If you get errors like:

    [...] error: array subscript 0 is outside array bounds [...]

use the workaround from this bug ticket:
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105523>

    --param=min-pagesize=0

The optimization for size is worse compared with GCC 10, even with -Oz.
If the code uses interrupt handlers use:

    -mcall-prologues

The defaults for branch cost and reorder algorithm may produce larger code.
Sometimes the following options give better results:

    -mbranch-cost=10
    -freorder-blocks-algorithm=stc

Do not use type int for 8-Bit values. Even for static functions the optimizer
may not detect that the additional bits will always be zero.

(Optimization for size tested with ATtiny88)
