[Bug ipa/127752] volatile member read of a never-written global dropped with -O2

[yqtian668 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127752

--- Comment #4 from Yongqiang Tian <yqtian668 at gmail dot com> ---
Created attachment 65771
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65771&action=edit
patch