[llvm-cov] Ignore unclosed line segments when setting line counts

This patch makes a slight change to the way llvm-cov determines line
execution counts. If there are multiple line segments on a line, the
line count is the max count among the regions which start *and* end on
the line. This avoids an issue posed by deferred regions which start on
the same line as a terminated region, e.g:

  if (false)
    return; //< The line count should be 0, even though a new region
            //< starts at the semi-colon.
  foo();

Another change is that counts from line segments which don't correspond
to region entries are considered. This enables the first change, and
corrects an outstanding issue (see the showLineExecutionCounts.cpp test
change).

This is related to D35925.

Testing: check-profile, llvm-cov lit tests

Differential Revision: https://reviews.llvm.org/D36014

llvm-svn: 310012

1 files changed, 37 insertions, 8 deletions

diff --git a/llvm/tools/llvm-cov/SourceCoverageView.cpp b/llvm/tools/llvm-cov/SourceCoverageView.cpp
index 52b8ff1..6630f33 100644
--- a/llvm/tools/llvm-cov/SourceCoverageView.cpp
+++ b/llvm/tools/llvm-cov/SourceCoverageView.cpp
@@ -83,6 +83,41 @@ CoveragePrinter::create(const CoverageViewOptions &Opts) {
   llvm_unreachable("Unknown coverage output format!");
 }
 
+LineCoverageStats::LineCoverageStats(
+    ArrayRef<const coverage::CoverageSegment *> LineSegments,
+    const coverage::CoverageSegment *WrappedSegment) {
+  // Find the minimum number of regions which start in this line.
+  unsigned MinRegionCount = 0;
+  auto isStartOfRegion = [](const coverage::CoverageSegment *S) {
+    return S->HasCount && S->IsRegionEntry;
+  };
+  for (unsigned I = 0; I < LineSegments.size() && MinRegionCount < 2; ++I)
+    if (isStartOfRegion(LineSegments[I]))
+      ++MinRegionCount;
+
+  ExecutionCount = 0;
+  HasMultipleRegions = MinRegionCount > 1;
+  Mapped = (WrappedSegment && WrappedSegment->HasCount) || (MinRegionCount > 0);
+
+  if (!Mapped)
+    return;
+
+  // Pick the max count among regions which start and end on this line, to
+  // avoid erroneously using the wrapped count, and to avoid picking region
+  // counts which come from deferred regions.
+  if (LineSegments.size() > 1) {
+    for (unsigned I = 0; I < LineSegments.size() - 1; ++I)
+      ExecutionCount = std::max(ExecutionCount, LineSegments[I]->Count);
+    return;
+  }
+
+  // Just pick the maximum count.
+  if (WrappedSegment && WrappedSegment->HasCount)
+    ExecutionCount = WrappedSegment->Count;
+  if (!LineSegments.empty())
+    ExecutionCount = std::max(ExecutionCount, LineSegments[0]->Count);
+}
+
 unsigned SourceCoverageView::getFirstUncoveredLineNo() {
   auto CheckIfUncovered = [](const coverage::CoverageSegment &S) {
     return S.HasCount && S.Count == 0;
@@ -207,17 +242,11 @@ void SourceCoverageView::print(raw_ostream &OS, bool WholeFile,
     while (NextSegment != EndSegment && NextSegment->Line == LI.line_number())
       LineSegments.push_back(&*NextSegment++);
 
-    // Calculate a count to be for the line as a whole.
-    LineCoverageStats LineCount;
-    if (WrappedSegment && WrappedSegment->HasCount)
-      LineCount.addRegionCount(WrappedSegment->Count);
-    for (const auto *S : LineSegments)
-      if (S->HasCount && S->IsRegionEntry)
-        LineCount.addRegionStartCount(S->Count);
-
     renderLinePrefix(OS, ViewDepth);
     if (getOptions().ShowLineNumbers)
       renderLineNumberColumn(OS, LI.line_number());
+
+    LineCoverageStats LineCount{LineSegments, WrappedSegment};
     if (getOptions().ShowLineStats)
       renderLineCoverageColumn(OS, LineCount);