[Bug tree-optimization/102511] [12 Regression] GCC produces incorrect code for -O3: first element of the array is skipped

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102511

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So the difference between -O2 and -O3 that matters here is -ftree-vectorize but
it is not the vectorizer that is making the difference but rather ch_vect.
But I can't figure out what is going wrong.

Also adding -fwrapv fixes it too.