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from typing import List, Tuple
from torchgen.api import cpp
from torchgen.api.types import Binding, CppSignatureGroup, CType
from torchgen.model import (
Argument,
BaseTy,
BaseType,
ListType,
NativeFunction,
OptionalType,
Type,
)
# This file generates the code for unboxing wrappers, i.e., the glue logic to unbox a boxed operator and convert the
# ivalues from stack to correct arguments to the unboxed kernel, based on corresponding JIT schema. This codegen is
# an alternative way to generate unboxing wrappers similar to the existing C++ metaprogramming approach but gets the
# job done statically. These generated unboxing wrappers will be useful under the scenario where we need to register
# a fixed set of operators known at compile time and thus can save some time in runtime initialization phase.
#
# Here's an example on how the codegen works:
#
# - Function Schema (source of truth)
#
# aten::empty.names(int[] size, *, Dimname[]? names,
# ScalarType? dtype=None, Layout? layout=None,
# Device? device=None, bool? pin_memory=None,
# MemoryFormat? memory_format=None) -> Tensor
# - Argument Conversion
# Generates C++ code to convert an ivalue (from stack) to its underlying C++ type.
# - int[] size
# ```cpp
# const c10::List<c10::IValue> size_list_in = (std::move(peek(stack, 0, 7))).toList();
#
# std::vector<int64_t> size_vec;
# for (c10::IValue size_elem: size_list_in) {
# int64_t size_base = size_elem.to<int64_t>();
# size_vec.push_back(size_base);
# }
# at::ArrayRef<int64_t> size_list_out(size_vec);
# ~~~~~~~~~~~~~ <-- The converted argument from ivalues in the stack.
# Will be passed to unboxed kernel.
# ```
# - Dimname[]? names
# ```cpp
# c10::optional<c10::IValue> names_opt = (std::move(peek(stack, 1, 7))).toOptional<c10::IValue>();
# c10::optional<at::ArrayRef<at::Dimname>> names_opt_out;
# if (names_opt.has_value()) {
# ~~~~~~~~~~~ <-- Unwrapping optional shell
# const c10::IValue names_opt_in = names_opt.value();
# const c10::List<c10::IValue> names_list_in = names_opt_in.toList();
#
# std::vector<at::Dimname> names_vec;
# for (c10::IValue names_elem: names_list_in) {
# ~~~~~~~~~~~~~~~~~~~~~~~~~ <-- Unrolling list, then convert elements one by one.
# at::Dimname names_base = names_elem.to<at::Dimname>();
# names_vec.push_back(names_base);
# }
# at::ArrayRef<at::Dimname> names_list_out(names_vec);
#
# names_opt_out = c10::optional<at::ArrayRef<at::Dimname>>(names_list_out);
# } else {
# names_opt_out = c10::optional<at::ArrayRef<at::Dimname>>();
# }
# ```
# - ScalarType? dtype (similarly for the rest of the arguments)
# ```cpp
# c10::optional<c10::IValue> dtype_opt = (std::move(peek(stack, 2, 7))).toOptional<c10::IValue>();
# c10::optional<at::ScalarType> dtype_opt_out;
# if (dtype_opt.has_value()) {
# const c10::IValue dtype_opt_in = dtype_opt.value();
# at::ScalarType dtype_base = dtype_opt_in.to<at::ScalarType>();
# ~~~~~~~~~~~~~~~~~~~~ <-- For base types, convert ivalue to it
# directly using ".to<T>()" API.
# dtype_opt_out = c10::optional<at::ScalarType>(dtype_base);
# } else {
# dtype_opt_out = c10::optional<at::ScalarType>();
# }
# ```
#
# - Unboxed Kernel Call
# ```cpp
# auto result_ = torch::empty(
# size_list_out,
# names_opt_out,
# options,
# memory_format_opt_out
# );
# ```
#
# - Push Result Back to Stack
# ```cpp
# drop(stack, 7);
# pack(stack, std::move(result_));
# ```
connector = "\n\t"
# Return unboxing function name for a NativeFunction
def name(f: NativeFunction) -> str:
return f.func.name.unambiguous_name()
# Convert all the arguments in a NativeFunction to C++ code
def convert_arguments(f: NativeFunction) -> Tuple[List[Binding], List[str]]:
# we need the 'self' argument so method needs to be False
args = (
CppSignatureGroup.from_native_function(f, method=False)
.most_faithful_signature()
.arguments()
)
code_list = [
f"c10::IValue {args[i].name} = std::move(peek(stack, {i}, {len(args)}));"
for i in range(len(args))
] + [""]
binding_list = []
for arg in args:
# expecting only Argument
if not isinstance(arg.argument, Argument):
raise Exception(
f"Unexpected argument type, expecting `Argument` but got {arg}"
)
argument: Argument = arg.argument
unboxed_name, _, code, decl = argumenttype_ivalue_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
# 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
def argumenttype_ivalue_convert(
t: Type, arg_name: str, *, mutable: bool = False
) -> Tuple[str, CType, List[str], List[str]]:
# Unboxing is for mobile, which doesn't care about SymInts
ctype = cpp.argumenttype_type(
t=t, mutable=mutable, binds=arg_name, symint=False
).type
if isinstance(t, BaseType):
out_name = f"{arg_name}_base"
code, decl = _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 = _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 = _gen_code_list_type(
arg_name=arg_name,
out_name=out_name,
t=t,
ctype=ctype,
)
else:
raise Exception(f"Cannot handle type {t}. arg_name: {arg_name}")
return out_name, ctype, code, decl
def _gen_code_base_type(
arg_name: str, out_name: str, ctype: CType
) -> Tuple[List[str], List[str]]:
return [
f"{ctype.cpp_type(strip_ref=True)} {out_name} = {arg_name}.to<{ctype.cpp_type(strip_ref=True)}>();"
], []
def _gen_code_optional_type(
arg_name: str, out_name: str, t: OptionalType, ctype: CType
) -> Tuple[List[str], List[str]]:
in_name = f"{arg_name}_opt_in"
res_name, _, res_code, decl = argumenttype_ivalue_convert(t.elem, in_name)
return (
f"""
c10::optional<c10::IValue> {arg_name}_opt = {arg_name}.toOptional<c10::IValue>();
{ctype.cpp_type(strip_ref=True)} {out_name};
if ({arg_name}_opt.has_value()) {{
const c10::IValue {in_name} = {arg_name}_opt.value();
{connector.join(res_code)}
{out_name} = {ctype.cpp_type(strip_ref=True)}({res_name});
}} else {{
{out_name} = {ctype.cpp_type(strip_ref=True)}();
}}
""".split(
"\n"
),
decl,
)
def _gen_code_list_type(
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 = [f"const c10::List<c10::IValue> {in_name} = {arg_name}.toList();"]
res_name, res_ctype, res_code, decl = argumenttype_ivalue_convert(t.elem, elem_name)
# handle list type with size, e.g., bool[4]
if isinstance(t.elem, BaseType) and t.elem.name == BaseTy.bool and t.size:
code.extend(
f"""
{ctype.cpp_type(strip_ref=True)} {out_name} = as_array<{res_ctype.cpp_type(strip_ref=True)}, {t.size}>({in_name});
""".split(
"\n"
)
)
# we have to use c10::List for optional element. e.g., Tensor?[] -> c10::List<c10::optional<at::Tensor>>
elif isinstance(t.elem, OptionalType):
code.extend(
f"""
{ctype.cpp_type(strip_ref=True)} {out_name};
for (c10::IValue {elem_name}: {in_name}) {{
{connector.join(res_code)}
{out_name}.push_back({res_name});
}}
""".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 (c10::IValue {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