Try to insert dbg.declare to entry.resume basic block in resume function. In this way, we could print alloca such as __promise in gdb/lldb under O2, which would be beneficial to debug coroutine program.
I am not sure whether this change is correct. I only test it by C++ programs locally. I would update the test case if needed. It could print __promise in all of the C++ coroutines I tested.
By the way, I think it is very beneficial to print the coroutine frame by keywords like __coro_frame. But I find it seems a little hard to implement.