PR27754: CXXRecordDecl::data() needs to perform an update even if it's called

on a declaration that already knows the location of the DefinitionData object.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@269858 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 14 insertions, 34 deletions

diff --git a/include/clang/AST/DeclCXX.h b/include/clang/AST/DeclCXX.h
index 20aa7d1ab4..cd1e1d6b8d 100644
--- a/include/clang/AST/DeclCXX.h
+++ b/include/clang/AST/DeclCXX.h
@@ -257,30 +257,6 @@ public:
   TypeSourceInfo *getTypeSourceInfo() const { return BaseTypeInfo; }
 };
 
-/// \brief A lazy pointer to the definition data for a declaration.
-/// FIXME: This is a little CXXRecordDecl-specific that the moment.
-template<typename Decl, typename T> class LazyDefinitionDataPtr {
-  llvm::PointerUnion<T *, Decl *> DataOrCanonicalDecl;
-
-  LazyDefinitionDataPtr update() {
-    if (Decl *Canon = DataOrCanonicalDecl.template dyn_cast<Decl*>()) {
-      if (Canon->isCanonicalDecl())
-        Canon->getMostRecentDecl();
-      else
-        // Declaration isn't canonical any more;
-        // update it and perform path compression.
-        *this = Canon->getPreviousDecl()->DefinitionData.update();
-    }
-    return *this;
-  }
-
-public:
-  LazyDefinitionDataPtr(Decl *Canon) : DataOrCanonicalDecl(Canon) {}
-  LazyDefinitionDataPtr(T *Data) : DataOrCanonicalDecl(Data) {}
-  T *getNotUpdated() { return DataOrCanonicalDecl.template dyn_cast<T*>(); }
-  T *get() { return update().getNotUpdated(); }
-};
-
 /// \brief Represents a C++ struct/union/class.
 class CXXRecordDecl : public RecordDecl {
 
@@ -543,11 +519,7 @@ class CXXRecordDecl : public RecordDecl {
     CXXBaseSpecifier *getVBasesSlowCase() const;
   };
 
-  typedef LazyDefinitionDataPtr<CXXRecordDecl, struct DefinitionData>
-      DefinitionDataPtr;
-  friend class LazyDefinitionDataPtr<CXXRecordDecl, struct DefinitionData>;
-
-  mutable DefinitionDataPtr DefinitionData;
+  struct DefinitionData *DefinitionData;
 
   /// \brief Describes a C++ closure type (generated by a lambda expression).
   struct LambdaDefinitionData : public DefinitionData {
@@ -610,8 +582,14 @@ class CXXRecordDecl : public RecordDecl {
        
   };
 
+  struct DefinitionData *dataPtr() const {
+    // Complete the redecl chain (if necessary).
+    getMostRecentDecl();
+    return DefinitionData;
+  }
+
   struct DefinitionData &data() const {
-    auto *DD = DefinitionData.get();
+    auto *DD = dataPtr();
     assert(DD && "queried property of class with no definition");
     return *DD;
   }
@@ -619,7 +597,7 @@ class CXXRecordDecl : public RecordDecl {
   struct LambdaDefinitionData &getLambdaData() const {
     // No update required: a merged definition cannot change any lambda
     // properties.
-    auto *DD = DefinitionData.getNotUpdated();
+    auto *DD = DefinitionData;
     assert(DD && DD->IsLambda && "queried lambda property of non-lambda class");
     return static_cast<LambdaDefinitionData&>(*DD);
   }
@@ -696,11 +674,13 @@ public:
   }
 
   CXXRecordDecl *getDefinition() const {
-    auto *DD = DefinitionData.get();
+    // We only need an update if we don't already know which
+    // declaration is the definition.
+    auto *DD = DefinitionData ? DefinitionData : dataPtr();
     return DD ? DD->Definition : nullptr;
   }
 
-  bool hasDefinition() const { return DefinitionData.get(); }
+  bool hasDefinition() const { return DefinitionData || dataPtr(); }
 
   static CXXRecordDecl *Create(const ASTContext &C, TagKind TK, DeclContext *DC,
                                SourceLocation StartLoc, SourceLocation IdLoc,
@@ -1044,7 +1024,7 @@ public:
   /// \brief Determine whether this class describes a lambda function object.
   bool isLambda() const {
     // An update record can't turn a non-lambda into a lambda.
-    auto *DD = DefinitionData.getNotUpdated();
+    auto *DD = DefinitionData;
     return DD && DD->IsLambda;
   }