[llvm] [RISCV] Guard CFI emission code with MF.needsFrameMoves() (PR #136060)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> Instruction precise (a.k.a. asynchronous) tables are significantly larger in terms of object size, so we'd like to avoid generating them until the user explicitly requests it by passing `-g` or whichever option. That would lead us to the same issue, wouldn't it?

Yes... -g and -g0's assembly output is different, which is probably a larger issue than the CFI vs non-CFI assembly output issue... 

> That is, we would always generate CFI, but not always the same CFI. Any idea how this can be solved? Or this doesn't look like an issue given the current llvm support for asynchronous mode?

I think that stopping unused CFI earlier makes sense for the compile time... 

https://github.com/llvm/llvm-project/pull/136060