[Bug target/94373] 548.exchange2_r run time is 7-12% worse than GCC 9 at -O2 and generic march/mtune

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94373

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note the cited commit simply caused more complete unrolling to happen.  Too
much actually which is why I reverted it.  Note GCC 9.2 does not have that more
unrolling so the difference must be something else in the end.