[Bug c/90267] [7.3 regression] wrong code generated wth -O2 as missing data dependence base on memory

[zhongyunde at huawei dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90267

--- Comment #3 from vfdff <zhongyunde at huawei dot com> ---
but it doesn't warning anything, even with  -Wstrict-aliasing -Wall.

Accord to http://blog.sina.com.cn/s/blog_74caf0ce010173up.html, We expect an
warning similar the following infomation.

warning: dereferencing type-punned pointer will break strict-aliasing rules