* replace paddle.fluid.layers.data and remove io.data

* partial commit

* partial commit

* partial commit

* partial commit

* partial commit

* partial commit

* remove data in fluid.layers.io.__all__

* fix errors

* fix unitests

* fix unitest

* fix unitests

* fix unitest

* fix unitest

* fix unitests

* fix unitest

* fix test_layers unitests

* fix typro

* fix unitest

* fix unitest

* fix unitest

* fix typro

* fix unitest test_model_cast_to_bf16

* fix test_reducescatter

* fix collective unitest

* fix collective unitests

* fix collective unitests

* add coverage

* fix add layers.data

* re run ci

* fix some typro

* fix samplecode error

* fix samplecode error

* remove pool2d

move paddle.fluid.layers.tensor.create_parameter to paddle.tensor.creation.create_parameter (#48579)

* remove fluid.reduce_sum

* remove fluid.reduce_sum

* modify axis and import paddle

* modify keepdim and out_name

* modift unittest

* modift unittest

* modify CI_static and loss.py

* modify test_mse_loss

* modify static ci

* modify static ci datatype

* add import paddle in test

* fix conflict

* fix conflict

* modify ci

* modify ci

* fix_conflict

* fix bug

* code_style

* remove expand and eye under fluid.layers

* delete expand API test case

* remove reshape in nn.py under fluid

* remove reshape reference

* fix test case

* fix test case in distribution.uniform

* remove fluid reshape reference

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* [CodeStyle] remove all future import

* revert test_error.py

* restore future import in example code

* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* add pad3d_double_grad yaml and test case

* add squeeze and unsqueeze double grad

* add double grad config

* add pad_grad and pad_double_grad yaml

* add pad_double_grad in config

* add tile double_grad yaml and test case

* add expand double yaml and test case

* add clip dobule grad yaml and test case

* add concat dobule grad yaml and test case

* add abs double grad yaml and test case

* add pool2d double grad yaml

* add pool2d dygraph double grad test case

* enable new executor by default

* enable stream safe allocator

* test=document_fix;test=coverage

* do not use scope in op kernel

* fit empty program for new executor

* fix communication depend

* fix test_sync_batch_norm

* skip unsupported place

* refine datatransfer

* fit for dirtributed program

* fix dependencpy

* fix some ut

* add pool2d grad grad

* dbg

* add unittest

* update format

* add more unittests

* dbg

* add constant pad double grad

* add transpose double grad test=develop

* Add double grad in Squeeze and Unsqueeze

* Add double grad in Squeeze and Unsqueeze

* add matmul doublegrad op

* fix compile errors

* modify code according to review

* delete float16

* add double grad for tile, test=develop

* add double grad for expand_v2 op, test=develop

* add double grad for expand, test=develop

* set default value to strategy in distributed_optimizer test=develop

* support slice double grad, test=develop
* merge two doublegradopmaker to one doublegradopmaker,test=develop
* change the shape of slice_OP's unittest, test=develop

* support reshape doubel grad, test=develop

* fix reshape double grad, pass converage, test=develop

* fix review, test=develop

* cpu conv_grad_grad

* double backward, elementwise_div

* fix dx empty. test=develop

* bug fix (#17392)

fix secure bug

* Eanble stack operator for a Ngraph, test=develop (#17406)

* fix sqrt_grad_grad unittest. test=develop (#17410)

* fix sqrt_grad_grad unittest. test=develop

* disable sqrt_grad_grad unittest. test=develop

* test=develop, fix unittest

* test=develop, fix unittest

* test=develop, fix unittest

* test=develop, fix bug

* fix unittest. test=develop

* fix unittest dx. test=develop

* tmp fix! for test... test=develop

* reduce tmp, test=develop

* test=develop, reduce tmp

* fix broadcast unittest. test=develop

* fix format. test=develop

* refine code. test=develop

* refine code. test=develop

* refine GetDoubleGradSafeTensor. test=develop

* fix format. test=develop

add elementwise_sub_grad_grad op for backward of backward calculation

* fix sqrt_grad_grad unittest. test=develop

* disable sqrt_grad_grad unittest. test=develop

* double backward sqrt

* refine unittest. test=develop

* refine test. test=develop

* remove alpha in unittest. test=develop

* test=develop, double backward reduce_mean

* add comment. test=develop

* fix format. test=develop

* rename GradGrad -> DoubleGrad. test=develop

* fix op_use_default_grad_op_maker.spec. test=develop

* add elementwise_add_grad_grad op. test=develop

* use defined GradMaker. test=develop

* add double grad for mul_op. test=develop

* fix format. test=develop

* fix format. test=develop

* fix format. test=develop

* refine code. test=develop

* remove setzero. test=develop

* fix dx/dy init bug. test=develop

* fix format. test=develop