[Coverage] Add support for Branch Coverage in LLVM Source-Based Code Coverage

This is an enhancement to LLVM Source-Based Code Coverage in clang to track how
many times individual branch-generating conditions are taken (evaluate to TRUE)
and not taken (evaluate to FALSE).  Individual conditions may comprise larger
boolean expressions using boolean logical operators.  This functionality is
very similar to what is supported by GCOV except that it is very closely
anchored to the ASTs.

Differential Revision: https://reviews.llvm.org/D84467

1 files changed, 14 insertions, 2 deletions

diff --git a/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp b/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
index 8d3c429..65b83d1 100644
--- a/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
+++ b/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
@@ -80,10 +80,14 @@ public:
                               ArrayRef<CounterMappingRegion> MappingRegions)
       : Expressions(Expressions) {
     AdjustedExpressionIDs.resize(Expressions.size(), 0);
-    for (const auto &I : MappingRegions)
+    for (const auto &I : MappingRegions) {
       mark(I.Count);
-    for (const auto &I : MappingRegions)
+      mark(I.FalseCount);
+    }
+    for (const auto &I : MappingRegions) {
       gatherUsed(I.Count);
+      gatherUsed(I.FalseCount);
+    }
   }
 
   void mark(Counter C) {
@@ -201,6 +205,7 @@ void CoverageMappingWriter::write(raw_ostream &OS) {
       PrevLineStart = 0;
     }
     Counter Count = Minimizer.adjust(I->Count);
+    Counter FalseCount = Minimizer.adjust(I->FalseCount);
     switch (I->Kind) {
     case CounterMappingRegion::CodeRegion:
     case CounterMappingRegion::GapRegion:
@@ -226,6 +231,13 @@ void CoverageMappingWriter::write(raw_ostream &OS) {
                         << Counter::EncodingCounterTagAndExpansionRegionTagBits,
                     OS);
       break;
+    case CounterMappingRegion::BranchRegion:
+      encodeULEB128(unsigned(I->Kind)
+                        << Counter::EncodingCounterTagAndExpansionRegionTagBits,
+                    OS);
+      writeCounter(MinExpressions, Count, OS);
+      writeCounter(MinExpressions, FalseCount, OS);
+      break;
     }
     assert(I->LineStart >= PrevLineStart);
     encodeULEB128(I->LineStart - PrevLineStart, OS);