[Coverage] Do not write out coverage mappings with zero entries

After r275121, we stopped mapping regions from system headers. Lambdas
declared in regions belonging to system headers started producing empty
coverage mappings, since the files corresponding to their spelling locs
were being ignored.

The coverage reader doesn't know what to do with these empty mappings.
This commit makes sure that we don't produce them and adds a test. I'll
make the reader stricter in a follow-up commit.

llvm-svn: 276716

diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
index 4debc7e..da6fa2a 100644 (file)
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -352,6 +352,9 @@ struct EmptyCoverageMappingBuilder : public CoverageMappingBuilder {
     gatherFileIDs(FileIDMapping);
     emitSourceRegions();
 
+    if (MappingRegions.empty())
+      return;
+
     CoverageMappingWriter Writer(FileIDMapping, None, MappingRegions);
     Writer.write(OS);
   }
@@ -605,6 +608,9 @@ struct CounterCoverageMappingBuilder
     emitExpansionRegions();
     gatherSkippedRegions();
 
+    if (MappingRegions.empty())
+      return;
+
     CoverageMappingWriter Writer(VirtualFileMapping, Builder.getExpressions(),
                                  MappingRegions);
     Writer.write(OS);
@@ -621,6 +627,11 @@ struct CounterCoverageMappingBuilder
 
   void VisitDecl(const Decl *D) {
     Stmt *Body = D->getBody();
+
+    // Do not propagate region counts into system headers.
+    if (Body && SM.isInSystemHeader(SM.getSpellingLoc(getStart(Body))))
+      return;
+
     propagateCounts(getRegionCounter(Body), Body);
   }
 

diff --git a/clang/test/CoverageMapping/system_macro.c b/clang/test/CoverageMapping/system_macro.cpp
similarity index 50%
rename from clang/test/CoverageMapping/system_macro.c
rename to clang/test/CoverageMapping/system_macro.cpp
index bddc822..ce0da17 100644 (file)
--- a/clang/test/CoverageMapping/system_macro.c
+++ b/clang/test/CoverageMapping/system_macro.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name system_macro.c -o - %s | FileCheck %s
+// RUN: %clang_cc1 -std=c++11 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name system_macro.cpp -o - %s | FileCheck %s
 
 #ifdef IS_SYSHEADER
 
@@ -11,13 +11,16 @@
 #define IS_SYSHEADER
 #include __FILE__
 
-// CHECK-LABEL: doSomething:
+// CHECK-LABEL: doSomething
 void doSomething(int x) { // CHECK: File 0, [[@LINE]]:25 -> {{[0-9:]+}} = #0
   Func(x);
   return;
   SomeType *f; // CHECK: File 0, [[@LINE]]:11 -> {{[0-9:]+}} = 0
 }
 
-int main() {}
+// CHECK-LABEL: main
+int main() { // CHECK: File 0, [[@LINE]]:12 -> [[@LINE+2]]:2 = #0
+  Func([] { return true; }());
+}
 
 #endif