* dist train support lr decay

* update by comment

* revert elementwise method creator

* delete comment

* Refine target_assign_op to unify the classification and regression targets assignment.

* Fix the unit testing.

* Fix conflicts.

move paddle/pybind/pybind.h to paddle/fluid/pybind/pybind.h, and cancel the test_parallel_op temporary

* Added an elementary test case for CSP

* removed input

* Rename test file to avoid running in CI

* Fix YAPF error

* Remove one line function handler

* Add unit-test and example

* Fix type error

* Fix unit test cases

* Fix init error for cudaplace

* Change unit-test options

* initial commit

* fix bug

* end of file fix

* address comments

* initial commit

* minor fix

* remove redundency

* address comments

* Save the inference model in Python example of recommender_system.

* Add infer() in Python unittest recommender_system.

* Add C++ inference unittest of recommender_system.

* Refine load

* Address review comments: round 1

* Make API consistent with python-save/load

* Add another unit test

* Remove commented function

* Fix GPU bug

* Address review comments

* Modify wrt PR 8147

* Fix filenames for combined case

* Fix typo

* Address review comments: round 2

* Unify TestInference by keeping default param in template

* Address review comment

* Fix spacing

* Fix parallel.do with batch norm

* Change log level

* CopyShare AllPlaces

* disable nccl test

* bring back parallel_do test

* init polynomial_decay

* test polynomial_decay

* complete polynomial_decay

* fix conditional block op

* init scalar-switch-case-op

* switch op can compile

* complete forward switch_op

* add GetMatchCaseIndex

* add switch_grad_op

* init switch Python API

* add test_switch

* support set block list in python

* fix scope problem

* complete test

* optimize test

* optimize test

* rm backward part

* clear grad op

* polynomial_decay use switch op

* revert conditional_block_op and reshape_op

* add piecewise_decay and test

* fix piecewise_decay

* try to use condition op for switch

* can work

* clean old code

* revert

* rm switch_op.cc

* optimize code

* add attr is_scalar_condition for condition_block_op

* fix comment

* fix comment

* add export

* refine get cfgs method in memory optimization transpiler

* clean code

Impl scalar switch case op with condition op