[llvm] [IR] Add llvm.raw.sections named metadata (PR #226954)

[Alexis Engelke via llvm-commits]

https://github.com/aengelke commented:

More thoughts on alloc sections: One missing thing is support for relocations and symbol definitions. This might be ok for non-alloc sections, but for alloc sections, this makes this feature much harder/more limiting to use. E.g., one potential use case would be to embed functions that are precompiled (or compiled with an alternative back-end) into the module, but this mechanism is too limited for that purpose.

Therefore, in the interest of simplicity and avoiding unused/not-really-usable extension points, it might be good to limit currently supported flags to the value zero (so that other values are reserved for later extensions, once there is a clear need for that).

https://github.com/llvm/llvm-project/pull/226954