[Coverage] Make MCDCRecord::Folded as [false/true] with BitVector. NFC. (#121190)

For merging `MCDCRecord`s, `Folded` is expected to be promoted as
"Non-folded".

Author: chapuni

llvm/include/llvm/ProfileData/Coverage/CoverageMapping.h

@@ -439,7 +439,7 @@ struct MCDCRecord {
   };
 
   using TestVectors = llvm::SmallVector<std::pair<TestVector, CondState>>;
-  using BoolVector = llvm::SmallVector<bool>;
+  using BoolVector = std::array<BitVector, 2>;
   using TVRowPair = std::pair<unsigned, unsigned>;
   using TVPairMap = llvm::DenseMap<unsigned, TVRowPair>;
   using CondIDMap = llvm::DenseMap<unsigned, unsigned>;
@@ -467,7 +467,9 @@ struct MCDCRecord {
     return Region.getDecisionParams().NumConditions;
   }
   unsigned getNumTestVectors() const { return TV.size(); }
-  bool isCondFolded(unsigned Condition) const { return Folded[Condition]; }
+  bool isCondFolded(unsigned Condition) const {
+    return Folded[false][Condition] || Folded[true][Condition];
+  }
 
   /// Return the evaluation of a condition (indicated by Condition) in an
   /// executed test vector (indicated by TestVectorIndex), which will be True,

llvm/lib/ProfileData/Coverage/CoverageMapping.cpp

@@ -392,8 +392,9 @@ class MCDCRecordProcessor : NextIDsBuilder, mcdc::TVIdxBuilder {
       : NextIDsBuilder(Branches), TVIdxBuilder(this->NextIDs), Bitmap(Bitmap),
         Region(Region), DecisionParams(Region.getDecisionParams()),
         Branches(Branches), NumConditions(DecisionParams.NumConditions),
-        Folded(NumConditions, false), IndependencePairs(NumConditions),
-        ExecVectors(ExecVectorsByCond[false]), IsVersion11(IsVersion11) {}
+        Folded{{BitVector(NumConditions), BitVector(NumConditions)}},
+        IndependencePairs(NumConditions), ExecVectors(ExecVectorsByCond[false]),
+        IsVersion11(IsVersion11) {}
 
 private:
   // Walk the binary decision diagram and try assigning both false and true to
@@ -485,7 +486,6 @@ class MCDCRecordProcessor : NextIDsBuilder, mcdc::TVIdxBuilder {
   /// location is also tracked, as well as whether it is constant folded (in
   /// which case it is excuded from the metric).
   MCDCRecord processMCDCRecord() {
-    unsigned I = 0;
     MCDCRecord::CondIDMap PosToID;
     MCDCRecord::LineColPairMap CondLoc;
 
@@ -499,11 +499,12 @@ class MCDCRecordProcessor : NextIDsBuilder, mcdc::TVIdxBuilder {
     //   visualize where the condition is.
     // - Record whether the condition is constant folded so that we exclude it
     //   from being measured.
-    for (const auto *B : Branches) {
+    for (auto [I, B] : enumerate(Branches)) {
       const auto &BranchParams = B->getBranchParams();
       PosToID[I] = BranchParams.ID;
       CondLoc[I] = B->startLoc();
-      Folded[I++] = (B->Count.isZero() || B->FalseCount.isZero());
+      Folded[false][I] = B->FalseCount.isZero();
+      Folded[true][I] = B->Count.isZero();
     }
 
     // Using Profile Bitmap from runtime, mark the executed test vectors.