[Coverage] Suppress creating a code region if the same area is covered by an expansion region.

In most cases these code regions are just redundant, but sometimes they
could be assigned to the counter of the parent code region instead of
the counter of the nested block.

Differential Revision: https://reviews.llvm.org/D23987

llvm-svn: 280199

1 files changed, 23 insertions, 5 deletions

diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
index 080525c8e6c..e008f44fc6f 100644
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -92,6 +92,14 @@ public:
   /// \brief The source mapping regions for this function.
   std::vector<SourceMappingRegion> SourceRegions;
 
+  /// \brief A set of regions which can be used as a filter.
+  ///
+  /// It is produced by emitExpansionRegions() and is used in
+  /// emitSourceRegions() to suppress producing code regions if
+  /// the same area is covered by expansion regions.
+  typedef llvm::SmallSet<std::pair<SourceLocation, SourceLocation>, 8>
+      SourceRegionFilter;
+
   CoverageMappingBuilder(CoverageMappingModuleGen &CVM, SourceManager &SM,
                          const LangOptions &LangOpts)
       : CVM(CVM), SM(SM), LangOpts(LangOpts) {}
@@ -249,7 +257,7 @@ public:
 
   /// \brief Generate the coverage counter mapping regions from collected
   /// source regions.
-  void emitSourceRegions() {
+  void emitSourceRegions(const SourceRegionFilter &Filter) {
     for (const auto &Region : SourceRegions) {
       assert(Region.hasEndLoc() && "incomplete region");
 
@@ -269,6 +277,13 @@ public:
       assert(SM.isWrittenInSameFile(LocStart, LocEnd) &&
              "region spans multiple files");
 
+      // Don't add code regions for the area covered by expansion regions.
+      // This not only suppresses redundant regions, but sometimes prevents
+      // creating regions with wrong counters if, for example, a statement's
+      // body ends at the end of a nested macro.
+      if (Filter.count(std::make_pair(LocStart, LocEnd)))
+        continue;
+
       // Find the spilling locations for the mapping region.
       unsigned LineStart = SM.getSpellingLineNumber(LocStart);
       unsigned ColumnStart = SM.getSpellingColumnNumber(LocStart);
@@ -283,7 +298,8 @@ public:
   }
 
   /// \brief Generate expansion regions for each virtual file we've seen.
-  void emitExpansionRegions() {
+  SourceRegionFilter emitExpansionRegions() {
+    SourceRegionFilter Filter;
     for (const auto &FM : FileIDMapping) {
       SourceLocation ExpandedLoc = FM.second.second;
       SourceLocation ParentLoc = getIncludeOrExpansionLoc(ExpandedLoc);
@@ -299,6 +315,7 @@ public:
       SourceLocation LocEnd = getPreciseTokenLocEnd(ParentLoc);
       assert(SM.isWrittenInSameFile(ParentLoc, LocEnd) &&
              "region spans multiple files");
+      Filter.insert(std::make_pair(ParentLoc, LocEnd));
 
       unsigned LineStart = SM.getSpellingLineNumber(ParentLoc);
       unsigned ColumnStart = SM.getSpellingColumnNumber(ParentLoc);
@@ -309,6 +326,7 @@ public:
           *ParentFileID, *ExpandedFileID, LineStart, ColumnStart, LineEnd,
           ColumnEnd));
     }
+    return Filter;
   }
 };
 
@@ -350,7 +368,7 @@ struct EmptyCoverageMappingBuilder : public CoverageMappingBuilder {
   void write(llvm::raw_ostream &OS) {
     SmallVector<unsigned, 16> FileIDMapping;
     gatherFileIDs(FileIDMapping);
-    emitSourceRegions();
+    emitSourceRegions(SourceRegionFilter());
 
     if (MappingRegions.empty())
       return;
@@ -605,8 +623,8 @@ struct CounterCoverageMappingBuilder
   void write(llvm::raw_ostream &OS) {
     llvm::SmallVector<unsigned, 8> VirtualFileMapping;
     gatherFileIDs(VirtualFileMapping);
-    emitSourceRegions();
-    emitExpansionRegions();
+    SourceRegionFilter Filter = emitExpansionRegions();
+    emitSourceRegions(Filter);
     gatherSkippedRegions();
 
     if (MappingRegions.empty())