[llvm] [AVR] No cli for SPWRITE on XMEGA (PR #147210)

[Ben Shi via llvm-commits]

benshi001 wrote:

@tomtor Sorry for my late response. I also work on llvm in my spare time without any payment. I can not serve reviewing works in time. For that reason, my two core points are

1. Stability is much more important than optimization, especially bug fixes. I would rather sub optimized code is generated than broken code. So I quite concern if optimization for newer devices will harm older devices.
2. Fix defects against avr-gcc-7.3 tool chain, arduino still uses gcc-7.3 as its main tool chain.

https://github.com/llvm/llvm-project/pull/147210