[clang] [llvm] [AArch64] Add support for C1 CPUs (PR #171124)

[Simon Tatham via llvm-commits]

statham-arm wrote:

> As for MOPS, I'm just concerned that -mcpu=c1-* will result in memcpy and memset to be inlined unconditionally, which according to Arm's errata will result in performance degradation,

On the other hand, if someone explicitly writes a MOPS instruction in assembly language, it shouldn't fail to assemble. The questions of "does the CPU understand this instruction?" and "is it a good idea to use it in code generation?" are conceptually separate.

https://github.com/llvm/llvm-project/pull/171124