* add API switch_case. test=develop

add Nest

* modify code according to reviews:
1.Attr(branch_index) support 'uint8' and 'int64' besides 'int32'.
2.remove useless code.
test=develop

* replace fluid.layers.data with fluid.data and polish API document. test=develop

* Support  more ops in post training quantization, and save the output scale in quantized op.
* Update docs in post training quantization and qat 

* fix cache table bug
* add save_paddle_inference_model
* fix hdfs util bug
* test=develop

* copy some feasigns and corresponding embeddings from one sparse table to another
* copy all feasigns and corresponding embeddings from one sparse table to another
* copy all dense params from one table to another
* copy some local vars to other local vars

* friendly trace interface, test=develop

* refine TracedLayer, test=develop

* add some docs, test=develop

* add input type and dtype check template, and update some APIs check

* refine check template, and update some APIs check in nn.py

* update some APIs check in loss.py

test=develop

test=develop

use 2 cards test=develop

* Split some APIs from nn.py to loss.py

test=develop

* fix test_detection unit-test

test=develop

* Add Asypadding for conv fusion.

test=develop

reference: pr/20042

* Fix eigen build link error

* Change back file mode

* Use math function & add more checks.

modify the implementation of save_persistables and save_inference_model for fleet collective mode (#20802)

* modify the implementation of  save_persistables and save_inference_model functions for fleet collective, test=develop

* add ut, test=develop

* fix instance norm

* update unitest,test=develop

* set the default value of alpha for prelu to 0.25, test=develop

* add the call to __syncthreads(), test=develop

* fix the implementation of cpu prelu, test=develop

* repair the implementation of element mode prelu, test=develop

* modify test_prelu_op.py, test=develop

* Add the check of lod_level between compile-time and runtime.
test=develop

* Fix bug in check_compile_vs_runtime.
test=develop

* Fix the check of output when it is dispensiable or intermediate.
test=develop

* Share lod of x to out in match_matrix_tensor op in compile-time.

* Implement GetLoDLevel in InferShapeContext.

* Set the default value of check_compile_vs_runtime to False and enable it in test_sequence_pad_op.
test=develop

* Enable check_compile_vs_runtime in test_match_matrix_tensor.

* Add the implementation of SetLoDLevel in InferShapeContext.

* Remove the implementation of IncreaseLoDLevel and call Get/SetLoDLevel instead.

* Remove the implementation of DecreaseLoDLevel and call Set/GetLoDLevel instead.

* Refine some ops and unittests.
test=develop

* Fix a typo.
test=develop

* Remove the check of var type, and change int to int32_t.
test=develop

* Add unittest for Get/SetLoDLevel.
test=develop

* split some APIs from nn.py to rnn.py

* split some APIs from nn.py to sequence_lod.py

test=develop

* fix unit-test bug

test=develop

* fix test_layers unit-test bug

test=develop

* Add transpose2 INT8 for mkl-dnn

test=develop

* Fix test_transpose_int8_mkldnn

test=develop

* Revert "Merge branch 'develop' into transpose_int8_mkldnn_2"

This reverts commit 34011bdb, reversing
changes made to 2ce6473f.

* Revert "Revert "Merge branch 'develop' into transpose_int8_mkldnn_2""

This reverts commit 23754dd7.

* Add template to TransposeMKLDNNHandler

test=develop

* Resolve conflict

test=develop

* Restore get_size and refactor

test=develop

fix bug in pool/conv/conv_transpose: UpdatePaddingAndDilation, _get_padding_with_SAME and conv2dtranspose_forward_naive. (#20997)

* fix bug in pool/conv/conv_transpose:
1. It should be stride[i] not stride[0] in UpdatePaddingAndDilation;
2. fix bug of func  _get_padding_with_SAME in test_conv/conv_transpose_op.py;
3. fix bug of the computation process in function conv2dtranspose_forward_naive.
test=develop

* change test to make the data of different dimensions different. test=develop

* Add asymetric padding support for mkldnn pooling
test=develop

* Add asymetric padding support for mkldnn conv
test=develop

* Add asymetric padding support for mkldnn conv_transpose
test=develop

These ops are useful in control flow.

* fix uniform random; test=develop

* add uniform random test; test=develop

test=develop

* Fix bug for inserting add_quant_dequant_op to same variable repetitively in add_quant_dequant_pass, test=develop

* add post training quantization, test=develop
* specify the quantizable op type, test=develop

* Add c++ global current tracer for dygraph, test=develop

* add tracer property in c++, test=develop

* support different place, test=develop

* add unittest for tracer, test=develop

* remove duplicate code and duplicate config of master+patch
* drop all ins which has conflict slot or size < merge_size
* user only need to set merge size，if ins num of same id is not equal to merge size, just drop these ins
* user must make sure master data and patch data has no same slot whose feasigns are both non-zero, otherwise these ins will be dropped. (slot list should still be the same of both master and patch)
* test=develop