Testing this, there seems to be something messed up. We are dealing with
unsigned numbers. "Each operand is treated as an unsigned binary integer."
Let's just implement as written in the PoP:
"A subtraction is performed by adding the contents of
the second operand with the bitwise complement of
the third operand along with a borrow indication from
the rightmost bit position of the fourth operand and
the result is placed in the first operand."
We can reuse gen_ac2_i64().
Fixes: 48390a7c27 ("s390x/tcg: Implement VECTOR SUBTRACT WITH BORROW INDICATION")
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20191021085715.3797-6-david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
2cb8a68d37