* Create elementwise_heaviside_op.cc

* add ElementwiseHeavisideFunctor

* Create test_elementwise_heaviside_op.py

* 增加heaviside的python接口

* add heaviside in white list

* 增加heaviside的签名

* 增加heaviside的核函数

* 增加heaviside梯度的核函数

* 增加heaviside梯度的注册

* 调整代码格式

* Update elementwise_sig.cc

* add heaviside in __all__

* Update heaviside docs

* Update math.py

* Update math.py

* Update math.py

Revert "Revert "[Phi] Move elementwise_floordiv and elementwise_pow to phi (#40993)" (#41065)" (#41110)

This reverts commit 3a6f1135.

This reverts commit b532315d.

* mv floordiv to phi

* mv elementwise_pow to phi

* fix as review

* move elementwise_div grad

* change mutable_data to alloc

* fix compile bugs

* move elementwise function to funcs directory

* fix compile bugs

* modify according to comment

* remove SetAllocationForOutputTenosr

* add place param for copy kernel

* recover SetAllocationForOutputTenosr

* polish code

* fix empty_dev api bug

* test=allcases

* test=allcases

* fix bug

* recover empty

* recover modify

* rename pten dir to phi

* rename namespace to phi

* rename infrt pten dir to phi

* resolve conflict

* rename pten to phi in cmake

* revert all infrt change

* change needed files

* fix infrt failed

* fix inference failed

[Pten]Refactor elementwise_add grad / double grad / triple grad Kernel and move them to pten (#39048)

* refactor elementwise add grad

* fix compile bugs

* fix unit test bugs

* fix file conflicts

* fix bugs when buildPtenContext