[llvm] [dyndbg][AsmPrinter] Add tail padding attributes (PR #194852)

[Orlando Cazalet-Hyams via llvm-commits]

OCHyams wrote:

> I'm a little worried your debugger people are going to come back at some point and say they can't actually reliably detect whether a function is on the stack. For example, with hot-cold splitting, there's a non-obvious connection between the cold part and the hot part. But I guess we can go with the simpler approach for now.

Yeah we (try to) block outlining/specialization for that reason using the `nooutline`  and (new) `noipa`* and attributes, but I see that hot-cold split isn't covered by `nooutline`, I wonder if it should be. If the debugger can't detour to an unoptimized version it can at least continue debugging the optimized code instead so it's not the end of the world IMO, but I agree we should try to minimize it as much as possible. (* `noipa` also covers the more critical requirement of keeping the function interfaces the same between opt/unopt binaries)

Thanks all for the reviews

https://github.com/llvm/llvm-project/pull/194852