rn == 31 always means SP (not XZR) whether an add_sub_ext
instruction is setting the flags or not; only rd has behaviour
dependent on whether we are setting flags.
Reported-by: NLaurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-3-git-send-email-peter.maydell@linaro.org