[llvm] [Legacy ThinLTO] Use code model from IR when creating TargetMachine (PR #113617)

[Steven Wu via llvm-commits]

cachemeifyoucan wrote:

In general, the change direction looks good to me. I think this patch needs to be slightly improved in following ways:
* I think we should add the CodeModel to TargetMachineBuilder and initialize it there with the code model from the module
* CodeModel should be updated in lto::Config, so it is reflected in the ThinLTO cache key.
* LTOCodeGenerator needs to be updated to respect CodeModel too.



https://github.com/llvm/llvm-project/pull/113617