constexpr: support for evaluation and codegen of typeid constants.

llvm-svn: 147290

clang/include/clang/Basic/DiagnosticASTKinds.td

@@ -33,6 +33,9 @@ def note_constexpr_past_end : Note<
   "%select{temporary|%2}1 is not a constant expression">;
 def note_constexpr_var_init_non_constant : Note<
   "initializer of %0 is not a constant expression">;
+def note_constexpr_typeid_polymorphic : Note<
+  "typeid applied to expression of polymorphic type %0 is "
+  "not allowed in a constant expression">;
 def note_constexpr_temporary_here : Note<"temporary created here">;
 def note_constexpr_literal_here : Note<"literal written here">;
 def note_constexpr_depth_limit_exceeded : Note<

clang/lib/AST/ExprConstant.cpp

@@ -697,6 +697,7 @@ static bool IsGlobalLValue(APValue::LValueBase B) {
   case Expr::PredefinedExprClass:
   case Expr::ObjCStringLiteralClass:
   case Expr::ObjCEncodeExprClass:
+  case Expr::CXXTypeidExprClass:
     return true;
   case Expr::CallExprClass:
     return IsStringLiteralCall(cast<CallExpr>(E));
@@ -2329,6 +2330,7 @@ public:
 // - Literals
 //  * CompoundLiteralExpr in C
 //  * StringLiteral
+//  * CXXTypeidExpr
 //  * PredefinedExpr
 //  * ObjCStringLiteralExpr
 //  * ObjCEncodeExpr
@@ -2356,6 +2358,7 @@ public:
   bool VisitMemberExpr(const MemberExpr *E);
   bool VisitStringLiteral(const StringLiteral *E) { return Success(E); }
   bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
+  bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
   bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
   bool VisitUnaryDeref(const UnaryOperator *E);
 
@@ -2451,6 +2454,19 @@ LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
   return Success(E);
 }
 
+bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
+  if (E->isTypeOperand())
+    return Success(E);
+  CXXRecordDecl *RD = E->getExprOperand()->getType()->getAsCXXRecordDecl();
+  if (RD && RD->isPolymorphic()) {
+    Info.Diag(E->getExprLoc(), diag::note_constexpr_typeid_polymorphic)
+      << E->getExprOperand()->getType()
+      << E->getExprOperand()->getSourceRange();
+    return false;
+  }
+  return Success(E);
+}
+
 bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
   // Handle static data members.
   if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) {

clang/lib/CodeGen/CGExprConstant.cpp

@@ -934,6 +934,15 @@ public:
 
       return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str());
     }
+    case Expr::CXXTypeidExprClass: {
+      CXXTypeidExpr *Typeid = cast<CXXTypeidExpr>(E);
+      QualType T;
+      if (Typeid->isTypeOperand())
+        T = Typeid->getTypeOperand();
+      else
+        T = Typeid->getExprOperand()->getType();
+      return CGM.GetAddrOfRTTIDescriptor(T);
+    }
     }
 
     return 0;

clang/test/CXX/expr/expr.const/p2-0x.cpp

@@ -280,11 +280,10 @@ namespace std {
 namespace TypeId {
   struct S { virtual void f(); };
   constexpr S *p = 0;
-  constexpr const std::type_info &ti1 = typeid(*p); // expected-error {{must be initialized by a constant expression}}
+  constexpr const std::type_info &ti1 = typeid(*p); // expected-error {{must be initialized by a constant expression}} expected-note {{typeid applied to expression of polymorphic type 'TypeId::S'}}
 
-  // FIXME: Implement typeid evaluation.
   struct T {} t;
-  constexpr const std::type_info &ti2 = typeid(t); // unexpected-error {{must be initialized by a constant expression}}
+  constexpr const std::type_info &ti2 = typeid(t);
 }
 
 // - a new-expression (5.3.4);

clang/test/CodeGenCXX/typeid-cxx11.cpp

@@ -0,0 +1,30 @@
+// RUN: %clang_cc1 -I%S %s -triple x86_64-apple-darwin10 -emit-llvm -std=c++11 -o - | FileCheck %s
+#include <typeinfo>
+
+namespace Test1 {
+
+struct Item {
+  const std::type_info &ti;
+  const char *name;
+  void *(*make)();
+};
+
+template<typename T> void *make_impl() { return new T; }
+template<typename T> constexpr Item item(const char *name) {
+  return { typeid(T), name, make_impl<T> };
+}
+
+struct A { virtual ~A(); };
+struct B : virtual A {};
+struct C { int n; };
+
+// FIXME: check we produce a constant array for this, once we support IRGen of
+// folded structs and arrays.
+constexpr Item items[] = {
+  item<A>("A"), item<B>("B"), item<C>("C"), item<int>("int")
+};
+
+// CHECK: @_ZN5Test11xE = constant %"class.std::type_info"* bitcast (i8** @_ZTIN5Test11AE to %"class.std::type_info"*), align 8
+constexpr auto &x = items[0].ti;
+
+}

clang/test/CodeGenCXX/typeid.cpp

@@ -6,6 +6,27 @@ namespace Test1 {
 // PR7400
 struct A { virtual void f(); };
 
+// CHECK: @_ZN5Test16int_tiE = constant %"class.std::type_info"* bitcast (i8** @_ZTIi to %"class.std::type_info"*), align 8
+const std::type_info &int_ti = typeid(int);
+
+// CHECK: @_ZN5Test14A_tiE = constant %"class.std::type_info"* bitcast (i8** @_ZTIN5Test11AE to %"class.std::type_info"*), align 8
+const std::type_info &A_ti = typeid(const volatile A &);
+
+volatile char c;
+
+// CHECK: @_ZN5Test14c_tiE = constant %"class.std::type_info"* bitcast (i8** @_ZTIc to %"class.std::type_info"*), align 8
+const std::type_info &c_ti = typeid(c);
+
+extern const double &d;
+
+// CHECK: @_ZN5Test14d_tiE = constant %"class.std::type_info"* bitcast (i8** @_ZTId to %"class.std::type_info"*), align 8
+const std::type_info &d_ti = typeid(d);
+
+extern A &a;
+
+// CHECK: @_ZN5Test14a_tiE = global
+const std::type_info &a_ti = typeid(a);
+
 // CHECK: define i8* @_ZN5Test11fEv
 const char *f() {
   try {