[Bug sanitizer/120471] -fsanitize=undefined causes read of uninitialized variable when accessing element in an array at -O0 level

[xiaohuba2021 at 163 dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120471

--- Comment #1 from xiaohuba2021 <xiaohuba2021 at 163 dot com> ---
sorry, there is a blank line on the top of the source code. so line 5 should
actually be `volatile int v = (ll % 2 ? b : ib)[c % 3];`