Speed up clang-tidy when profiling in on.

[sbenza]

Summary

Speed up clang-tidy when profiling in on.
It makes profiling runs twice as fast by reusing the time samples between the
different actions.
It also joins together the sampling of different matchers of the same check.

[alexfh]

Looks good!

lib/ASTMatchers/ASTMatchFinder.cpp

494 ↗

(On Diff #15411)

Please add a short comment on how to use this class.

[sbenza]

Added comment

[sbenza]

Closed by commit rL220682 (authored by @sbenza).

cfe/trunk/lib/ASTMatchers/ASTMatchFinder.cpp

public:
   ~MatchASTVisitor() {
     if (Options.CheckProfiling) {
       Options.CheckProfiling->Records = std::move(TimeByBucket);
     }
   }
 
   void onStartOfTranslationUnit() {
     const bool EnableCheckProfiling = Options.CheckProfiling.hasValue();
+    TimeBucketRegion Timer;
     for (MatchCallback *MC : Matchers->AllCallbacks) {
-      TimeRegion Timer(EnableCheckProfiling ? &TimeByBucket[MC->getID()]
-                                            : nullptr);
+      if (EnableCheckProfiling)
+        Timer.setBucket(&TimeByBucket[MC->getID()]);
       MC->onStartOfTranslationUnit();
     }
   }
 
   void onEndOfTranslationUnit() {
     const bool EnableCheckProfiling = Options.CheckProfiling.hasValue();
+    TimeBucketRegion Timer;
     for (MatchCallback *MC : Matchers->AllCallbacks) {
-      TimeRegion Timer(EnableCheckProfiling ? &TimeByBucket[MC->getID()]
-                                            : nullptr);
+      if (EnableCheckProfiling)
+        Timer.setBucket(&TimeByBucket[MC->getID()]);
       MC->onEndOfTranslationUnit();
     }
   }
 
   void set_active_ast_context(ASTContext *NewActiveASTContext) {
     ActiveASTContext = NewActiveASTContext;
   }
 
public:
 
   bool shouldVisitTemplateInstantiations() const { return true; }
   bool shouldVisitImplicitCode() const { return true; }
   // Disables data recursion. We intercept Traverse* methods in the RAV, which
   // are not triggered during data recursion.
   bool shouldUseDataRecursionFor(clang::Stmt *S) const { return false; }
 
 private:
-  class TimeRegion {
+  class TimeBucketRegion {
   public:
-    TimeRegion(llvm::TimeRecord *Record) : Record(Record) {
-      if (Record)
-        *Record -= llvm::TimeRecord::getCurrentTime(true);
-    }
-    ~TimeRegion() {
-      if (Record)
-        *Record += llvm::TimeRecord::getCurrentTime(false);
+    TimeBucketRegion() : Bucket(nullptr) {}
+    ~TimeBucketRegion() { setBucket(nullptr); }
+
+    /// \brief Start timing for \p NewBucket.
+    ///
+    /// If there was a bucket already set, it will finish the timing for that
+    /// other bucket.
+    /// \p NewBucket will be timed until the next call to \c setBucket() or
+    /// until the \c TimeBucketRegion is destroyed.
+    /// If \p NewBucket is the same as the currently timed bucket, this call
+    /// does nothing.
+    void setBucket(llvm::TimeRecord *NewBucket) {
+      if (Bucket != NewBucket) {
+        auto Now = llvm::TimeRecord::getCurrentTime(true);
+        if (Bucket)
+          *Bucket += Now;
+        if (NewBucket)
+          *NewBucket -= Now;
+        Bucket = NewBucket;
+      }
     }
 
   private:
-    llvm::TimeRecord *Record;
+    llvm::TimeRecord *Bucket;
   };
 
   /// \brief Runs all the \p Matchers on \p Node.
   ///
   /// Used by \c matchDispatch() below.
   template <typename T, typename MC>
   void matchImpl(const T &Node, const MC &Matchers) {
     const bool EnableCheckProfiling = Options.CheckProfiling.hasValue();
+    TimeBucketRegion Timer;
     for (const auto &MP : Matchers) {
-      TimeRegion Timer(EnableCheckProfiling ? &TimeByBucket[MP.second->getID()]
-                                            : nullptr);
+      if (EnableCheckProfiling)
+        Timer.setBucket(&TimeByBucket[MP.second->getID()]);
       BoundNodesTreeBuilder Builder;
       if (MP.first.matches(Node, this, &Builder)) {
         MatchVisitor Visitor(ActiveASTContext, MP.second);
         Builder.visitMatches(&Visitor);
       }
     }
   }