[llvm] Added const reference for params wth size >= 16 bytes (PR #125074)

[James Henderson via llvm-commits]

jh7370 wrote:

> I can split this PR into different branches with others PR, and I also analyzed all structures and classes as parameters under Linux, if there is changing size from OS, more code reviewers (Windows, MacOS, BSD) are needed.

I think you need consensus on the idea that 16 bytes is a reasonably boundary. I'm not convinced it is. Certainly, I don't think a 16-byte struct should be passed by `const &` unconditionally. As this is a wide-impacting change, that will likely need a coding standards update, I suggest you raise this on LLVM's Discourse before proceeding further. See https://discourse.llvm.org/.

https://github.com/llvm/llvm-project/pull/125074