https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113045
--- Comment #26 from Richard Earnshaw <rearnsha at gcc dot gnu.org> --- I think it's more likely that this is at the start of the buffer rather than the end, and related to rounding the address down to a 16-byte alignment. But it could also occur at the end of the buffer as well if the buffer is (nearly) full.
