[llvm] [clang] [clang][CoverageMapping] Refactor when setting MC/DC True/False (PR #78202)

[NAKAMURA Takumi via llvm-commits]

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@@ -1018,13 +1011,15 @@ struct CounterCoverageMappingBuilder
     return (Cond->EvaluateAsInt(Result, CVM.getCodeGenModule().getContext()));
   }
 
+  using MCDCDecisionIDPair = MCDCCoverageBuilder::DecisionIDPair;
+
   /// Create a Branch Region around an instrumentable condition for coverage
   /// and add it to the function's SourceRegions.  A branch region tracks a
   /// "True" counter and a "False" counter for boolean expressions that
   /// result in the generation of a branch.
-  void createBranchRegion(const Expr *C, Counter TrueCnt, Counter FalseCnt,
-                          MCDCConditionID ID = 0, MCDCConditionID TrueID = 0,
-                          MCDCConditionID FalseID = 0) {
+  void
+  createBranchRegion(const Expr *C, Counter TrueCnt, Counter FalseCnt,
+                     const MCDCDecisionIDPair &IDPair = MCDCDecisionIDPair()) {
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chapuni wrote:

Oops, I have suggested dropping initial values in `DecisionIDPair`.
We have to introduce the explicit initializer, or use `Sentinel`, or leave `DecisionIDPair` with initializers.

It's also possible to pass `{poison, poison}` as the default value and assert they are not poison before using.

https://github.com/llvm/llvm-project/pull/78202