[cfe-commits] r129256 - in /cfe/trunk: include/clang/AST/Expr.h include/clang/AST/OperationKinds.h lib/AST/Expr.cpp lib/AST/ExprConstant.cpp lib/CodeGen/CGExpr.cpp lib/CodeGen/CGExprAgg.cpp lib/CodeGen/CGExprConstant.cpp lib/CodeGen/CGExprScalar.
Eli Friedman
eli.friedman at gmail.com
Sun Apr 10 18:09:26 PDT 2011
On Sun, Apr 10, 2011 at 1:33 PM, Anders Carlsson <andersca at mac.com> wrote:
> Author: andersca
> Date: Sun Apr 10 15:33:22 2011
> New Revision: 129256
>
> URL: http://llvm.org/viewvc/llvm-project?rev=129256&view=rev
> Log:
> As a first step towards fixing PR9641, add a CK_DynamicToNull cast kind which
> represents a dynamic cast where we know that the result is always null.
>
> For example:
>
> struct A {
> virtual ~A();
> };
> struct B final : A { };
> struct C { };
>
> bool f(B* b) {
> return dynamic_cast<C*>(b);
> }
Adding an extra cast kind seems to complicate things for what should
be a very rare case.
-Eli
> Modified:
> cfe/trunk/include/clang/AST/Expr.h
> cfe/trunk/include/clang/AST/OperationKinds.h
> cfe/trunk/lib/AST/Expr.cpp
> cfe/trunk/lib/AST/ExprConstant.cpp
> cfe/trunk/lib/CodeGen/CGExpr.cpp
> cfe/trunk/lib/CodeGen/CGExprAgg.cpp
> cfe/trunk/lib/CodeGen/CGExprConstant.cpp
> cfe/trunk/lib/CodeGen/CGExprScalar.cpp
> cfe/trunk/lib/Sema/SemaCXXCast.cpp
> cfe/trunk/lib/StaticAnalyzer/Core/ExprEngine.cpp
>
> Modified: cfe/trunk/include/clang/AST/Expr.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Expr.h?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/AST/Expr.h (original)
> +++ cfe/trunk/include/clang/AST/Expr.h Sun Apr 10 15:33:22 2011
> @@ -2183,6 +2183,7 @@
> // These should not have an inheritance path.
> case CK_BitCast:
> case CK_Dynamic:
> + case CK_DynamicToNull:
> case CK_ToUnion:
> case CK_ArrayToPointerDecay:
> case CK_FunctionToPointerDecay:
>
> Modified: cfe/trunk/include/clang/AST/OperationKinds.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/OperationKinds.h?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/AST/OperationKinds.h (original)
> +++ cfe/trunk/include/clang/AST/OperationKinds.h Sun Apr 10 15:33:22 2011
> @@ -82,6 +82,10 @@
> /// CK_Dynamic - A C++ dynamic_cast.
> CK_Dynamic,
>
> + /// CK_DynamicToNull - A C++ dynamic_cast that can be proven to
> + /// always yield a null result.
> + CK_DynamicToNull,
> +
> /// CK_ToUnion - The GCC cast-to-union extension.
> /// int -> union { int x; float y; }
> /// float -> union { int x; float y; }
>
> Modified: cfe/trunk/lib/AST/Expr.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/lib/AST/Expr.cpp (original)
> +++ cfe/trunk/lib/AST/Expr.cpp Sun Apr 10 15:33:22 2011
> @@ -987,6 +987,8 @@
> return "UncheckedDerivedToBase";
> case CK_Dynamic:
> return "Dynamic";
> + case CK_DynamicToNull:
> + return "DynamicToNull";
> case CK_ToUnion:
> return "ToUnion";
> case CK_ArrayToPointerDecay:
>
> Modified: cfe/trunk/lib/AST/ExprConstant.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/lib/AST/ExprConstant.cpp (original)
> +++ cfe/trunk/lib/AST/ExprConstant.cpp Sun Apr 10 15:33:22 2011
> @@ -1768,6 +1768,7 @@
> case CK_DerivedToBase:
> case CK_UncheckedDerivedToBase:
> case CK_Dynamic:
> + case CK_DynamicToNull:
> case CK_ToUnion:
> case CK_ArrayToPointerDecay:
> case CK_FunctionToPointerDecay:
> @@ -2315,6 +2316,7 @@
> case CK_DerivedToBase:
> case CK_UncheckedDerivedToBase:
> case CK_Dynamic:
> + case CK_DynamicToNull:
> case CK_ToUnion:
> case CK_ArrayToPointerDecay:
> case CK_FunctionToPointerDecay:
>
> Modified: cfe/trunk/lib/CodeGen/CGExpr.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExpr.cpp?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGExpr.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGExpr.cpp Sun Apr 10 15:33:22 2011
> @@ -1867,7 +1867,8 @@
> return MakeAddrLValue(V, E->getType());
> }
>
> - case CK_Dynamic: {
> + case CK_Dynamic:
> + case CK_DynamicToNull: {
> LValue LV = EmitLValue(E->getSubExpr());
> llvm::Value *V = LV.getAddress();
> const CXXDynamicCastExpr *DCE = cast<CXXDynamicCastExpr>(E);
>
> Modified: cfe/trunk/lib/CodeGen/CGExprAgg.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprAgg.cpp?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGExprAgg.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGExprAgg.cpp Sun Apr 10 15:33:22 2011
> @@ -255,7 +255,10 @@
> }
>
> switch (E->getCastKind()) {
> - case CK_Dynamic: {
> + case CK_Dynamic:
> + case CK_DynamicToNull: {
> +
> + // FIXME: Actually handle DynamicToNull here.
> assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
> LValue LV = CGF.EmitCheckedLValue(E->getSubExpr());
> // FIXME: Do we also need to handle property references here?
>
> Modified: cfe/trunk/lib/CodeGen/CGExprConstant.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprConstant.cpp?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGExprConstant.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGExprConstant.cpp Sun Apr 10 15:33:22 2011
> @@ -552,6 +552,7 @@
> case CK_GetObjCProperty:
> case CK_ToVoid:
> case CK_Dynamic:
> + case CK_DynamicToNull:
> case CK_ResolveUnknownAnyType:
> return 0;
>
>
> Modified: cfe/trunk/lib/CodeGen/CGExprScalar.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprScalar.cpp?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGExprScalar.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGExprScalar.cpp Sun Apr 10 15:33:22 2011
> @@ -1053,7 +1053,8 @@
> CE->path_begin(), CE->path_end(),
> ShouldNullCheckClassCastValue(CE));
> }
> - case CK_Dynamic: {
> + case CK_Dynamic:
> + case CK_DynamicToNull: {
> Value *V = Visit(const_cast<Expr*>(E));
> const CXXDynamicCastExpr *DCE = cast<CXXDynamicCastExpr>(CE);
> return CGF.EmitDynamicCast(V, DCE);
>
> Modified: cfe/trunk/lib/Sema/SemaCXXCast.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaCXXCast.cpp?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaCXXCast.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaCXXCast.cpp Sun Apr 10 15:33:22 2011
> @@ -522,6 +522,14 @@
> return;
> }
>
> + // If the source class is marked 'final', and the destination class does not
> + // derive from the source class, then we know that the result is always null.
> + if (SrcRecord->getDecl()->hasAttr<FinalAttr>() &&
> + !Self.IsDerivedFrom(DestPointee, SrcPointee)) {
> + Kind = CK_DynamicToNull;
> + return;
> + }
> +
> // C++ 5.2.7p5
> // Upcasts are resolved statically.
> if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) {
>
> Modified: cfe/trunk/lib/StaticAnalyzer/Core/ExprEngine.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/ExprEngine.cpp?rev=129256&r1=129255&r2=129256&view=diff
> ==============================================================================
> --- cfe/trunk/lib/StaticAnalyzer/Core/ExprEngine.cpp (original)
> +++ cfe/trunk/lib/StaticAnalyzer/Core/ExprEngine.cpp Sun Apr 10 15:33:22 2011
> @@ -2178,6 +2178,7 @@
> // Various C++ casts that are not handled yet.
> case CK_ResolveUnknownAnyType:
> case CK_Dynamic:
> + case CK_DynamicToNull:
> case CK_ToUnion:
> case CK_BaseToDerived:
> case CK_NullToMemberPointer:
>
>
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