Change the representation of builtin functions in the AST

(__builtin_* etc.) so that it isn't possible to take their address.
Specifically, introduce a new type to represent a reference to a builtin
function, and a new cast kind to convert it to a function pointer in the
operand of a call.  Fixes PR13195.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162962 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 17 insertions, 2 deletions

diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 42a5fa37b1..df1273cb1e 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -803,6 +803,9 @@ void ASTContext::InitBuiltinTypes(const TargetInfo &Target) {
   // Placeholder type for unbridged ARC casts.
   InitBuiltinType(ARCUnbridgedCastTy,  BuiltinType::ARCUnbridgedCast);
 
+  // Placeholder type for builtin functions.
+  InitBuiltinType(BuiltinFnTy,  BuiltinType::BuiltinFn);
+
   // C99 6.2.5p11.
   FloatComplexTy      = getComplexType(FloatTy);
   DoubleComplexTy     = getComplexType(DoubleTy);
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index cad8341afa..2ede77ec03 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1310,12 +1310,16 @@ void CastExpr::CheckCastConsistency() const {
     assert(getType()->isBlockPointerType());
     assert(getSubExpr()->getType()->isBlockPointerType());
     goto CheckNoBasePath;
-      
+
+  case CK_FunctionToPointerDecay:
+    assert(getType()->isPointerType());
+    assert(getSubExpr()->getType()->isFunctionType());
+    goto CheckNoBasePath;
+
   // These should not have an inheritance path.
   case CK_Dynamic:
   case CK_ToUnion:
   case CK_ArrayToPointerDecay:
-  case CK_FunctionToPointerDecay:
   case CK_NullToMemberPointer:
   case CK_NullToPointer:
   case CK_ConstructorConversion:
@@ -1356,6 +1360,7 @@ void CastExpr::CheckCastConsistency() const {
   case CK_IntegralComplexToBoolean:
   case CK_LValueBitCast:            // -> bool&
   case CK_UserDefinedConversion:    // operator bool()
+  case CK_BuiltinFnToFnPtr:
   CheckNoBasePath:
     assert(path_empty() && "Cast kind should not have a base path!");
     break;
@@ -1468,6 +1473,8 @@ const char *CastExpr::getCastKindName() const {
     return "NonAtomicToAtomic";
   case CK_CopyAndAutoreleaseBlockObject:
     return "CopyAndAutoreleaseBlockObject";
+  case CK_BuiltinFnToFnPtr:
+    return "BuiltinFnToFnPtr";
   }
 
   llvm_unreachable("Unhandled cast kind!");
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index fb0c4d26ea..2cd7f04e92 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -5357,6 +5357,7 @@ bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
   case CK_IntegralRealToComplex:
   case CK_IntegralComplexCast:
   case CK_IntegralComplexToFloatingComplex:
+  case CK_BuiltinFnToFnPtr:
     llvm_unreachable("invalid cast kind for integral value");
 
   case CK_BitCast:
@@ -5843,6 +5844,7 @@ bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
   case CK_ARCReclaimReturnedObject:
   case CK_ARCExtendBlockObject:
   case CK_CopyAndAutoreleaseBlockObject:
+  case CK_BuiltinFnToFnPtr:
     llvm_unreachable("invalid cast kind for complex value");
 
   case CK_LValueToRValue:
diff --git a/lib/AST/NSAPI.cpp b/lib/AST/NSAPI.cpp
index 39077d1766..0837509194 100644
--- a/lib/AST/NSAPI.cpp
+++ b/lib/AST/NSAPI.cpp
@@ -344,6 +344,7 @@ NSAPI::getNSNumberFactoryMethodKind(QualType T) const {
   case BuiltinType::ARCUnbridgedCast:
   case BuiltinType::Half:
   case BuiltinType::PseudoObject:
+  case BuiltinType::BuiltinFn:
     break;
   }
   
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index abefae44b2..7445152d62 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -1480,6 +1480,7 @@ StringRef BuiltinType::getName(const PrintingPolicy &Policy) const {
   case Dependent:         return "<dependent type>";
   case UnknownAny:        return "<unknown type>";
   case ARCUnbridgedCast:  return "<ARC unbridged cast type>";
+  case BuiltinFn:         return "<builtin fn type>";
   case ObjCId:            return "id";
   case ObjCClass:         return "Class";
   case ObjCSel:           return "SEL";
diff --git a/lib/AST/TypeLoc.cpp b/lib/AST/TypeLoc.cpp
index c7bb7da4d1..bd30a65259 100644
--- a/lib/AST/TypeLoc.cpp
+++ b/lib/AST/TypeLoc.cpp
@@ -241,6 +241,7 @@ TypeSpecifierType BuiltinTypeLoc::getWrittenTypeSpec() const {
   case BuiltinType::ObjCId:
   case BuiltinType::ObjCClass:
   case BuiltinType::ObjCSel:
+  case BuiltinType::BuiltinFn:
     return TST_unspecified;
   }