r276716 - [Coverage] Do not write out coverage mappings with zero entries

[Vedant Kumar via cfe-commits]

Author: vedantk
Date: Mon Jul 25 19:24:59 2016
New Revision: 276716

URL: http://llvm.org/viewvc/llvm-project?rev=276716&view=rev
Log:
[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.

Added:
    cfe/trunk/test/CoverageMapping/system_macro.cpp
      - copied, changed from r276711, cfe/trunk/test/CoverageMapping/system_macro.c
Removed:
    cfe/trunk/test/CoverageMapping/system_macro.c
Modified:
    cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp

Modified: cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp?rev=276716&r1=276715&r2=276716&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp (original)
+++ cfe/trunk/lib/CodeGen/CoverageMappingGen.cpp Mon Jul 25 19:24:59 2016
@@ -352,6 +352,9 @@ struct EmptyCoverageMappingBuilder : pub
     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);
   }
 

Removed: cfe/trunk/test/CoverageMapping/system_macro.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CoverageMapping/system_macro.c?rev=276715&view=auto
==============================================================================
--- cfe/trunk/test/CoverageMapping/system_macro.c (original)
+++ cfe/trunk/test/CoverageMapping/system_macro.c (removed)
@@ -1,23 +0,0 @@
-// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name system_macro.c -o - %s | FileCheck %s
-
-#ifdef IS_SYSHEADER
-
-#pragma clang system_header
-#define Func(x) if (x) {}
-#define SomeType int
-
-#else
-
-#define IS_SYSHEADER
-#include __FILE__
-
-// 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() {}
-
-#endif

Copied: cfe/trunk/test/CoverageMapping/system_macro.cpp (from r276711, cfe/trunk/test/CoverageMapping/system_macro.c)
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CoverageMapping/system_macro.cpp?p2=cfe/trunk/test/CoverageMapping/system_macro.cpp&p1=cfe/trunk/test/CoverageMapping/system_macro.c&r1=276711&r2=276716&rev=276716&view=diff
==============================================================================
--- cfe/trunk/test/CoverageMapping/system_macro.c (original)
+++ cfe/trunk/test/CoverageMapping/system_macro.cpp Mon Jul 25 19:24:59 2016
@@ -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