* add all_reduce, reduce kernel and api

* fix all_reduce reduce ut

fix reduce op maker conflict

fix merge conflicts

* fix conflicts, rename ReduceOp->ReduceBaseOp in reduce_ops

rename allreduce op, to remove

* fix code format

fix comments

* modify test_collective_reduce_api ut timeout

* fix PR-CI-Build

fix comments: format phi operator

* clear extra attrs of reduce op in opmaker

* fix reduce_mean

* [OpAttr]Adapt tensor axis for reduce_min/max/mean/sum/prod

* move reduce_mean_grad kernel into phi

* move reduce_max/min_grad into phi

* remove raw max/min grad kernel

* fix bug

* fix max/min grad error

* move all reduce_grad kernel into one file

* add prod grad kernel

* add infermeta for prod kernel

* add reduce_max kernel

* add reduce max kernel

* update reduce max Argumentmapping

* remove reduce_max kernel

* remove reduce_max kernel

* add reduce max infermeta

* rename reduce infermeta

* replace prefix pt by pd

* replace added kernel

* revert util change

* pd kernel to phi

* resolve conflict

* resolve conflict

* modify infershape utils and rm reduce infershape

* merge develop

* fix infermete bug

* add IsForInferShape func in ArgumentMappingContext

* add reduce_mean infermeta

* modify annotation

* add default dims

* rm reduce_sum raw kernel

* remove reduce_mean kernel

* remove reduce_mean kernel

* reduce support int and int64_t

* mean support int and int64_t type

* add double grad implementation for dygraph, test=develop

* polish code, add uts, test=develop

* fix place bug, test=develop

* polish codes, add more uts for coverages, test=develop

* add no_grad_set, test=develop

* add star gan ut, test=develop

* follow comments, test=develop

* refine grad maker, test=develop

* refactor tracer stage 1, test=develop

* merge develop to solve conflict third times, test=develop

* refactor dygraph,test=develop

* fix failed unittest,test=develop

* polish code,test=develop

* check windows ci error,test=develop
try to fix windows ci error by np.allclose,test=develop

* polish vlog and profiler, test=develop

* try to fix preceding ops order,test=develop

* test transformer in windows ci, test=develop

* use python c-api to speed up tracer.trace,test=develop

* test=develop, fix docker with paddle nccl problem

* test=develop, add ut for debug string and gradient_accumulator

* test=develop, add tests for layer/gradient_accumulator/prepared_op

* test=develop, fix complie error for test_prepared_op

* test=develop, add more ut for dygraph

* test=develop, create API.spec for dygraph api change

* optimize grad maker; test=develop

* optimize grad maker

* test

* grad make optim; test=develop

* fix unittest bugs; test=develop

* add dygraph grad op maker and split_op

* grad op maker refactor; test=develop

* add dygraph grad maker; test=develop

* fix op deformable_conv_v1_op bug; test=develop

* fix deformable_conv prroi pool bugs;

* fix new op grad op maker bug; test=develop

* fix split by ref bug; test=develop

* fix dygraph auto prune bug; test=develop

* fix test_trace bug; test=develop

* fix fused emb seq pool bug; test=develop

* remove useless code in op_desc file; test=develop

* remove useless code, StrVarBaseNode; test=develop

* fix review issues; test=develop

* fix rank_loss grad maker; test=develop

* remove flag in VarBase; test=develop

* fix distributed_notify_op compile bug ; test=develop

* fix reshape op double grad; test=develop

* fix expand as op; test=develop

* add impertive type_defs.h for demo_train; test=develop

* fix inference lib cmake; test=develop

* fix inference lib; test=develop

* fix infernce_lib; test=develop

* fix inference cmake; test=develop

* fix inference lib; test=develop

* fix inference lib; test=develop

* remove condition dygraph grad maker, modify local name; test=develop

* fix split grad maker bug; test=develop

* fix pyramid_op bug; test=develop

* change travis time out limit; test=develop

* restore travis; test=develop

* change timeout limit; test=develop

* Update backward.py:
     - If there is no input grad var in all outputs of previous ops, do not append this op into graph.
     - Only apply this stragety when double backward.
* Update some double backward op.
* Update sum_op to judge whether a tensor is empty by numel or IsInitialized().

* test=develop, double backward reduce_mean

* add comment. test=develop

* fix format. test=develop

* rename GradGrad -> DoubleGrad. test=develop

* fix op_use_default_grad_op_maker.spec. test=develop

* wip simplify operator framework

* wip

* wip

* done test=develop

* clean test=develop

* fix test=develop

* fix deps test=develop

* fix cpu build test=develop

* fix tensorrt build test=develop

* fix tests test=develop

* fix test=develop

* fix cpu build test=develop

* "split into multiple .ccl"

* "refine file structure"

* "refine files"

* "remove the cmakelist"

* "fix typo"

* "fix typo"

* fix ci