[Coverage] Use the most-recent completed region count (PR35437)

This is a fix for the coverage segment builder.

If multiple regions must be popped off the active stack at once, and
more than one of them end at the same location, emit a segment using the
count from the most-recent completed region.

Fixes PR35437, rdar://35760630

Testing: invoked llvm-cov on a stage2 build of clang, additional unit
tests, check-profile

llvm-svn: 319391

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/unittests/ProfileData/CoverageMappingTest.cpp b/llvm/unittests/ProfileData/CoverageMappingTest.cpp
index 7c94ece1adc..26a8e511b4f 100644
--- a/llvm/unittests/ProfileData/CoverageMappingTest.cpp
+++ b/llvm/unittests/ProfileData/CoverageMappingTest.cpp
@@ -466,6 +466,32 @@ TEST_P(CoverageMappingTest, multiple_regions_end_after_parent_ends) {
   EXPECT_EQ(CoverageSegment(9, 9, false), Segments[7]);
 }
 
+TEST_P(CoverageMappingTest, multiple_completed_segments_at_same_loc) {
+  ProfileWriter.addRecord({"func1", 0x1234, {0, 1, 2}}, Err);
+  startFunction("func1", 0x1234);
+
+  // PR35437
+  addCMR(Counter::getCounter(1), "file1", 2, 1, 18, 2);
+  addCMR(Counter::getCounter(0), "file1", 8, 12, 14, 6);
+  addCMR(Counter::getCounter(1), "file1", 9, 1, 14, 6);
+  addCMR(Counter::getCounter(2), "file1", 11, 13, 11, 14);
+
+  EXPECT_THAT_ERROR(loadCoverageMapping(), Succeeded());
+  const auto FunctionRecords = LoadedCoverage->getCoveredFunctions();
+  const auto &FunctionRecord = *FunctionRecords.begin();
+  CoverageData Data = LoadedCoverage->getCoverageForFunction(FunctionRecord);
+  std::vector<CoverageSegment> Segments(Data.begin(), Data.end());
+
+  ASSERT_EQ(6U, Segments.size());
+  EXPECT_EQ(CoverageSegment(2, 1, 1, true), Segments[0]);
+  EXPECT_EQ(CoverageSegment(8, 12, 0, true), Segments[1]);
+  EXPECT_EQ(CoverageSegment(9, 1, 1, true), Segments[2]);
+  EXPECT_EQ(CoverageSegment(11, 13, 2, true), Segments[3]);
+  // Use count=1 (from 9:1 -> 14:6), not count=0 (from 8:12 -> 14:6).
+  EXPECT_EQ(CoverageSegment(11, 14, 1, false), Segments[4]);
+  EXPECT_EQ(CoverageSegment(18, 2, false), Segments[5]);
+}
+
 TEST_P(CoverageMappingTest, dont_emit_redundant_segments) {
   ProfileWriter.addRecord({"func1", 0x1234, {1, 1}}, Err);
   startFunction("func1", 0x1234);