[llvm] Refactor processing of BranchRegions associated with an MCDCDecisionRegion (PR #78819)

[Alan Phipps via llvm-commits]

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@@ -636,20 +657,56 @@ Error CoverageMapping::loadFunctionRecord(
       Record.MappingRegions[0].Count.isZero() && Counts[0] > 0)
     return Error::success();
 
-  unsigned NumConds = 0;
-  const CounterMappingRegion *MCDCDecision;
-  std::vector<CounterMappingRegion> MCDCBranches;
-
   FunctionRecord Function(OrigFuncName, Record.Filenames);
-  for (const auto &Region : Record.MappingRegions) {
+
+  const auto &RegionsBegin = Record.MappingRegions.begin();
+  const auto &RegionsEnd = Record.MappingRegions.end();
+  for (auto It = RegionsBegin; It != RegionsEnd; ++It) {
+    const auto &Region = *It;
+
     // If an MCDCDecisionRegion is seen, track the BranchRegions that follow
     // it according to Region.NumConditions.
     if (Region.Kind == CounterMappingRegion::MCDCDecisionRegion) {
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evodius96 wrote:

I think the handling of DecisionRegions is much cleaner -- being assembled and processed in one iteration rather than rely on successive iterations of the loop.

https://github.com/llvm/llvm-project/pull/78819