[clang] [llvm] [X86] Enhance kCFI type IDs with a 3-bit arity indicator. (PR #117121)

[Ramon de C Valle via cfe-commits]

rcvalle wrote:

This all too architecture specific and isn't the level that LLVM CFI and KCFI originally work. The arity test should be at the language level. E.g.:

void foo(void) is arity zero
void bar(int) is arity 1
int baz(int) is arity 2
int qux(int, int) is arity 3

And so on. If we tried to cover every possible corner case for every ABI or at the architecture level we would end up with a different CFI implementation for every ABI and architecture (and possibly every combination of those).

https://github.com/llvm/llvm-project/pull/117121