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import textwrap
from dataclasses import dataclass
from typing import List, Optional, Sequence, Tuple
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"""\
Tensor {name}_value;
optional<int64_t> {name}_bdim;
std::tie({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"""\
optional<Tensor> {name}_value;
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) -> Optional[str]:
# 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) -> Optional[str]:
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)
if not all(ret.type.is_tensor_like() for ret in returns):
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) -> Optional[str]:
opname = str(f.func.name)
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
"""