[clang] [llvm] [X86] Extend kCFI with a 3-bit arity indicator (PR #121070)

[Scott Constable via llvm-commits]

================
@@ -181,8 +181,26 @@ void X86AsmPrinter::emitKCFITypeId(const MachineFunction &MF) {
   // Embed the type hash in the X86::MOV32ri instruction to avoid special
   // casing object file parsers.
   EmitKCFITypePadding(MF);
+
+  Register MovReg = X86::EAX;
+  const auto &Triple = MF.getTarget().getTargetTriple();
+  if (Triple.isArch64Bit() && Triple.isOSLinux()) {
----------------
scottconstable wrote:

Is this check necessary? I notice that all of the x86-based kCFI tests use the `x86_64-unknown-linux-gnu` triple. If 64-bit Linux is the only supported x86 subtarget then I think this check is redundant. But I'm not 100% certain.

https://github.com/llvm/llvm-project/pull/121070