[llvm-branch-commits] [llvm] llvm-cov: Introduce `--merge-instantiations=<MergeStrategy>` (PR #121194)

[NAKAMURA Takumi via llvm-branch-commits]

https://github.com/chapuni commented:

@stma247 
Re. lcov, I concluded:
- Don't preserve the behavior of `--unify-instantiations=false`.

Rationale:
- Duplicated `BRDA`(s) were not intentional. They just looked like "per-instances" but actually "per-ID".
- As far as I investigated, gcc's toolchains don't define per-instantiation `BRDA`.
- Other fields, for example `DA`, are unaware of instantiation.

See also my comments in #121192.

https://github.com/llvm/llvm-project/pull/121194