[llvm] [LLVM][DWARF] Add support for .debug_names with split dwarf (PR #73872)

[David Blaikie via llvm-commits]

https://github.com/dwblaikie approved this pull request.

Looks good to me.

The DWARF spec I think is a smidge vague on how the IDX_type_unit works with the local and foreign type units. (like if you had 5 local and 5 foreign type units (won't happen for us with object files, but would happen with the linked index) - presumably an IDX_type_unit value of 5 means the first foreign type unit? and 4 means the last local one?))

(also, total aside: be interesting to measure the size of `.debug_names` relative to `.debug_gnu_pubnames` and consider including a flag for producing `.debug_names` without the hash table in object files (if it's going to be merged into a unified index by the linker anyway, we don't need the hash table in the object file, probably))

https://github.com/llvm/llvm-project/pull/73872