[llvm] [llvm-cov] Export decision coverage to output json (PR #144335)

[via llvm-commits]

https://github.com/uthmanna created https://github.com/llvm/llvm-project/pull/144335

This commit adds decision coverage to the JSON output of llvm-cov, as discussed here: [Missing Decision Coverage (DC) in output json](https://discourse.llvm.org/t/missing-decision-coverage-dc-in-output-json/86783) with @evodius96 


>From cb87084d4cdd0cab86585226ed4ee4ebc964c8bf Mon Sep 17 00:00:00 2001
From: uthmanna <andre.uthmann at vector.com>
Date: Mon, 16 Jun 2025 13:18:55 +0200
Subject: [PATCH] [llvm-cov] Export decision coverage to output json

---
 .../llvm/ProfileData/Coverage/CoverageMapping.h  |  3 +++
 llvm/tools/llvm-cov/CoverageExporterJson.cpp     | 16 ++++++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/llvm/include/llvm/ProfileData/Coverage/CoverageMapping.h b/llvm/include/llvm/ProfileData/Coverage/CoverageMapping.h
index d1230b0ba7c58..c9854e08a38e8 100644
--- a/llvm/include/llvm/ProfileData/Coverage/CoverageMapping.h
+++ b/llvm/include/llvm/ProfileData/Coverage/CoverageMapping.h
@@ -494,6 +494,9 @@ struct MCDCRecord {
     return TV[TestVectorIndex].first[PosToID[Condition]];
   }
 
+  /// Return the executed test vectors.
+  const TestVectors &getTV() const { return TV; }
+
   /// Return the Result evaluation for an executed test vector.
   /// See MCDCRecordProcessor::RecordTestVector().
   CondState getTVResult(unsigned TestVectorIndex) {
diff --git a/llvm/tools/llvm-cov/CoverageExporterJson.cpp b/llvm/tools/llvm-cov/CoverageExporterJson.cpp
index 4088c1b053aa8..cae7b86bc6b0c 100644
--- a/llvm/tools/llvm-cov/CoverageExporterJson.cpp
+++ b/llvm/tools/llvm-cov/CoverageExporterJson.cpp
@@ -62,7 +62,7 @@
 #include <utility>
 
 /// The semantic version combined as a string.
-#define LLVM_COVERAGE_EXPORT_JSON_STR "2.0.1"
+#define LLVM_COVERAGE_EXPORT_JSON_STR "3.0.0"
 
 /// Unique type identifier for JSON coverage export.
 #define LLVM_COVERAGE_EXPORT_JSON_TYPE_STR "llvm.coverage.json.export"
@@ -108,10 +108,22 @@ json::Array gatherConditions(const coverage::MCDCRecord &Record) {
   return Conditions;
 }
 
+std::pair<unsigned, unsigned> getDecisions(const coverage::MCDCRecord &Record) {
+  const coverage::MCDCRecord::TestVectors &TestVectors = Record.getTV();
+  const unsigned TrueConditions =
+      std::count_if(TestVectors.begin(), TestVectors.end(), [](const auto &TV) {
+        return TV.second == coverage::MCDCRecord::CondState::MCDC_True;
+      });
+
+  return {TrueConditions, TestVectors.size() - TrueConditions};
+}
+
 json::Array renderMCDCRecord(const coverage::MCDCRecord &Record) {
   const llvm::coverage::CounterMappingRegion &CMR = Record.getDecisionRegion();
+  const auto [TrueConditions, FalseConditions] = getDecisions(Record);
   return json::Array({CMR.LineStart, CMR.ColumnStart, CMR.LineEnd,
-                      CMR.ColumnEnd, CMR.ExpandedFileID, int64_t(CMR.Kind),
+                      CMR.ColumnEnd, TrueConditions, FalseConditions,
+                      CMR.ExpandedFileID, int64_t(CMR.Kind),
                       gatherConditions(Record)});
 }