[Bug target/70941] [5/6 Regression] Test miscompiled with -O2.

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70941

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
unsigned char perhaps?  Let me fix up the testcase.
It has other non-portable assumptions.