[llvm] [llvm][IR] Add per-global code model attribute (PR #72077)

[via llvm-commits]

heiher wrote:

Thanks for the comments.

> Can you please add a test that shows the code model is correctly copied if e.g. GlobalOpt performs a transform on the global?

Done.

> 
> I'd also like some clarity what kind of globals support code_model. You placed the APIs on GlobalObject, but the AsmParser support looks like this is only actually supported on GlobalVariable?
> 
> Either these APIs should be on GlobalVariable, or code_model should also be supported on Functions.

Just global variable. Moved to GlobalVariable.

https://github.com/llvm/llvm-project/pull/72077