Paul Muntean via llvm-dev
2016-Dec-16 06:51 UTC
[llvm-dev] Help needed: How to get during compile time the base class of casted C++ object inside static_cast<> and dynamic_cast<> and the pointer of the casted object
I want to detect bad casts in C++ code by using the Clang compiler. The approach is similar to what Caver and TypeSan do but without using the compiler-rt. Caver and TypeSan: https://www.usenix.org/system/files/conference/usenixsecurity15/sec15-paper-lee.pdf https://nebelwelt.net/publications/files/16CCS2.pdf For example if I have the following C++ code snippet where I want to cast object b into object D. D* obj = static_cast<D*>(b); from where (inside Clang, LTO, thinLTO, etc.) can I get the base class of D and the base class ob b. Is this available in the Clang compiler or LTO? Also, if b is an object of a virtual Class (class with inherited or its own virtual functions) can I get its virtual pointer at compile time by using the LTO? I found out that in CodeGen/CGExpr.cpp the explicit case "BaseToDerived" is handled and you can retrieve TypeSourceInfo using the function getTypeInfoAsWritten(). It seems that this information is enough to get the exact type of this cast at compile-time and should also work for Template programming, as my, understanding is that Clang should have abstracted the code into, specific types at this point. Am I wrong here? Is there any case where the type of the objects used inside the cast not known at compile time? Can the, 'real' type be hidden behind a pointer?
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- *********How to get during compile time the base class of casted C++ object inside static_cast<> and dynamic_cast<> and the pointer of the casted object
- *********How to get during compile time the base class of casted C++ object inside static_cast<> and dynamic_cast<> and the pointer of the casted object
- *********How to get during compile time the base class of casted C++ object inside static_cast<> and dynamic_cast<> and the pointer of the casted object