* rewrite the sigmoid_focal_loss code example. test=develop

* fix spelling mistake in comments of code example.test=develop

The random failure at Windows may due to some random gt_boxes can cause some numbers in YoloV3 to be negative thus access the invalid memory. This PR tries to solve it.

* add user defined func test=develop

* update test=develop

* update test=develop

* fix name conflicts test=develop

* add unittest test=develop

* change 2018 to 2020 test=develop

* add comment test=develop

* add comment for function test=develop

* fix details test=develop

* fix details test=develop

Add Yolov3 as ProgramTranslator Unit Test. The YoloV3 code is referred from PaddlePaddle/models/dygraph/yolov3

* add the support of device index for device_guard.

* add mock barrier all
test=develop

* fix
test=develop

* fix
test=develop

* fix
test=develop

* add queue_generator_op, dequeue_op, enqueue_op and ut, test=develop

* Fix the field length in LoD scenario
* Fix the missed lod info when copy tensor in dump field
* Add some log to make debug easy

* add amp_check_finite_and_scale op, test=develop

* add cpu kernel, test=develop

* use bool, test=develop

* follow comments, test=develop

* fix bilinear initializer, test=develop

* add test_bmn_model test=develop

* remove random test=develop

* fix logger of FetchHandler，which may print log twice
* test=develop

* support for iter & enumerate varbase, test=develop

* revert IsControlFlowVisitor change, test=develop

* Support return variable in only one of if body or else. 

* remove after_visit in IfElseTransformer.

* Modify the result of get_name_ids in test_ifelse_basic.py 

* Add unittest to test the new case. 

* Modify code according to reviews. 

test=develop

* Support convert_while_loop. 

* Comment code that not supported 'if' in test_break_continue. 

* Convert int into tensor to support 'if' stmt in for/while loop. 

* Add unittest to test all cases of convert_logical_XX. 

* Add unittest to test all cases of convert_while_loop. 

* Fix bug in LogicalOpTransformer. test=develop

* add crypto helper for paddle, test=develop

* cryptopp.cmake bug fixed, test=develop

* remove debug build type, test=develop

* fixed CMakeLists for new target, test=develop

* fix CI bug, test=develop

* add cmake option flag DWITH_CRYPTO, test=develop

* add crypto api for python, test=develop

* Revert "add crypto api for python, test=develop"

This reverts commit 3a1cfa9d.

* Revert "Add crypto api (#24694)"

This reverts commit 5a7a517c.

* Revert "Revert "Add crypto api (#24694)""

This reverts commit f952b19f.

* fixed cryptopp cmake building error, test=develop

* change WITH_CRYPTO building option to OFF, test=develop

* â€fixed cipher test failed, test=develop

* "add crypto api for python, test=develop"

This reverts commit 83fb55c0.

* travis CI bug fixed, test=develop

* fixed test in python3

* test=develop

* fixed unittest, test=develop

* add histc operator, test=develop

* update english doc to 2.0 API, test=develop

* update API from histc to histogram, test=develop
Co-authored-by: Nroot <root@yq01-gpu-255-129-15-00.epc.baidu.com>

* Post_training_quantization supports optimize model by fusing, test=develop

Enhance error message of checkpoint_notify_op, fake_init_op gen_nccl_id_op and listen_and_serv_op (#24554)

test=develop

The PR: https://github.com/PaddlePaddle/Paddle/pull/24651 seems causes new random failure of unit test test_parallel_executor_seresnext_base_cpu. The reason is that smaller batch size causes random optimization of neural network. I distinguished cpu/gpu batch size to fix the unittest.

replace join to terminate

* support nested input and output test=develop

* remove code of convert type(output) in unittest test=develop

* add warning test=develop

添加loss自适应的学习率衰减策略。

* Fix bug of different dtype in dygraph math_op_patch, test=develop

* support np.dtype and str, test=develop

* add unit test, test=develop

* [dy2stat] Support len

* add convert_call func

* refine code test=develop