[Bug tree-optimization/65492] Bad optimization in -O3 due to if-conversion and/or unrolling

[linux at carewolf dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65492

--- Comment #8 from Allan Jensen <linux at carewolf dot com> ---
You can remove the branches in the inner loop and still reproduce the issue.
There were no branches in the original code, I only added them to the reduced
case because I was using a smaller lookup table.

I appears after removing the branches, the execution time with and without
-fno-tree-vectorize on -O3 is the same. So they also cause some issue, but is
the main one.