[llvm] [AVR] Support stack realignment (PR #187129)

[Ben Shi via llvm-commits]

benshi001 wrote:

I got two failures in `make check-llvm-codegen-avr -j` against this patch.

```
********************
********************
Failed Tests (2):
  LLVM :: CodeGen/AVR/pseudo/COPY.mir
  LLVM :: CodeGen/AVR/pseudo/LDDWRdYQ.mir


Testing Time: 0.66s

Total Discovered Tests: 195
  Passed           : 190 (97.44%)
  Expectedly Failed:   3 (1.54%)
  Failed           :   2 (1.03%)
make[3]: *** [test/CMakeFiles/check-llvm-codegen-avr.dir/build.make:71: test/CMakeFiles/check-llvm-codegen-avr] Error 1
make[2]: *** [CMakeFiles/Makefile2:240599: test/CMakeFiles/check-llvm-codegen-avr.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:240606: test/CMakeFiles/check-llvm-codegen-avr.dir/rule] Error 2
make: *** [Makefile:38019: check-llvm-codegen-avr] Error 2
```

https://github.com/llvm/llvm-project/pull/187129