[clang] [llvm] [clang][DebugInfo] Add symbol for debugger with VTable information. (PR #130255)

[Pavel Labath via llvm-commits]

labath wrote:

IIUC, your debugger parses all of debug info upfront and builds up a vtable pointer->class DIE map. That's not something we would want to do in lldb, but I think we could still make use of this by first searching for the type using the name from the vtable (like we do now) and then confirming the match using the new information. It would be better if we could go from the vtable pointer straight to the right type DIE, but I don't think we can do that without inventing a new sort of an accelerator table (which I guess we don't have an appetite for).

> To work out which class A this refers to would involve parsing the template parameter correctly and matching to the correct anonymous namespace. While this technically isn’t impossible

Are you sure about that? Anonymous types are confined to a single CU statically, but their values can definitely leak out at runtime. So if I'm stopped in a random CU and I see am object whose dynamic type is `(anonymous namespace)::X`, I don't see how one could determine which type (out of possibly many) is that vtable referring to.

https://github.com/llvm/llvm-project/pull/130255