[clang-tidy] Remove duplicated logic in UnnecessaryValueParamCheck and use FunctionParmMutationAnalyzer instead.

Reviewers: alexfh, JonasToth, george.karpenkov

Subscribers: xazax.hun, kristof.beyls, chrib, a.sidorin, Szelethus, cfe-commits

Differential Revision: https://reviews.llvm.org/D52158

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@342403 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 12 insertions, 15 deletions

diff --git a/clang-tidy/performance/UnnecessaryValueParamCheck.cpp b/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
index 29a8b84c..db5a12f9 100644
--- a/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
+++ b/clang-tidy/performance/UnnecessaryValueParamCheck.cpp
@@ -13,7 +13,6 @@
 #include "../utils/FixItHintUtils.h"
 #include "../utils/Matchers.h"
 #include "../utils/TypeTraits.h"
-#include "clang/Analysis/Analyses/ExprMutationAnalyzer.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Lex/Preprocessor.h"
@@ -92,21 +91,11 @@ void UnnecessaryValueParamCheck::check(const MatchFinder::MatchResult &Result) {
   const auto *Param = Result.Nodes.getNodeAs<ParmVarDecl>("param");
   const auto *Function = Result.Nodes.getNodeAs<FunctionDecl>("functionDecl");
 
-  // Do not trigger on non-const value parameters when they are mutated either
-  // within the function body or within init expression(s) when the function is
-  // a ctor.
-  if (ExprMutationAnalyzer(*Function->getBody(), *Result.Context)
-          .isMutated(Param))
+  FunctionParmMutationAnalyzer &Analyzer =
+      MutationAnalyzers.try_emplace(Function, *Function, *Result.Context)
+          .first->second;
+  if (Analyzer.isMutated(Param))
     return;
-  // CXXCtorInitializer might also mutate Param but they're not part of function
-  // body, so check them separately here.
-  if (const auto *Ctor = dyn_cast<CXXConstructorDecl>(Function)) {
-    for (const auto *Init : Ctor->inits()) {
-      if (ExprMutationAnalyzer(*Init->getInit(), *Result.Context)
-              .isMutated(Param))
-        return;
-    }
-  }
 
   const bool IsConstQualified =
       Param->getType().getCanonicalType().isConstQualified();
@@ -186,6 +175,10 @@ void UnnecessaryValueParamCheck::storeOptions(
                 utils::IncludeSorter::toString(IncludeStyle));
 }
 
+void UnnecessaryValueParamCheck::onEndOfTranslationUnit() {
+  MutationAnalyzers.clear();
+}
+
 void UnnecessaryValueParamCheck::handleMoveFix(const ParmVarDecl &Var,
                                                const DeclRefExpr &CopyArgument,
                                                const ASTContext &Context) {
diff --git a/clang-tidy/performance/UnnecessaryValueParamCheck.h b/clang-tidy/performance/UnnecessaryValueParamCheck.h
index cbf0a3bb..ae5ef7e9 100644
--- a/clang-tidy/performance/UnnecessaryValueParamCheck.h
+++ b/clang-tidy/performance/UnnecessaryValueParamCheck.h
@@ -12,6 +12,7 @@
 
 #include "../ClangTidy.h"
 #include "../utils/IncludeInserter.h"
+#include "clang/Analysis/Analyses/ExprMutationAnalyzer.h"
 
 namespace clang {
 namespace tidy {
@@ -29,11 +30,14 @@ public:
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
   void registerPPCallbacks(CompilerInstance &Compiler) override;
   void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+  void onEndOfTranslationUnit() override;
 
 private:
   void handleMoveFix(const ParmVarDecl &Var, const DeclRefExpr &CopyArgument,
                      const ASTContext &Context);
 
+  llvm::DenseMap<const FunctionDecl *, FunctionParmMutationAnalyzer>
+      MutationAnalyzers;
   std::unique_ptr<utils::IncludeInserter> Inserter;
   const utils::IncludeSorter::IncludeStyle IncludeStyle;
 };