llvm-project

4a011ac8 - [Coverage] Introduce "partial fold" on BranchRegion (#112694)

[Coverage] Introduce "partial fold" on BranchRegion (#112694) Currently both True/False counts were folded. It lost the information, "It is True or False before folding." It prevented recalling branch counts in merging template instantiations. In `llvm-cov`, a folded branch is shown as: - `[True: n, Folded]` - `[Folded, False n]` In the case If `n` is zero, a branch is reported as "uncovered". This is distinguished from "folded" branch. When folded branches are merged, `Folded` may be dissolved. In the coverage map, either `Counter` is `Zero`. Currently both were `Zero`. Since "partial fold" has been introduced, either case in `switch` is omitted as `Folded`. Each `case:` in `switch` is reported as `[True: n, Folded]`, since `False` count doesn't show meaningful value. When `switch` doesn't have `default:`, `switch (Cond)` is reported as `[Folded, False: n]`, since `True` count was just the sum of `case`(s). `switch` with `default` can be considered as "the statement that doesn't have any `False`(s)".