[clang] [llvm] [clang][RISCV] Emit RISCV function-signature-based CFI label in llvm::Function metadata (PR #111661)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

The issues I've raised are tied up with quality of implementation, even if the spec doesn't change.

For missing prototypes, we can statically detect calls which pass arguments to function without a prototype.  Generating code we know will never work, without a diagnostic, is a bad idea.

For the type merging issue, we can't detect it completely reliably, but we can detect function definitions which aren't compatible with the corresponding function declaration, and diagnose that.

https://github.com/llvm/llvm-project/pull/111661