[LLVM][Coverage][Unittest] Fix dangling reference in unittest

[kikairoya]

In loop of writeAndReadCoverageRegions, OutputFunctions[I].Filenames references to contents of Filenames after returning from readCoverageRegions but Filenames will be cleared in next call of readCoverageRegions, causes dangling reference.
The lifetime of the contents of Filenames must be equal or longer than OutputFunctions[I], thus it has been moved into OutputFunctions[I] (typed OutputFunctionCoverageData).

[llvmbot]

@llvm/pr-subscribers-pgo

Author: Tomohiro Kashiwada (kikairoya)

Changes

In loop of writeAndReadCoverageRegions, OutputFunctions[I].Filenames references to contents of Filenames after returning from readCoverageRegions but Filenames will be cleared in next call of readCoverageRegions, causes dangling reference.
The lifetime of the contents of Filenames must be equal or longer than OutputFunctions[I], thus it has been moved into OutputFunctions[I] (typed OutputFunctionCoverageData).

---

Full diff: https://github.com/llvm/llvm-project/pull/147118.diff

1 Files Affected:

• (modified) llvm/unittests/ProfileData/CoverageMappingTest.cpp (+8-9)

diff --git a/llvm/unittests/ProfileData/CoverageMappingTest.cpp b/llvm/unittests/ProfileData/CoverageMappingTest.cpp
index ec81e5f274efa..59c381a1b4e82 100644
--- a/llvm/unittests/ProfileData/CoverageMappingTest.cpp
+++ b/llvm/unittests/ProfileData/CoverageMappingTest.cpp
@@ -64,6 +64,7 @@ namespace {
 struct OutputFunctionCoverageData {
   StringRef Name;
   uint64_t Hash;
+  std::vector<std::string> FilenamesStorage;
   std::vector<StringRef> Filenames;
   std::vector<CounterMappingRegion> Regions;
   std::vector<CounterExpression> Expressions;
@@ -71,8 +72,10 @@ struct OutputFunctionCoverageData {
   OutputFunctionCoverageData() : Hash(0) {}
 
   OutputFunctionCoverageData(OutputFunctionCoverageData &&OFCD)
-      : Name(OFCD.Name), Hash(OFCD.Hash), Filenames(std::move(OFCD.Filenames)),
-        Regions(std::move(OFCD.Regions)) {}
+      : Name(OFCD.Name), Hash(OFCD.Hash),
+        FilenamesStorage(std::move(OFCD.FilenamesStorage)),
+        Filenames(std::move(OFCD.Filenames)), Regions(std::move(OFCD.Regions)) {
+  }
 
   OutputFunctionCoverageData(const OutputFunctionCoverageData &) = delete;
   OutputFunctionCoverageData &
@@ -135,7 +138,6 @@ struct InputFunctionCoverageData {
 struct CoverageMappingTest : ::testing::TestWithParam<std::tuple<bool, bool>> {
   bool UseMultipleReaders;
   StringMap<unsigned> Files;
-  std::vector<std::string> Filenames;
   std::vector<InputFunctionCoverageData> InputFunctions;
   std::vector<OutputFunctionCoverageData> OutputFunctions;
 
@@ -233,13 +235,10 @@ struct CoverageMappingTest : ::testing::TestWithParam<std::tuple<bool, bool>> {
 
   void readCoverageRegions(const std::string &Coverage,
                            OutputFunctionCoverageData &Data) {
-    // We will re-use the StringRef in duplicate tests, clear it to avoid
-    // clobber previous ones.
-    Filenames.clear();
-    Filenames.resize(Files.size() + 1);
+    Data.FilenamesStorage.resize(Files.size() + 1);
     for (const auto &E : Files)
-      Filenames[E.getValue()] = E.getKey().str();
-    ArrayRef<std::string> FilenameRefs = llvm::ArrayRef(Filenames);
+      Data.FilenamesStorage[E.getValue()] = E.getKey().str();
+    ArrayRef<std::string> FilenameRefs = llvm::ArrayRef(Data.FilenamesStorage);
     RawCoverageMappingReader Reader(Coverage, FilenameRefs, Data.Filenames,
                                     Data.Expressions, Data.Regions);
     EXPECT_THAT_ERROR(Reader.read(), Succeeded());