Kill CK_Unknown and flesh out the documentation for the existing CastKinds.

llvm-svn: 119331

clang/include/clang/AST/Expr.h

@@ -2004,7 +2004,6 @@ private:
       // fallthrough to check for null base path
 
     case CK_Dependent:
-    case CK_Unknown:
     case CK_NoOp:
     case CK_PointerToBoolean:
     case CK_IntegralToBoolean:

clang/include/clang/AST/OperationKinds.h

@@ -17,116 +17,169 @@
 
 namespace clang {
   
-/// CastKind - the kind of cast this represents.
+/// CastKind - The kind of operation required for a conversion.
 enum CastKind {
-  /// CK_Unknown - Unknown cast kind.
-  /// FIXME: The goal is to get rid of this and make all casts have a
-  /// kind so that the AST client doesn't have to try to figure out what's
-  /// going on.
-  CK_Unknown,
-
-  /// CK_Dependent - This explicit cast cannot yet be analyzed because
-  /// the type or expression is dependent.
+  /// CK_Dependent - A conversion which cannot yet be analyzed because
+  /// either the expression or target type is dependent.  These are
+  /// created only for explicit casts; dependent ASTs aren't required
+  /// to even approximately type-check.
+  ///   (T*) malloc(sizeof(T))
+  ///   reinterpret_cast<intptr_t>(A<T>::alloc());
   CK_Dependent,
 
-  /// CK_BitCast - Used for reinterpret_cast.
+  /// CK_BitCast - A conversion which causes a bit pattern of one type
+  /// to be reinterpreted as a bit pattern of another type.  Generally
+  /// the operands must have equivalent size and unrelated types.
+  ///
+  /// The pointer conversion char* -> int* is a bitcast.  Many other
+  /// pointer conversions which are "physically" bitcasts are given
+  /// special cast kinds.
+  ///
+  /// Vector coercions are bitcasts.
   CK_BitCast,
 
-  /// CK_LValueBitCast - Used for reinterpret_cast of expressions to
-  /// a reference type.
+  /// CK_LValueBitCast - A conversion which reinterprets the address of
+  /// an l-value as an l-value of a different kind.  Used for
+  /// reinterpret_casts of l-value expressions to reference types.
+  ///    bool b; reinterpret_cast<char&>(b) = 'a';
   CK_LValueBitCast,
     
-  /// CK_NoOp - Used for const_cast.
+  /// CK_NoOp - A conversion which does not affect the type other than
+  /// (possibly) adding qualifiers.
+  ///   int    -> int
+  ///   char** -> const char * const *
   CK_NoOp,
 
-  /// CK_BaseToDerived - Base to derived class casts.
+  /// CK_BaseToDerived - A conversion from a C++ class pointer/reference
+  /// to a derived class pointer/reference.
+  ///   B *b = static_cast<B*>(a);
   CK_BaseToDerived,
 
-  /// CK_DerivedToBase - Derived to base class casts.
+  /// CK_DerivedToBase - A conversion from a C++ class pointer
+  /// to a base class pointer.
+  ///   A *a = new B();
   CK_DerivedToBase,
 
-  /// CK_UncheckedDerivedToBase - Derived to base class casts that
-  /// assume that the derived pointer is not null.
+  /// CK_UncheckedDerivedToBase - A conversion from a C++ class
+  /// pointer/reference to a base class that can assume that the
+  /// derived pointer is not null.
+  ///   const A &a = B();
+  ///   b->method_from_a();
   CK_UncheckedDerivedToBase,
 
-  /// CK_Dynamic - Dynamic cast.
+  /// CK_Dynamic - A C++ dynamic_cast.
   CK_Dynamic,
 
-  /// CK_ToUnion - Cast to union (GCC extension).
+  /// CK_ToUnion - The GCC cast-to-union extension.
+  ///   int   -> union { int x; float y; }
+  ///   float -> union { int x; float y; }
   CK_ToUnion,
 
   /// CK_ArrayToPointerDecay - Array to pointer decay.
+  ///   int[10] -> int*
+  ///   char[5][6] -> char(*)[6]
   CK_ArrayToPointerDecay,
 
   /// CK_FunctionToPointerDecay - Function to pointer decay.
+  ///   void(int) -> void(*)(int)
   CK_FunctionToPointerDecay,
 
-  /// CK_NullToPointer - Null pointer to pointer.
+  /// CK_NullToPointer - Null pointer constant to pointer, ObjC
+  /// pointer, or block pointer.
+  ///   (void*) 0
+  ///   void (^block)() = 0;
   CK_NullToPointer,
 
-  /// CK_NullToMemberPointer - Null pointer to member pointer.
+  /// CK_NullToMemberPointer - Null pointer constant to member pointer.
+  ///   int A::*mptr = 0;
+  ///   int (A::*fptr)(int) = nullptr;
   CK_NullToMemberPointer,
 
   /// CK_BaseToDerivedMemberPointer - Member pointer in base class to
   /// member pointer in derived class.
+  ///   int B::*mptr = &A::member;
   CK_BaseToDerivedMemberPointer,
 
   /// CK_DerivedToBaseMemberPointer - Member pointer in derived class to
   /// member pointer in base class.
+  ///   int A::*mptr = static_cast<int A::*>(&B::member);
   CK_DerivedToBaseMemberPointer,
     
+  /// CK_MemberPointerToBoolean - Member pointer to boolean.  A check
+  /// against the null member pointer.
+  CK_MemberPointerToBoolean,
+
   /// CK_UserDefinedConversion - Conversion using a user defined type
   /// conversion function.
+  ///    struct A { operator int(); }; int i = int(A());
   CK_UserDefinedConversion,
 
-  /// CK_ConstructorConversion - Conversion by constructor
+  /// CK_ConstructorConversion - Conversion by constructor.
+  ///    struct A { A(int); }; A a = A(10);
   CK_ConstructorConversion,
     
-  /// CK_IntegralToPointer - Integral to pointer
+  /// CK_IntegralToPointer - Integral to pointer.  A special kind of
+  /// reinterpreting conversion.  Applies to normal, ObjC, and block
+  /// pointers.
+  ///    (char*) 0x1001aab0
+  ///    reinterpret_cast<int*>(0)
   CK_IntegralToPointer,
     
-  /// CK_PointerToIntegral - Pointer to integral
+  /// CK_PointerToIntegral - Pointer to integral.  A special kind of
+  /// reinterpreting conversion.  Applies to normal, ObjC, and block
+  /// pointers.
+  ///    (intptr_t) "help!"
   CK_PointerToIntegral,
 
-  /// CK_PointerToBoolean - Pointer to boolean (i.e. is not null)
+  /// CK_PointerToBoolean - Pointer to boolean conversion.  A check
+  /// against null.  Applies to normal, ObjC, and block pointers.
   CK_PointerToBoolean,
     
-  /// CK_ToVoid - Cast to void.
+  /// CK_ToVoid - Cast to void, discarding the computed value.
+  ///    (void) malloc(2048)
   CK_ToVoid,
     
-  /// CK_VectorSplat - Casting from an integer/floating type to an extended
-  /// vector type with the same element type as the src type. Splats the 
-  /// src expression into the destination expression.
+  /// CK_VectorSplat - A conversion from an arithmetic type to a
+  /// vector of that element type.  Fills all elements ("splats") with
+  /// the source value.
+  ///    __attribute__((ext_vector_type(4))) int v = 5;
   CK_VectorSplat,
     
-  /// CK_IntegralCast - A truncating or extending cast between integral
-  /// types of different size.
+  /// CK_IntegralCast - A cast between integral types (other than to
+  /// boolean).  Variously a bitcast, a truncation, a sign-extension,
+  /// or a zero-extension.
+  ///    long l = 5;
+  ///    (unsigned) i
   CK_IntegralCast,
 
-  /// CK_IntegralToBoolean - Integral to boolean.
+  /// CK_IntegralToBoolean - Integral to boolean.  A check against zero.
+  ///    (bool) i
   CK_IntegralToBoolean,
 
   /// CK_IntegralToFloating - Integral to floating point.
+  ///    float f = i;
   CK_IntegralToFloating,
     
-  /// CK_FloatingToIntegral - Floating point to integral.
+  /// CK_FloatingToIntegral - Floating point to integral.  Rounds
+  /// towards zero, discarding any fractional component.
+  ///    (int) f
   CK_FloatingToIntegral,
 
   /// CK_FloatingToBoolean - Floating point to boolean.
+  ///    (bool) f
   CK_FloatingToBoolean,
     
   /// CK_FloatingCast - Casting between floating types of different size.
+  ///    (double) f
+  ///    (float) ld
   CK_FloatingCast,
     
-  /// CK_MemberPointerToBoolean - Member pointer to boolean
-  CK_MemberPointerToBoolean,
-
-  /// CK_AnyPointerToObjCPointerCast - Casting any pointer to objective-c 
-  /// pointer
+  /// CK_AnyPointerToObjCPointerCast - Casting any other pointer kind
+  /// to an Objective-C pointer.
   CK_AnyPointerToObjCPointerCast,
 
-  /// CK_AnyPointerToBlockPointerCast - Casting any pointer to block 
-  /// pointer
+  /// CK_AnyPointerToBlockPointerCast - Casting any other pointer kind
+  /// to a block pointer.
   CK_AnyPointerToBlockPointerCast,
 
   /// \brief Converting between two Objective-C object types, which
@@ -134,34 +187,52 @@ enum CastKind {
   /// object.
   CK_ObjCObjectLValueCast,
 
-  /// \brief Floating point real to floating point complex
+  /// \brief A conversion of a floating point real to a floating point
+  /// complex of the original type.  Injects the value as the real
+  /// component with a zero imaginary component.
+  ///   float -> _Complex float
   CK_FloatingRealToComplex,
 
-  /// \brief Floating pointer complex to floating point real
+  /// \brief Converts a floating point complex to floating point real
+  /// of the source's element type.  Just discards the imaginary
+  /// component.
+  ///   _Complex long double -> long double
   CK_FloatingComplexToReal,
 
-  /// \brief Converting a floating complex to bool
+  /// \brief Converts a floating point complex to bool by comparing
+  /// against 0+0i.
   CK_FloatingComplexToBoolean,
 
-  /// \brief Casting between floating point complex types of different size
+  /// \brief Converts between different floating point complex types.
+  ///   _Complex float -> _Complex double
   CK_FloatingComplexCast,
 
-  /// \brief Casting from a floating complex to an integral complex
+  /// \brief Converts from a floating complex to an integral complex.
+  ///   _Complex float -> _Complex int
   CK_FloatingComplexToIntegralComplex,
 
-  /// \brief Integral real to integral complex
+  /// \brief Converts from an integral real to an integral complex
+  /// whose element type matches the source.  Injects the value as
+  /// the real component with a zero imaginary component.
+  ///   long -> _Complex long
   CK_IntegralRealToComplex,
 
-  /// \brief Integral complex to integral real
+  /// \brief Converts an integral complex to an integral real of the
+  /// source's element type by discarding the imaginary component.
+  ///   _Complex short -> short
   CK_IntegralComplexToReal,
 
-  /// \brief Converting an integral complex to bool
+  /// \brief Converts an integral complex to bool by comparing against
+  /// 0+0i.
   CK_IntegralComplexToBoolean,
 
-  /// \brief Casting between integral complex types of different size
+  /// \brief Converts between different integral complex types.
+  ///   _Complex char -> _Complex long long
+  ///   _Complex unsigned int -> _Complex signed int
   CK_IntegralComplexCast,
 
-  /// \brief Casting from an integral complex to a floating complex
+  /// \brief Converts from an integral complex to a floating complex.
+  ///   _Complex unsigned -> _Complex float
   CK_IntegralComplexToFloatingComplex
 };
 

clang/lib/AST/Expr.cpp

@@ -740,8 +740,6 @@ MemberExpr *MemberExpr::Create(ASTContext &C, Expr *base, bool isarrow,
 
 const char *CastExpr::getCastKindName() const {
   switch (getCastKind()) {
-  case CK_Unknown:
-    return "Unknown";
   case CK_Dependent:
     return "Dependent";
   case CK_BitCast:

clang/lib/AST/ExprConstant.cpp

@@ -532,35 +532,6 @@ bool PointerExprEvaluator::VisitCastExpr(CastExpr* E) {
   default:
     break;
 
-  case CK_Unknown: {
-    // FIXME: The handling for CK_Unknown is ugly/shouldn't be necessary!
-
-    // Check for pointer->pointer cast
-    if (SubExpr->getType()->isPointerType() ||
-        SubExpr->getType()->isObjCObjectPointerType() ||
-        SubExpr->getType()->isNullPtrType() ||
-        SubExpr->getType()->isBlockPointerType())
-      return Visit(SubExpr);
-
-    if (SubExpr->getType()->isIntegralOrEnumerationType()) {
-      APValue Value;
-      if (!EvaluateIntegerOrLValue(SubExpr, Value, Info))
-        break;
-
-      if (Value.isInt()) {
-        Value.getInt().extOrTrunc((unsigned)Info.Ctx.getTypeSize(E->getType()));
-        Result.Base = 0;
-        Result.Offset = CharUnits::fromQuantity(Value.getInt().getZExtValue());
-        return true;
-      } else {
-        Result.Base = Value.getLValueBase();
-        Result.Offset = Value.getLValueOffset();
-        return true;
-      }
-    }
-    break;
-  }
-
   case CK_NoOp:
   case CK_BitCast:
   case CK_LValueBitCast:

clang/lib/Checker/GRExprEngine.cpp

@@ -2541,7 +2541,6 @@ void GRExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex,
     }
     return;
 
-  case CK_Unknown:
   case CK_Dependent:
   case CK_ArrayToPointerDecay:
   case CK_BitCast:

clang/lib/CodeGen/CGExpr.cpp

@@ -1804,7 +1804,6 @@ LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
     }
     // Fall through to synthesize a temporary.
 
-  case CK_Unknown:
   case CK_BitCast:
   case CK_ArrayToPointerDecay:
   case CK_FunctionToPointerDecay:

clang/lib/CodeGen/CGExprAgg.cpp

@@ -285,8 +285,6 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
     break;
   }
 
-  // FIXME: Remove the CK_Unknown check here.
-  case CK_Unknown:
   case CK_NoOp:
   case CK_UserDefinedConversion:
   case CK_ConstructorConversion:

clang/lib/CodeGen/CGExprScalar.cpp

@@ -999,11 +999,6 @@ Value *ScalarExprEmitter::EmitCastExpr(CastExpr *CE) {
   switch (Kind) {
   case CK_Dependent: llvm_unreachable("dependent cast kind in IR gen!");
       
-  case CK_Unknown:
-    // FIXME: All casts should have a known kind!
-    //assert(0 && "Unknown cast kind!");
-    break;
-
   case CK_LValueBitCast: 
   case CK_ObjCObjectLValueCast: {
     Value *V = EmitLValue(E).getAddress();

clang/lib/Sema/SemaCXXCast.cpp

@@ -526,7 +526,7 @@ CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
       Self.Diag(OpRange.getBegin(), msg) << CT_Static
       << SrcExpr->getType() << DestType << OpRange;
   }
-  else if (Kind == CK_Unknown || Kind == CK_BitCast)
+  else if (Kind == CK_BitCast)
     Self.CheckCastAlign(SrcExpr, DestType, OpRange);
 }
 
@@ -1413,7 +1413,7 @@ Sema::CXXCheckCStyleCast(SourceRange R, QualType CastTy, Expr *&CastExpr,
         << CastExpr->getType() << CastTy << R;
     }
   }
-  else if (Kind == CK_Unknown || Kind == CK_BitCast)
+  else if (Kind == CK_BitCast)
     CheckCastAlign(CastExpr, CastTy, R);
 
   return tcr != TC_Success;

clang/lib/Sema/SemaChecking.cpp

@@ -2280,8 +2280,6 @@ IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
     IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
 
     bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
-    if (!isIntegerCast && CE->getCastKind() == CK_Unknown)
-      isIntegerCast = CE->getSubExpr()->getType()->isIntegerType();
 
     // Assume that non-integer casts can span the full range of the type.
     if (!isIntegerCast)