def check_forward_ad_formula(op: Callable, args, kwargs, gradcheck_wrapper=None):
CCT = generate_cct(enable_recursive_torch_dispatch=True, autograd_view_consistency=False)
# Permutations of arg and kwargs in CCT.
for choice in generate_subclass_choices_args_kwargs(args, kwargs, CCT):
new_args, new_kwargs, which_args_are_wrapped, which_kwargs_are_wrapped = choice
def maybe_tangent(t):
assert type(t) is not CCT
# Generate `tangent` tensor
# if given object is a Tensor and requires grad is set.
if isinstance(t, torch.Tensor) and t.requires_grad:
return torch.randn_like(t)
elif is_tensorlist(t):
return list(torch.randn_like(e) if e.requires_grad else None for e in t)
return None
tangent_args = tuple(maybe_tangent(arg) for arg in args)
flat_kwargs, spec = tree_flatten(kwargs)
flat_tangent_kwargs = tuple(maybe_tangent(arg) for arg in flat_kwargs)
tangent_kwargs = tree_unflatten(flat_tangent_kwargs, spec)
# Permutations tangent arg and tangent kwargs in CCT.
for tang_choice in generate_subclass_choices_args_kwargs(tangent_args, tangent_kwargs, CCT):
new_tang_args, new_tang_kwargs, \
which_tang_args_are_wrapped, which_tang_kwargs_are_wrapped = tang_choice
with fwAD.dual_level():
def maybe_make_dual(dual):
# Returns dual tensor if primal is a tensor/tensor subclass
# with requires_grad set.
primal, tangent = dual
if isinstance(primal, torch.Tensor) and primal.requires_grad:
return fwAD.make_dual(primal, tangent)
elif is_tensorlist(primal):
return tuple(fwAD.make_dual(pri, tang) if tang is not None else pri
for pri, tang in zip(primal, tangent))
return primal
op_args = tuple(map(maybe_make_dual, zip(new_args, new_tang_args)))
op_kwargs = {k: maybe_make_dual((v, new_tang_kwargs[k])) for k, v in new_kwargs.items()}
try:
if gradcheck_wrapper is None:
op(*op_args, **op_kwargs)
else:
gradcheck_wrapper(op, *op_args, **op_kwargs)
# see NOTE: [What errors are Composite Compiance trying to catch?]
except RuntimeError as err:
raise_composite_compliance_error(
err,
f"- wrapped_args: {which_args_are_wrapped}\n"
f"- wrapped_kwargs: {which_kwargs_are_wrapped}\n"
f"- wrapped_tangent_args: {which_tang_args_are_wrapped}\n"
f"- wrapped_tangent_kwargs: {which_tang_kwargs_are_wrapped}\n"
)
import torch.autograd.forward_ad as fwAD
primal = torch.randn(10, 10)
tangent = torch.randn(10, 10)
def fn(x, y):
return x ** 2 + y ** 2
# All forward AD computation must be performed in the context of
# a ``dual_level`` context. All dual tensors created in such a context
# will have their tangents destroyed upon exit. This is to ensure that
# if the output or intermediate results of this computation are reused
# in a future forward AD computation, their tangents (which are associated
# with this computation) won't be confused with tangents from the later
# computation.
with fwAD.dual_level():
# To create a dual tensor we associate a tensor, which we call the
# primal with another tensor of the same size, which we call the tangent.
# If the layout of the tangent is different from that of the primal,
# The values of the tangent are copied into a new tensor with the same
# metadata as the primal. Otherwise, the tangent itself is used as-is.
#
# It is also important to note that the dual tensor created by
# ``make_dual`` is a view of the primal.
dual_input = fwAD.make_dual(primal, tangent)
assert fwAD.unpack_dual(dual_input).tangent is tangent
# To demonstrate the case where the copy of the tangent happens,
# we pass in a tangent with a layout different from that of the primal
dual_input_alt = fwAD.make_dual(primal, tangent.T)
assert fwAD.unpack_dual(dual_input_alt).tangent is not tangent
