ubsan: Add checking for invalid downcasts. Per [expr.static.cast]p2 and p11,
base-to-derived casts have undefined behavior if the object is not actually an
instance of the derived type.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175078 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index 49494be..7b86c04 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -1220,7 +1220,15 @@
const CXXRecordDecl *DerivedClassDecl = DestTy->getPointeeCXXRecordDecl();
assert(DerivedClassDecl && "BaseToDerived arg isn't a C++ object pointer!");
- return CGF.GetAddressOfDerivedClass(Visit(E), DerivedClassDecl,
+ llvm::Value *V = Visit(E);
+
+ // C++11 [expr.static.cast]p11: Behavior is undefined if a downcast is
+ // performed and the object is not of the derived type.
+ if (CGF.SanitizePerformTypeCheck)
+ CGF.EmitTypeCheck(CodeGenFunction::TCK_DowncastPointer, CE->getExprLoc(),
+ V, DestTy->getPointeeType());
+
+ return CGF.GetAddressOfDerivedClass(V, DerivedClassDecl,
CE->path_begin(), CE->path_end(),
ShouldNullCheckClassCastValue(CE));
}