arm/translate-a64: add FP16 FMOV to simd_mod_imm

Only one half-precision instruction has been added to this group.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180227143852.11175-29-alex.bennee@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/translate-a64.c

@@ -6234,6 +6234,8 @@ static void disas_simd_copy(DisasContext *s, uint32_t insn)
  *   MVNI - move inverted (shifted) imm into register
  *   ORR  - bitwise OR of (shifted) imm with register
  *   BIC  - bitwise clear of (shifted) imm with register
+ * With ARMv8.2 we also have:
+ *   FMOV half-precision
  */
 static void disas_simd_mod_imm(DisasContext *s, uint32_t insn)
 {
@@ -6248,8 +6250,11 @@ static void disas_simd_mod_imm(DisasContext *s, uint32_t insn)
     uint64_t imm = 0;
 
     if (o2 != 0 || ((cmode == 0xf) && is_neg && !is_q)) {
-        unallocated_encoding(s);
-        return;
+        /* Check for FMOV (vector, immediate) - half-precision */
+        if (!(arm_dc_feature(s, ARM_FEATURE_V8_FP16) && o2 && cmode == 0xf)) {
+            unallocated_encoding(s);
+            return;
+        }
     }
 
     if (!fp_access_check(s)) {
@@ -6307,19 +6312,29 @@ static void disas_simd_mod_imm(DisasContext *s, uint32_t insn)
                     imm |= 0x4000000000000000ULL;
                 }
             } else {
-                imm = (abcdefgh & 0x3f) << 19;
-                if (abcdefgh & 0x80) {
-                    imm |= 0x80000000;
-                }
-                if (abcdefgh & 0x40) {
-                    imm |= 0x3e000000;
+                if (o2) {
+                    /* FMOV (vector, immediate) - half-precision */
+                    imm = vfp_expand_imm(MO_16, abcdefgh);
+                    /* now duplicate across the lanes */
+                    imm = bitfield_replicate(imm, 16);
                 } else {
-                    imm |= 0x40000000;
+                    imm = (abcdefgh & 0x3f) << 19;
+                    if (abcdefgh & 0x80) {
+                        imm |= 0x80000000;
+                    }
+                    if (abcdefgh & 0x40) {
+                        imm |= 0x3e000000;
+                    } else {
+                        imm |= 0x40000000;
+                    }
+                    imm |= (imm << 32);
                 }
-                imm |= (imm << 32);
             }
         }
         break;
+    default:
+        fprintf(stderr, "%s: cmode_3_1: %x\n", __func__, cmode_3_1);
+        g_assert_not_reached();
     }
 
     if (cmode_3_1 != 7 && is_neg) {