Implement the MVE incrementing/decrementing dup insns VIDUP, VDDUP,
VIWDUP and VDWDUP. These fill the elements of a vector with
successively incrementing values, starting at the offset specified in
a general purpose register. The final value of the offset is written
back to this register. The wrapping variants take a second general
purpose register which specifies the point where the count should
wrap back to 0.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>