[clang] [Clang][CodeGen] Emit dereferenceable and nofree for indirect arguments (PR #213347)

[Sayan Sivakumaran via cfe-commits]

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sivakusayan wrote:

I tried to understand if the correct thing to do here was add `byref` instead of the individual `dereferenceable` and `nofree` attributes. I think that, looking at [the original PR](https://reviews.llvm.org/D79744) and the [LangRef](https://llvm.org/docs/LangRef.html#:~:text=target%2Dspecific%20assumption.-,byref,-\(%3Cty%3E), the attribute seems to be used for ABI constraints. So I'm not sure what the TODO is referring to, and I think it's not relevant for us.

https://github.com/llvm/llvm-project/pull/213347