target/loongarch: Implement vabsd

This patch includes:
- VABSD.{B/H/W/D}[U].

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-12-gaosong@loongson.cn>
diff --git a/target/loongarch/lsx_helper.c b/target/loongarch/lsx_helper.c
index b683a1c..f0baffa 100644
--- a/target/loongarch/lsx_helper.c
+++ b/target/loongarch/lsx_helper.c
@@ -307,3 +307,14 @@
 DO_3OP(vavgr_hu, 16, UH, DO_VAVGR)
 DO_3OP(vavgr_wu, 32, UW, DO_VAVGR)
 DO_3OP(vavgr_du, 64, UD, DO_VAVGR)
+
+#define DO_VABSD(a, b)  ((a > b) ? (a -b) : (b-a))
+
+DO_3OP(vabsd_b, 8, B, DO_VABSD)
+DO_3OP(vabsd_h, 16, H, DO_VABSD)
+DO_3OP(vabsd_w, 32, W, DO_VABSD)
+DO_3OP(vabsd_d, 64, D, DO_VABSD)
+DO_3OP(vabsd_bu, 8, UB, DO_VABSD)
+DO_3OP(vabsd_hu, 16, UH, DO_VABSD)
+DO_3OP(vabsd_wu, 32, UW, DO_VABSD)
+DO_3OP(vabsd_du, 64, UD, DO_VABSD)