[llvm] [X86][MC] Added support for -msse2avx option in llvm-mc (PR #96860)

[Phoebe Wang via llvm-commits]

phoebewang wrote:

> * GCC already have this option https://gcc.gnu.org/onlinedocs/gcc-14.1.0/gcc/x86-Options.html.

The document says it's GCC option and turn on with `-mavx`, but I don't know in which case it affects compiler codegen. Do we have an example about that. I checked both inline asm and SSE intrinsic, but didn't find any difference between GCC and LLVM: https://godbolt.org/z/6hj91nKzY

https://github.com/llvm/llvm-project/pull/96860