SDCC is the open source compiler of choice for stm8. It's not GCC, but it's enough. I'd be tempted to agree about the registers except that it takes wider inst

SDCC is the open source compiler of choice for stm8. It's not GCC, but it's enough. I'd be tempted to agree about the registers except that it takes wider instructions to encode the registers used so a well thought out accumulator based architecture can result in very compact code. stm8 has a lot of one byte instructions and most except for branches and word operations are single cycle as well.