+
+# Helper function: given an inplace FunctionSchema, generate its corresponding out= variant
+# Example before:
+#   _add_relu_.Scalar(Tensor(a!) self, Scalar other, Scalar alpha=1) -> Tensor(a!)
+# Example after:
+#   _add_relu.Scalar_out(Tensor self, Scalar other, Scalar alpha=1, *, Tensor(a!) out)
+def self_to_out_signature(func: FunctionSchema) -> FunctionSchema:
+    # Generating an out= schema from an inplace schema.
+    assert func.kind() == SchemaKind.inplace
+    assert func.arguments.self_arg is not None
+    # The new out= schema has:
+    # - a new out argument with the same type as "func" (but with a mutable annotation)
+    # - The returns (if any) now alias the out= argument instead of "func"
+    # - an "out" overload name
+    return FunctionSchema(
+        name=func.name.remove_inplace().with_overload(
+            get_expected_out_variant_overload_name(func.name.overload_name)
+        ),
+        arguments=func.arguments.remove_self_annotation().with_out_args(
+            [
+                Argument(
+                    name="out",
+                    type=func.arguments.self_arg.argument.type,
+                    default=None,
+                    annotation=func.arguments.self_arg.argument.annotation,
+                )
+            ]
+        ),
+        returns=func.returns,
+    )
+
+
+# Helper function: given a functional FunctionSchema, generate its corresponding out= variant
+# Example before:
+#   _to_copy(Tensor self, *, ScalarType? dtype=None, Layout? layout=None, Device? device=None,
+#       bool? pin_memory=None, bool non_blocking=False, MemoryFormat? memory_format=None) -> Tensor
+# Example after:
+#   _to_copy._out(Tensor self, *, bool non_blocking=False, MemoryFormat? memory_format=None,
+#       Tensor(a!) out) -> Tensor(a!)
+def functional_to_out_signature(func: FunctionSchema) -> FunctionSchema:
+    # Generating an out= schema from a functional schema.
+    assert func.kind() == SchemaKind.functional
+
+    new_returns, new_out_args = generate_out_args_from_schema(func)
+    # The new out= schema has:
+    # - one or more new out argument(s) with the same type as returns (but with a mutable annotation)
+    # - The returns now alias the out= arguments
+    # - an "_out" overload name
+    return FunctionSchema(
+        name=func.name.with_overload(
+            get_expected_out_variant_overload_name(func.name.overload_name)
+        ),
+        arguments=func.arguments.signature().with_out_args(
+            new_out_args,
+        ),
+        returns=tuple(new_returns),
+    )
+
+
+# Helper function: given a function schema, generate corresponding out arguments, also the updated return annotations.
+def generate_out_args_from_schema(
+    func: FunctionSchema,
+) -> tuple[list[Return], list[Argument]]:
+    # More of a sanity check - our existing restrictions on schemas should enforce that
+    # mutable schema kinds never return their mutable arguments.
+    assert not any(
+        r.annotation is not None and r.annotation.is_write for r in func.returns
+    )
+
+    tensorlike_rets = [r for r in func.returns if r.type.is_tensor_like()]
+    assert len(tensorlike_rets) > 0
+
+    used_annotations = concatMap(
+        lambda a: [] if a.annotation is None else a.annotation.alias_set,
+        func.arguments.flat_all,
+    )
+    valid_annotations = [
+        x for x in "abcdefghijklmnopqrstuvwxyz" if x not in used_annotations
+    ]
+
+    all_rets_are_tensors = all(r.type == BaseType(BaseTy.Tensor) for r in func.returns)
+
+    new_out_args: list[Argument] = []
+    # The end result of new_returns is that:
+    # - If every return is a plain tensor, then the new returns == the old returns, but with the out= alias annotations added.
+    # - Otherwise, none of the out arguments show up in the returns (and we're only left with non-tensor-like returns, if any).
+    new_returns: list[Return] = []
+    for i, r in enumerate(func.returns):
+        if r.type.is_tensor_like():
+            new_out = Argument(
+                name="out" if len(func.returns) == 1 else f"out{i}",
+                type=r.type,
+                default=None,
+                annotation=Annotation.parse(f"{valid_annotations[i]}!"),
+            )
+            new_out_args.append(new_out)
+            if all_rets_are_tensors:
+                # The convention for out= schemas is that they only return their out arguments
+                # if the return is a plain Tensor (or if it's a tuple of plain Tensors)
+                new_ret = Return(
+                    name=None, type=new_out.type, annotation=new_out.annotation
+                )
+                new_returns.append(new_ret)
+        else:
+            new_returns.append(r)
+    return new_returns, new_out_args
+
+
+# Helper function: given a mutable FunctionSchema, generate its corresponding out= variant
+# Example before:
+#   _fused_moving_avg_obs_fq_helper(Tensor self, Tensor observer_on, Tensor fake_quant_on, Tensor(a!) running_min, Tensor(b!) running_max, Tensor(c!) scale, Tensor(d!) zero_point, float averaging_const, int quant_min, int quant_max, int ch_axis, bool per_row_fake_quant=False, bool symmetric_quant=False) -> (Tensor output, Tensor mask)  # noqa: B950
+# Example after:
+#   _fused_moving_avg_obs_fq_helper._out(Tensor self, Tensor observer_on, Tensor fake_quant_on, Tensor(a!) running_min, Tensor(b!) running_max, Tensor(c!) scale, Tensor(d!) zero_point, float averaging_const, int quant_min, int quant_max, int ch_axis, bool per_row_fake_quant=False, bool symmetric_quant=False, *, Tensor(e!) out0, Tensor(f!) out1) -> (Tensor(e!), Tensor(f!))  # noqa: B950
+def mutable_to_out_signature(func: FunctionSchema) -> FunctionSchema:
+    # Generating an out= schema from a mutable schema.
+    assert func.kind() == SchemaKind.mutable
+    # The new out= schema has:
+    # - Any non-aliased tensor-like returns are converted to mutable, aliased out= arguments
+    #   (if the argument is a tensor then we also return it for method chaining,
+    #   otherwise we return nothing)
+    # - an "out" overload name
+    #
+    # Note that:
+    # (1) This also means that we can *only* generate an out= variant from a mutable schema
+    #     if the mutable schema has at least one tensor-like non-aliasing return.
+    # (2) The generated out= variant still has mutable positional arguments,
+    #     but if necessary we could probably add another out= variant that also
+    #     functionalizes the mutable arguments (a functional_out variant)
+
+    new_returns, new_out_args = generate_out_args_from_schema(func)
+
+    return FunctionSchema(
+        name=func.name.remove_inplace().with_overload(
+            get_expected_out_variant_overload_name(func.name.overload_name)
+        ),
+        arguments=func.arguments.with_out_args(new_out_args),
+        returns=tuple(new_returns),
+    )
+
+
+# This function, given function of one SchemaKind, as well as a target SchemaKind,
+# generates a new NativeFunction with the same properties, but using the target SchemaKind.
+# We only actually generate functions for either functional or out= SchemaKinds.
+# This function returns a tuple, with:
+# - The generated NativeFunction
+# - a dictionary of `BackendIndex` objects, describing which dispatch keys
+#   we will generate kernels for, for the new NativeFunction.
+#   Details are in the function, but we only generate composite kernels (in some cases) today.
+def generate_function(
+    f: NativeFunction, k: SchemaKind
+) -> tuple[NativeFunction, dict[DispatchKey, dict[OperatorName, BackendMetadata]]]:
+    from torchgen.api import cpp
+
+    if k == SchemaKind.functional:
+        assert f.func.kind() != SchemaKind.functional
+        # The new "functional" NativeFunction has:
+        # - any mutable arguments have been converted into (immutable) returns.
+        #   (if a mutable argument was not also a return, it gets converted to one)
+        # - "_functional" appended to the base name, ONLY IF this op has a mutable variant.
+        #   See Note [Overload Ambiguity With Functional Variants]
+        # The default grouping logic in signature() actually already does this,
+        # so we can piggy-back off it (but we still want return names)
+        func = f.func.signature(keep_return_names=True).with_name(
+            OperatorName(
+                name=BaseOperatorName(
+                    base=f.func.name.name.base,
+                    inplace=False,
+                    dunder_method=f.func.name.name.dunder_method,
+                    # See Note [Overload Ambiguity With Functional Variants]
+                    functional_overload=f.func.kind() == SchemaKind.mutable,
+                ),
+                overload_name=f.func.name.overload_name,
+            )
+        )
+    elif k == SchemaKind.out:
+        # We generate out= ops mostly just so that we can pair up NativeFunctions into groups easily,
+        # but at least today, there is no good reason to actually use them.
+        # we'll generate a dispatcher entry for them, but won't actually register any kernels for them.
+        if f.func.kind() == SchemaKind.inplace:
+            func = self_to_out_signature(f.func)
+        elif f.func.kind() == SchemaKind.mutable:
+            func = mutable_to_out_signature(f.func)
+        elif f.func.kind() == SchemaKind.functional:
+            func = functional_to_out_signature(f.func)
+        else:
+            raise AssertionError(
+                "We only bother generating out= functions from either inplace or mutable or functional variants"
+            )
+    else:
+        raise AssertionError(
+            "We currently only generate either functional or out= NativeFunctions"
+        )
+
+    # Generated kernel naming convention for out: <op_name>_<overload_name>. The reason for this is to
+    # disambiguate operator with the same name but different overload name, e.g., `randn.names_out` and
+    # `randn.generator_with_names_out`.
+    kernel_name = (
+        func.name.unambiguous_name()
+        if func.kind() == SchemaKind.out
+        else cpp.name(func)
+    )
+    if f.func.has_symint():
+        kernel_name += "_symint"
+    backend_metadata = {
+        DispatchKey.CompositeExplicitAutograd: {
+            func.name: BackendMetadata(
+                kernel=kernel_name,
+                structured=False,
+                cpp_namespace=DEFAULT_KERNEL_NAMESPACE,
+            )
+        }
+    }
+    tags = {"generated"} | set(
+        f.tags & {"nondeterministic_seeded", "view_copy", "pt2_compliant_tag"}
+    )
+
+    return (
+        NativeFunction(
+            func=func,
+            use_const_ref_for_mutable_tensors=f.use_const_ref_for_mutable_tensors,
+            # These generated fn's aren't meant to be user friendly- don't generate methods.
+            variants={Variant.function},
+            structured=False,
+            structured_delegate=None,
+            structured_inherits=None,
+            precomputed=None,
+            autogen=[],
+            ufunc_inner_loop={},
+            manual_kernel_registration=False,
+            manual_cpp_binding=False,
+            python_module=None,
+            category_override=None,
+            device_guard=False,
+            device_check=DeviceCheckType.NoCheck,
+            loc=f.loc,
+            cpp_no_default_args=set(),
+            is_abstract=f.is_abstract,
+            has_composite_implicit_autograd_kernel=False,
+            has_composite_implicit_autograd_nested_tensor_kernel=False,
+            has_composite_explicit_autograd_kernel=True,
+            has_composite_explicit_autograd_non_functional_kernel=False,
+            # Every generated NativeFunction gets a "generated" tag, so it's easy to tell
+            # which NativeFunction objects did not come directly from native_functions.yaml.
+            tags=tags,
+            namespace=f.namespace,
+        ),
+        backend_metadata,
+    )
+
+
+# This function is responsible for adding generated NativeFunctions which don't appear
+# explicitly in the codegen.
+# You can inspect the full list of NativeFunctions yourself with the torchgen package, by running
+# torchgen.parse_native_yaml("aten/src/ATen/native/native_functions.yaml", "aten/src/ATen/native/tags.yaml")
+# (Maybe we should make a friendly API for this)
+#
+# Note: this function *mutates* its two inputs,
+# adding the new NativeFunctions / BackendMetadata to them
+def add_generated_native_functions(
+    rs: list[NativeFunction],
+    indices: dict[DispatchKey, dict[OperatorName, BackendMetadata]],
+) -> None:
+    # The main code for generating new NativeFunctions
+    # First we group of NativeFunctions by schema kind,
+    # then we detect which ones are missing and generate them.
+    pre_grouped_native_functions = pre_group_native_functions(rs)
+    for d in pre_grouped_native_functions.values():
+        has_functional = SchemaKind.functional in d
+        has_inplace = SchemaKind.inplace in d
+        has_mutable = SchemaKind.mutable in d
+        has_out = SchemaKind.out in d
+
+        # We automatically generate a few native functions that don't exist in the yaml, for a few reasons:
+        # (1) If an operator has an inplace/out= variant but no functional variant, we can generate
+        #     a simple functional variant that the functionalization pass can consume.
+        # (2) If an operator has an inplace or functional but no out= variant, we generate an out=
+        #     variant, mostly so we can easily pair up functions into NativeFunctionsGroup,
+        #     while maintaining the constraint that the out= variant is "required".
+        if has_mutable or has_inplace or has_out or has_functional:
+            # Don't bother generating functions trio's for native functions that bypass the dispatcher.
+            are_manual = all(f.manual_cpp_binding for f in d.values())
+            # Don't bother generating functional + out= variants for view operators
+            # set_ is technically an inplace_view, but for now it is treated
+            # as a normal inplace op in the codegen
+            has_view_ops = any(
+                f.is_view_op and str(f.func.name.name) != "set_" for f in d.values()
+            )
+            # Don't generate the other variants for CompositeImplicitAutograd operators.
+            # We could probably do this, but the main benefit of generating the function triplets
+            # is for transforms that need them, and transforms don't need to act directly
+            # on CompositeImplicitAutograd operators (since we let them decompose).
+            are_composite_implicit = all(
+                f.has_composite_implicit_autograd_kernel for f in d.values()
+            )
+            if are_manual or has_view_ops or are_composite_implicit:
+                continue
+            if has_out and len(d.values()) == 1:
+                # Note: [Out ops with functional variants that don't get grouped properly]
+                # In theory we could validly have an out= operator in native_functions.yaml
+                # that has no other variants.
+                # But today, all of the operators where that's the case actually do have
+                # functional variants, that we are just unable to pair up properly.
+                # I think banning this all together is probably safer
+                # (you can always add a functional variant yourself if you want to add a new out= operator).
+                #
+                # We should probably fix the existing cases; this check is to prevent us from adding more over time.
+                if (
+                    str(d[SchemaKind.out].func.name)
+                    not in OUT_OPS_THAT_DONT_GET_GROUPED_PROPERLY
+                ):
+                    raise AssertionError(
+                        f"Found an out= operator that we could not find any other variants of: {str(d[SchemaKind.out].func)}"
+                    )
+                continue
+
+            # Some inplace ops that have problematic schemas (that we should fix), which prevent us
+            # from generating out= and functional variants
+            if (
+                has_inplace
+                and str(d[SchemaKind.inplace].func.name)
+                in INPLACE_OPS_THAT_DONT_GET_GROUPED_PROPERLY
+            ):
+                continue
+
+            base_fn = (
+                d[SchemaKind.inplace]
+                if has_inplace
+                else d[SchemaKind.mutable]
+                if has_mutable
+                else d[SchemaKind.out]
+                if has_out
+                else d[SchemaKind.functional]
+            )
+
+            # Note: [Mutable ops that cannot get an out variant]
+            # We can only generate an out= variant if either:
+            # - the original function has tensor-like returns (since we can convert them to out kwargs)
+            # - or it's inplace (since we can convert `self` to an out kwarg)
+            # There are only two functions that don't fit this criteria today though,
+            # and they both look like they should be fixed to be out= variants,
+            # so if feels safer to ban this schema all-together
+            base_fn_valid = base_fn.func.kind() == SchemaKind.inplace or any(
+                r.type.is_tensor_like() for r in base_fn.func.returns
+            )
+            # Note: [Loosen the assertion that all functional should have out variant]
+            # By design all functional operators should have our variants. The needs_out check
+            # is loosening this requirement, changing it to only generate out variant if there's
+            # an `autogen` block in the native function, in the long run it should be removed.
+            # FIXME: Remove this after figuring out CI job failures related to min, max, mean
+            needs_out = any("out" in str(op_name) for op_name in base_fn.autogen)
+            gets_out_variant = not has_out and base_fn_valid and needs_out
+            if not has_out and not base_fn_valid:
+                if (
+                    str(base_fn.func.name)
+                    not in MUTABLE_OPS_THAT_CANNOT_GET_AN_OUT_VARIANT
+                    and str(base_fn.func.name)
+                    not in FUNCTIONAL_OPS_THAT_CANNOT_GET_AN_OUT_VARIANT
+                ):
+                    raise AssertionError(
+                        f"""Found an operator that we could not generate an out= variant for: {str(base_fn.func)}.
+This type of operators don't have tensor-like return, making it difficult to generate a proper out= variant. If
+out= variant is not needed, please add the function name into FUNCTIONAL_OPS_THAT_CANNOT_GET_AN_OUT_VARIANT list."""
+                    )
+
+            # Generate an out= variant
+            if gets_out_variant:
+                fn, metadata = generate_function(base_fn, SchemaKind.out)
+                d[SchemaKind.out] = fn
+                BackendIndex.grow_index(indices, metadata)
+                rs.append(fn)
+
+            # Generate a functional variant, but only do it if the operator got an out= variant
+            # (Functional variants are only useful if we can group up the variants,
+            # which we can only do if they have an out= variant)
+            if not has_functional and (has_out or gets_out_variant):
+                fn, metadata = generate_function(base_fn, SchemaKind.functional)
+                d[SchemaKind.functional] = fn
+                BackendIndex.grow_index(indices, metadata)
+                rs.append(fn)
+
+
+def return_str(rets: tuple[Return, ...], names: list[str]) -> str:
+    assert len(rets) == len(names)
+    if len(rets) == 0:
+        return ""
+    elif len(rets) == 1:
+        return f"return {names[0]};"
+    else:
+        return f"return {dispatcher.returns_type(rets).cpp_type()}({', '.join(names)});"
+
+
+# Given a function, and the name of a variable corresponding to the output of that function,
+# gather up all of the individual returns that are not aliased
+def gather_nonaliased_inner_rets(func: FunctionSchema, out_var: str) -> list[str]:
+    aliased_rets = func.aliased_return_names()
+    non_aliased_names = []
+    is_out_var_a_tuple = len(func.returns) > 1
+    for i, r in enumerate(aliased_rets):
+        if r is None:
+            non_aliased_names.append(
+                f"std::get<{i}>({out_var})" if is_out_var_a_tuple else out_var
+            )
+    return non_aliased_names
+
+
+# Generates functional kernels in terms of their inplace.mutable counterparts.
+# We only do this for "generated" NativeFunctions
+@with_native_function
+def gen_composite_functional_kernel(g: NativeFunctionsGroup) -> str | None:
+    # We should only be generating these for code-generated NativeFunctions
+    if "generated" not in g.functional.tags:
+        return None
+    # And we always write the kernel for a generated op in terms of a non-generated op.
+    if g.inplace is not None and "generated" not in g.inplace.tags:
+        target_f = g.inplace
+    elif g.mutable is not None and "generated" not in g.mutable.tags:
+        target_f = g.mutable
+    else:
+        # We should be guaranteed to have a valid inplace/mutable variant to call into.
+        # See Note: [Mutable Ops Not Using Functionalization]
+        raise AssertionError(str(g.functional.func))
+
+    sig = DispatcherSignature(g.functional.func)
+    target_sig = DispatcherSignature(target_f.func)
+
+    context: list[Binding | Expr] = []
+    clone_mutable_inputs = []
+    cloned_return_names = []
+    # We can't just directly pass all of the arguments from the functional op into the mutating op.
+    # We need to check for which inputs to the mutating operator are mutable,
+    # and clone those inputs first.
+    for a_curr, a_tgt in zip(
+        dispatcher.jit_arguments(g.functional.func),
+        dispatcher.jit_arguments(target_f.func),
+    ):
+        if a_tgt.annotation is not None and a_tgt.annotation.is_write:
+            clone_mutable_inputs.append(
+                f"auto {a_curr.name}_clone = clone_arg({a_curr.name});"
+            )
+            context.append(
+                Expr(
+                    expr=f"{a_curr.name}_clone",
+                    type=dispatcher.argument_type(a_curr, binds=a_curr.name),
+                )
+            )
+            # Invariant: mutable arguments on the inner mutable op are always returns on the functional op.
+            cloned_return_names.append(f"{a_curr.name}_clone")
+        else:
+            context.append(dispatcher.argument(a_curr))
+    exprs = ", ".join([e.expr for e in translate(context, target_sig.arguments())])
+
+    out_name = "output"
+    maybe_assign = f"auto {out_name} = " if len(target_f.func.returns) > 0 else ""
+    inner_return_names = gather_nonaliased_inner_rets(target_f.func, out_name)
+    ret_str = return_str(
+        g.functional.func.returns, inner_return_names + cloned_return_names
+    )
+
+    clone_mutable_inputs_str = "\n".join(clone_mutable_inputs)
+    return f"""
+{sig.defn(name=sig.name() + ("_symint" if g.out.func.has_symint() else ""))} {{
+  {clone_mutable_inputs_str}
+  {maybe_assign}at::_ops::{target_f.func.name.unambiguous_name()}::call({exprs});
+  {ret_str}
+}}
+"""
+
+
+# Generates out= kernels in terms of their functional counterparts.
+# We only do this for "generated" NativeFunctions
+@with_native_function
+def gen_composite_out_kernel(g: NativeFunctionsGroup) -> str | None:
+    # We should only be generating these for code-generated NativeFunctions
+    if "generated" not in g.out.tags:
+        return None
+    # And we always write the kernel for the out= op in terms of the functional.
+    # Note that the functional op might have also been generated, but we don't have to
+    # worry about cycles, because the generated functional kernels are always implemented
+    # in terms of non-generated kernels (see gen_composite_functional_kernel).
+
+    sig = DispatcherSignature(g.out.func)
+    target_sig = DispatcherSignature(g.functional.func)
+
+    exprs = ", ".join(
+        [e.expr for e in translate(sig.arguments(), target_sig.arguments())]
+    )
+
+    copy_outs = []
+    out_name = "tmp_output"
+    for i, out_arg in enumerate(g.out.func.arguments.out):
+        functional_return_name = (
+            out_name
+            if len(g.functional.func.returns) == 1
+            else f"std::get<{i}>({out_name})"
+        )
+        copy_outs.append(
+            f"""\
+  resize_out_helper({out_arg.name}, {functional_return_name});
+  copy_arg({out_arg.name}, {functional_return_name});"""
+        )
+
+    rets = []
+    # For each return arg in the calling (out=) operator,
+    # If it corresponds to an aliased input, return the input.
+    # Otherwise, return the corresponding output from calling the functional operator.
+    for i, ret_name in enumerate(g.out.func.aliased_return_names()):
+        if ret_name is not None:
+            rets.append(ret_name)
+        else:
+            functional_return_name = (
+                out_name
+                if len(g.functional.func.returns) == 1
+                else f"std::get<{i}>({out_name})"
+            )
+            rets.append(functional_return_name)
+
+    copy_outs_str = "\n".join(copy_outs)
+
+    # Kernel name needs to follow the naming convention defined in `generate_function()`
+    return f"""
+{sig.defn(name=g.out.func.name.unambiguous_name() + ("_symint" if g.out.func.has_symint() else ""))} {{
+  auto {out_name} = at::_ops::{g.functional.func.name.unambiguous_name()}::call({exprs});
+  {copy_outs_str}
+  {return_str(g.out.func.returns, rets)}
+}}
+"""

vllm/lib/python3.10/site-packages/torchgen/operator_versions/gen_mobile_upgraders.py

@@ -0,0 +1,395 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+
+import os
+from enum import Enum
+from operator import itemgetter
+from pathlib import Path
+from typing import Any
+
+import torch
+from torch.jit.generate_bytecode import generate_upgraders_bytecode
+from torchgen.code_template import CodeTemplate
+from torchgen.operator_versions.gen_mobile_upgraders_constant import (
+    MOBILE_UPGRADERS_HEADER_DESCRIPTION,
+)
+
+
+class ByteCode(Enum):
+    instructions = 1
+    constants = 2
+    types = 3
+    operators = 4
+    register_size = 5
+
+
+EXCLUDED_OP_SET = [
+    "aten::full.names",
+    "aten::full.out",
+    "aten::full",
+]
+
+EXCLUE_UPGRADER_SET = ["full_0_4", "full_out_0_4"]
+
+ONE_INSTRUCTION = CodeTemplate(
+    """
+    Instruction{OpCode::${operator_name}, ${X}, ${N}},"""
+)
+
+INSTRUCTION_LIST = CodeTemplate(
+    """std::vector<Instruction>({
+        ${instruction_list}
+    }), // instructions list"""
+)
+
+ONE_CONSTANT = CodeTemplate(
+    """
+    c10::IValue(${constant}),"""
+)
+
+CONSTANT_LIST = CodeTemplate(
+    """std::vector<c10::IValue>({
+        ${constant_list}
+    }), // constants list"""
+)
+
+CONSTANTS_LIST_EMPTY = """std::vector<c10::IValue>(), // constants list"""
+
+ONE_TYPE = CodeTemplate("""c10::parseType("${type_str}"),""")
+
+TYPE_LIST = CodeTemplate(
+    """std::vector<c10::TypePtr>({
+        ${type_list}
+    }), // types list"""
+)
+
+TYPE_LIST_EMPTY = """std::vector<c10::TypePtr>(), // types list"""
+
+ONE_OPERATOTR_STRING = CodeTemplate(
+    """
+    OperatorString({"${operator_name}", "${overload_name}", ${num_of_args}}),"""
+)
+
+OPERATOR_STRING_LIST = CodeTemplate(
+    """
+    std::vector<OperatorString>({
+        ${operator_string_list}
+    }), // operators list"""
+)
+
+ONE_UPGRADER_FUNCTION = CodeTemplate(
+    """
+    mobile::Function::registerFunc(
+        "${upgrader_name}",
+        ${instruction_list},
+        ${constant_list},
+        ${type_list},
+        ${register_size}
+    )"""
+)
+
+ONE_UPGRADER_SRC = CodeTemplate(
+    """
+    ByteCodeFunctionWithOperator({
+        ${bytecode_function},
+        ${operator_string_list}
+    }),"""
+)
+
+
+ONE_UPGRADER_IN_VERSION_MAP = CodeTemplate(
+    """Upgrader({${upgrader_min_version}, ${upgrader_max_version}, "${upgrader_name}", ${bytecode_func_index}})"""
+)  # noqa: E501
+
+ONE_OPERATOR_IN_VERSION_MAP = CodeTemplate(
+    """
+    {std::string("${operator_name}"),
+        std::vector<Upgrader>({
+            ${upgrader_list_in_version_map}
+        })},"""
+)
+
+
+OPERATOR_VERSION_MAP = CodeTemplate(
+    """
+const std::unordered_map<std::string, std::vector<Upgrader>>
+getOperatorVersionMapForMobile() {
+  static std::unordered_map<std::string, std::vector<Upgrader>>
+        operatorVersionMapForMobile({
+            ${operator_list_in_version_map}
+      });
+  return operatorVersionMapForMobile;
+}
+"""
+)
+
+
+UPGRADER_CPP_SRC = CodeTemplate(
+    MOBILE_UPGRADERS_HEADER_DESCRIPTION
+    + """
+#include <caffe2/serialize/versions.h>
+#include <torch/csrc/jit/mobile/upgrader_mobile.h>
+
+namespace c10 {
+TypePtr parseType(const std::string& pythonStr);
+} // namespace c10
+
+namespace torch {
+namespace jit {
+
+// clang-format off
+
+// From operator_versions_map
+${operator_version_map}
+
+const std::vector<ByteCodeFunctionWithOperator>& getUpgraderBytecodeList() {
+  auto generate_upgrader_bytecode_list = []() {
+    std::vector<ByteCodeFunctionWithOperator> upgrader_function_list({
+               ${upgrader_bytecode}
+            });
+    for (const auto& upgrader_function : upgrader_function_list) {
+      for (const auto& op : upgrader_function.operators) {
+        upgrader_function.function.append_operator(
+            op.name,
+            op.overload_name,
+            op.num_specified_args);
+      }
+    }
+    return upgrader_function_list;
+  };
+  static std::vector<ByteCodeFunctionWithOperator> upgraderBytecodeList =
+      generate_upgrader_bytecode_list();
+  return upgraderBytecodeList;
+}
+
+// clang-format on
+
+} // namespace jit
+} // namespace torch
+"""
+)
+
+UPGRADER_MOBILE_FILE_NAME = "upgrader_mobile.cpp"
+
+UPGRADER_ELEMENT = CodeTemplate(
+    """\
+Upgrader({${min_version}, ${max_version}, ${operator_name}, ${index}}),
+"""
+)
+
+PER_OPERATOR_UPGRADER_LIST = CodeTemplate(
+    """\
+{
+  std::string(${operator_name}),
+  std::vector<Upgrader>({${upgrader_list}});
+}
+"""
+)
+
+
+def construct_instruction(instruction_list_from_yaml: list[Any]) -> str:
+    instruction_list_part = []
+    for instruction in instruction_list_from_yaml:
+        instruction_list_part.append(
+            ONE_INSTRUCTION.substitute(
+                operator_name=instruction[0],
+                X=instruction[1],
+                N=instruction[2],
+            )
+        )
+    return INSTRUCTION_LIST.substitute(
+        instruction_list="".join(instruction_list_part).lstrip("\n")
+    )
+
+
+def construct_constants(constants_list_from_yaml: list[Any]) -> str:
+    constants_list_part = []
+    for constant_from_yaml in constants_list_from_yaml:
+        convert_constant = None
+        if isinstance(constant_from_yaml, str):
+            # Add quotes if it's string
+            convert_constant = f'"{constant_from_yaml}"'
+        elif isinstance(constant_from_yaml, bool):
+            convert_constant = "true" if constant_from_yaml else "false"
+        elif constant_from_yaml is None:
+            convert_constant = ""
+        elif isinstance(constant_from_yaml, int):
+            convert_constant = str(constant_from_yaml)
+        else:
+            raise ValueError(
+                f"The type of {constant_from_yaml} is {type(constant_from_yaml)}. "
+                "Please add change in construct_constants function in gen_mobile_upgraders.py."
+            )
+        constants_list_part.append(ONE_CONSTANT.substitute(constant=convert_constant))
+    if len(constants_list_part) == 0:
+        return CONSTANTS_LIST_EMPTY
+    return CONSTANT_LIST.substitute(
+        constant_list="".join(constants_list_part).lstrip("\n")
+    )
+
+
+def construct_operators(operator_list_from_yaml: list[Any]) -> str:
+    operator_list_part = []
+    for operator in operator_list_from_yaml:
+        operator_list_part.append(
+            ONE_OPERATOTR_STRING.substitute(
+                operator_name=operator[0],
+                overload_name=operator[1],
+                num_of_args=operator[2],
+            )
+        )
+    return OPERATOR_STRING_LIST.substitute(
+        operator_string_list="".join(operator_list_part).lstrip("\n")
+    )
+
+
+def construct_types(types_tr_list_from_yaml: list[Any]) -> str:
+    types_tr_list_part = []
+    for types_tr in types_tr_list_from_yaml:
+        types_tr_list_part.append(ONE_TYPE.substitute(type_str=types_tr))
+    if len(types_tr_list_part) == 0:
+        return TYPE_LIST_EMPTY
+    return TYPE_LIST.substitute(type_list="".join(types_tr_list_part).lstrip("\n"))
+
+
+def construct_register_size(register_size_from_yaml: int) -> str:
+    if not isinstance(register_size_from_yaml, int):
+        raise ValueError(
+            f"Input register size is {register_size_from_yaml} and"
+            "it's type is {type(register_size_from_yaml)}. An int type is expected."
+        )
+    return str(register_size_from_yaml)
+
+
+def construct_version_maps(
+    upgrader_bytecode_function_to_index_map: dict[str, Any]
+) -> str:
+    version_map = torch._C._get_operator_version_map()
+    sorted_version_map_ = sorted(version_map.items(), key=itemgetter(0))  # type: ignore[no-any-return]
+    sorted_version_map = dict(sorted_version_map_)
+
+    operator_list_in_version_map_part = []
+    for op_name in sorted_version_map:
+        upgraders_in_version_map_part = []
+        # TODO: remove the skip after these two operators schemas are fixed
+        if op_name in EXCLUDED_OP_SET:
+            continue
+        upgrader_ranges = torch._C._get_upgrader_ranges(op_name)
+        upgrader_entries = sorted_version_map[op_name]
+        assert len(upgrader_ranges) == len(upgrader_entries)
+        for idx, upgrader_entry in enumerate(upgrader_entries):
+            upgrader_name = upgrader_entry.upgrader_name
+            bytecode_function_index = upgrader_bytecode_function_to_index_map[
+                upgrader_name
+            ]
+            upgraders_in_version_map_part.append(
+                ONE_UPGRADER_IN_VERSION_MAP.substitute(
+                    upgrader_min_version=upgrader_ranges[idx].min_version,
+                    upgrader_max_version=upgrader_ranges[idx].max_version,
+                    upgrader_name=upgrader_name,
+                    bytecode_func_index=bytecode_function_index,
+                )
+            )
+        operator_list_in_version_map_part.append(
+            ONE_OPERATOR_IN_VERSION_MAP.substitute(
+                operator_name=op_name,
+                upgrader_list_in_version_map="".join(upgraders_in_version_map_part),
+            )
+        )
+    return OPERATOR_VERSION_MAP.substitute(
+        operator_list_in_version_map="".join(operator_list_in_version_map_part).lstrip(
+            "\n"
+        )
+    )
+
+
+def get_upgrader_bytecode_function_to_index_map(
+    upgrader_dict: list[dict[str, Any]]
+) -> dict[str, Any]:
+    upgrader_bytecode_function_to_index_map = {}
+    index = 0
+    for upgrader_bytecode in upgrader_dict:
+        for upgrader_name in upgrader_bytecode.keys():
+            if upgrader_name in EXCLUE_UPGRADER_SET:
+                continue
+            upgrader_bytecode_function_to_index_map[upgrader_name] = index
+            index += 1
+    return upgrader_bytecode_function_to_index_map
+
+
+def write_cpp(cpp_path: str, upgrader_dict: list[dict[str, Any]]) -> None:
+    body_parts = []
+    upgrader_bytecode_function_to_index_map = (
+        get_upgrader_bytecode_function_to_index_map(upgrader_dict)
+    )
+    version_map_src = construct_version_maps(upgrader_bytecode_function_to_index_map)
+    all_upgrader_src_string = []
+    for upgrader_bytecode in upgrader_dict:
+        for upgrader_name, bytecode in upgrader_bytecode.items():
+            # TODO: remove the skip after these two operators schemas are fixed
+            if upgrader_name in EXCLUE_UPGRADER_SET:
+                continue
+            instruction_list_str = ""
+            constant_list_str = ""
+            type_list_str = ""
+            register_size_str = ""
+            operator_list_str = ""
+            for table_name, contents in bytecode.items():
+                element = ByteCode[table_name]
+                body_string = ""
+                if element is ByteCode.instructions:
+                    instruction_list_str = construct_instruction(contents)
+                elif element is ByteCode.constants:
+                    constant_list_str = construct_constants(contents)
+                elif element is ByteCode.operators:
+                    operator_list_str = construct_operators(contents)
+                elif element is ByteCode.types:
+                    type_list_str = construct_types(contents)
+                elif element is ByteCode.register_size:
+                    register_size_str = construct_register_size(contents)
+
+            one_upgrader_function_string = ONE_UPGRADER_FUNCTION.substitute(
+                upgrader_name=upgrader_name,
+                instruction_list=instruction_list_str,
+                constant_list=constant_list_str,
+                type_list=type_list_str,
+                register_size=register_size_str,
+            )
+            one_upgrader_src_string = ONE_UPGRADER_SRC.substitute(
+                bytecode_function=one_upgrader_function_string.lstrip("\n"),
+                operator_string_list=operator_list_str.lstrip("\n"),
+            )
+            all_upgrader_src_string.append(one_upgrader_src_string)
+
+    upgrader_file_content = UPGRADER_CPP_SRC.substitute(
+        operator_version_map=version_map_src,
+        upgrader_bytecode="".join(all_upgrader_src_string).lstrip("\n"),
+    )
+    body_parts.append(upgrader_file_content)
+    print("writing file to : ", cpp_path + "/" + UPGRADER_MOBILE_FILE_NAME)
+    with open(os.path.join(cpp_path, UPGRADER_MOBILE_FILE_NAME), "wb") as out_file:
+        final_output = "".join(body_parts)
+        out_file.write(upgrader_file_content.encode("utf-8"))
+
+
+def sort_upgrader(upgrader_list: list[dict[str, Any]]) -> list[dict[str, Any]]:
+    sorted_upgrader_list = sorted(
+        upgrader_list, key=lambda one_upgrader: next(iter(one_upgrader))
+    )
+    return sorted_upgrader_list
+
+
+def main() -> None:
+    upgrader_list = generate_upgraders_bytecode()
+    sorted_upgrader_list = sort_upgrader(upgrader_list)
+    for up in sorted_upgrader_list:
+        print("after sort upgrader : ", next(iter(up)))
+
+    pytorch_dir = Path(__file__).resolve().parents[2]
+    upgrader_path = pytorch_dir / "torch" / "csrc" / "jit" / "mobile"
+    write_cpp(str(upgrader_path), sorted_upgrader_list)
+
+
+if __name__ == "__main__":
+    main()

vllm/lib/python3.10/site-packages/torchgen/operator_versions/gen_mobile_upgraders_constant.py

@@ -0,0 +1,7 @@
+MOBILE_UPGRADERS_HEADER_DESCRIPTION = """/**
+ * @generated
+ * This is an auto-generated file. Please do not modify it by hand.
+ * To re-generate, please run:
+ * cd ~/pytorch && python torchgen/operator_versions/gen_mobile_upgraders.py
+ */
+"""

vllm/lib/python3.10/site-packages/torchgen/packaged/autograd/BUILD.bazel

@@ -0,0 +1,4 @@
+load("//:tools/bazel.bzl", "rules")
+load(":build.bzl", "define_targets")
+
+define_targets(rules = rules)

vllm/lib/python3.10/site-packages/torchgen/packaged/autograd/gen_annotated_fn_args.py

@@ -0,0 +1,132 @@
+"""
+For procedural tests needed for __torch_function__, we use this function
+to export method names and signatures as needed by the tests in
+test/test_overrides.py.
+
+python -m tools.autograd.gen_annotated_fn_args \
+       aten/src/ATen/native/native_functions.yaml \
+       aten/src/ATen/native/tags.yaml \
+       $OUTPUT_DIR \
+       tools/autograd
+
+Where $OUTPUT_DIR is where you would like the files to be
+generated.  In the full build system, OUTPUT_DIR is
+torch/testing/_internal/generated
+"""
+
+from __future__ import annotations
+
+import argparse
+import os
+import textwrap
+from collections import defaultdict
+from typing import Any, Sequence, TYPE_CHECKING
+
+import torchgen.api.python as python
+from torchgen.context import with_native_function
+from torchgen.gen import parse_native_yaml
+from torchgen.utils import FileManager
+
+from .gen_python_functions import (
+    is_py_fft_function,
+    is_py_linalg_function,
+    is_py_nn_function,
+    is_py_special_function,
+    is_py_torch_function,
+    is_py_variable_method,
+    should_generate_py_binding,
+)
+
+
+if TYPE_CHECKING:
+    from torchgen.model import Argument, BaseOperatorName, NativeFunction
+
+
+def gen_annotated(
+    native_yaml_path: str, tags_yaml_path: str, out: str, autograd_dir: str
+) -> None:
+    native_functions = parse_native_yaml(
+        native_yaml_path, tags_yaml_path
+    ).native_functions
+    mappings = (
+        (is_py_torch_function, "torch._C._VariableFunctions"),
+        (is_py_nn_function, "torch._C._nn"),
+        (is_py_linalg_function, "torch._C._linalg"),
+        (is_py_special_function, "torch._C._special"),
+        (is_py_fft_function, "torch._C._fft"),
+        (is_py_variable_method, "torch.Tensor"),
+    )
+    annotated_args: list[str] = []
+    for pred, namespace in mappings:
+        groups: dict[BaseOperatorName, list[NativeFunction]] = defaultdict(list)
+        for f in native_functions:
+            if not should_generate_py_binding(f) or not pred(f):
+                continue
+            groups[f.func.name.name].append(f)
+        for group in groups.values():
+            for f in group:
+                annotated_args.append(f"{namespace}.{gen_annotated_args(f)}")
+
+    template_path = os.path.join(autograd_dir, "templates")
+    fm = FileManager(install_dir=out, template_dir=template_path, dry_run=False)
+    fm.write_with_template(
+        "annotated_fn_args.py",
+        "annotated_fn_args.py.in",
+        lambda: {
+            "annotated_args": textwrap.indent("\n".join(annotated_args), "    "),
+        },
+    )
+
+
+@with_native_function
+def gen_annotated_args(f: NativeFunction) -> str:
+    def _get_kwargs_func_exclusion_list() -> list[str]:
+        # functions that currently don't work with kwargs in test_overrides.py
+        return [
+            "diagonal",
+            "round_",
+            "round",
+            "scatter_",
+        ]
+
+    def _add_out_arg(
+        out_args: list[dict[str, Any]], args: Sequence[Argument], *, is_kwarg_only: bool
+    ) -> None:
+        for arg in args:
+            if arg.default is not None:
+                continue
+            out_arg: dict[str, Any] = {}
+            out_arg["is_kwarg_only"] = str(is_kwarg_only)
+            out_arg["name"] = arg.name
+            out_arg["simple_type"] = python.argument_type_str(
+                arg.type, simple_type=True
+            )
+            size_t = python.argument_type_size(arg.type)
+            if size_t:
+                out_arg["size"] = size_t
+            out_args.append(out_arg)
+
+    out_args: list[dict[str, Any]] = []
+    _add_out_arg(out_args, f.func.arguments.flat_positional, is_kwarg_only=False)
+    if f"{f.func.name.name}" not in _get_kwargs_func_exclusion_list():
+        _add_out_arg(out_args, f.func.arguments.flat_kwarg_only, is_kwarg_only=True)
+
+    return f"{f.func.name.name}: {repr(out_args)},"
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Generate annotated_fn_args script")
+    parser.add_argument(
+        "native_functions", metavar="NATIVE", help="path to native_functions.yaml"
+    )
+    parser.add_argument("tags", metavar="TAGS", help="path to tags.yaml")
+    parser.add_argument("out", metavar="OUT", help="path to output directory")
+    parser.add_argument(
+        "autograd", metavar="AUTOGRAD", help="path to template directory"
+    )
+    args = parser.parse_args()
+    gen_annotated(args.native_functions, args.tags, args.out, args.autograd)
+
+
+if __name__ == "__main__":
+    main()

vllm/lib/python3.10/site-packages/torchgen/packaged/autograd/gen_autograd.py

@@ -0,0 +1,147 @@
+"""
+To run this file by hand from the root of the PyTorch
+repository, run:
+
+python -m tools.autograd.gen_autograd \
+       aten/src/ATen/native/native_functions.yaml \
+       aten/src/ATen/native/tags.yaml \
+       $OUTPUT_DIR \
+       tools/autograd
+
+Where $OUTPUT_DIR is where you would like the files to be
+generated.  In the full build system, OUTPUT_DIR is
+torch/csrc/autograd/generated/
+"""
+
+# gen_autograd.py generates C++ autograd functions and Python bindings.
+#
+# It delegates to the following scripts:
+#
+#  gen_autograd_functions.py: generates subclasses of torch::autograd::Node
+#  gen_variable_type.py: generates VariableType.h which contains all tensor methods
+#  gen_python_functions.py: generates Python bindings to THPVariable
+#
+
+from __future__ import annotations
+
+import argparse
+import os
+
+from torchgen.api import cpp
+from torchgen.api.autograd import (
+    match_differentiability_info,
+    NativeFunctionWithDifferentiabilityInfo,
+)
+from torchgen.gen import parse_native_yaml
+from torchgen.selective_build.selector import SelectiveBuilder
+
+from . import gen_python_functions
+from .gen_autograd_functions import (
+    gen_autograd_functions_lib,
+    gen_autograd_functions_python,
+)
+from .gen_inplace_or_view_type import gen_inplace_or_view_type
+from .gen_trace_type import gen_trace_type
+from .gen_variable_factories import gen_variable_factories
+from .gen_variable_type import gen_variable_type
+from .gen_view_funcs import gen_view_funcs
+from .load_derivatives import load_derivatives
+
+
+def gen_autograd(
+    native_functions_path: str,
+    tags_path: str,
+    out: str,
+    autograd_dir: str,
+    operator_selector: SelectiveBuilder,
+    disable_autograd: bool = False,
+) -> None:
+    # Parse and load derivatives.yaml
+    differentiability_infos, used_dispatch_keys = load_derivatives(
+        os.path.join(autograd_dir, "derivatives.yaml"), native_functions_path, tags_path
+    )
+
+    template_path = os.path.join(autograd_dir, "templates")
+
+    native_funcs = parse_native_yaml(native_functions_path, tags_path).native_functions
+    fns = sorted(
+        filter(
+            operator_selector.is_native_function_selected_for_training, native_funcs
+        ),
+        key=lambda f: cpp.name(f.func),
+    )
+    fns_with_diff_infos: list[
+        NativeFunctionWithDifferentiabilityInfo
+    ] = match_differentiability_info(fns, differentiability_infos)
+
+    # Generate VariableType.h/cpp
+    if not disable_autograd:
+        gen_variable_type(
+            out,
+            native_functions_path,
+            tags_path,
+            fns_with_diff_infos,
+            template_path,
+            used_dispatch_keys,
+        )
+
+        gen_inplace_or_view_type(
+            out, native_functions_path, tags_path, fns_with_diff_infos, template_path
+        )
+
+        # operator filter not applied as tracing sources are excluded in selective build
+        gen_trace_type(out, native_funcs, template_path)
+    # Generate Functions.h/cpp
+    gen_autograd_functions_lib(out, differentiability_infos, template_path)
+
+    # Generate variable_factories.h
+    gen_variable_factories(out, native_functions_path, tags_path, template_path)
+
+    # Generate ViewFuncs.h/cpp
+    gen_view_funcs(out, fns_with_diff_infos, template_path)
+
+
+def gen_autograd_python(
+    native_functions_path: str,
+    tags_path: str,
+    out: str,
+    autograd_dir: str,
+) -> None:
+    differentiability_infos, _ = load_derivatives(
+        os.path.join(autograd_dir, "derivatives.yaml"), native_functions_path, tags_path
+    )
+
+    template_path = os.path.join(autograd_dir, "templates")
+
+    # Generate Functions.h/cpp
+    gen_autograd_functions_python(out, differentiability_infos, template_path)
+
+    # Generate Python bindings
+    deprecated_path = os.path.join(autograd_dir, "deprecated.yaml")
+    gen_python_functions.gen(
+        out, native_functions_path, tags_path, deprecated_path, template_path
+    )
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Generate autograd C++ files script")
+    parser.add_argument(
+        "native_functions", metavar="NATIVE", help="path to native_functions.yaml"
+    )
+    parser.add_argument("tags", metavar="NATIVE", help="path to tags.yaml")
+    parser.add_argument("out", metavar="OUT", help="path to output directory")
+    parser.add_argument(
+        "autograd", metavar="AUTOGRAD", help="path to autograd directory"
+    )
+    args = parser.parse_args()
+    gen_autograd(
+        args.native_functions,
+        args.tags,
+        args.out,
+        args.autograd,
+        SelectiveBuilder.get_nop_selector(),
+    )
+
+
+if __name__ == "__main__":
+    main()