[cfe-dev] Inheritance Information in Debug Information

[Jon Eyolfson via cfe-dev]

Hello, I'm trying to understand why I'm not getting all the inheritance
information for the following example:

    class TwoVirtual {
    public:
      virtual void foo();
      virtual void bar() const;
    };
    
    class TwoImpl : public TwoVirtual {
      TwoImpl() {}
    public:
      virtual void foo() {}
      virtual void bar() const {}
    };
    
    class NoSubOrSuper {
      TwoImpl t;
      void baz() {}
    };
    
    class OneSuper : public TwoImpl {
      void baz() {}
    };

I'm generating llvm code with the following command:

    clang++ -std=c++14 -g -O1 -Xclang -disable-llvm-optzns -emit-llvm
            -femit-all-decls -S -c TestFile.cpp -o TestFile.ll

I'm using -O1 because I need TBAA information present.

What I get is only one DIDerivedType with the DW_TAG_inheritance tag.
This connects TwoImpl to TwoVirtual. However there isnt an inheritance
tag between OneSuper and TwoImpl. Is there a reason for this? I'm trying
to determine in the llvm code that NoSubOrSuper and OneSuper are different
(on has an inheritance relation and the other doesn't). Thanks!