Filter the toplevel matchers by kind.

Summary:
Filter the toplevel matchers by kind.
Decl and Stmt matchers are tied to a specific node kind and trying to
match incompatible nodes is a waste.
Precalculate a filtered list of matchers that have a chance of matching
the node and ignore the rest.
Speeds up our clang-tidy benchmark by ~10%

Reviewers: klimek

Subscribers: klimek, cfe-commits

Differential Revision: http://reviews.llvm.org/D6361

llvm-svn: 222688

clang/include/clang/AST/ASTTypeTraits.h

@@ -23,6 +23,7 @@
 #include "clang/AST/TemplateBase.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/LLVM.h"
+#include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/Support/AlignOf.h"
 
 namespace llvm {
@@ -90,6 +91,21 @@ public:
   static ASTNodeKind getMostDerivedCommonAncestor(ASTNodeKind Kind1,
                                                   ASTNodeKind Kind2);
 
+  /// \brief Hooks for using ASTNodeKind as a key in a DenseMap.
+  struct DenseMapInfo {
+    // ASTNodeKind() is a good empty key because it is represented as a 0.
+    static inline ASTNodeKind getEmptyKey() { return ASTNodeKind(); }
+    // NKI_NumberOfKinds is not a valid value, so it is good for a
+    // tombstone key.
+    static inline ASTNodeKind getTombstoneKey() {
+      return ASTNodeKind(NKI_NumberOfKinds);
+    }
+    static unsigned getHashValue(const ASTNodeKind &Val) { return Val.KindId; }
+    static bool isEqual(const ASTNodeKind &LHS, const ASTNodeKind &RHS) {
+      return LHS.KindId == RHS.KindId;
+    }
+  };
+
 private:
   /// \brief Kind ids.
   ///
@@ -375,4 +391,12 @@ template <typename T, typename EnablerT> struct DynTypedNode::BaseConverter {
 } // end namespace ast_type_traits
 } // end namespace clang
 
+namespace llvm {
+
+template <>
+struct DenseMapInfo<clang::ast_type_traits::ASTNodeKind>
+    : clang::ast_type_traits::ASTNodeKind::DenseMapInfo {};
+
+}  // end namespace llvm
+
 #endif

clang/include/clang/ASTMatchers/ASTMatchFinder.h

@@ -199,9 +199,9 @@ public:
   /// \brief For each \c Matcher<> a \c MatchCallback that will be called
   /// when it matches.
   struct MatchersByType {
-    std::vector<std::pair<DeclarationMatcher, MatchCallback *>> Decl;
+    std::vector<std::pair<internal::DynTypedMatcher, MatchCallback *>>
+        DeclOrStmt;
     std::vector<std::pair<TypeMatcher, MatchCallback *>> Type;
-    std::vector<std::pair<StatementMatcher, MatchCallback *>> Stmt;
     std::vector<std::pair<NestedNameSpecifierMatcher, MatchCallback *>>
         NestedNameSpecifier;
     std::vector<std::pair<NestedNameSpecifierLocMatcher, MatchCallback *>>

clang/include/clang/ASTMatchers/ASTMatchersInternal.h

@@ -289,6 +289,11 @@ public:
 
   void setAllowBind(bool AB) { AllowBind = AB; }
 
+  /// \brief Check whether this matcher could ever match a node of kind \p Kind.
+  /// \return \c false if this matcher will never match such a node. Otherwise,
+  /// return \c true.
+  bool canMatchNodesOfKind(ast_type_traits::ASTNodeKind Kind) const;
+
   /// \brief Return a matcher that points to the same implementation, but
   ///   restricts the node types for \p Kind.
   DynTypedMatcher dynCastTo(const ast_type_traits::ASTNodeKind Kind) const;
@@ -297,6 +302,14 @@ public:
   bool matches(const ast_type_traits::DynTypedNode &DynNode,
                ASTMatchFinder *Finder, BoundNodesTreeBuilder *Builder) const;
 
+  /// \brief Same as matches(), but skips the kind check.
+  ///
+  /// It is faster, but the caller must ensure the node is valid for the
+  /// kind of this matcher.
+  bool matchesNoKindCheck(const ast_type_traits::DynTypedNode &DynNode,
+                          ASTMatchFinder *Finder,
+                          BoundNodesTreeBuilder *Builder) const;
+
   /// \brief Bind the specified \p ID to the matcher.
   /// \return A new matcher with the \p ID bound to it if this matcher supports
   ///   binding. Otherwise, returns an empty \c Optional<>.

clang/lib/ASTMatchers/ASTMatchFinder.cpp

@@ -20,6 +20,7 @@
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/RecursiveASTVisitor.h"
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/Support/Timer.h"
 #include <deque>
@@ -523,7 +524,7 @@ private:
   ///
   /// Used by \c matchDispatch() below.
   template <typename T, typename MC>
-  void matchImpl(const T &Node, const MC &Matchers) {
+  void matchWithoutFilter(const T &Node, const MC &Matchers) {
     const bool EnableCheckProfiling = Options.CheckProfiling.hasValue();
     TimeBucketRegion Timer;
     for (const auto &MP : Matchers) {
@@ -537,22 +538,66 @@ private:
     }
   }
 
+  void matchWithFilter(const ast_type_traits::DynTypedNode &DynNode) {
+    auto Kind = DynNode.getNodeKind();
+    auto it = MatcherFiltersMap.find(Kind);
+    const auto &Filter =
+        it != MatcherFiltersMap.end() ? it->second : getFilterForKind(Kind);
+
+    if (Filter.empty())
+      return;
+
+    const bool EnableCheckProfiling = Options.CheckProfiling.hasValue();
+    TimeBucketRegion Timer;
+    auto &Matchers = this->Matchers->DeclOrStmt;
+    for (unsigned short I : Filter) {
+      auto &MP = Matchers[I];
+      if (EnableCheckProfiling)
+        Timer.setBucket(&TimeByBucket[MP.second->getID()]);
+      BoundNodesTreeBuilder Builder;
+      if (MP.first.matchesNoKindCheck(DynNode, this, &Builder)) {
+        MatchVisitor Visitor(ActiveASTContext, MP.second);
+        Builder.visitMatches(&Visitor);
+      }
+    }
+  }
+
+  const std::vector<unsigned short> &
+  getFilterForKind(ast_type_traits::ASTNodeKind Kind) {
+    auto &Filter = MatcherFiltersMap[Kind];
+    auto &Matchers = this->Matchers->DeclOrStmt;
+    assert((Matchers.size() < USHRT_MAX) && "Too many matchers.");
+    for (unsigned I = 0, E = Matchers.size(); I != E; ++I) {
+      if (Matchers[I].first.canMatchNodesOfKind(Kind)) {
+        Filter.push_back(I);
+      }
+    }
+    return Filter;
+  }
+
   /// @{
   /// \brief Overloads to pair the different node types to their matchers.
-  void matchDispatch(const Decl *Node) { matchImpl(*Node, Matchers->Decl); }
-  void matchDispatch(const Stmt *Node) { matchImpl(*Node, Matchers->Stmt); }
+  void matchDispatch(const Decl *Node) {
+    return matchWithFilter(ast_type_traits::DynTypedNode::create(*Node));
+  }
+  void matchDispatch(const Stmt *Node) {
+    return matchWithFilter(ast_type_traits::DynTypedNode::create(*Node));
+  }
+
   void matchDispatch(const Type *Node) {
-    matchImpl(QualType(Node, 0), Matchers->Type);
+    matchWithoutFilter(QualType(Node, 0), Matchers->Type);
   }
   void matchDispatch(const TypeLoc *Node) {
-    matchImpl(*Node, Matchers->TypeLoc);
+    matchWithoutFilter(*Node, Matchers->TypeLoc);
+  }
+  void matchDispatch(const QualType *Node) {
+    matchWithoutFilter(*Node, Matchers->Type);
   }
-  void matchDispatch(const QualType *Node) { matchImpl(*Node, Matchers->Type); }
   void matchDispatch(const NestedNameSpecifier *Node) {
-    matchImpl(*Node, Matchers->NestedNameSpecifier);
+    matchWithoutFilter(*Node, Matchers->NestedNameSpecifier);
   }
   void matchDispatch(const NestedNameSpecifierLoc *Node) {
-    matchImpl(*Node, Matchers->NestedNameSpecifierLoc);
+    matchWithoutFilter(*Node, Matchers->NestedNameSpecifierLoc);
   }
   void matchDispatch(const void *) { /* Do nothing. */ }
   /// @}
@@ -685,6 +730,18 @@ private:
   llvm::StringMap<llvm::TimeRecord> TimeByBucket;
 
   const MatchFinder::MatchersByType *Matchers;
+
+  /// \brief Filtered list of matcher indices for each matcher kind.
+  ///
+  /// \c Decl and \c Stmt toplevel matchers usually apply to a specific node
+  /// kind (and derived kinds) so it is a waste to try every matcher on every
+  /// node.
+  /// We precalculate a list of matchers that pass the toplevel restrict check.
+  /// This also allows us to skip the restrict check at matching time. See
+  /// use \c matchesNoKindCheck() above.
+  llvm::DenseMap<ast_type_traits::ASTNodeKind, std::vector<unsigned short>>
+      MatcherFiltersMap;
+
   const MatchFinder::MatchFinderOptions &Options;
   ASTContext *ActiveASTContext;
 
@@ -855,7 +912,7 @@ MatchFinder::~MatchFinder() {}
 
 void MatchFinder::addMatcher(const DeclarationMatcher &NodeMatch,
                              MatchCallback *Action) {
-  Matchers.Decl.push_back(std::make_pair(NodeMatch, Action));
+  Matchers.DeclOrStmt.push_back(std::make_pair(NodeMatch, Action));
   Matchers.AllCallbacks.push_back(Action);
 }
 
@@ -867,7 +924,7 @@ void MatchFinder::addMatcher(const TypeMatcher &NodeMatch,
 
 void MatchFinder::addMatcher(const StatementMatcher &NodeMatch,
                              MatchCallback *Action) {
-  Matchers.Stmt.push_back(std::make_pair(NodeMatch, Action));
+  Matchers.DeclOrStmt.push_back(std::make_pair(NodeMatch, Action));
   Matchers.AllCallbacks.push_back(Action);
 }
 

clang/lib/ASTMatchers/ASTMatchersInternal.cpp

@@ -149,6 +149,11 @@ DynTypedMatcher DynTypedMatcher::trueMatcher(
   return DynTypedMatcher(NodeKind, NodeKind, &*TrueMatcherInstance);
 }
 
+bool DynTypedMatcher::canMatchNodesOfKind(
+    ast_type_traits::ASTNodeKind Kind) const {
+  return RestrictKind.isBaseOf(Kind);
+}
+
 DynTypedMatcher DynTypedMatcher::dynCastTo(
     const ast_type_traits::ASTNodeKind Kind) const {
   auto Copy = *this;
@@ -172,6 +177,20 @@ bool DynTypedMatcher::matches(const ast_type_traits::DynTypedNode &DynNode,
   return false;
 }
 
+bool DynTypedMatcher::matchesNoKindCheck(
+    const ast_type_traits::DynTypedNode &DynNode, ASTMatchFinder *Finder,
+    BoundNodesTreeBuilder *Builder) const {
+  assert(RestrictKind.isBaseOf(DynNode.getNodeKind()));
+  if (Implementation->dynMatches(DynNode, Finder, Builder)) {
+    return true;
+  }
+  // Delete all bindings when a matcher does not match.
+  // This prevents unexpected exposure of bound nodes in unmatches
+  // branches of the match tree.
+  Builder->removeBindings([](const BoundNodesMap &) { return true; });
+  return false;
+}
+
 llvm::Optional<DynTypedMatcher> DynTypedMatcher::tryBind(StringRef ID) const {
   if (!AllowBind) return llvm::None;
   auto Result = *this;