[Bug fortran/105558] simple 8-bit integer calculation fails with -O3 / march=core-avx2 on some gfortran 8/9/10 versions

[federico.perini at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105558

--- Comment #3 from federico <federico.perini at gmail dot com> ---
-fno-vect-cost model also does not change behavior on gcc 11/7/6/5 (all OK)