1 files changed, 56 insertions, 4 deletions

diff --git a/lib/ProfileData/Coverage/CoverageMapping.cpp b/lib/ProfileData/Coverage/CoverageMapping.cpp
index afd6618e7cb3e..8d5e56e26c0ff 100644
--- a/lib/ProfileData/Coverage/CoverageMapping.cpp
+++ b/lib/ProfileData/Coverage/CoverageMapping.cpp
@@ -194,6 +194,15 @@ void FunctionRecordIterator::skipOtherFiles() {
     *this = FunctionRecordIterator();
 }
 
+ArrayRef<unsigned> CoverageMapping::getImpreciseRecordIndicesForFilename(
+    StringRef Filename) const {
+  size_t FilenameHash = hash_value(Filename);
+  auto RecordIt = FilenameHash2RecordIndices.find(FilenameHash);
+  if (RecordIt == FilenameHash2RecordIndices.end())
+    return {};
+  return RecordIt->second;
+}
+
 Error CoverageMapping::loadFunctionRecord(
     const CoverageMappingRecord &Record,
     IndexedInstrProfReader &ProfileReader) {
@@ -249,6 +258,20 @@ Error CoverageMapping::loadFunctionRecord(
     return Error::success();
 
   Functions.push_back(std::move(Function));
+
+  // Performance optimization: keep track of the indices of the function records
+  // which correspond to each filename. This can be used to substantially speed
+  // up queries for coverage info in a file.
+  unsigned RecordIndex = Functions.size() - 1;
+  for (StringRef Filename : Record.Filenames) {
+    auto &RecordIndices = FilenameHash2RecordIndices[hash_value(Filename)];
+    // Note that there may be duplicates in the filename set for a function
+    // record, because of e.g. macro expansions in the function in which both
+    // the macro and the function are defined in the same file.
+    if (RecordIndices.empty() || RecordIndices.back() != RecordIndex)
+      RecordIndices.push_back(RecordIndex);
+  }
+
   return Error::success();
 }
 
@@ -270,6 +293,16 @@ Expected<std::unique_ptr<CoverageMapping>> CoverageMapping::load(
   return std::move(Coverage);
 }
 
+// If E is a no_data_found error, returns success. Otherwise returns E.
+static Error handleMaybeNoDataFoundError(Error E) {
+  return handleErrors(
+      std::move(E), [](const CoverageMapError &CME) {
+        if (CME.get() == coveragemap_error::no_data_found)
+          return static_cast<Error>(Error::success());
+        return make_error<CoverageMapError>(CME.get());
+      });
+}
+
 Expected<std::unique_ptr<CoverageMapping>>
 CoverageMapping::load(ArrayRef<StringRef> ObjectFilenames,
                       StringRef ProfileFilename, ArrayRef<StringRef> Arches) {
@@ -289,12 +322,21 @@ CoverageMapping::load(ArrayRef<StringRef> ObjectFilenames,
         CovMappingBufOrErr.get()->getMemBufferRef();
     auto CoverageReadersOrErr =
         BinaryCoverageReader::create(CovMappingBufRef, Arch, Buffers);
-    if (Error E = CoverageReadersOrErr.takeError())
-      return std::move(E);
+    if (Error E = CoverageReadersOrErr.takeError()) {
+      E = handleMaybeNoDataFoundError(std::move(E));
+      if (E)
+        return std::move(E);
+      // E == success (originally a no_data_found error).
+      continue;
+    }
     for (auto &Reader : CoverageReadersOrErr.get())
       Readers.push_back(std::move(Reader));
     Buffers.push_back(std::move(CovMappingBufOrErr.get()));
   }
+  // If no readers were created, either no objects were provided or none of them
+  // had coverage data. Return an error in the latter case.
+  if (Readers.empty() && !ObjectFilenames.empty())
+    return make_error<CoverageMapError>(coveragemap_error::no_data_found);
   return load(Readers, *ProfileReader);
 }
 
@@ -607,7 +649,12 @@ CoverageData CoverageMapping::getCoverageForFile(StringRef Filename) const {
   CoverageData FileCoverage(Filename);
   std::vector<CountedRegion> Regions;
 
-  for (const auto &Function : Functions) {
+  // Look up the function records in the given file. Due to hash collisions on
+  // the filename, we may get back some records that are not in the file.
+  ArrayRef<unsigned> RecordIndices =
+      getImpreciseRecordIndicesForFilename(Filename);
+  for (unsigned RecordIndex : RecordIndices) {
+    const FunctionRecord &Function = Functions[RecordIndex];
     auto MainFileID = findMainViewFileID(Filename, Function);
     auto FileIDs = gatherFileIDs(Filename, Function);
     for (const auto &CR : Function.CountedRegions)
@@ -627,7 +674,12 @@ CoverageData CoverageMapping::getCoverageForFile(StringRef Filename) const {
 std::vector<InstantiationGroup>
 CoverageMapping::getInstantiationGroups(StringRef Filename) const {
   FunctionInstantiationSetCollector InstantiationSetCollector;
-  for (const auto &Function : Functions) {
+  // Look up the function records in the given file. Due to hash collisions on
+  // the filename, we may get back some records that are not in the file.
+  ArrayRef<unsigned> RecordIndices =
+      getImpreciseRecordIndicesForFilename(Filename);
+  for (unsigned RecordIndex : RecordIndices) {
+    const FunctionRecord &Function = Functions[RecordIndex];
     auto MainFileID = findMainViewFileID(Filename, Function);
     if (!MainFileID)
       continue;