def __enter__(self):
assert not self.entered, "Forward mode manager can be entered only once."
self.entered = True
impl.get_runtime().materialize()
if not isinstance(self.loss, list):
self.loss = [self.loss]
# Currently we only support only one N-D field as a group of parameters,
# which is sufficient for computing Jacobian-vector product(Jvp).
# For cases with multiple groups of parameters, it requires to run the forward ad multiple times,
# which is out of scope of the current design for this interface.
# TODO: support vector field and matrix field
assert isinstance(self.parameters, ScalarField)
all_fields = [*self.loss, self.parameters]
fields_without_dual = []
for x in all_fields:
if not x.snode.ptr.has_dual():
fields_without_dual.append(x)
if len(fields_without_dual) > 0:
dual_root = FieldsBuilder()
for x in fields_without_dual:
allocate_dual(x, dual_root)
dual_root.finalize()
def shape_flatten(shape):
return reduce((lambda x, y: x * y), list(shape))
parameters_shape_flatten = shape_flatten(self.parameters.shape)
# Handle 0-D field
if parameters_shape_flatten == 0:
parameters_shape_flatten = 1
if not self.seed:
# Compute the derivative respect to the first variable by default
self.seed = [0.0 for _ in range(parameters_shape_flatten)]
self.seed[0] = 1.0
else:
assert parameters_shape_flatten == len(self.seed)
# Set seed for each variable
if len(self.seed) == 1:
self.parameters.dual[None] = 1.0 * self.seed[0]
else:
for idx, s in enumerate(self.seed):
self.parameters.dual[idx] = 1.0 * s
# Clear gradients
if self.clear_gradients:
for ls in self.loss:
ls.dual.fill(0)
# Attach the context manager to the runtime
self.runtime.fwd_mode_manager = self
def materialize_root_fb(is_first_call):
if root.finalized:
return
if not is_first_call and root.empty:
# We have to forcefully finalize when `is_first_call` is True (even
# if the root itself is empty), so that there is a valid struct
# llvm::Module, if no field has been declared before the first kernel
# invocation. Example case:
# https://github.com/taichi-dev/taichi/blob/27bb1dc3227d9273a79fcb318fdb06fd053068f5/tests/python/test_ad_basics.py#L260-L266
return
root.finalize(raise_warning=not is_first_call)
global _root_fb
_root_fb = FieldsBuilder()