[Bug target/71921] missed vectorization optimization

[arjan at linux dot intel.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71921

--- Comment #19 from Arjan van de Ven <arjan at linux dot intel.com> ---
>  GCC is not just about x86.

I know that, which is why I know my patch is not correct, but more of a precise
bug report... clearly this need to be done in a way that does not hurt other
architectures.