* Open fuse all reduce op
test=develop

* Add Fuse optimization op log

* Add log in fuse_optimizer op pass and fuse all_reduce op pass

* replace with boost::optional<bool>
test=develop

* Polish code
test=develop

* fix code coverage
test=develop

* add one_hot_v2_op to remove last_dims==1 test=develop

* add api unittest code for CI_Coverage test=develop

* improve CI_Coverage rate by adding test_with_depth test=develop

test=develop

- fix to BWD

test=develop

TemporaryAllocator is a singleton used for allocating memory for Cudnn. Since it is a singleton, we can delete it for better performance in memory.

We replace TemporaryAllocator by CUDADeviceContextAllocator and CUDADeviceContextAllocation, which uses stream callback to delete the memory allocated for the stream to avoid singleton.

Also added data_feed_proto to operator to fix CI in CPU compilation

* make leaky relu inplacable, test=develop

* force add unittests to pass coverage, test=develop

Fix test_parallel_executor_test_while_train 

* fix vlog level and fuse option type
test=develop

test=develop

- Cosmetic fixes

test=develop

* Refine the codes related to fc op.

* Add GPU implementation for fc functor.

* Apply fc_fuse_pass in GPU inference.
test=develop

* Change the cmake for fc op.

* Change PADDLE_ENFORCE to PADDLE_ENFORCE_EQ.

* Add an attribute to set the activation type in fc_op.

* Enhance the unittest of fc_op.
test=develop

* Remove the declaration of FCOpGrad back to the header file.
test=develop

* Set default value for newly added arguments in test_fc_op.
test=develop

* Remove constraint that last dimension is forced to be 1 in huber_loss
test=develop

* add y[rank-1] == 1 when x_rank=y_rank test=develop

* modify into contain_unknown_dim test=develop

* Enable fused_all_reduce_op_handle support GPU and CPU Gradients

* update dygraph api-doc and backward api-doc, test=develop

* update dygraph api-doc and backward api-doc, update api.spec, test=develop

* update dygraph api-doc and backward api-doc, update api.spec, test=develop

* update API.spec, test=develop

* fix dygraph partitial backward problem, test=develop

* add unittest, fix ClearGradient. test=develop

* add filter and error in python side, test=develop

* rebase develop, test=develop

* bug fix for list equals in py3.5, test=develop

* bug fix for list equals, test=develop

remove unused accuracy-diff warpctc-cudnn implementation

test=develop

* split teacher checkpoints with student checkpoints, test=develop

* add unittest for graph.merge(), test=develop

* MKLDNN handler cleanup

* MKLDNN handler cleanup
test=develop

test=develop

Add document annotations for FLAGS that need to be open to external developers test=develop (#19692)

Add document annotations for FLAGS that need to be open to external developers

* merge_empty_lod_tensor, test=develop

* fix multiclass_nms, test=develop

* refine API.spec, test=develop

* add unittest case for fetch, test=develop

* add lod tensor test, test=develop

* return index for multiclass_nms, test=develop

* add api for multiclass_nms2

* update API.spc, test=develop

* refine api doc, test=develop

* fix test_detection.py, test=develop

* polish code, test=develop

* add more unittest case, test=develop

* fix instag op

* fix instag bug: Some tiny logical error, occurring when ins_tag (2nd input) is multiple. test=develop

Fix float16 optimizer

* add prune when test_program.clone is executed after optimizer.minimize

* add unittest, test=develop

* add resnet and transformer test case, test=develop

* add regularization for optimizer & program compare function, test=develop

* add lstm unittest, test=develop

* polish code based on review comment, test=develop

* adapt to interface change in framework._prune, test=develop

* update API.spec, test=develop

* add kernel for unsqueeze_op, test=develop

* add kernel for unsqueeze_op, test=develop

* add kernel for unsqueeze_op, test=develop

* delete args on linear_chain_crf_op doc

* delete args on linear_chain_crf_op doc

* delete args on linear_chain_crf_op doc

* add code example

* fix api doc

* fix doc of crf

* fix doc of crf

* add test=develop

* modify API.spec, test=develop

* paddle::framework::vectorize() templatization

test=develop

* update pybind/imperative.cc

test=develop

* revert update on unsqueeze_op.cc and warpctc_cudnn_op.cu.cc

test=develop

Update README_cn.md to latest version v1.5.2

Update README.md to latest version v1.5.2

fix cmakelist deps: remove unnecessary deps and add proper op deps

* remove -Wmaybe-uninitialized warning

test=develop

* remove uninitialized op_handle_ in scale_loss_grad_op_handle.cc

test=develop