The previous implementation of coro-split didn't collect values used by dbg instructions into the spills which made a log debug info unavailable with optimization on.
This patch tries to collect these uses which are used by dbg.values. In this way, the debugbility of coroutine could be as powerful as normal functions with optimization on.
To avoid enlarging the coroutine frame, this patch only collects dbg.value whose value is already in the coroutine frame. This decision may make some debug info getting unavailable. But if we are with optimization on, the performance issue should be considered first. And this patch would make the debugbility of coroutine to be better only without changing the layout of the frame.