Updating the list with some progress: Alexander narrowed it down to
pgaio_io_wait() being inlined into pgaio_io_was_recycled(). It seems
to have some instructions in the wrong order, and that can be
reproduced standalone, so I've asked about it here:
https://github.com/llvm/llvm-project/issues/164194
I'm not seeing how that could be our fault, but let's see...
