[clang] [llvm] [RISCV] Add MC layer support for XSfmm*. (PR #133031)

[Craig Topper via cfe-commits]

topperc wrote:

> I still get compiler error for the above case, but with additional error message:
> 
> ```
> fatal error: error in backend: Invalid size request on a scalable vector.
> PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
> Stack dump:
> 0.      Program arguments: /nix/store/n44qhrqxb3qnbylypsfq75jl2lfsvbp6-clang-21.0.0-unstable-2025-03-23/bin/clang @/tmp/nix-shell.9YUR38/cc-params.lXn6o1
> 1.      <eof> parser at end of file
> 2.      Code generation
> 3.      Running pass 'Function Pass Manager' on module 'test.c'.
> 4.      Running pass 'RISC-V DAG->DAG Pattern Instruction Selection' on function '@utf8_count_SWAR_popc_bithack_autovec'
> ```
> 
> And here is the debug files:
> 
> [test.c.txt](https://github.com/user-attachments/files/20348260/test.c.txt) [test.sh.txt](https://github.com/user-attachments/files/20348266/test.sh.txt)

Please file a new issue. This error and the previous error are not related to this PR.

https://github.com/llvm/llvm-project/pull/133031