[libunwind] [llvm] [MC][AArch64] Add .cfi_llvm_set_ra_sign_state for PAuth_LR (PR #205442)

[via cfe-commits]

================
@@ -7282,6 +7283,8 @@ bool AArch64AsmParser::ParseDirective(AsmToken DirectiveID) {
     parseDirectiveCFINegateRAState();
   else if (IDVal == ".cfi_negate_ra_state_with_pc")
     parseDirectiveCFINegateRAStateWithPC();
+  else if (IDVal == ".cfi_llvm_set_ra_state")
----------------
walkerkd wrote:

Looking at how the existing directives have been named I think it would make sense to call it `.cfi_set_ra_state`.

If we go with `.cfi_llvm_set_ra_state` then when binutils implements it with the expected name `.cfi_set_ra_state` we will either have to rename to follow suit (and all users uses of it) or have to add an alias so existing users code doesn't break.

Personally I think going with the name  `.cfi_set_ra_state` is cleaner for the longer term.

I think if this directive was only expected to be implemented in LLVM then having `llvm` in the name would make sense.  But as is expected to be implemented in both (and possibly other) toolchains at some point, the name without `llvm` make more sense to me.

https://github.com/llvm/llvm-project/pull/205442