* Move function 'convert_len' to file convert_operators.py 

* Support that for statements are transformed to while statements.

* Fix bug: raise None -> return None. 

* Support variable loaded and created in loop.

* Use int64 in Py2 and Py3 in function to_static_variable.

Fix the bug for elementwise_div op, when the first var is scalar; Use the shape 1 replace the -1 in shape.

[Dy2stat] Add word2vec as unittest

Add the support the 5d,6d tensor support for the reduce ops;
Add the same time, the compile time, it was 22 minutes, it was 21 minutes after fixed.

test=develop

* modify coverage gcc48 and gcc8 dockerfile trt's url, add gcc8 dockerfile pip tuna source,test=develop,test=document_fix

* delete pip tuna source,test=develop,test=document_fix

* add openmpi's description,test=develop,test=document_fix

test=develop

* add -DPADDLE_CUDA_BINVER. test=develop, test=win_gpu

* nvcc will use add_compile_options, avoid using it if you don't want to pass arguments to nvcc. test=develop

* test=develop, test=win_gpu

fixes the CUDAPlace info in the Print op

* Support LoDTensorArray in reverse_op test=develop

* polish en doc and unittest code test=develop

* refine sample code test=develop

* add example of LoDTensorArray test=develop

* fix typo test=develop

* refine err_msg of pybind.cc, test=develop

* refine err_msg in tensor_py.h, test=develop

* refine error msg, test=develop

* fix test_exception, test=develop

* follow comments, test=develop

* refine isfinite, test=develop

* use namespace std of isfinite, test=develop, test=win_gpu

* cast var in convert_logical_XX. 

* Add convert_ifelse function in convert_operators.py  

* Add logical_transformer. Remove LogicalTransformer from loop_transformer.py 

* Revert modified tests in PR24799(convert_while_stmt). 

* Comment and modify code that doesn't support `return` statement. 

* Remove unnecessary class: MergeAssignTransformer, NodeTestTransformer and IfConditionVisitor in ifelse_transformer. 

* support selectedrows allreduce in multi-cards dygraph, test=develop

* remove useless import modules in unittests, test=develop

* add nccl cmake to get nccl version, test=develop

* add if-condition to compiled correctly, test=develop

* add detail version parseing for old nccl, test=develop

* polish camke details, test=develop

* fix remove test cmake error, test=develop

* fix cmake condition, test=develop

* change unittest camke list, test=develop

* fix unittest cmake rule, test=develop, test=framep0

* rewrite the sigmoid_focal_loss code example. test=develop

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

* support CUDA using cmake built-in way (#24395)

* support CUDA using cmake built-in way. test=develop

* test=develop

* cmake_minimum_required 3.10

* test=develop

* test=develop, fix a bug

* test=develop, remove the macro of PADDLE_DLL_INFERENCE

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 grep enforce shell, test=develop, test=document_fix

* add copyright desc, test=develop, test=document_fix

* refactor four scripts, test=develop, test=document_fix

* change white list var, test=develop, test=document_fix

* add args for count_enforce_by_file, test=develop, test=document_fix

* 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