If the control flow of M5's executable and statetrace's target process get out
of sync even a little, there will be a LOT of output, very little of which
will be useful. There's also almost no hope for recovery. In those cases, we
might as well give up and not generate a huge, mostly worthless trace file.
When registers have incorrect values but aren't actively changing, it's likely
they're not being modified at all. The fact that they're still wrong isn't
very important.