[LLD] Support --print-dependencies

[ogiekako]

mold has --print-dependencies flag, which is useful for analyzing file to file or function to function dependencies. An example use case of the flag is to build a dependency graph and mechanically detect unused files/functions.

I'd appreciate it if lld supports the equivalent functionality. I could use mold, but my project doesn't/won't officially support it, so using it is risky.

[fioraking]

@MaskRay once had a very similar feature, but it was later discarded. I haven’t seen a specific reason for this, and I personally think this feature is very useful. If it’s still considered worthwhile, I’d be happy to take it on as my first contribution.

[MaskRay]

You might consider --cref, which is supported in both GNU ld and lld
https://maskray.me/blog/2022-02-27-analysis-and-introspection-options-in-linkers#cref