Add a method for checking whether a function is one of the reserved global

placement allocation or deallocation functions.  These functions cannot be
replaced by the user and are exempt from the normal requirements on
allocation functions (e.g. that they must return unaliased memory).

llvm-svn: 131386

2 files changed, 45 insertions, 6 deletions

diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index 6ca14ce8749..e1dad644c99 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -1644,10 +1644,25 @@ public:
   bool isDeletedAsWritten() const { return IsDeleted && !IsDefaulted; }
   void setDeletedAsWritten(bool D = true) { IsDeleted = D; }
 
-  /// \brief Determines whether this is a function "main", which is
-  /// the entry point into an executable program.
+  /// \brief Determines whether this function is "main", which is the
+  /// entry point into an executable program.
   bool isMain() const;
 
+  /// \brief Determines whether this operator new or delete is one
+  /// of the reserved global placement operators:
+  ///    void *operator new(size_t, void *);
+  ///    void *operator new[](size_t, void *);
+  ///    void operator delete(void *, void *);
+  ///    void operator delete[](void *, void *);
+  /// These functions have special behavior under [new.delete.placement]:
+  ///    These functions are reserved, a C++ program may not define
+  ///    functions that displace the versions in the Standard C++ library.
+  ///    The provisions of [basic.stc.dynamic] do not apply to these
+  ///    reserved placement forms of operator new and operator delete.
+  ///
+  /// This function must be an allocation or deallocation function.
+  bool isReservedGlobalPlacementOperator() const;
+
   /// \brief Determines whether this function is a function with
   /// external, C linkage.
   bool isExternC() const;
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index d4df017383d..1e98998002f 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1475,10 +1475,34 @@ void FunctionDecl::setPure(bool P) {
 }
 
 bool FunctionDecl::isMain() const {
-  ASTContext &Context = getASTContext();
-  return !Context.getLangOptions().Freestanding &&
-    getDeclContext()->getRedeclContext()->isTranslationUnit() &&
-    getIdentifier() && getIdentifier()->isStr("main");
+  const TranslationUnitDecl *tunit =
+    dyn_cast<TranslationUnitDecl>(getDeclContext()->getRedeclContext());
+  return tunit &&
+         tunit->getASTContext().getLangOptions().Freestanding &&
+         getIdentifier() &&
+         getIdentifier()->isStr("main");
+}
+
+bool FunctionDecl::isReservedGlobalPlacementOperator() const {
+  assert(getDeclName().getNameKind() == DeclarationName::CXXOperatorName);
+  assert(getDeclName().getCXXOverloadedOperator() == OO_New ||
+         getDeclName().getCXXOverloadedOperator() == OO_Delete ||
+         getDeclName().getCXXOverloadedOperator() == OO_Array_New ||
+         getDeclName().getCXXOverloadedOperator() == OO_Array_Delete);
+
+  if (isa<CXXRecordDecl>(getDeclContext())) return false;
+  assert(getDeclContext()->getRedeclContext()->isTranslationUnit());
+
+  const FunctionProtoType *proto = getType()->castAs<FunctionProtoType>();
+  if (proto->getNumArgs() != 2 || proto->isVariadic()) return false;
+
+  ASTContext &Context =
+    cast<TranslationUnitDecl>(getDeclContext()->getRedeclContext())
+      ->getASTContext();
+
+  // The result type and first argument type are constant across all
+  // these operators.  The second argument must be exactly void*.
+  return (proto->getArgType(1).getCanonicalType() == Context.VoidPtrTy);
 }
 
 bool FunctionDecl::isExternC() const {