[llvm] [llvm][DebugInfo] Attach object-pointer to DISubprogram declarations (PR #122742)

[Michael Buch via llvm-commits]

Michael137 wrote:

> One alternate solution that comes to mind is to use a boolean to just say "this function /has/ an object pointer" (flag present, really really cheap to encode), but doesn't say which parameter is the object pointer (can leave that on the definition).

That would be a good start, though LLDB also deduces the function CV qualifiers from the object pointer. 

> we could consider using a parameter index (one byte, instead of 4 bytes of DIE offset), I thought we'd standardized a more general purpose constant-stored-in-abbrev like flag_present, in which case we could use that to encode the value 0 (zeroth parameter is the object pointer)...

But I like this idea. Will have a look at doing that tomorrow. But feel free to revert in the meantime if this is causing issues

https://github.com/llvm/llvm-project/pull/122742