* add to and detach for Variable in dygraph, test=develop

* add detach for Variable in dygraph, test=develop

* add detach for Variable in dygraph, test=develop

* add detach for Variable in dygraph, test=develop

* add detach for Variable in dygraph, test=develop

* add detach for Variable in dygraph, test=develop

* add exception check, test=develop

* test=develop, Support for online compilation of openblas

* test=develop, Modify the prefix of openblas static library

test=develop

test=develop

test=develop

* Add a interface to enable cudnn for inference.

* Add cudnn_placement_pass.
test=develop

* Set the default value of cudnn_enabled_op_types to null.
test=develop

* Write the common basic class, placement_pass_base, to refine the codes.
test=develop

* Call EnableCUDNN in unittest.
test=develop

* Refine cudnn_placement_pass tester.

* Enable the testing of cudnn_placement_pass in inference's unittest.
test=develop

* Add the check of op kernels.
test=develop

* modify paddle_build.sh for Paddle python3 version image generation, test=develop

* modify paddle_build.sh for Paddle python3 image generation, test=develop

* using MKLDNNMemoryFormat = mkldnn::memory::format changes
test=develop

* PADDLE_ENFORCE update
test=develop

Disable test_boxps in win32.
Adjust filename to avoid latent multi-thread problem.

* update ngraph ops test=develop

* update unittest test=develop

* increase coverage test=develop

* remove unused PADDLE_ASSERT(_IS_NOT_ERROR)

* replace PADDLE_ASSERT with PADDLE_ASSERT_MSG

test=develop

Change backward_guard to optimize_guard to maximize the allreduce overlap

* fix batchnorm api param: data_layout

* fix batchnorm data_layout param; test=develop

test=develop, test=document_preview

* add padding in linear_chain_crf op

* modify API.spec

* add linear_chain_crf_op.cc and linear_chain_crf_op.h

* remove useless unit test , test=develop

* modify API.spec, test=develop

* remove some blanks in nn.py , test=develop

* fix some bugs on nn.py and API.spec ,test=develop

* fix nn.py, test=develop

* fix API.spec ,test=develop

* fix bug of CI test in test_linear_chain_crf_op.py

* fix bug of CI test in test_linear_chain_crf_op.py, test=develop

* remove paddle_enforce, test=develop

* remove paddle_enforce, test=develop

* remove paddle_enforce, test=develop

* remove paddle_enforce, test=develop

* remove paddle_enforce, test=develop

* remove paddle_enforce, test=develop

* modify nn.py, test=develop

* fix API.spec, test=develop

* fix unittest bug, test=develop

* remove the obsolete cmake options, test=develop

* remove unittests, test=develop

* delete options in paddle/scripts/paddle_build.sh

* add place to reader, remove snappy dependency

* remove snappy dependency from train demo

test=develop

* - First set of modifications

- Compilation fixes

- compilation fix

- Another compilation fix

- Moved AcquireSoftmaxPrimitiveDescriptor call into handler

- MKL-DNN Softmax PD refactor

test=develop

- Compilation fix

test=develop

- another compilation fix

- cosmetcis

test=develop

- Compilation fix

- Fix to crash when softmax backward is created

* - Fixes after review of softmax refactoring

test=develop

* add retry_allocator for gpu, test=develop

* follow chengduoZH's comments, test=develop

* follow huihuang's comments,test=develop

* change f,l in enforce.h to be file,line, test=develop

* increase code coverage by adding unittests, test=develop

* fix CMakeLists.txt, test=develop

* Support looking up embeddings from BoxPS.
* Add a _pull_box_sparse op, for now this op is not exposed to users.
* Add a BoxHelper class, providing 'BeginPass', 'EndPass', 'FeedPass' functions and so on.
* Add 'BoxPSDataset' in python code.
* Add a compile options WITH_BOX_PS and a MACRO PADDLE_WITH_BOX_PS.
* Add UT.
* More concrete information pls refer to: https://github.com/PaddlePaddle/Paddle/pull/18982

* fixed the code for coverage

* fixed the document,test=document_preview test=develop

- Refactor step 1

- Compilation fix

- Yet another compilation fix

- Even more compilation fix

- Lint fixes

test=develop

- Removed deprectaed PADDLE_ENFORCE occurance

test=develop

- Candidate fix to BN forward

- Lint fixes

test=develop

- Refactoring in data_layout_transform

- compilation fix

- Another comppilation fix

- Step further into darkness

- Yet another compilation fix

- Yet another compilation fix

- missing header

- compilation fix

- Added MKLDNN -> Paddle conversion in fetch op

test=develop

- Compilation fix

test=develop

- Lint

test=develop

- Mul fix

- Fix to MKLDNN MUL op and Elementwise MUL UT

test=develop

- Workaround for diffrent weights with groups representation Paddle vs
  MKL-DNN.

test=develop

- Candidate fix for 5D convolution with groups

- Refactor of fix for conv3d and conv2d in fetch op

test=develop

- Compilation fix

- Still same compilation fix

- Compilation fix

- Compilation fix

- Reverted refactoring of fixes

- Adapted test_conv2d_int8_mkldnn so it exects data in NCHW format
  not NHWC

test=develop

- minor fix in UT

test=develop

- Lint fixes

test=develop

* Modify the dropout op to multi-thread
test=develop

* define parallel
test=develop

test=develop

* add topk_avg_pooling

* refine api doc and modify api.spec test=develop

* Disable GC in test_parallel_executor_se_resnext
test=develop

* add thread scope stat accurate metrics test=develop

* fix style

* fix style

* fix style

* fix style test=develop

* fix style test=develop

* fix style test=develop

* fix style test=develop

* fix style test=develop

* fix style test=develop

* fix style test=develop

* fix conflict

* fix style

* fix style test=develop

* fix error test=develop

* fix error test=develop

Fix mean_iou api misleading example

test=develop