ai-content-maker/.venv/Lib/site-packages/torch/_subclasses/meta_utils.py

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2024-05-03 04:18:51 +03:00
import contextlib
import warnings
import weakref
from typing import ContextManager, Dict, List, Optional, Tuple, TYPE_CHECKING
import torch
from torch._C._functorch import (
_add_batch_dim,
_unwrap_functional_tensor,
_wrap_functional_tensor,
current_level,
get_unwrapped,
is_batchedtensor,
is_functorch_wrapped_tensor,
is_gradtrackingtensor,
maybe_get_bdim,
maybe_get_level,
peek_interpreter_stack,
TransformType,
)
from torch._guards import Source
from torch.multiprocessing.reductions import StorageWeakRef
from torch.utils._python_dispatch import (
is_traceable_wrapper_subclass,
transform_subclass,
)
from torch.utils.weak import WeakIdRef
if TYPE_CHECKING:
# Import the following modules during type checking to enable code intelligence features,
# Do not import unconditionally, as they import sympy and importing sympy is very slow
from torch.fx.experimental.symbolic_shapes import SymbolicContext
DimList = List
def safe_is_leaf(t):
try:
return t.is_leaf
except RuntimeError:
# inference mode can trigger this
return False
def safe_grad(t):
with warnings.catch_warnings():
warnings.filterwarnings("ignore", "The .grad attribute of a Tensor")
return t.grad
def assert_eq(a, b):
assert a == b, f"{a} != {b}"
def assert_metadata_eq(assert_eq, m1, m2, *, skip_symbolic=False):
def go(m1, m2):
assert_eq(m1.dtype, m2.dtype)
if not skip_symbolic:
assert_eq(m1.shape, m2.shape)
assert_eq(m1.requires_grad, m2.requires_grad)
assert_eq(m1.is_leaf, m2.is_leaf)
assert_eq(m1.grad_fn is None, m2.grad_fn is None)
assert_eq(m1.is_sparse, m2.is_sparse)
assert_eq(m1.is_inference(), m2.is_inference())
assert_eq(m1.is_conj(), m2.is_conj())
assert_eq(m1.is_neg(), m2.is_neg())
assert_eq(safe_grad(m1) is not None, safe_grad(m2) is not None)
if safe_grad(m1) is not None:
go(safe_grad(m1), safe_grad(m2))
if m1.is_sparse:
assert_eq(m1.dense_dim(), m2.dense_dim())
assert_eq(m1.sparse_dim(), m2.sparse_dim())
assert_eq(m1.is_coalesced(), m2.is_coalesced())
else:
if not skip_symbolic:
assert_eq(m1.stride(), m2.stride())
assert_eq(m1.storage_offset(), m2.storage_offset())
assert_eq(m1._is_view(), m2._is_view())
if m1._is_view():
go(m1._base, m2._base)
# TODO: test if is resizable (no direct query for this atm)
# TODO: audit AutogradMeta to see if it matches
# TODO: test forward AD
return go(m1, m2)
def is_sparse_coo(t):
return isinstance(t, torch.Tensor) and t.layout is torch.sparse_coo
def is_sparse_compressed(t):
return isinstance(t, torch.Tensor) and t.layout in {
torch.sparse_csr,
torch.sparse_csc,
torch.sparse_bsr,
torch.sparse_bsc,
}
def is_sparse_any(t):
return is_sparse_coo(t) or is_sparse_compressed(t)
# This is a class for converting multiple tensors into meta tensors which
# share the same view/storage structure. The operation model is you allocate
# one of these, and then call it repeatedly on all the tensors you want to
# convert. It's important to use the same object for tensors you want to
# share storage because this is how we correlate shared storages to the same
# meta storages. This class will hold weak references to cached tenosrs
# and tensor storages.
class MetaConverter:
def __init__(self):
self.storage_memo = {}
self.tensor_memo: weakref.WeakValueDictionary = weakref.WeakValueDictionary()
self.maybe_storages_to_delete = []
self.check_expired_frequency = 128
self.check_expired_count = 0
self.hit = 0
self.miss = 0
self.del_hook = None
self.arg_cnt = 0
def successful(self):
return self.hit > 0 and self.miss == 0
def check_for_expired_weak_storages(self):
new_li = []
stor_to_delete = []
for obj in self.maybe_storages_to_delete:
if not obj.expired():
new_li.append(obj)
else:
stor_to_delete.append(obj)
for obj in stor_to_delete:
self.storage_memo.pop(obj, None)
self.maybe_storages_to_delete = new_li
# if for some reason we have aquired many storages which have not expired
# even though a tensor with their storage has expired (aliasing or otherwise)
# check for expired storages less often so as to bound the amount of work we
# do checking for expired storages
self.check_expired_frequency = max(
self.check_expired_frequency, len(self.maybe_storages_to_delete)
)
def get_tensor_memo(self, t):
return self.tensor_memo.get(WeakIdRef(t), None)
def set_tensor_memo(self, t, v):
# hold a weak ref to self, otherwise it will be kept alive
# by the del_ten closure
self_weak_ref = weakref.ref(self)
if is_sparse_any(t) or t.is_mkldnn or is_functorch_wrapped_tensor(t):
weak_st = None
else:
weak_st = StorageWeakRef(t._typed_storage())
tensor_ref_key = WeakIdRef(t)
def del_ten():
# tensor outlives the converter
self_ref = self_weak_ref()
if self_ref is None:
return
# on shutdown, tensor_ref_key may not be in memo
self_ref.tensor_memo.pop(tensor_ref_key, None)
if weak_st and weak_st.expired():
self_ref.storage_memo.pop(weak_st, None)
elif weak_st is not None:
# [expired-storages]
# NB: even though the tensor has died,
# the deallocation of its storage can take longer,
# even when the storage has no other uses/views.
# In this case, the StorageWeakRef object will be kept alive
# longer than it needs to be, however the storage itself
# will be deallocated. We retain the possibly dead storages
# and periodically check if any of them are expired and
# can be freed.
self_ref.maybe_storages_to_delete.append(weak_st)
weakref.finalize(t, del_ten)
self.tensor_memo[tensor_ref_key] = v
# NB: doesn't actually return a storage, because meta storage is
# not supported
def meta_storage(self, s, callback):
# NB: TypedStorage is freshly allocated and cannot be used as hash
# key index.
# Use a Weak Ref to s in order to not leak memory
swr = StorageWeakRef(s)
if swr not in self.storage_memo:
self.storage_memo[swr] = callback(
lambda: torch.empty(s.size(), dtype=torch.uint8, device="meta")
).untyped_storage()
return self.storage_memo[swr]
# This function assumes that it's possible to do the conversion
# NB: name here is used in a conventional way by Dynamo; it corresponds
# precisely to the Source.name() of the tensor we're fakeifying and
# corresponds to a valid Python expression. When we construct sub-names
# as part of this process, we will maintain this invariant! (Even though
# other users of this may not need it this property to be upheld.)
def meta_tensor(
self,
t,
shape_env=None,
callback=lambda t: t(),
source: Optional[Source] = None,
symbolic_context: Optional["SymbolicContext"] = None,
):
if source is None:
from torch._dynamo.source import ConstantSource
# TODO: make a dedicated UnknownSource for this?
source = ConstantSource(
f"__meta_utils_unknown_tensor{len(self.tensor_memo)}"
)
# This indicates you set no_dispatch() before calling into this
# function. This is an error: we may be creating fake tensors and
# will perform operations on them which need fake tensor mode to
# be active. You will segfault if you are in a no_dispatch() block.
assert not torch._C._dispatch_tls_local_exclude_set().has(
torch._C.DispatchKey.Python
)
arg_cnt = self.arg_cnt
self.arg_cnt += 1
# When we make as_strided calls, we end up generating a guard
# that the new as_strided tensor is in bounds for the old storage
# for the base (since as_strided calls can "bust" out of their
# bounding box.) This guard is unnecessary: if a user is able
# to provide us a tensor with the view base setup this way, we
# don't need to produce a guard, because the fact that they
# were able to produce the view base means its in bounds.
#
# Now, ordinarily, this guard would be harmless. However, the
# generated guard refers to variables bound on the base variable.
# At the moment, Dynamo doesn't actually guard on x._base, because
# according to Voz this results in a lot of spurious invalidations,
# and also if the user doesn't directly make use of _base, its
# pointless anyway (because programs should be parametric over
# whether or not the input tensor is a view or not--unless you're
# mutating the input, but that's a whole 'nother ballgame). So
# for expediency, we suppress these guards so we don't have to
# deal with this (yet, anyway.)
#
# NB: An old version of this code suppressed guards for ALL operations
# happening during meta conversion, not just as_strided calls.
# This is too aggressive: we do duck sizing and 0/1 simplification
# as we allocate variables, and we do need to register guards for
# these cases.
maybe_suppress = contextlib.nullcontext
if shape_env is not None:
maybe_suppress = shape_env.suppress_guards
def sym_sizes_strides_storage_offset(
t, src, symbolic_context=symbolic_context
) -> Tuple[Tuple[int, ...], Tuple[int, ...], int]:
if shape_env is not None:
fake_mode = torch._subclasses.fake_tensor.maybe_get_fake_mode(t)
if fake_mode is not None and fake_mode.shape_env is shape_env:
# Don't reallocate the sizes; the shape envs are the same,
# so reuse the old sizes/strides/etc
return (t.size(), t.stride(), t.storage_offset())
else:
return shape_env.create_symbolic_sizes_strides_storage_offset(
t,
src,
symbolic_context=symbolic_context,
)
else:
assert symbolic_context is None
return (t.size(), t.stride(), t.storage_offset())
def empty_create(inner_t, inner_src, symbolic_context=symbolic_context):
(
inner_sizes,
inner_strides,
inner_storage_offset,
) = sym_sizes_strides_storage_offset(inner_t, inner_src, symbolic_context)
return torch.empty_strided(
inner_sizes,
inner_strides,
dtype=inner_t.dtype,
device="meta",
)
# Creates a subclass instance with empty inner tensors according to the specified
# symbolic context.
def empty_create_subclass(
t,
outer_size,
outer_stride,
symbolic_context=symbolic_context,
callback=callback,
source=source,
):
from torch._dynamo.source import AttrSource
from torch.fx.experimental.symbolic_shapes import SubclassSymbolicContext
assert symbolic_context is None or isinstance(
symbolic_context, SubclassSymbolicContext
)
# Note: transform_subclass will use __tensor_unflatten__ to generate
# a fresh subclass wrapper with outer sizes / strides according to the
# outer symbolic context (passed in to this function). Inner size / stride
# / storage offset symbols are allocated according to the appropriate inner
# symbolic contexts, after which the checks in transform_subclass() will
# relate them to the outer metadata as possible.
return transform_subclass(
t,
lambda attr, inner_t: callback(
lambda: empty_create(
inner_t,
AttrSource(source, attr),
symbolic_context=(
None
if symbolic_context is None
else symbolic_context.inner_contexts[attr]
),
)
),
outer_size=outer_size,
outer_stride=outer_stride,
)
# Returns an all-dynamic symbolic context used for metafying the given tensor with
# fully dynamic dims. This is useful when fake-ifying intermediate tensors in
# closed-over ViewFunc state, as we don't have symbolic contexts for them, but we
# don't want to over-specialize during view replay.
def all_dynamic_symbolic_context(t, source, shape_env, callback):
from torch._dynamo.source import AttrSource
from torch.fx.experimental.symbolic_shapes import (
DimDynamic,
StatelessSymbolicContext,
SubclassSymbolicContext,
SymbolicContext,
)
view_base_context: Optional[SymbolicContext] = None
if t._is_view():
view_base_context = all_dynamic_symbolic_context(
t._base, AttrSource(source, "_base"), shape_env, callback
)
t_symbolic_context: SymbolicContext
t_dynamic_sizes = [DimDynamic.DYNAMIC] * t.dim()
if is_traceable_wrapper_subclass(t):
inner_contexts: Dict[str, SymbolicContext] = {}
attrs, _ = t.__tensor_flatten__()
for attr in attrs:
assert isinstance(attr, str)
inner = getattr(t, attr)
inner_contexts[attr] = all_dynamic_symbolic_context(
inner, AttrSource(source, attr), shape_env, callback
)
t_symbolic_context = SubclassSymbolicContext(
dynamic_sizes=t_dynamic_sizes,
constraint_sizes=[None] * t.dim(),
inner_contexts=inner_contexts,
tensor_source=source,
view_base_context=view_base_context,
)
else:
t_symbolic_context = StatelessSymbolicContext(
dynamic_sizes=t_dynamic_sizes,
constraint_sizes=[None] * t.dim(),
view_base_context=view_base_context,
)
return t_symbolic_context
# Returns a fake-ified version of an input view tensor t, given an already fake-ified
# base. At a high level, we want two things:
# 1. fake_t should have the same view relationship to the given fake base as the
# input t has to its _base.
# 2. fake_t should have symbolic sizes / strides / storage offset according to the
# appropriate symbolic context (i.e. from the automatic dynamic algorithm).
#
# We currently take different strategies across view types:
# * For dense -> dense views, accomplish both (1) and (2) simultaneously via an
# as_strided() call on the fake-ified base, passing symbolic metadata.
# * For views involving subclasses, perform view replay using view funcs to
# achieve (1). It's necessary for (2) to swap out any closed-over state in
# the view funcs with symbolicized SymInts and fake-ified tensors. Doing this
# avoids specialization (and thus over-eager simplification of symbols) that
# could occur during view replay on the fake-ified base.
#
# Examples:
# * t.unsqueeze(-1) with dense t is a dense -> dense view. It can be modeled
# with an as_strided() call on the fake base passing symbolic metadata.
# * sub.select(dim=0, index=3) is a subclass -> subclass view. The index arg
# is made symbolic to avoid invalid specialization and view replay is then
# done to reconstruct the view.
# * _nested_from_jagged(values, offsets) is a dense -> subclass view
# that returns a subclass instance from a dense values tensor. The offsets
# tensor is closed over in the view func, as it can be considered view metadata.
# First, the offsets tensor is fake-ified according to the inner symbolic
# context and with the correct relationship to the outer size / stride metadata.
# Then view replay is done, swapping in the fake offsets so the view replay output
# is fully fake with no invalid specialization.
def view_from_base(base, t, source=source, shape_env=shape_env):
# fake-ify t's metadata according to the outer symbolic context
(sizes, strides, storage_offset) = sym_sizes_strides_storage_offset(
t, source
)
if not is_traceable_wrapper_subclass(
t
) and not is_traceable_wrapper_subclass(base):
# Dense -> Dense view case uses as_strided() to construct view relationship.
# TODO: Change this logic to use view replay for consistency?
# It's likely there is no view func available.
return base.as_strided(sizes, strides, storage_offset)
from torch._dynamo.source import EphemeralSource
from torch.fx.experimental.symbolic_shapes import sym_eq
def symint_visitor_fn(s):
if shape_env is None:
return s
# NB: The symbol here is expected to be simplified out because we a priori
# allocate inner and outer symbols according to the appropriate symbolic
# contexts and prefer those over this symbol during symbol simplification
# (via usage of EphemeralSource below). This -shouldn't- happen, but if
# this symbol somehow leaks out beyond the view tensor's shape metadata, our
# assumption of it being simplified out will fail and it may be guarded on,
# which will hard error.
sym_source = EphemeralSource("symint_visitor_fn")
symbol = shape_env.create_symbol(s, sym_source)
return shape_env.create_symintnode(symbol, hint=s, source=sym_source)
real_to_fake_mapping = {}
if is_traceable_wrapper_subclass(t):
# Fake-ify t naively here; this is only done so we can get fake-ified inner
# tensors with the correct relationships to the outer sizes / strides for use
# in view replay. It's done beforehand here because it's not easy to do when
# visiting tensors one-by-one during view replay.
#
# Example:
# Consider a Dense -> NJT view. NJT has (values, offsets) components and we
# want a view of values with the offsets closed over. As the offsets component
# is needed to describe the output view, it's important that it's fakeified
# correctly.
fake_t = empty_create_subclass(
t, outer_size=sizes, outer_stride=strides
)
attrs, _ = fake_t.__tensor_flatten__()
for attr in attrs:
real_to_fake_mapping[getattr(t, attr)] = getattr(fake_t, attr)
def tensor_visitor_fn(
visited_t, shape_env=shape_env, callback=callback, source=source
):
# It's possible to close over an undefined tensor (e.g. NJT's lengths).
if visited_t is None:
return None
# Fake inner tensors of view subclasses will come from the mapping built above.
fake_visited_t = real_to_fake_mapping.get(visited_t, None)
if fake_visited_t is not None:
return fake_visited_t
# For other closed-over tensor state, fake-ify it as all dynamic with an
# ephemeral source. This avoids invalid specialization during view replay.
# If we find that in practice the usage of ephemeral sources isn't enough
# to guarantee that we don't have guards on these symbols, we may need to
# explicitly suppress guards (as is done for _base in the dense -> dense
# view case).
temp_source = EphemeralSource("tensor_visitor_fn")
return self.meta_tensor(
visited_t,
shape_env,
callback,
source=temp_source,
symbolic_context=all_dynamic_symbolic_context(
visited_t, temp_source, shape_env, callback
),
)
# Replay the view, swapping out any non-symbolic SymInts or real tensors
# for symbolic SymInts or fake tensors.
fake_t = t._view_func_unsafe(base, symint_visitor_fn, tensor_visitor_fn)
# Ensure the output has symbolic shapes according to the outer symbolic context.
# These checks should simplify out any symbols created for closed-over view func
# SymInts.
torch._check(sym_eq(fake_t.size(), sizes))
torch._check(sym_eq(fake_t.stride(), strides))
torch._check(sym_eq(fake_t.storage_offset(), storage_offset))
return fake_t
# see expired-storages
self.check_expired_count += 1
if self.check_expired_count >= self.check_expired_frequency:
self.check_for_expired_weak_storages()
self.check_expired_count = 0
if self.get_tensor_memo(t) is None:
with torch.inference_mode(t.is_inference()):
if t.is_sparse:
is_leaf = safe_is_leaf(t)
# The lambda function below is similar to
# `t.to(device='meta')` except the latter
# preserves nnz value
r = callback(
lambda: torch.ops.aten._sparse_coo_tensor_with_dims(
t.sparse_dim(),
t.dense_dim(),
t.shape,
dtype=t.dtype,
layout=torch.sparse_coo,
device="meta",
)
)
assert safe_is_leaf(r), "the callback you passed in doesn't detach"
# Note [is_coalesced is dispatched]
# Strangely enough, is_coalesced() is a dispatched operator,
# which means that it will get caught by fake tensor mode.
# Ordinarily this would error, but there's some logic in
# fake tensor ensure this doesn't happen.
r._coalesced_(t.is_coalesced())
if t.requires_grad:
r.requires_grad = True
if t.requires_grad and not is_leaf:
with torch.enable_grad():
r = r.clone()
r._coalesced_(t.is_coalesced())
elif is_sparse_compressed(t):
is_leaf = safe_is_leaf(t)
def mk_meta():
nnz = 0
batch_dim = t.ndim - t.sparse_dim() - t.dense_dim()
batch_size = t.shape[:batch_dim]
if t.layout in {torch.sparse_csr, torch.sparse_bsr}:
index_dtype = t.crow_indices().dtype
compressed_indices = torch.empty(
t.crow_indices().shape, device="meta", dtype=index_dtype
)
plain_indices = torch.empty(
(*t.col_indices().shape[:-1], nnz),
device="meta",
dtype=index_dtype,
)
else:
index_dtype = t.ccol_indices().dtype
compressed_indices = torch.empty(
t.ccol_indices().shape, device="meta", dtype=index_dtype
)
plain_indices = torch.empty(
(*t.row_indices().shape[:-1], nnz),
device="meta",
dtype=index_dtype,
)
values_shape = t.values().shape
values = torch.empty(
(
*values_shape[:batch_dim],
nnz,
*values_shape[batch_dim + 1 :],
),
dtype=t.dtype,
device="meta",
)
return torch.ops.aten.sparse_compressed_tensor(
compressed_indices,
plain_indices,
values,
t.shape,
layout=t.layout,
dtype=t.dtype,
device="meta",
)
# `mk_meta()` is similar to `t.to(device='meta'))`
# except `to('meta')` preserves nnz value while
# `mk_meta` result has nnz == 0.
r = callback(mk_meta)
assert safe_is_leaf(r), "the callback you passed in doesn't detach"
if t.requires_grad:
r.requires_grad = True
if t.requires_grad and not is_leaf:
with torch.enable_grad():
r = r.clone()
elif t.is_nested and not is_traceable_wrapper_subclass(t):
# TODO: Handle this better in Dynamo?
# There are checks there now, but this can still be triggered by a dense
# tensor graph input that is a view of a strided NT.
from torch._dynamo.exc import unimplemented
unimplemented(
"strided nested tensors are not supported by meta conversion"
)
elif t.is_mkldnn:
is_leaf = safe_is_leaf(t)
sizes, strides, _storage_offset = sym_sizes_strides_storage_offset(
t, source
)
r = callback(
lambda: torch.empty_strided(
sizes, strides, dtype=t.dtype, device="meta"
)
)
assert safe_is_leaf(r), "the callback you passed in doesn't detach"
if t.requires_grad:
r.requires_grad = True
if t.requires_grad and not is_leaf:
with torch.enable_grad():
r = r.clone()
elif is_functorch_wrapped_tensor(t):
if t._is_view():
from torch._dynamo.exc import unimplemented
unimplemented(
"view functorch tensors are not supported by meta conversion"
)
# Wraps a functorch tensor class (BatchedTensor, GradTrackingTensor)
# in a FakeTensor
def _to_fake_tensor(t):
if is_batchedtensor(t):
ft = _to_fake_tensor(get_unwrapped(t))
lvl = maybe_get_level(t)
bdim = maybe_get_bdim(t)
r = _add_batch_dim(ft, bdim, lvl)
elif is_gradtrackingtensor(t):
disable_functorch = torch._C._DisableFuncTorch
with disable_functorch():
ft = _to_fake_tensor(get_unwrapped(t))
lvl = torch._C._functorch.maybe_get_level(t)
r = torch._C._functorch._wrap_for_grad(ft, lvl)
is_leaf = safe_is_leaf(t)
if t.requires_grad and safe_is_leaf(r):
r.requires_grad = True
elif t.requires_grad and not is_leaf:
with torch.enable_grad():
r = r.clone()
else:
sizes = t.size()
strides = t.stride()
r = callback(
lambda: torch.empty_strided(
sizes,
strides,
dtype=t.dtype,
device="meta",
)
)
return r
r = _to_fake_tensor(t)
elif t._is_view():
# Construct views in two steps: recursively meta-fy their
# base, and then create view(s) off that. NB: doing it
# directly from storage is WRONG because this won't cause
# version counters to get shared.
assert t._is_view()
base_symbolic_context = None
if shape_env and symbolic_context is not None:
from torch.fx.experimental.symbolic_shapes import (
StatelessSymbolicContext,
)
assert isinstance(symbolic_context, StatelessSymbolicContext)
# NB: This should generally be set when the input is a view,
# but the exception right now is for fake-ifying grads, which is
# a work in progress.
if symbolic_context.view_base_context is not None:
base_symbolic_context = symbolic_context.view_base_context
base = self.meta_tensor(
t._base,
shape_env,
callback,
source=torch._dynamo.source.AttrSource(source, "_base"),
symbolic_context=base_symbolic_context,
)
def is_c_of_r(complex_dtype, real_dtype):
return (
utils.is_complex_dtype(complex_dtype)
and utils.corresponding_real_dtype(complex_dtype)
== real_dtype
)
# In some situations, MetaConverter may be called in a
# context where autograd is disabled. For the _is_view
# assert to pass, we have to setup the autograd view
# metadata anyway. Do this by reenabling the
# ADInplaceOrView key. This is kind of a hack.
old_exclude = torch._C._dispatch_tls_is_dispatch_key_excluded(
torch._C.DispatchKey.ADInplaceOrView
)
torch._C._dispatch_tls_set_dispatch_key_excluded(
torch._C.DispatchKey.ADInplaceOrView, False
)
try:
if base.dtype == t.dtype:
pass
elif is_c_of_r(base.dtype, t.dtype):
base = torch.view_as_real(base)
elif is_c_of_r(t.dtype, base.dtype):
base = torch.view_as_complex(base)
else:
# This is not guaranteed to succeed. If it fails, it
# means there is another dtype-converting view function
# that hasn't been handled here
base = base.view(t.dtype)
# This is very tricky. Naively, you might expect this
# to hold:
#
# if t.requires_grad and not safe_is_leaf(t)
# assert t._base.requires_grad
#
# But it's not true! As you can see in the following
# program:
#
# x = torch.zeros(4)
# y = x.view(1, 4)
# y.requires_grad = True
# z = y.view(1, 1, 4)
# assert z._base is x
#
# So we may have to do *two* views out of the base to
# recreate this situation.
if safe_is_leaf(t):
# Leaf views that track view metadata are created by
# creating a view inside a no_grad block
with torch.no_grad(), maybe_suppress():
r = view_from_base(base, t)
# As it's a leaf, we can directly assign requires_grad
r.requires_grad = t.requires_grad
else:
if t._base.requires_grad == t.requires_grad:
# Easy case, just run the view op
with torch.enable_grad(), maybe_suppress():
r = view_from_base(base, t)
# NB: We don't actaully faithfully replicate
# autograd connectivity, but that doesn't matter
# today. See following for more info:
# https://gist.github.com/soulitzer/e03f015b314c3f5fcf80888c69390913
else:
# Obscure case. Create a leaf view and give it the
# correct requires_grad, then do the final view.
# NB: Can't have a non-leaf without requiring grad!
assert t.requires_grad
with torch.no_grad():
mid = base.view(base.shape)
mid.requires_grad = t.requires_grad
with torch.enable_grad(), maybe_suppress():
r = view_from_base(mid, t)
# The CreationMeta influences whether or not inplace
# mutation is an error or not. So we need to make
# sure we properly propagate this as well.
torch._C._autograd._set_creation_meta(
r, torch._C._autograd._get_creation_meta(t)
)
finally:
torch._C._dispatch_tls_set_dispatch_key_excluded(
torch._C.DispatchKey.ADInplaceOrView, old_exclude
)
else:
is_leaf = safe_is_leaf(t)
(
sizes,
strides,
storage_offset,
) = sym_sizes_strides_storage_offset(t, source, symbolic_context)
# If we have a subclass that desugars into dense tensors,
# perform our callback on each inner tensor.
if is_traceable_wrapper_subclass(t):
r = empty_create_subclass(
t, outer_size=sizes, outer_stride=strides
)
else:
r = callback(
lambda: torch.empty_strided(
sizes,
strides,
dtype=t.dtype,
device="meta",
)
)
assert safe_is_leaf(r), "the callback you passed in doesn't detach"
if t.requires_grad:
r.requires_grad = t.requires_grad
if not is_leaf:
# Fake up some autograd history.
with torch.enable_grad():
# preserve_format is the default, but we want to
# emphasize how important it is to preserve
# format here
r = r.clone(memory_format=torch.preserve_format)
# Graph-Break for wrapped tensors
if not (
is_batchedtensor(t) or is_gradtrackingtensor(t)
) and torch._C._functorch.is_functorch_wrapped_tensor(t):
return NotImplemented
s = t.untyped_storage()
swr = StorageWeakRef(s)
if swr not in self.storage_memo and (
r.is_nested
or (
r.stride() == strides
and r.storage_offset() == storage_offset
)
):
# You're normal and happy, install the fresh storage into the memo
self.storage_memo[swr] = r.untyped_storage()
else:
# You're in crazy town; somehow you gave us a tensor
# that wasn't a view, but had nonzero storage offset,
# nontrivial strides (such that clone() couldn't
# preserve them), or already aliases with another
# tensor's storage. The most typical way to end
# up here is with set_. So use set_ to bludgeon this
# in.
r_s = self.meta_storage(s, callback=callback)
# NB: In principle, this should always work, but there
# is some subtle difference in the autograd metadata
# that means we will backprop the set_ call, even if
# r is declared as an input to grad.
# See https://github.com/pytorch/pytorch/issues/87956
# for the reproducer.
# NB: The in_kernel_invocation_manager here is necessary
# for fake tensor. If we run the set_ call with fake
# tensor on, r will improperly report that it is NOT a
# meta tensor but a cpu tensor, and then the set_ call
# will fail due to device mismatch. no_dispatch() is
# not enough, because the fake tensor will still claim
# to be a CPU tensor and you'll end up in the CPU
# kernel. Arguably this is a hack; a cleaner way to
# solve this is to have a FakeStorage concept which
# would report it's CPU device--no problem now! But
# this is difficult to do because we don't have storage
# subclasses. Relevant test is
# DynamicShapesFunctionTests::test_add_dynamic_shapes in
# test/dynamo/test_dynamic_shapes.py
maybe_fake_mgr: ContextManager[None] = contextlib.nullcontext()
from torch._subclasses.fake_tensor import (
in_kernel_invocation_manager,
maybe_get_fake_mode,
)
mb_fake_mode = maybe_get_fake_mode(r)
if mb_fake_mode is not None:
maybe_fake_mgr = in_kernel_invocation_manager(mb_fake_mode)
with maybe_fake_mgr, torch.no_grad():
r.set_(r_s, storage_offset, sizes, strides)
if safe_grad(t) is not None:
from torch._dynamo.source import AttrSource
# TODO: Use a valid grad-specific symbolic context instead of recycling
# the one from t. This isn't correct if e.g. t._is_view() != t.grad._is_view().
r.grad = self.meta_tensor(
safe_grad(t),
shape_env,
callback,
source=AttrSource(source, "grad"),
symbolic_context=symbolic_context,
)
torch._C._set_conj(r, t.is_conj())
torch._C._set_neg(r, t.is_neg())
# This can be skipped if necessary for performance reasons
assert_metadata_eq(assert_eq, t, r, skip_symbolic=True)
self.set_tensor_memo(t, r)
return self.get_tensor_memo(t)
def __call__(
self,
t,
shape_env=None,
*,
callback=lambda t: t(),
source=None,
symbolic_context=None,
):
# TODO: zero tensors? We appear to have eliminated them by
# excluding complex for now
if isinstance(t, torch.Tensor) or is_traceable_wrapper_subclass(t):
if t.device.type != "xla" and any(
[
t.is_quantized,
t._is_view() and t._base is not None and t._base.is_sparse,
torch._is_functional_tensor(t),
t.device.type in ("lazy"),
# We need a way to test if a tensor is batched but there
# is no official APi to do it
# torch._C._is_batched(t),
]
):
# TODO: sparse should support meta
# NB technically to('meta') does work but our logging
# instrumentation will see the meta conversions and the
# tests all break so we just exclude this. In any case
# the to conversion isn't really right anyhow.
if torch._is_functional_tensor(t) and t.device.type != "lazy":
if t._is_view():
raise RuntimeError(
"Cannot safely fakify a view because this process drops the view information right now."
)
st = peek_interpreter_stack()
assert (
st is None or st.key() == TransformType.Functionalize
), "Expect st to be either None or have Functionalize transform key."
if st is None:
# the case of AOTAutograd
torch._sync(t)
unwrap_t = torch._from_functional_tensor(t)
with torch._dispatch.python.suspend_functionalization():
fake_t = self.meta_tensor(
unwrap_t,
shape_env=shape_env,
callback=callback,
source=source,
symbolic_context=symbolic_context,
)
out = torch._to_functional_tensor(fake_t)
torch._mirror_autograd_meta_to(fake_t, out)
return out
else:
# torch.func.functionalize
reapply_views = torch._C._functionalization_reapply_views_tls()
unwrap_t = _unwrap_functional_tensor(t, reapply_views)
pop_st_ctx = (
torch._functorch.pyfunctorch.temporarily_pop_interpreter_stack()
)
with pop_st_ctx:
fake_t = self.meta_tensor(
unwrap_t,
shape_env=shape_env,
callback=callback,
source=source,
symbolic_context=symbolic_context,
)
return _wrap_functional_tensor(fake_t, current_level())
self.miss += 1
return NotImplemented
else:
self.hit += 1
disable_functorch = torch._C._DisableFuncTorch
with disable_functorch():
r = self.meta_tensor(
t,
shape_env=shape_env,
callback=callback,
source=source,
symbolic_context=symbolic_context,
)
if type(t) is torch.nn.Parameter:
# NB: Cannot directly use Parameter constructor
# because that would force a detach, not desirable
r._is_param = True
return r
elif torch.overrides.is_tensor_like(t):
self.miss += 1
return NotImplemented
else:
# non-Tensor types don't count as hit or miss
return t
import torch._prims_common as utils