3 files changed, 51 insertions, 21 deletions

diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index ee8e3f4..4b66207 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -1105,7 +1105,9 @@ namespace clang {
       /// \brief An OMPThreadPrivateDecl record.
       DECL_OMP_THREADPRIVATE,
       /// \brief An EmptyDecl record.
-      DECL_EMPTY
+      DECL_EMPTY,
+      /// \brief An ObjCTypeParamDecl record.
+      DECL_OBJC_TYPE_PARAM,
     };
 
     /// \brief Record codes for each kind of statement or expression.
diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index ef5b107..9377dfa 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -42,6 +42,7 @@
 #include "llvm/ADT/TinyPtrVector.h"
 #include "llvm/Bitcode/BitstreamReader.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Timer.h"
 #include <deque>
 #include <map>
 #include <memory>
@@ -380,6 +381,9 @@ private:
   /// \brief The module manager which manages modules and their dependencies
   ModuleManager ModuleMgr;
 
+  /// \brief A timer used to track the time spent deserializing.
+  std::unique_ptr<llvm::Timer> ReadTimer;
+
   /// \brief The location where the module file will be considered as
   /// imported from. For non-module AST types it should be invalid.
   SourceLocation CurrentImportLoc;
@@ -976,12 +980,14 @@ private:
       MergedLookups;
 
   typedef llvm::DenseMap<Decl *, SmallVector<serialization::DeclID, 2> >
-    MergedDeclsMap;
+    KeyDeclsMap;
     
-  /// \brief A mapping from canonical declarations to the set of additional
-  /// (global, previously-canonical) declaration IDs that have been merged with
-  /// that canonical declaration.
-  MergedDeclsMap MergedDecls;
+  /// \brief A mapping from canonical declarations to the set of global
+  /// declaration IDs for key declaration that have been merged with that
+  /// canonical declaration. A key declaration is a formerly-canonical
+  /// declaration whose module did not import any other key declaration for that
+  /// entity. These are the IDs that we use as keys when finding redecl chains.
+  KeyDeclsMap KeyDecls;
   
   /// \brief A mapping from DeclContexts to the semantic DeclContext that we
   /// are treating as the definition of the entity. This is used, for instance,
@@ -1054,6 +1060,36 @@ public:
   void ResolveImportedPath(ModuleFile &M, std::string &Filename);
   static void ResolveImportedPath(std::string &Filename, StringRef Prefix);
 
+  /// \brief Returns the first key declaration for the given declaration. This
+  /// is one that is formerly-canonical (or still canonical) and whose module
+  /// did not import any other key declaration of the entity.
+  Decl *getKeyDeclaration(Decl *D) {
+    D = D->getCanonicalDecl();
+    if (D->isFromASTFile())
+      return D;
+
+    auto I = KeyDecls.find(D);
+    if (I == KeyDecls.end() || I->second.empty())
+      return D;
+    return GetExistingDecl(I->second[0]);
+  }
+  const Decl *getKeyDeclaration(const Decl *D) {
+    return getKeyDeclaration(const_cast<Decl*>(D));
+  }
+
+  /// \brief Run a callback on each imported key declaration of \p D.
+  template <typename Fn>
+  void forEachImportedKeyDecl(const Decl *D, Fn Visit) {
+    D = D->getCanonicalDecl();
+    if (D->isFromASTFile())
+      Visit(D);
+
+    auto It = KeyDecls.find(const_cast<Decl*>(D));
+    if (It != KeyDecls.end())
+      for (auto ID : It->second)
+        Visit(GetExistingDecl(ID));
+  }
+
 private:
   struct ImportedModule {
     ModuleFile *Mod;
@@ -1124,18 +1160,6 @@ private:
   /// merged into its redecl chain.
   Decl *getMostRecentExistingDecl(Decl *D);
 
-  template <typename Fn>
-  void forEachFormerlyCanonicalImportedDecl(const Decl *D, Fn Visit) {
-    D = D->getCanonicalDecl();
-    if (D->isFromASTFile())
-      Visit(D);
-
-    auto It = MergedDecls.find(const_cast<Decl*>(D));
-    if (It != MergedDecls.end())
-      for (auto ID : It->second)
-        Visit(GetExistingDecl(ID));
-  }
-
   RecordLocation DeclCursorForID(serialization::DeclID ID,
                                  unsigned &RawLocation);
   void loadDeclUpdateRecords(serialization::DeclID ID, Decl *D);
@@ -1261,12 +1285,16 @@ public:
   ///
   /// \param UseGlobalIndex If true, the AST reader will try to load and use
   /// the global module index.
+  ///
+  /// \param ReadTimer If non-null, a timer used to track the time spent
+  /// deserializing.
   ASTReader(Preprocessor &PP, ASTContext &Context,
             const PCHContainerOperations &PCHContainerOps,
             StringRef isysroot = "", bool DisableValidation = false,
             bool AllowASTWithCompilerErrors = false,
             bool AllowConfigurationMismatch = false,
-            bool ValidateSystemInputs = false, bool UseGlobalIndex = true);
+            bool ValidateSystemInputs = false, bool UseGlobalIndex = true,
+            std::unique_ptr<llvm::Timer> ReadTimer = {});
 
   ~ASTReader() override;
 
@@ -1690,7 +1718,7 @@ public:
   /// \brief Notify ASTReader that we started deserialization of
   /// a decl or type so until FinishedDeserializing is called there may be
   /// decls that are initializing. Must be paired with FinishedDeserializing.
-  void StartedDeserializing() override { ++NumCurrentElementsDeserializing; }
+  void StartedDeserializing() override;
 
   /// \brief Notify ASTReader that we finished the deserialization of
   /// a decl or type. Must be paired with StartedDeserializing.
diff --git a/include/clang/Serialization/ASTWriter.h b/include/clang/Serialization/ASTWriter.h
index c966d3e..e830fdc 100644
--- a/include/clang/Serialization/ASTWriter.h
+++ b/include/clang/Serialization/ASTWriter.h
@@ -398,7 +398,7 @@ private:
                  
   /// \brief The set of declarations that may have redeclaration chains that
   /// need to be serialized.
-  llvm::SmallSetVector<Decl *, 4> Redeclarations;
+  llvm::SmallVector<const Decl *, 16> Redeclarations;
                                       
   /// \brief Statements that we've encountered while serializing a
   /// declaration or type.