Reland "[llvm-cov] Export decision coverage to output json (#144335)" (#145325)

Tests fixed

This commit adds decision coverage counts derived from MC/DC test vector execution 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

Author: uthmanna

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

@@ -31,6 +31,7 @@
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/raw_ostream.h"
+#include <algorithm>
 #include <cassert>
 #include <cstdint>
 #include <iterator>
@@ -494,6 +495,17 @@ struct MCDCRecord {
     return TV[TestVectorIndex].first[PosToID[Condition]];
   }
 
+  /// Return the number of True and False decisions for all executed test
+  /// vectors.
+  std::pair<unsigned, unsigned> getDecisions() const {
+    const unsigned TrueDecisions =
+        std::count_if(TV.begin(), TV.end(), [](const auto &TestVec) {
+          return TestVec.second == CondState::MCDC_True;
+        });
+
+    return {TrueDecisions, TV.size() - TrueDecisions};
+  }
+
   /// Return the Result evaluation for an executed test vector.
   /// See MCDCRecordProcessor::RecordTestVector().
   CondState getTVResult(unsigned TestVectorIndex) {

llvm/test/tools/llvm-cov/Inputs/binary-formats.canonical.json

@@ -33,4 +33,4 @@ CHECK-SAME:     "mcdc":{"count":0,"covered":0,"notcovered":0,"percent":0},
 CHECK-SAME:     "regions":{"count":1,"covered":1,"notcovered":0,"percent":100}}}
 CHECK-SAME: ],
 CHECK-SAME: "type":"llvm.coverage.json.export"
-CHECK-SAME: "version":"2.0.1"
+CHECK-SAME: "version":"3.0.0"

llvm/test/tools/llvm-cov/mcdc-export-json.test

@@ -1,10 +1,10 @@
 // RUN: llvm-profdata merge %S/Inputs/mcdc-general.proftext -o %t.profdata
 // RUN: llvm-cov export --format=text %S/Inputs/mcdc-general.o -instr-profile %t.profdata | FileCheck %s
 
-// CHECK: 12,7,12,27,0,5,[true,true,true,true]
-// CHECK: 15,7,15,13,0,5,[true,true]
-// CHECK: 15,19,15,25,0,5,[true,false]
-// CHECK: 18,7,19,15,0,5,[true,true,false,true]
+// CHECK: 12,7,12,27,2,4,0,5,[true,true,true,true]
+// CHECK: 15,7,15,13,1,2,0,5,[true,true]
+// CHECK: 15,19,15,25,1,1,0,5,[true,false]
+// CHECK: 18,7,19,15,1,3,0,5,[true,true,false,true]
 // CHECK: "mcdc":{"count":12,"covered":10,"notcovered":2,"percent":83.333333333333343}
 
 Instructions for regenerating the test:

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"
@@ -110,8 +110,10 @@ json::Array gatherConditions(const coverage::MCDCRecord &Record) {
 
 json::Array renderMCDCRecord(const coverage::MCDCRecord &Record) {
   const llvm::coverage::CounterMappingRegion &CMR = Record.getDecisionRegion();
+  const auto [TrueDecisions, FalseDecisions] = Record.getDecisions();
   return json::Array({CMR.LineStart, CMR.ColumnStart, CMR.LineEnd,
-                      CMR.ColumnEnd, CMR.ExpandedFileID, int64_t(CMR.Kind),
+                      CMR.ColumnEnd, TrueDecisions, FalseDecisions,
+                      CMR.ExpandedFileID, int64_t(CMR.Kind),
                       gatherConditions(Record)});
 }