The basic idea is: exploits data dependency to control the execution order
of side-effect operations, and keep the semantics of ANF unchanged.

The ControlDepend primitive is removed and there are two primitives added:

1. UpdateState:
```
  a = Assign(para, value)
```
became:
```
  a = Assign(para, value, u)
  u = UpdateState(u, a)
```

2. Load:
```
  x = Add(para, value)
```
became:
```
  p = Load(para, u)
  x = Add(p, value)
  u = UpdateState(u, p)
```

From: @limingqi107
Reviewed-by: @cristoval,@kisnwang
Signed-off-by: @kisnwang

From: @tronzhang
Reviewed-by: @ckey_dou,@gaoxiong1
Signed-off-by: @gaoxiong1

Merge pull request !6180 from laiyongqiang/codex

Signed-off-by: zhoufeng <zhoufeng54@huawei.com>

Merge pull request !3636 from Kang/opt

Merge pull request !3246 from zyli2020/refine_gpu_mem_swap

Merge pull request !3117 from laiyongqiang/refnode_input

Merge pull request !3171 from limingqi107/master

Merge pull request !2966 from laiyongqiang/hcom_memreuse

move pre-execution of debugger from rungraph to build/compile graph

support partial mem reuse for a scope of nodes

set default mem reuse to be true for debugger

remove some redundant lines

remove redundant code and fix a bug for supporting partial no mem reuse a scope of nodes

resolve CI errors

Solve CI errors

solve cpplint errors

solve CI build error

manually fix the CI compile UT error

Optimize code for mem reuse support

Debug optimization of debugger memory reuse

debug code for debugger memory reuse part2

address clang-format errors

Switch memory reuse on and off based on environment variable

Fix typo

Fix typo

Load watchpoint value only

fix bugs

Addressed comments from lupengcheng

fix typo

Fix typo

fix CI errors

refactor some code

fix typo

addressed comments from canadian teamates

remove locking from TensorLoader

fix CI errors

add lock to tensor_loader

fix rebase-to-master conflict

fix rebase conflicts

fix rebase conflicts part 2

fix rebase conflicts part 3