Introduce an r-value to l-value cast kind. I'm not promising anything

about the reliability of this yet.

llvm-svn: 120422

clang/include/clang/AST/Expr.h

@@ -2055,6 +2055,7 @@ private:
       // fallthrough to check for null base path
 
     case CK_Dependent:
+    case CK_LValueToRValue:
     case CK_NoOp:
     case CK_PointerToBoolean:
     case CK_IntegralToBoolean:

clang/include/clang/AST/OperationKinds.h

@@ -44,6 +44,11 @@ enum CastKind {
   ///    bool b; reinterpret_cast<char&>(b) = 'a';
   CK_LValueBitCast,
   
+  /// CK_LValueToRValue - A conversion which causes the extraction of
+  /// an r-value from the operand gl-value.  The result of an r-value
+  /// conversion is always unqualified.
+  CK_LValueToRValue,
+    
   /// CK_NoOp - A conversion which does not affect the type other than
   /// (possibly) adding qualifiers.
   ///   int    -> int

clang/lib/AST/Expr.cpp

@@ -822,6 +822,8 @@ const char *CastExpr::getCastKindName() const {
     return "BitCast";
   case CK_LValueBitCast:
     return "LValueBitCast";
+  case CK_LValueToRValue:
+    return "LValueToRValue";
   case CK_NoOp:
     return "NoOp";
   case CK_BaseToDerived:

clang/lib/Checker/GRExprEngine.cpp

@@ -2650,6 +2650,7 @@ void GRExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex,
       Dst.Add(*I);
     return;
 
+  case CK_LValueToRValue:
   case CK_NoOp:
   case CK_FunctionToPointerDecay:
     for (ExplodedNodeSet::iterator I = S2.begin(), E = S2.end(); I != E; ++I) {

clang/lib/CodeGen/CGExpr.cpp

@@ -1789,8 +1789,7 @@ LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
     llvm_unreachable("dependent cast kind in IR gen!");
 
   case CK_NoOp:
-    if (E->getSubExpr()->Classify(getContext()).getKind() 
+    if (!E->getSubExpr()->isRValue()) {
-                                          != Expr::Classification::CL_PRValue) {
       LValue LV = EmitLValue(E->getSubExpr());
       if (LV.isPropertyRef() || LV.isKVCRef()) {
         QualType QT = E->getSubExpr()->getType();
@@ -1805,6 +1804,7 @@ LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
     }
     // Fall through to synthesize a temporary.
 
+  case CK_LValueToRValue:
   case CK_BitCast:
   case CK_ArrayToPointerDecay:
   case CK_FunctionToPointerDecay:

clang/lib/CodeGen/CGExprAgg.cpp

@@ -250,8 +250,6 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
   }
 
   switch (E->getCastKind()) {
-  default: assert(0 && "Unhandled cast kind!");
-
   case CK_Dynamic: {
     assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
     LValue LV = CGF.EmitCheckedLValue(E->getSubExpr());
@@ -286,6 +284,7 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
   }
 
   case CK_NoOp:
+  case CK_LValueToRValue:
   case CK_UserDefinedConversion:
   case CK_ConstructorConversion:
     assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
@@ -295,8 +294,43 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
     break;
       
   case CK_LValueBitCast:
-    llvm_unreachable("there are no lvalue bit-casts on aggregates");
+    llvm_unreachable("should not be emitting lvalue bitcast as rvalue");
     break;
+      
+  case CK_Dependent:
+  case CK_BitCast:
+  case CK_ArrayToPointerDecay:
+  case CK_FunctionToPointerDecay:
+  case CK_NullToPointer:
+  case CK_NullToMemberPointer:
+  case CK_BaseToDerivedMemberPointer:
+  case CK_DerivedToBaseMemberPointer:
+  case CK_MemberPointerToBoolean:
+  case CK_IntegralToPointer:
+  case CK_PointerToIntegral:
+  case CK_PointerToBoolean:
+  case CK_ToVoid:
+  case CK_VectorSplat:
+  case CK_IntegralCast:
+  case CK_IntegralToBoolean:
+  case CK_IntegralToFloating:
+  case CK_FloatingToIntegral:
+  case CK_FloatingToBoolean:
+  case CK_FloatingCast:
+  case CK_AnyPointerToObjCPointerCast:
+  case CK_AnyPointerToBlockPointerCast:
+  case CK_ObjCObjectLValueCast:
+  case CK_FloatingRealToComplex:
+  case CK_FloatingComplexToReal:
+  case CK_FloatingComplexToBoolean:
+  case CK_FloatingComplexCast:
+  case CK_FloatingComplexToIntegralComplex:
+  case CK_IntegralRealToComplex:
+  case CK_IntegralComplexToReal:
+  case CK_IntegralComplexToBoolean:
+  case CK_IntegralComplexCast:
+  case CK_IntegralComplexToFloatingComplex:
+    llvm_unreachable("cast kind invalid for aggregate types");
   }
 }
 

clang/lib/CodeGen/CGExprScalar.cpp

@@ -1102,6 +1102,10 @@ Value *ScalarExprEmitter::EmitCastExpr(CastExpr *CE) {
     llvm_unreachable("scalar cast to non-scalar value");
     break;
       
+  case CK_LValueToRValue:
+    assert(CGF.getContext().hasSameUnqualifiedType(E->getType(), DestTy));
+    return Visit(const_cast<Expr*>(E));
+
   case CK_IntegralToPointer: {
     Value *Src = Visit(const_cast<Expr*>(E));
 

clang/lib/Sema/SemaExpr.cpp

@@ -247,21 +247,27 @@ void Sema::DefaultFunctionArrayConversion(Expr *&E) {
 void Sema::DefaultFunctionArrayLvalueConversion(Expr *&E) {
   DefaultFunctionArrayConversion(E);
   
-  QualType Ty = E->getType();
+  // C++ [conv.lval]p1:
-  assert(!Ty.isNull() && "DefaultFunctionArrayLvalueConversion - missing type");
+  //   A glvalue of a non-function, non-array type T can be
-  if (!Ty->isDependentType() && Ty.hasQualifiers() &&
+  //   converted to a prvalue.
-      (!getLangOptions().CPlusPlus || !Ty->isRecordType()) &&
+  if (E->isGLValue()) {
-      E->isLValue()) {
     // C++ [conv.lval]p1:
-    //   [...] If T is a non-class type, the type of the rvalue is the
+    //   [...] If T is a non-class type, the type of the prvalue is the
     //   cv-unqualified version of T. Otherwise, the type of the
-    //   rvalue is T
+    //   rvalue is T.
     //
     // C99 6.3.2.1p2:
     //   If the lvalue has qualified type, the value has the unqualified
     //   version of the type of the lvalue; otherwise, the value has the
     //   type of the lvalue.
-    ImpCastExprToType(E, Ty.getUnqualifiedType(), CK_NoOp);
+    QualType T = E->getType();
+    assert(!T.isNull() && "r-value conversion on typeless expression?");
+    
+    if (T.hasQualifiers() && !T->isDependentType() &&
+        (!getLangOptions().CPlusPlus || !T->isRecordType()))
+      T = T.getUnqualifiedType();
+    
+    ImpCastExprToType(E, T, CK_LValueToRValue);
   }
 }
 
@@ -271,36 +277,43 @@ void Sema::DefaultFunctionArrayLvalueConversion(Expr *&E) {
 /// sometimes surpressed. For example, the array->pointer conversion doesn't
 /// apply if the array is an argument to the sizeof or address (&) operators.
 /// In these instances, this routine should *not* be called.
-Expr *Sema::UsualUnaryConversions(Expr *&Expr) {
+Expr *Sema::UsualUnaryConversions(Expr *&E) {
-  QualType Ty = Expr->getType();
+  // First, convert to an r-value.
+  DefaultFunctionArrayLvalueConversion(E);
+  
+  QualType Ty = E->getType();
   assert(!Ty.isNull() && "UsualUnaryConversions - missing type");
   
-  // C99 6.3.1.1p2:
+  // Try to perform integral promotions if the object has a theoretically
-  //
+  // promotable type.
-  //   The following may be used in an expression wherever an int or
+  if (Ty->isIntegralOrUnscopedEnumerationType()) {
-  //   unsigned int may be used:
+    // C99 6.3.1.1p2:
-  //     - an object or expression with an integer type whose integer
+    //
-  //       conversion rank is less than or equal to the rank of int
+    //   The following may be used in an expression wherever an int or
-  //       and unsigned int.
+    //   unsigned int may be used:
-  //     - A bit-field of type _Bool, int, signed int, or unsigned int.
+    //     - an object or expression with an integer type whose integer
-  //
+    //       conversion rank is less than or equal to the rank of int
-  //   If an int can represent all values of the original type, the
+    //       and unsigned int.
-  //   value is converted to an int; otherwise, it is converted to an
+    //     - A bit-field of type _Bool, int, signed int, or unsigned int.
-  //   unsigned int. These are called the integer promotions. All
+    //
-  //   other types are unchanged by the integer promotions.
+    //   If an int can represent all values of the original type, the
-  QualType PTy = Context.isPromotableBitField(Expr);
+    //   value is converted to an int; otherwise, it is converted to an
-  if (!PTy.isNull()) {
+    //   unsigned int. These are called the integer promotions. All
-    ImpCastExprToType(Expr, PTy, CK_IntegralCast);
+    //   other types are unchanged by the integer promotions.
-    return Expr;
+  
-  }
+    QualType PTy = Context.isPromotableBitField(E);
-  if (Ty->isPromotableIntegerType()) {
+    if (!PTy.isNull()) {
-    QualType PT = Context.getPromotedIntegerType(Ty);
+      ImpCastExprToType(E, PTy, CK_IntegralCast);
-    ImpCastExprToType(Expr, PT, CK_IntegralCast);
+      return E;
-    return Expr;
+    }
+    if (Ty->isPromotableIntegerType()) {
+      QualType PT = Context.getPromotedIntegerType(Ty);
+      ImpCastExprToType(E, PT, CK_IntegralCast);
+      return E;
+    }
   }
 
-  DefaultFunctionArrayLvalueConversion(Expr);
+  return E;
-  return Expr;
 }
 
 /// DefaultArgumentPromotion (C99 6.5.2.2p6). Used for function calls that