C++ ABI issues list

Question

I've seen a lot of discussion about how C++ doesn't have a Standard ABI quite in the same way that C does. I'm curious as to what, exactly, the issues are. So far, I've come up with

1. Name mangling
2. Exception handling
3. RTTI

Are there any other ABI issues pertaining to C++?

Answer 1

Off the top of my head:

C++ Specific:

• Where the 'this' parameter can be found.
• How virtual functions are called
  • ie does it use a vtable or other
  • What is the layout of the structures used for implementing this.
• How are multiple definitions handled
  • Multiple template instantiations
  • Inline functions that were not inlined.
• Static Storage Duration Objects
  • How to handle creation (in the global scope)
  • How to handle creation of function local (how do you add it to the destructor list)
  • How to handle destruction (destroy in reverse order of creation)
• You mention exceptions. But also how exceptions are handled outside main()
  • ie before or after main()

Generic.

• Parameter passing locations
• Return value location
• Member alignment
• Padding
• Register usage (which registers are preserved which are scratch)
• size of primitive types (such as int)
• format of primitive types (Floating point format)

Answer 2

The big problem, in my experience, is the C++ standard library. Even if you had an ABI that dictates how a class should be laid out, different compilers provide different implementations of standard objects like std::string and std::vector.

I'm not saying that it would not be possible to standardize the internal layout of C++ library objects, only that it has not been done before.