[llvm] [Coverage] Rework Decision/Expansion/Branch (PR #78969)

[Jessica Paquette via llvm-commits]

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@@ -582,6 +583,87 @@ static unsigned getMaxBitmapSize(const CounterMappingContext &Ctx,
   return MaxBitmapID + (SizeInBits / CHAR_BIT);
 }
 
+/// This holds the DecisionRegion and MCDCBranch(es) under it.
+/// Also traverses Expansion(s).
+struct DecisionRow {
+  /// The subject
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ornata wrote:

This comment is confusing

https://github.com/llvm/llvm-project/pull/78969