coro transformations insert unreachable in destroy fn?

I have this input IR in the final cleanup block of my coroutine:

// call the free function

call fastcc void %22(%Allocator* %20, %"[]u8"* byval %4), !dbg !244

// based on whether this is an early return or a normal return, we want to

// either return to the caller, or resume the handle of the awaiter

br i1 %19, label %Resume, label %Return, !dbg !244

Resume: ; preds = %CheckFree
%31 = load i8*, i8** %14, align 8, !dbg !244
call void @llvm.coro.resume(i8* %31), !dbg !244

// after resuming the awaiter, we return to the caller

br label %Return, !dbg !244

Return: ; preds = %Resume, %CheckFree
ret i8* undef, !dbg !244

When CoroSplit creates the destroy function for this coroutine, it generates this:

call fastcc void %2(%Allocator* %0, %"[]u8"* byval %.reload.addr4), !dbg !296
unreachable

How did that unreachable get there? What happened to my code above to resume or return to the caller?

Found the problem.

Instead of the Return block I needed to use the Suspend block, which has the llvm.coro.end in it.