[llvm] Implement MCDCTVIdxBuilder (LLVM side) (PR #80676)

[Alan Phipps via llvm-commits]

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@@ -283,35 +408,38 @@ class MCDCRecordProcessor {
   // Walk the binary decision diagram and try assigning both false and true to
   // each node. When a terminal node (ID == 0) is reached, fill in the value in
   // the truth table.
-  void buildTestVector(MCDCRecord::TestVector &TV, unsigned ID,
+  void buildTestVector(MCDCRecord::TestVector &TV, int ID, int TVIdx,
                        unsigned Index) {
-    const CounterMappingRegion *Branch = Map[ID];
-
-    TV[ID - 1] = MCDCRecord::MCDC_False;
-    if (Branch->MCDCParams.FalseID > 0)
-      buildTestVector(TV, Branch->MCDCParams.FalseID, Index);
-    else
-      recordTestVector(TV, Index, MCDCRecord::MCDC_False);
-
-    Index |= 1 << (ID - 1);
-    TV[ID - 1] = MCDCRecord::MCDC_True;
-    if (Branch->MCDCParams.TrueID > 0)
-      buildTestVector(TV, Branch->MCDCParams.TrueID, Index);
-    else
-      recordTestVector(TV, Index, MCDCRecord::MCDC_True);
+    const auto &Node = Nodes[ID];
+
+    for (unsigned I = 0; I < 2; ++I) {
+      auto MCDCCond = (I ? MCDCRecord::MCDC_True : MCDCRecord::MCDC_False);
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evodius96 wrote:

Combining the True and False processing using a 2-iteration loop works (I had considered doing this too, since it's really doing the same thing for True and False), but it seems slightly less readable and a bit more complicated than what was there before.

https://github.com/llvm/llvm-project/pull/80676