* add pure fp16 major function in auto_cast & tracer

* support master weight in dygraph for pure fp16

* check mix dtype of fp16&fp32 for check_finite_and_unscale op

* change pure fp16 funtion name

* refine some bug in auto_cast

* refine auto_cast interface logic

* add param _casted_by_pure_fp16 for class Layer

* support state_dict hook for save model by user appointed dtype in pure_fp16_decorator

* refine pure_fp16_decorator as decorator

* add unittest

* add comment

* add comment

* support recompute

* add comment for auto_cast and decorator

* support to_static_state_dict for paddle.jit.save

* unlimite models num and optimizers num

* add lookup_table in black_list

* fix momentum and layer state_dict

* fix bug in layer state_dict

* fix bug in layer state_dict_helper

* refine unittest

* refine test_momentun_op

* refine interface and some code

* refine amp_decorator interface

* refine pure fp16 interface

* refine master weight interface

* add layerwise learning rate for adamw

* fix format

* add unitest

* add NotImplementedError

* add gpu unitest

* update gpuplace

* fix warning error , test=document_fix

* fix warning error , test=document_fix

* fix warning error , test=document_fix

* fix warning error , test=document_fix

* fix warning error , test=document_fix

* fix warning error , test=document_fix

* fix warning error , test=document_fix

* adamw support cuda

* adamw support cuda

* fix paddle.optimizer test=document_fix

* fix paddle.optimizer test=document_fix

* fix lr in param group

* add unittest for adamw

* cache core.ops, test=develop

* refine, test=develop

* exclude lr scheduler's state from accumulators_holder

* fix when there is no learning rate scheduler

* make a copy of the loaded state dict to avoid modifying it

* opt dygraph python API, test=develop

* Fix unbind bug in manipulation.py

This reverts commit b2afc8df.

* fix Undefined variables

* fix Undefined variables

* fuse L2Decay and momentum when param.regularizer is set

* add unittest

* refine

* refine _create_regularization_of_grad of momentum

* improve append_optimizer_op

* support params groups, test=develop

* simplify updating opt attr

* update according to review

add __all__=[] to python files not in API public list; import * only support in API public list files (#32643)

* add input EpsilonTensor for adam

* update python api

* add unit test

* add npu test

* add more ut

* fixed docs.

* Fixed docs. test=document_fix

code bak.

fixed docs. test=document_fix

* Revert to previous version of python/paddle/fluid/backward.py

* fixed bugs.

* test=document_fix. Fixed examples.

* add support for optimizer with varbase input

* refine cond

* fix failed unittest

* add test for coverage

* Use correct master weights in AdamW.

* Just modify the master weight.

* Update for CI Coverage.

* Modify the calculation logic of LambOptimizer

* add cast ops before and after unsupported fp16 ops.

* Keep partial net in FP32 pattern.

* Support check_finite_and_unscale and update_loss_scaling for FP16 calculation mode.

* Add fp16 support for adam op.

* add multi precision attr for adam.

* Fix the bug of test_multi_precision_fp16_train UT.

* Code format for CI.

* Fix the redefine error about MPTypeTrait on windows.

* fix bugs of the _create_accumulators func in Momentum.

* fix bug when inserting post cast op.

* Add the update_loss_scaling op in allow_set of UnusedVarCheck.

* Update for ci coverage.

* Add some doc for OptimizerWithMixedPrecision.

* Fix the code style.

* Imporve the doc of `amp_init`.

* Change for fp16 testing if users have the infer program defined in separate way.

* fix code bugs

* fix code bugs test=document_fix

* fix code bugs test=document_fix

* merge amp related function in Momentum from paddle.fluid.contrib.optimizer into paddle.optimizer.

* Add unittest for 2.0  Momentum API.

* fix some bugs in weight_decay.

* fix 3 doc

* fix 3 doc

* Update adadelta.py

* add lamb optimizer and unittest

* fix momentum resume training

* fix momentum acc