* custom python backward

* polish up the code

* polish up the code

* polish up the code.

* Fix code format and comments.

* Delete redundant files.

* add unnittest.

* edit unnittest.

* edit unnittest.

* Remove redundant header files.

* Improve coverage and remove redundant code.

* support saving for backward.

* polish code according to comments.

* Add support type for PyLayer.

* Modify the DOC.

* polish Doc.

* polish Doc.

* polish Doc.

* polish Doc.

* polish Doc.

* polish Doc.

* polish code and make the code robust.

* Modify the code format.

* add register backward hook method

* add leaf grad accumullated test

* add layer.to api

* add layer.to api

* add layer.to api

* add the doc for Layer.to

* add input type checking

* modify assert and import bug

* format code style

* format code style

* make place support str type

* add SetGradVarBase method to set the gradient after conversion

* modify argument palce to device

* modify argument palce to device

* modify doc of layers.to API

* add xpuplace to device argument

* [feature] support npu allocator (#30840)

[feature] support npu allocator

* [feature] support npu operator (#30951)

[feature] support npu operator

* [feature] support npu allocator, part 2 (#30972)

* support npu allocator

* add npu device context

* fix some compile problem

* fix some compile problem

* add npu info

* compile ok

* fix include dir

* support naive_best_fit_allocator

* run ut ok, bug failed to exit

* call aclrtResetDevice before exit

* fix aclFinilize

* add system allocatot test

* add selected_gpus in gtest

* add tensor_test for npu

* support npu op, initial commit

* add npu stream

* add elementwise_add_op

* compile ok

* fix typo

* fix elementwise_add_op_npu_test

* support op run

* test can run but failed

* change aclopExecuteV2 to aclopCompileAndExecute

* support parsing ascend rank table file (#31000)

support parsing ascend rank table file

* Fix reshape on GE graph. (#31084)

Fix reshape on GE graph

* add npu kernel for elementwise_sub and elementwise_sub_grad (#30973)

* add npu sub op

* fix typo

* rename test

* fix bug

* fix bug

* add fp16 kernel

* fix typo

* support sub grad op

* support elementwise_sub_grad op
Co-authored-by: Nfrankwhzhang <frankwhzhang@126.com>

* Fix compilation problem (#31100)

Fix compilation problem (#31100)

* fix compile

* fix code stype

* remove const_cast

* support adding correct npu op in pybind.h (#31143)

* support adding correct npu op in pybind.h

* refine code

* [NPU] Support executor with NPU (#31057)

* [NPU] Support executor with NPU

* Fix code according to reviews

* Fix code

* Add unittest for sub op npu

* refactor npu device manager (#31154)

refactor npu device manager (#31154)

* fix selected npus

* fix compile

* fix reading flags from env

* format
Co-authored-by: Nxiayanming <41795079@qq.com>
Co-authored-by: Ngongweibao <weibao.gong@gmail.com>
Co-authored-by: Nfrankwhzhang <frankwhzhang@126.com>
Co-authored-by: Nliym27 <33742067+liym27@users.noreply.github.com>

* support control flow

* supoort sync_parameters_buffers

* fix the bug of sparse embedding

* add custom init grad for backward function

* add custom init grad for backward function

* handle when the grad_tensor is none

* handle when the grad_tensor is none

* fix the args type error on windows platform

* modify the args order and doc

* format code

* add grad_tensor to xpu

* modify the grad_tensor type check

* add paddle.backward api to support multi tensors gradient compute

* add paddle.backward api to support multi tensors gradient compute

* add paddle.atuograd module and backward api

* change tensor.backward func args

* modify tensor backward api

* remove create_graph intputs args

* add doc and examplex code for backward api

* when have the same tensor, throw error

* modify test Init func args

* modify the execute.Init func args in test files

* add paddle.autograd package in setup.py.in

* modify error msg, remove _run_backward method in class Tensor

* add test cases for backward api

* new group

* ci compatible fix

* assert nccl

* refactor and simplify hook design

* fix reducer add hook error

* add Tensor.register_hook basic impl

* refine prepare data impl

* revert prepare data change

* support register_hook for Tensor

* add hook test in model

* polish tests and doc example

* fix double grad test failed

* remove reduce hook func

* fix set empty error

* polish code by comments

* change reduce_hook to mutable_hook

* remove useless tmp_ins

* fix shape code format error

* fix shape code format error

* delete include framework.pb.h

* fix error

* add dict/str/list supprot for DataLoader. test=develop

[Kunlun]Multi xpu dygraph performance optimization , add distributed.spawn support for multi xpu and some bug-fixes (#31130)

* add cache for VariableWrapper

* modify args names and vlog level

* format code style

* add log when set cache to variable_wrapper

* add log when set cache to variable_wrapper

* add comment to variableWrapper cache

* format code style

* revert the modification of set_expected_place

* set device before op run

* add ut

* [ROCM] update fluid imperative for rocm (part1), test=develop

* [ROCM] update reducer.cc after merge, test=develop

* update reducer cmake after merge, test=develop

* use iwyu clean include second time, test=develop

* add some RecordEvent, for dygraph timeline, test=develop

* change GpuMemcpySync to memory::Copy, test=develop

* fix compile problem, test=develop

* fix compile problem, test=develop

* fix, test=develop

* fix, test=develop

* support layer_norm fp16 in dygraph amp

* add ut

* refine code

* add view strategy on squeeze,unsqueeze,reshape,flatten

* add squeeze unittest

* add unittests

* use View strategy as name rather than Reuse Allacation

* fix view api doc

* fix format

* use core.ops when input of reshape2 is Tensor

* fix test_cross_entropy_loss error because of reshape2

* fix test_cross_entropy_loss error because of reshape2

* add inplace strategy

* add elementwise_add sub

* let backward op not use inplace

* grad op do not use inplace

* fix memory increase error and add leaf error message

* delete selected_rows

* change op_function

* little change

* solve HandleViewBetweenInputAndOutput

* add unittest and leaf error message

* merge view error

* optimize op_function_generator format and support sum inplace op

* fix format of basic_engine

* fix format for framework

* little change of variable wrapper

* add reshape, squeeze, unsqueeze, scatter api

* add relu elu tanh softmax inplace api

* fix test_squeeze_op unittest

* fix test_relu_op unittest

* fix comment problems

* delete sample code of inplace api

* add reference of grad_pending_nodes in basic_engine

* fix unittest name

* add inplace apis into wlist

* fix error message

* add PADDLE_ENFORCE for set grad op twice

* fix head file error

* fix dtype of ungenerated grad var

* update ut

* refine code

* set default dtype

* fix could_use_cudnn bug

* remove debug code

* re-implement

* fix bug

* change to tensor copy sync

* change to tensor copy sync

* make copy_to safe when use TensorCopy

* refine code

* add ut

* add cudapinned garbagecollector

* add testcase: cpu place -> cuda pinned place

* simplify prepared op impl to improve performance

* fix kunlun compile error

* continue fix kunlun compile error

* only transform diff place when dtype diff

* fix failed unittests

* remove useless file

* polish impl by review comment

* support dygraph in xpu place; test=develop

* fix cpu/gpu compile error; test=develop

* fix compile error; test=develop

* fix xpu compile error; testd=develop

* try to add fwd op input dtypes

* refactor base impl

* return tmp_ins after dygraph prepare data

* fix typo found in debug

* polish comment & add complex net test

* revert detail change

* fix unittest failed

* add complex kernel condition control

* fix xpu test failed & polish comment

* polish details by review comments

* add support for complex grad accumulated

* add unittest for coverage

* update test dtype

* remove useless blank line