[Bug c/110683] wrong code with '-O2 -fpack-struct'

[19373742 at buaa dot edu.cn via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110683
--- Comment #3 from CTC <19373742 at buaa dot edu.cn> ---
The reduced program is

# cat mss.i
struct a {
  char b;
  int c;
};
union {
  struct a b;
  short c;
} d = {8, 1};
void main() { printf("%d\n", d.c); }