[Bug tree-optimization/100076] eembc/automotive/basefp01 has 30.3% regression compare -O2 -ftree-vectorize with -O2 on CLX/Znver3

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100076

--- Comment #2 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to H.J. Lu from comment #1)
> Is -O3 slower than -O3 -fno-tree-vectorize? If not, why?

For this case O3 is Ok, because O3 will enable pass_cunroll to complete unroll
the loop1/loop2/loop3, and later pass_fre will elimiate redudant load of polyX1
in loop2 and loop3 for both -O3 and -O3 -fno-tree-vectorize.