[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

1 files changed, 7 insertions, 0 deletions

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(