Clang-tidy: don't create ASTConsumers not needed for the set of checks we perform.

Summary:
This doesn't have any significant effect on the performance, but it
looks like a good thing to do.

Reviewers: djasper, klimek

Reviewed By: klimek

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2763

llvm-svn: 201340

2 files changed, 17 insertions, 10 deletions

diff --git a/clang-tools-extra/clang-tidy/ClangTidy.cpp b/clang-tools-extra/clang-tidy/ClangTidy.cpp
index aec2d98a2f7..6b5a4144f24 100644
--- a/clang-tools-extra/clang-tidy/ClangTidy.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidy.cpp
@@ -152,18 +152,24 @@ clang::ASTConsumer *ClangTidyASTConsumerFactory::CreateASTConsumer(
        I != E; ++I)
     (*I)->registerPPCallbacks(Compiler);
 
+  SmallVector<ASTConsumer *, 2> Consumers;
+  if (CheckFactories->empty())
+    Consumers.push_back(Finder.newASTConsumer());
+
   AnalyzerOptionsRef Options = Compiler.getAnalyzerOpts();
   Options->CheckersControlList = getCheckersControlList();
-  Options->AnalysisStoreOpt = RegionStoreModel;
-  Options->AnalysisDiagOpt = PD_NONE;
-  Options->AnalyzeNestedBlocks = true;
-  Options->eagerlyAssumeBinOpBifurcation = true;
-  ento::AnalysisASTConsumer *AnalysisConsumer = ento::CreateAnalysisConsumer(
-      Compiler.getPreprocessor(), Compiler.getFrontendOpts().OutputFile,
-      Options, Compiler.getFrontendOpts().Plugins);
-  AnalysisConsumer->AddDiagnosticConsumer(
-      new AnalyzerDiagnosticConsumer(Context));
-  ASTConsumer *Consumers[] = { Finder.newASTConsumer(), AnalysisConsumer };
+  if (!Options->CheckersControlList.empty()) {
+    Options->AnalysisStoreOpt = RegionStoreModel;
+    Options->AnalysisDiagOpt = PD_NONE;
+    Options->AnalyzeNestedBlocks = true;
+    Options->eagerlyAssumeBinOpBifurcation = true;
+    ento::AnalysisASTConsumer *AnalysisConsumer = ento::CreateAnalysisConsumer(
+        Compiler.getPreprocessor(), Compiler.getFrontendOpts().OutputFile,
+        Options, Compiler.getFrontendOpts().Plugins);
+    AnalysisConsumer->AddDiagnosticConsumer(
+        new AnalyzerDiagnosticConsumer(Context));
+    Consumers.push_back(AnalysisConsumer);
+  }
   return new MultiplexConsumer(Consumers);
 }
 
diff --git a/clang-tools-extra/clang-tidy/ClangTidyModule.h b/clang-tools-extra/clang-tidy/ClangTidyModule.h
index 830cbd5b15c..47a69331314 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyModule.h
+++ b/clang-tools-extra/clang-tidy/ClangTidyModule.h
@@ -90,6 +90,7 @@ public:
   typedef std::map<std::string, CheckFactoryBase *> FactoryMap;
   FactoryMap::const_iterator begin() const { return Factories.begin(); }
   FactoryMap::const_iterator end() const { return Factories.end(); }
+  bool empty() const { return Factories.empty(); }
 
 private:
   FactoryMap Factories;