[Bug tree-optimization/121589] wrong code at -O1 and above on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121589

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
That is the only defined values for b is -1. Otherwise e+1 would be after the
end and you deference that or e would cause an undefined value to appear.