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

[NAKAMURA Takumi via llvm-commits]

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@@ -580,6 +583,72 @@ static unsigned getMaxBitmapSize(const CounterMappingContext &Ctx,
   return MaxBitmapID + (SizeInBits / CHAR_BIT);
 }
 
+struct DecisionRow {
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chapuni wrote:

I have added comments in `DecisionRow`. Please give me suggestions.

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