target/s390x: Emulate CVDG

CVDG is the same as CVD, except that it converts 64 bits into 128,
rather than 32 into 64. Create a new helper, which uses Int128
wrappers.

Reported-by: Ido Plat <Ido.Plat@ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-ID: <20240205205830.6425-2-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
4 files changed