target/arm: Implement fp16 for Neon VABS, VNEG of floats

Rewrite Neon VABS/VNEG of floats to use gvec logical AND and XOR, so
that we can implement the fp16 version of the insns.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200828183354.27913-26-peter.maydell@linaro.org

target/arm/translate-neon.c.inc

@@ -3741,22 +3741,44 @@ static bool trans_VCNT(DisasContext *s, arg_2misc *a)
     return do_2misc(s, a, gen_helper_neon_cnt_u8);
 }
 
+static void gen_VABS_F(unsigned vece, uint32_t rd_ofs, uint32_t rm_ofs,
+                       uint32_t oprsz, uint32_t maxsz)
+{
+    tcg_gen_gvec_andi(vece, rd_ofs, rm_ofs,
+                      vece == MO_16 ? 0x7fff : 0x7fffffff,
+                      oprsz, maxsz);
+}
+
 static bool trans_VABS_F(DisasContext *s, arg_2misc *a)
 {
-    if (a->size != 2) {
+    if (a->size == MO_16) {
+        if (!dc_isar_feature(aa32_fp16_arith, s)) {
+            return false;
+        }
+    } else if (a->size != MO_32) {
         return false;
     }
-    /* TODO: FP16 : size == 1 */
-    return do_2misc(s, a, gen_helper_vfp_abss);
+    return do_2misc_vec(s, a, gen_VABS_F);
+}
+
+static void gen_VNEG_F(unsigned vece, uint32_t rd_ofs, uint32_t rm_ofs,
+                       uint32_t oprsz, uint32_t maxsz)
+{
+    tcg_gen_gvec_xori(vece, rd_ofs, rm_ofs,
+                      vece == MO_16 ? 0x8000 : 0x80000000,
+                      oprsz, maxsz);
 }
 
 static bool trans_VNEG_F(DisasContext *s, arg_2misc *a)
 {
-    if (a->size != 2) {
+    if (a->size == MO_16) {
+        if (!dc_isar_feature(aa32_fp16_arith, s)) {
+            return false;
+        }
+    } else if (a->size != MO_32) {
         return false;
     }
-    /* TODO: FP16 : size == 1 */
-    return do_2misc(s, a, gen_helper_vfp_negs);
+    return do_2misc_vec(s, a, gen_VNEG_F);
 }
 
 static bool trans_VRECPE(DisasContext *s, arg_2misc *a)