target/arm: Implement vector shifted FCVT for fp16

While we have some of the scalar paths for FCVT for fp16,
we failed to decode the fp16 version of these instructions.

Cc: qemu-stable@nongnu.org
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180502221552.3873-3-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/translate-a64.c

@@ -7448,19 +7448,28 @@ static void handle_simd_shift_fpint_conv(DisasContext *s, bool is_scalar,
                                          bool is_q, bool is_u,
                                          int immh, int immb, int rn, int rd)
 {
-    bool is_double = extract32(immh, 3, 1);
     int immhb = immh << 3 | immb;
-    int fracbits = (is_double ? 128 : 64) - immhb;
-    int pass;
+    int pass, size, fracbits;
     TCGv_ptr tcg_fpstatus;
     TCGv_i32 tcg_rmode, tcg_shift;
 
-    if (!extract32(immh, 2, 2)) {
-        unallocated_encoding(s);
-        return;
-    }
-
-    if (!is_scalar && !is_q && is_double) {
+    if (immh & 0x8) {
+        size = MO_64;
+        if (!is_scalar && !is_q) {
+            unallocated_encoding(s);
+            return;
+        }
+    } else if (immh & 0x4) {
+        size = MO_32;
+    } else if (immh & 0x2) {
+        size = MO_16;
+        if (!arm_dc_feature(s, ARM_FEATURE_V8_FP16)) {
+            unallocated_encoding(s);
+            return;
+        }
+    } else {
+        /* Should have split out AdvSIMD modified immediate earlier.  */
+        assert(immh == 1);
         unallocated_encoding(s);
         return;
     }
@@ -7472,11 +7481,12 @@ static void handle_simd_shift_fpint_conv(DisasContext *s, bool is_scalar,
     assert(!(is_scalar && is_q));
 
     tcg_rmode = tcg_const_i32(arm_rmode_to_sf(FPROUNDING_ZERO));
-    tcg_fpstatus = get_fpstatus_ptr(false);
+    tcg_fpstatus = get_fpstatus_ptr(size == MO_16);
     gen_helper_set_rmode(tcg_rmode, tcg_rmode, tcg_fpstatus);
+    fracbits = (16 << size) - immhb;
     tcg_shift = tcg_const_i32(fracbits);
 
-    if (is_double) {
+    if (size == MO_64) {
         int maxpass = is_scalar ? 1 : 2;
 
         for (pass = 0; pass < maxpass; pass++) {
@@ -7493,20 +7503,37 @@ static void handle_simd_shift_fpint_conv(DisasContext *s, bool is_scalar,
         }
         clear_vec_high(s, is_q, rd);
     } else {
-        int maxpass = is_scalar ? 1 : is_q ? 4 : 2;
-        for (pass = 0; pass < maxpass; pass++) {
-            TCGv_i32 tcg_op = tcg_temp_new_i32();
+        void (*fn)(TCGv_i32, TCGv_i32, TCGv_i32, TCGv_ptr);
+        int maxpass = is_scalar ? 1 : ((8 << is_q) >> size);
 
-            read_vec_element_i32(s, tcg_op, rn, pass, MO_32);
+        switch (size) {
+        case MO_16:
+            if (is_u) {
+                fn = gen_helper_vfp_toulh;
+            } else {
+                fn = gen_helper_vfp_toslh;
+            }
+            break;
+        case MO_32:
             if (is_u) {
-                gen_helper_vfp_touls(tcg_op, tcg_op, tcg_shift, tcg_fpstatus);
+                fn = gen_helper_vfp_touls;
             } else {
-                gen_helper_vfp_tosls(tcg_op, tcg_op, tcg_shift, tcg_fpstatus);
+                fn = gen_helper_vfp_tosls;
             }
+            break;
+        default:
+            g_assert_not_reached();
+        }
+
+        for (pass = 0; pass < maxpass; pass++) {
+            TCGv_i32 tcg_op = tcg_temp_new_i32();
+
+            read_vec_element_i32(s, tcg_op, rn, pass, size);
+            fn(tcg_op, tcg_op, tcg_shift, tcg_fpstatus);
             if (is_scalar) {
                 write_fp_sreg(s, rd, tcg_op);
             } else {
-                write_vec_element_i32(s, tcg_op, rd, pass, MO_32);
+                write_vec_element_i32(s, tcg_op, rd, pass, size);
             }
             tcg_temp_free_i32(tcg_op);
         }