1. Remove output parameter pool for ascend control flow;
2. Remove duplicate code for Switch and SwitchLayer;
3. Add 'return' attribute to label_goto that used for return;
4. Disable tail call optimize for graphs with 'recursive' flag.

From: @liangzelang
Reviewed-by: @jjfeing,@zhoufeng54
Signed-off-by: @zhoufeng54

Merge pull request !5172 from riemann_penn/remove_name_args_from_gradoperation

Merge pull request !3271 from vlne-v1/ref_demo

Merge pull request !5011 from riemann_penn/remove_global_grad_ops

add testcase of net of if by if

add testcase of st

add join for ref

adjust env eliminate to eliminate all env ops

add partial app cache

resolve while endless

fix env eliminate

support for "for while" cases

fix join shape error

insert assign at the end of graph

clear log

clear log 2

handle replace call of unreuse args

handle bug of replace node

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

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

Merge pull request !1082 from hewei/support_cont_break

To handle 'break' and 'continue' statement, a loop context is pushed
to a stack before we parse the loop body, and pop it after body parsed.
When a 'break', 'continue' statement is encountered, we retrieve current
loop contex from the stack, and let the current block jump to the end
block or header block;

For 'break' statement, we added an extra 'end_block' follow the 'after_block',
because 'after_block' is called from a ContionalJump in 'header_block', it can
not be set as jump target from other place. to support 'break', we let loop
body jump to the 'end_block' at the 'break' point. and 'after_block'
maybe a good place to handle loop 'else' clause in the future.

Handle 'pass' is simple, just bypass it when doing parse.

Signed-off-by: leonwanghui <leon.wanghui@huawei.com>