[PATCH] [RFC] Sanitize upcasts and conversion to virtual base

[Richard Smith]

================
Comment at: tools/clang/lib/CodeGen/CGClass.cpp:186
@@ +185,3 @@
+      EmitTypeCheck(TCK_Upcast, Loc, Value, DerivedTy, DerivedAlign,
+                    !NullCheckValue);
+    }
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I am not sure that the `SkipNullCheck` behavior here is right. If `NullCheckValue` is false, then I think we should be performing a null check inside `EmitTypeCheck` rather than assuming the pointer is non-null.

http://reviews.llvm.org/D5635