[llvm] [DirectX] Infrastructure to collect shader flags for each function (PR #112967)

[Justin Bogner via llvm-commits]

https://github.com/bogner commented:

This is looking pretty close. As both Damyan and Chris pointed out, this isn't the appropriate kind of error handling here - the only way to hit the error is to break an invariant, which means we don't need user facing errors at all. A few other comments below.

https://github.com/llvm/llvm-project/pull/112967