[llvm] [llvm-dwp] Add a new flag `--exec-dwo-path-remapping-file=<filename>`. (PR #157587)

[Michael Park via llvm-commits]

mpark wrote:

> Having to read a file seems a bit unfortunate - could we do something that matches existing debug info features like `-fdebug-prefix-map`?

Hi @dwblaikie, yes, good question. For our use case, the remapping is not from one directory to another but rather on a per-file basis, which is why this takes a file of mappings per file. This has to do with content-based hashes in output paths in Buck2. Specifically, under such a model the output path of an artifact is expected to include the hash of its contents, which of course can be different for every file within a directory.

It sounds like Bazel has this feature as well, maybe? [Experimental Content-Based Output Paths](https://docs.google.com/document/d/17snvmic26-QdGuwVw55Gl0oOufw9sCVuOAvHqGZJFr4/edit?tab=t.0#heading=h.5mcn15i0e1ch) Do you know how this situation is handled there?

https://github.com/llvm/llvm-project/pull/157587