* move fc from fluid to paddle2.0

* fix unit test

* fix some examples

* fix some examples

* replace cross_entropy in python/paddle/fluid/tests/unittests/test_[o-z]*.py plus test_dist_transpiler.py

* fix test_prune

* remove layers.matmul in nets.py

* remove layers.matmul in rnn_impl/test_quantization_pass/auto_parallel_gpt_model/test_auto_parallel_completion_gpt

* remove layers.matmul in other files

* fix

* fix

* remove layers.matmul itself

* remove ref in CMakeLists.txt and tools directory

* remove matmul in fluid.layers.nn.py

* remove matmul in fluid.dygraph.rnn.py && resotre test_matmul_op.py

* replace matmul in fluid.dygraph.rnn.py && clean api_test in test_matmul_op.py

* fix error && restore empty test_auto_search_dist_matmul_op.py

* fix check in test_auto_parallel_partitioner.py

* fix test_dist_matmul && test_flags_mkldnn_ops_on_off

* fix test_fused_attention_op_xpu.py && test_matmul_op_xpu.py

* remove test_auto_search_dist_matmul_op.py

* remove layers.matmul in auto_parallel_gpt_model.py && fix doc in fluid/io.py

* fix for matmul_grad

* fix codestyle

* fix codestyle

* resolve conflicts error

* restore unit test file but not compiled it for later remove

* fix codestyle

* fix wrong unittest skip

* fix unittest delete

* fix scale cost

* fix scale cost

* resolve conflicts error

* resolve conflicts error
Co-authored-by: Njakpiase <jakpia21@gmail.com>

* clear fluid apis in fleet and passes

* fix model.py

* fix model.py

* fix cpp_pass.py

* clear loss.py

* change test file

* fix some test_*.py

* fix adaround.py

* fix evaluator.py

* fix CI bug

* fix CI bug

* fix decode.py

* fix detection.py

* fix ci bug

* rm test_sigmoid_cross_entropy_with_logits_op_ipu.py and fix __init__.py

* fix ci bug

* fix ci BUG

* clear fluid api: sigmoid_cross_entropy_with_logits

* fix loss.py

* change paddle.nn.functional.sigmoid_cross_entropy_with_logits

* delete sigmoid_cross_entropy_with_logits

* fix binary_cross_entropy_with_logits

* fix ci bug

* fix ci buf

* isort all files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* revert conflicting files

* clear fluid api: warpctc, nce, identity_loss

* fix test_layers.py __init__.py

* fix loss.py

* change __init__.py and api calling method

* fix nce

* fix nce

* fix fluid.data

* delete warpctc api document

* fix loss.py

* fix ctc_loss

* fix test_warpctc_op.py

* fix test_layers.py

* fix some bug

* fix conflict

* fix ci bug

* Empty Commit test=allcase

* fix ci bug

* 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

* clear fluid apis: center_loss, bpr_loss, edit_distance, hsigmoid, sampled_softmax_with_cross_entropy, rank_loss, margin_rank_loss,  sigmoid_cross_entropy_with_logits, huber_loss

* fix python/paddle/fluid/layers/loss.py

* fix test_layers.py

* fix CI bug

* fix nn.py

* remove reshape in nn.py under fluid

* remove reshape reference

* fix test case

* fix test case in distribution.uniform

* remove fluid reshape reference

* [CodeStyle][py2] remove unnecessary u-prefix in string literal

* `"{}".format(x)` -> `x`

* remove duplicated dtype literals

* revert changes in data_feeder.py

* remove u-prefix in data_feeder

* revert remove duplicated dtype literals in data_feeder

* remove unnecessary convert to str

* for test

* add some comments

* refine comment

* restore a removed str conversion

* re-trigger all ci, empty commit

* [CodeStyle][py2][U008] remove unnecessary args in `super()`

* remove remained args

* revert changes in test_pylayer_op

* Revert "revert changes in test_pylayer_op"

This reverts commit ff185a9ae738afac3b0264f61bde6c6b7f72e7c4.

* revert some changes in example code

* 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

* change fluid.mean to paddle.mean

* reverse some old code examples

* 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

Integrated Trainer of Parameter Server (API add `fluid.contrib.layers.sparse_embedding` only) (#22957)

* Integrated Trainer of Parameter Server

* test=develop, bug fix for sparse recorder

* add fake init for the trainer, fix large memory hold in the trainer
* do not merge recv vars from a remote endpoint, test=develop
* add recv and save op, merge slice var in one op, save memory
* remove hsigmoid with pull sparse, test=develop

test=develop

test=develop

test=develop

checkpoint for distributed training.

* add nccl2 dist tests test=develop

* fix dist_base test=develop

* fix tests test=develop

* fix test on mac test=develop