[Bug target/70676] suboptimal code generation on AVR

[night_ghost at ykoctpa dot ru]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70676

--- Comment #6 from night_ghost at ykoctpa dot ru ---
I reported not one case but suboptimal behavior while optimizing size - GCC
optimization of sibling calls increases size of binary. There are a lot of such
places in this code.

And GCC never replaces call-ret sequence to jmp, relying on linkers optimizing
by -relax. But including -relax flag often spoils the project to complete
failure.