target/arm: Convert Neon VTBL, VTBX to decodetree

Convert the Neon VTBL, VTBX instructions to decodetree.  The actual
implementation of the insn is copied across to the new trans function
unchanged except for renaming 'tmp5' to 'tmp4'.

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

target/arm/neon-dp.decode

@@ -419,6 +419,9 @@ Vimm_1r          1111 001 . 1 . 000 ... .... cmode:4 0 . op:1 1 .... @1reg_imm
     ##################################################################
     VEXT         1111 001 0 1 . 11 .... .... imm:4 . q:1 . 0 .... \
                  vm=%vm_dp vn=%vn_dp vd=%vd_dp
+
+    VTBL         1111 001 1 1 . 11 .... .... 10 len:2 . op:1 . 0 .... \
+                 vm=%vm_dp vn=%vn_dp vd=%vd_dp
   ]
 
   # Subgroup for size != 0b11

target/arm/translate-neon.inc.c

@@ -2888,3 +2888,59 @@ static bool trans_VEXT(DisasContext *s, arg_VEXT *a)
     }
     return true;
 }
+
+static bool trans_VTBL(DisasContext *s, arg_VTBL *a)
+{
+    int n;
+    TCGv_i32 tmp, tmp2, tmp3, tmp4;
+    TCGv_ptr ptr1;
+
+    if (!arm_dc_feature(s, ARM_FEATURE_NEON)) {
+        return false;
+    }
+
+    /* UNDEF accesses to D16-D31 if they don't exist. */
+    if (!dc_isar_feature(aa32_simd_r32, s) &&
+        ((a->vd | a->vn | a->vm) & 0x10)) {
+        return false;
+    }
+
+    if (!vfp_access_check(s)) {
+        return true;
+    }
+
+    n = a->len + 1;
+    if ((a->vn + n) > 32) {
+        /*
+         * This is UNPREDICTABLE; we choose to UNDEF to avoid the
+         * helper function running off the end of the register file.
+         */
+        return false;
+    }
+    n <<= 3;
+    if (a->op) {
+        tmp = neon_load_reg(a->vd, 0);
+    } else {
+        tmp = tcg_temp_new_i32();
+        tcg_gen_movi_i32(tmp, 0);
+    }
+    tmp2 = neon_load_reg(a->vm, 0);
+    ptr1 = vfp_reg_ptr(true, a->vn);
+    tmp4 = tcg_const_i32(n);
+    gen_helper_neon_tbl(tmp2, tmp2, tmp, ptr1, tmp4);
+    tcg_temp_free_i32(tmp);
+    if (a->op) {
+        tmp = neon_load_reg(a->vd, 1);
+    } else {
+        tmp = tcg_temp_new_i32();
+        tcg_gen_movi_i32(tmp, 0);
+    }
+    tmp3 = neon_load_reg(a->vm, 1);
+    gen_helper_neon_tbl(tmp3, tmp3, tmp, ptr1, tmp4);
+    tcg_temp_free_i32(tmp4);
+    tcg_temp_free_ptr(ptr1);
+    neon_store_reg(a->vd, 0, tmp2);
+    neon_store_reg(a->vd, 1, tmp3);
+    tcg_temp_free_i32(tmp);
+    return true;
+}

target/arm/translate.c

@@ -5025,13 +5025,12 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn)
 {
     int op;
     int q;
-    int rd, rn, rm, rd_ofs, rm_ofs;
+    int rd, rm, rd_ofs, rm_ofs;
     int size;
     int pass;
     int u;
     int vec_size;
-    TCGv_i32 tmp, tmp2, tmp3, tmp5;
+    TCGv_i32 tmp, tmp2, tmp3;
-    TCGv_ptr ptr1;
 
     if (!arm_dc_feature(s, ARM_FEATURE_NEON)) {
         return 1;
@@ -5052,7 +5051,6 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn)
     q = (insn & (1 << 6)) != 0;
     u = (insn >> 24) & 1;
     VFP_DREG_D(rd, insn);
-    VFP_DREG_N(rn, insn);
     VFP_DREG_M(rm, insn);
     size = (insn >> 20) & 3;
     vec_size = q ? 16 : 8;
@@ -5577,39 +5575,8 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn)
                     break;
                 }
             } else if ((insn & (1 << 10)) == 0) {
-                /* VTBL, VTBX.  */
+                /* VTBL, VTBX: handled by decodetree */
-                int n = ((insn >> 8) & 3) + 1;
+                return 1;
-                if ((rn + n) > 32) {
-                    /* This is UNPREDICTABLE; we choose to UNDEF to avoid the
-                     * helper function running off the end of the register file.
-                     */
-                    return 1;
-                }
-                n <<= 3;
-                if (insn & (1 << 6)) {
-                    tmp = neon_load_reg(rd, 0);
-                } else {
-                    tmp = tcg_temp_new_i32();
-                    tcg_gen_movi_i32(tmp, 0);
-                }
-                tmp2 = neon_load_reg(rm, 0);
-                ptr1 = vfp_reg_ptr(true, rn);
-                tmp5 = tcg_const_i32(n);
-                gen_helper_neon_tbl(tmp2, tmp2, tmp, ptr1, tmp5);
-                tcg_temp_free_i32(tmp);
-                if (insn & (1 << 6)) {
-                    tmp = neon_load_reg(rd, 1);
-                } else {
-                    tmp = tcg_temp_new_i32();
-                    tcg_gen_movi_i32(tmp, 0);
-                }
-                tmp3 = neon_load_reg(rm, 1);
-                gen_helper_neon_tbl(tmp3, tmp3, tmp, ptr1, tmp5);
-                tcg_temp_free_i32(tmp5);
-                tcg_temp_free_ptr(ptr1);
-                neon_store_reg(rd, 0, tmp2);
-                neon_store_reg(rd, 1, tmp3);
-                tcg_temp_free_i32(tmp);
             } else if ((insn & 0x380) == 0) {
                 /* VDUP */
                 int element;