pytorch/torch/_prims/context.py
Ivan Yashchuk ae4fbac819 Enable nvprims.transpose fusions for nvFuser (#86967)
This PR allows transposes to be fused with other operations. If a fusion group is formed only from operations that just manipulate metadata in PyTorch (transpose, view, etc.) then this group is not sent to nvFuser.
On top of that if we have converted to `nvprims` but then decided to not form a fusion group we modify the graph use `prim.impl_aten` attribute instead of calling `prim(*args, **kwargs)` that has a higher overhead.

cc @kevinstephano @jjsjann123
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86967
Approved by: https://github.com/jjsjann123, https://github.com/SherlockNoMad
2022-10-26 17:00:07 +00:00

420 lines
14 KiB
Python

import functools
from contextlib import nullcontext
from typing import Any, Callable, Dict, Sequence
from warnings import warn
import torch
import torch._decomp
import torch._prims
import torch._refs
import torch._refs.nn
import torch._refs.nn.functional
import torch._refs.special
import torch.overrides
from torch._prims.nvfuser_executor import NvfuserPrimOperatorSupport
from torch._prims_common import torch_function_passthrough
from torch.fx.experimental.proxy_tensor import get_isolated_graphmodule
@functools.lru_cache(None)
def torch_to_refs_map():
"""
Mapping of torch API functions to torch._refs functions.
E.g. torch_to_refs_map()[torch.add] == torch._refs.add
"""
modules = [
(torch, torch._refs),
(torch.nn, torch._refs.nn),
(torch.nn.functional, torch._refs.nn.functional),
(torch.special, torch._refs.special),
(torch.fft, torch._refs.fft),
(torch.linalg, torch._refs.linalg),
]
r: Dict[Any, Any] = {
torch.Tensor.__invert__: torch._refs.bitwise_not,
torch.Tensor.__xor__: torch._refs.bitwise_xor,
torch.Tensor.__and__: torch._refs.bitwise_and,
torch.Tensor.__or__: torch._refs.bitwise_or,
torch.Tensor.__eq__: torch._refs.eq,
torch.Tensor.__rsub__: torch._refs.rsub,
torch.Tensor.__rtruediv__: torch._refs.rtruediv,
torch.Tensor.__floordiv__: torch._refs.floor_divide,
torch.Tensor.__rfloordiv__: torch._refs.rfloordiv,
torch.Tensor.__pow__: torch._refs.pow,
torch.Tensor.__rpow__: torch._refs.rpow,
torch.Tensor.new_empty: torch._refs.new_empty,
torch.Tensor.new_full: torch._refs.new_full,
torch.Tensor.new_zeros: torch._refs.new_zeros,
torch.Tensor.new_ones: torch._refs.new_ones,
torch.Tensor.fill_: torch._refs.fill_,
torch.Tensor.zero_: torch._refs.zero_,
torch.Tensor.to: torch._refs.to,
torch.Tensor.sum_to_size: torch._refs.sum_to_size,
# TODO: Should these methods be mapped some other way?
torch.Tensor.copy_: torch._prims.copy_to,
torch.Tensor.resize: torch._prims.resize,
}
for mod_torch, mod_refs in modules:
for s in mod_refs.__all__: # type: ignore[attr-defined]
r[mod_torch.__dict__.get(s)] = mod_refs.__dict__.get(s)
# Support remapping torch.Tensor.foo to _refs.foo
for s in dir(torch.Tensor):
if s in torch._refs.__all__:
r[getattr(torch.Tensor, s)] = torch._refs.__dict__.get(s)
# Support conversions
for s in torch._refs._conversions.__all__:
r[getattr(torch.Tensor, s)] = torch._refs._conversions.__dict__.get(s)
return r
@functools.lru_cache(None)
def all_prims():
"""
Set of all prim functions, e.g., torch._prims.add in all_prims()
"""
return {torch._prims.__dict__.get(s) for s in torch._prims.__all__}
class NvfuserPrimsMode(torch.overrides.TorchFunctionMode):
"""
Switches the interpretation of torch.ops.prims.* functions to
use nvFuser's prims in torch.ops.nvprims.*
>>> # xdoctest: +SKIP("undefined vars")
>>> with NvfuserPrimsMode():
... torch.ops.prims.add(x, y) # calls torch.ops.nvprims.add(x, y)
By default, this context manager will fall back on the torch.ops.prims* if the
nvprim does not exist.
It's possible to skip certain prims by passing their names to the skip_ops
argument. skip_ops is expected to be a sequence of strings, e.g.,
["prims.add.default"] In order to check the expected name of a prim, one can
use the `torch.overrides.resolve_name`.
>>> # xdoctest: +SKIP("undefined vars")
>>> with NvfuserPrimsMode(skips_ops=("prims.add.default")):
... torch.ops.prims.add.default(x, y) # does not call torch.ops.nvprims.add.default(x, y)
"""
def __init__(self, *, skip_ops=()):
self.skip_ops = skip_ops
def __torch_function__(
self,
orig_func: Callable,
types: Sequence,
args: Sequence[Any] = (),
kwargs: Dict = None,
):
if kwargs is None:
kwargs = {}
# If the function is in the skip list, then we don't want to
# remap it to the nvprims.
if torch.overrides.resolve_name(orig_func) in self.skip_ops:
return orig_func(*args, **kwargs)
if isinstance(orig_func, torch._ops.OpOverload) or isinstance(
orig_func, torch._ops.OpOverloadPacket
):
namespace = str(orig_func).split(".")[0]
name = str(orig_func).split(".")[1]
if namespace == "prims":
nvfunc = getattr(torch.ops.nvprims, name, None)
if nvfunc is not None:
return nvfunc(*args, **kwargs)
return orig_func(*args, **kwargs)
class TorchRefsMode(torch.overrides.TorchFunctionMode):
"""
Switches the interpretation of torch.* functions and Tensor methods to
use PrimTorch refs in torch._refs. (Direct calls to _refs are unaffected.)
>>> # xdoctest: +SKIP
>>> with TorchRefsMode():
... torch.add(x, y) # calls torch._refs.add(x, y)
By default, this context manager will fall back on the torch.* if the
ref does not exist; set strict=True to error if this occurs.
If the ref exists we still would like to fall back on the torch.* sometimes,
this behavior can be customized by passing a function to should_fallback_fn.
"""
def __init__(
self,
strict=False,
should_fallback_fn=lambda *_: False,
prims_mode_cls=nullcontext,
):
self.strict = strict
self.should_fallback_fn = should_fallback_fn
self.prims_mode_cls = prims_mode_cls
def __torch_function__(
self,
orig_func: Callable,
types: Sequence,
args: Sequence[Any] = (),
kwargs: Dict = None,
):
if kwargs is None:
kwargs = {}
# For primitive operations, run them as is without interception
# Unless we are in prims_mode, in which case we want to use nvprims
if orig_func in torch_function_passthrough or orig_func in all_prims():
with self.prims_mode_cls():
return orig_func(*args, **kwargs)
mapping = torch_to_refs_map()
func = mapping.get(orig_func, None)
# For torch.ops.aten.*, use registered decompositions from torch._decomp
# torch._decomp.decomposition_table provides a mapping from
# torch.ops.aten.* to torch._refs or torch._decomp.decompositions
# implementations.
# There're other ways to implement this functionality,
# see https://github.com/pytorch/pytorch/pull/82657#discussion_r939776417
if func is None and isinstance(orig_func, torch._ops.OpOverload):
func = torch._decomp.decomposition_table.get(orig_func, None)
if func is not None:
# If the ref exists query whether we should use it or not
if self.should_fallback_fn(self, orig_func, func, args, kwargs):
return orig_func(*args, **kwargs)
# torch calls inside func should be interpreted as refs calls
with self:
return func(*args, **kwargs)
if self.strict:
raise RuntimeError(
f"no _refs support for {torch.overrides.resolve_name(orig_func)}"
)
return orig_func(*args, **kwargs)
def _is_node_supported_nvfuser(node):
return (
node.op == "call_function"
and getattr(node.target, "impl_nvfuser", None) is not None
)
def _is_func_unsupported_nvfuser(
torch_function_mode, orig_func, func, args, kwargs, *, skip_ops=()
):
"""
This function traces the `func` under `torch_function_mode` and checks if
any of the traced nodes are not supported by nvFuser. If so, we should
fallback to the original function.
`skip_ops` argument is expected to be a list of strings of function names
that would match with `torch.overrides.resolve_name`.
Args:
torch_function_mode: The torch_function_mode context manager. orig_func:
The original function, its name will be used to check if
it should be skipped.
func: The function to be traced. args: The args to be passed to the
function. kwargs: The kwargs to be passed to the function.
Keyword args:
skip_ops: A list of ops to skip when checking if the function is
supported.
"""
# One supported case is easy to check: if the resolved name of the original
# function in the skip list, skip it.
if torch.overrides.resolve_name(orig_func) in skip_ops:
return True
with torch_function_mode:
try:
gm = get_isolated_graphmodule(func, args, kwargs)
except Exception as e:
warn(
"get_isolated_graphmodule failed on decomposition: "
+ func.__name__
+ " with error message: "
+ str(e)
)
# returns unsupported when tracing fails.
return True
supported_ops = NvfuserPrimOperatorSupport()
call_function_nodes = filter(lambda n: n.op == "call_function", gm.graph.nodes)
any_unsupported = any(
not supported_ops.is_node_supported(None, node) for node in call_function_nodes
)
return any_unsupported
class TorchRefsNvfuserCapabilityMode(TorchRefsMode):
def __init__(self, *, skip_ops=()):
aten_ops_to_skip = (
"aten._log_softmax.default",
"aten._log_softmax_backward_data.default",
"aten.expand.default",
)
self.skip_ops = tuple(skip_ops) + aten_ops_to_skip
super().__init__(
strict=False,
should_fallback_fn=functools.partial(
_is_func_unsupported_nvfuser,
skip_ops=tuple(skip_ops) + aten_ops_to_skip,
),
prims_mode_cls=functools.partial(NvfuserPrimsMode, skip_ops=skip_ops),
)
# TODO: remove this once version from _decomp/decompositions.py is working
# with this context manager
# This is a workaround for AOT Autograd graphs
def _cudnn_batch_norm(
self,
input,
weight,
bias,
running_mean,
running_var,
training,
exponential_average_factor,
epsilon,
):
a, b, c = torch.ops.nvprims.native_batch_norm(
input,
weight,
bias,
running_mean,
running_var,
training,
exponential_average_factor,
epsilon,
)
if training:
return (a, b, c, input.new_zeros((0,), dtype=torch.uint8))
return (
a,
weight.new_zeros((0,)),
weight.new_zeros((0,)),
input.new_zeros((0,), dtype=torch.uint8),
)
# This is a workaround for AOT Autograd graphs
def _cudnn_batch_norm_backward(
self,
input,
grad_output,
weight,
running_mean,
running_var,
save_mean,
save_var,
epsilon,
reserveSpace,
):
func = torch._decomp.decomposition_table[
torch.ops.aten.native_batch_norm_backward.default
]
return func(
grad_output,
input,
weight,
running_mean,
running_var,
save_mean,
save_var,
True,
epsilon,
[True, True, True],
)
def _is_var_mean(self, func):
return "torch.var_mean" == torch.overrides.resolve_name(func) or (
(
isinstance(func, torch._ops.OpOverload)
or isinstance(func, torch._ops.OpOverloadPacket)
)
and "aten.var_mean" in str(func)
)
def _is_view_or_reshape(self, func):
allowed_ops = {
"torch.Tensor.view",
"torch.Tensor.reshape",
"torch.view_copy",
"torch.reshape",
"aten.view.default",
"aten._unsafe_view.default",
"aten.view_copy.default",
} - set(self.skip_ops)
return torch.overrides.resolve_name(func) in allowed_ops
def _is_native_batch_norm(self, func):
return "torch.native_batch_norm" == torch.overrides.resolve_name(func) or (
func == torch.ops.aten.native_batch_norm.default
or func == torch.ops.aten.native_batch_norm
)
def _is_rand_like(self, func):
result = "torch.rand_like" == torch.overrides.resolve_name(func) or (
func == torch.ops.aten.rand_like or func == torch.ops.aten.rand_like.default
)
return result
def __torch_function__(
self,
orig_func: Callable,
types: Sequence,
args: Sequence[Any] = (),
kwargs: Dict = None,
):
if kwargs is None:
kwargs = {}
# First we intercept calls for nvfuser-specific prims bypassing generic torch._refs
if self._is_var_mean(orig_func):
return torch.ops.nvprims.var_mean(*args, **kwargs)
if (
orig_func == torch.ops.aten.cudnn_batch_norm.default
or orig_func == torch.ops.aten.cudnn_batch_norm
):
with self:
return self._cudnn_batch_norm(*args, **kwargs)
# A workaround for AOT Autograd graphs
# See https://github.com/pytorch/pytorch/pull/86115#issue-1394883782
if (
orig_func == torch.ops.aten.cudnn_batch_norm_backward.default
or orig_func == torch.ops.aten.cudnn_batch_norm_backward
):
with self:
return self._cudnn_batch_norm_backward(*args, **kwargs)
if self._is_view_or_reshape(orig_func):
a, *shape = args
shape = torch._prims_common.extract_shape_from_varargs(
shape, validate=False
) # type: ignore[assignment]
if len(kwargs) > 0:
warn("view has ignored kwargs!")
return torch.ops.nvprims.view(a, shape)
if orig_func == torch.ops.aten._reshape_alias.default:
a, shape, stride = args
if len(kwargs) > 0:
warn("view has ignored kwargs!")
return torch.ops.nvprims.view(a, shape)
if self._is_native_batch_norm(orig_func):
return torch.ops.nvprims.native_batch_norm(*args, **kwargs)
if self._is_rand_like(orig_func):
if len(kwargs) > 0:
warn("rand_like has ignored kwargs!")
return torch.ops.nvprims.rand_like(*args)
# Then we use TorchRefsMode to interpret the rest
return super().__torch_function__(orig_func, types, args, kwargs)