Implement the MVE long shifts by register, which perform shifts on a
pair of general-purpose registers treated as a 64-bit quantity, with
the shift count in another general-purpose register, which might be
either positive or negative.
Like the long-shifts-by-immediate, these encodings sit in the space
that was previously the UNPREDICTABLE MOVS/ORRS with Rm==13,15.
Because LSLL_rr and ASRL_rr overlap with both MOV_rxri/ORR_rrri and
also with CSEL (as one of the previously-UNPREDICTABLE Rm==13 cases),
we have to move the CSEL pattern into the same decodetree group.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210628135835.6690-17-peter.maydell@linaro.org
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