[Coverage] Report errors when reading malformed source regions

Each source region has a start and end location. Report an error when
the end location does not precede the begin location.

The old lineExecutionCounts.covmapping test actually had a buggy source
region in it. This commit introduces a regenerated copy of the coverage
and moves the old copy to malformedRegions.covmapping, for a test.

Differential Revision: https://reviews.llvm.org/D37387

llvm-svn: 312814

3 files changed, 25 insertions, 8 deletions

diff --git a/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp b/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp
index 346ac76a6f7..d2878d3283a 100644
--- a/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp
+++ b/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp
@@ -250,10 +250,15 @@ Expected<std::unique_ptr<CoverageMapping>> CoverageMapping::load(
     IndexedInstrProfReader &ProfileReader) {
   auto Coverage = std::unique_ptr<CoverageMapping>(new CoverageMapping());
 
-  for (const auto &CoverageReader : CoverageReaders)
-    for (const auto &Record : *CoverageReader)
+  for (const auto &CoverageReader : CoverageReaders) {
+    for (auto RecordOrErr : *CoverageReader) {
+      if (Error E = RecordOrErr.takeError())
+        return std::move(E);
+      const auto &Record = *RecordOrErr;
       if (Error E = Coverage->loadFunctionRecord(Record, ProfileReader))
         return std::move(E);
+    }
+  }
 
   return std::move(Coverage);
 }
diff --git a/llvm/lib/ProfileData/Coverage/CoverageMappingReader.cpp b/llvm/lib/ProfileData/Coverage/CoverageMappingReader.cpp
index fff0a03ccbe..9bf70c2e3aa 100644
--- a/llvm/lib/ProfileData/Coverage/CoverageMappingReader.cpp
+++ b/llvm/lib/ProfileData/Coverage/CoverageMappingReader.cpp
@@ -49,16 +49,18 @@ using namespace object;
 #define DEBUG_TYPE "coverage-mapping"
 
 void CoverageMappingIterator::increment() {
+  if (ReadErr != coveragemap_error::success)
+    return;
+
   // Check if all the records were read or if an error occurred while reading
   // the next record.
-  if (auto E = Reader->readNextRecord(Record)) {
+  if (auto E = Reader->readNextRecord(Record))
     handleAllErrors(std::move(E), [&](const CoverageMapError &CME) {
       if (CME.get() == coveragemap_error::eof)
         *this = CoverageMappingIterator();
       else
-        llvm_unreachable("Unexpected error in coverage mapping iterator");
+        ReadErr = CME.get();
     });
-  }
 }
 
 Error RawCoverageReader::readULEB128(uint64_t &Result) {
@@ -238,9 +240,12 @@ Error RawCoverageMappingReader::readMappingRegionsSubArray(
       dbgs() << "\n";
     });
 
-    MappingRegions.push_back(CounterMappingRegion(
-        C, InferredFileID, ExpandedFileID, LineStart, ColumnStart,
-        LineStart + NumLines, ColumnEnd, Kind));
+    auto CMR = CounterMappingRegion(C, InferredFileID, ExpandedFileID,
+                                    LineStart, ColumnStart,
+                                    LineStart + NumLines, ColumnEnd, Kind);
+    if (CMR.startLoc() > CMR.endLoc())
+      return make_error<CoverageMapError>(coveragemap_error::malformed);
+    MappingRegions.push_back(CMR);
   }
   return Error::success();
 }
diff --git a/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp b/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
index 6fe93530da2..4a1ce16c486 100644
--- a/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
+++ b/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
@@ -116,6 +116,13 @@ static void writeCounter(ArrayRef<CounterExpression> Expressions, Counter C,
 }
 
 void CoverageMappingWriter::write(raw_ostream &OS) {
+  // Check that we don't have any bogus regions.
+  assert(all_of(MappingRegions,
+                [](const CounterMappingRegion &CMR) {
+                  return CMR.startLoc() <= CMR.endLoc();
+                }) &&
+         "Source region does not begin before it ends");
+
   // Sort the regions in an ascending order by the file id and the starting
   // location. Sort by region kinds to ensure stable order for tests.
   std::stable_sort(