[clang-tidy] performance-inefficient-vector-operation: Support proto repeated field

Summary:
Finds calls that add element to protobuf repeated field in a loop
without calling Reserve() before the loop. Calling Reserve() first can avoid
unnecessary memory reallocations.

A new option EnableProto is added to guard this feature.

Patch by Cong Liu!

Reviewers: gribozavr, alexfh, hokein, aaron.ballman

Reviewed By: hokein

Subscribers: lebedev.ri, xazax.hun, Eugene.Zelenko, cfe-commits

Tags: #clang, #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D67135

llvm-svn: 371963

1 files changed, 10 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.h b/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.h
index bfd84d100c2..e224dcc9068 100644
--- a/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.h
+++ b/clang-tools-extra/clang-tidy/performance/InefficientVectorOperationCheck.h
@@ -18,6 +18,9 @@ namespace performance {
 /// Finds possible inefficient `std::vector` operations (e.g. `push_back`) in
 /// for loops that may cause unnecessary memory reallocations.
 ///
+/// When EnableProto, also finds calls that add element to protobuf repeated
+/// field without calling Reserve() first.
+///
 /// For the user-facing documentation see:
 /// http://clang.llvm.org/extra/clang-tidy/checks/performance-inefficient-vector-operation.html
 class InefficientVectorOperationCheck : public ClangTidyCheck {
@@ -28,7 +31,14 @@ public:
   void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
 
 private:
+  void AddMatcher(const ast_matchers::DeclarationMatcher &TargetRecordDecl,
+                  StringRef VarDeclName, StringRef VarDeclStmtName,
+                  const ast_matchers::DeclarationMatcher &AppendMethodDecl,
+                  StringRef AppendCallName, ast_matchers::MatchFinder *Finder);
   const std::vector<std::string> VectorLikeClasses;
+
+  // If true, also check inefficient operations for proto repeated fields.
+  bool EnableProto;
 };
 
 } // namespace performance