target/arm: Convert SHRN, RSHRN to decodetree

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240912024114.1097832-23-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/tcg/a64.decode

@@ -1277,3 +1277,11 @@ SSHLL_v         0.00 11110 .... ... 10100 1 ..... .....     @q_shli_s
 USHLL_v         0.10 11110 .... ... 10100 1 ..... .....     @q_shli_b
 USHLL_v         0.10 11110 .... ... 10100 1 ..... .....     @q_shli_h
 USHLL_v         0.10 11110 .... ... 10100 1 ..... .....     @q_shli_s
+
+SHRN_v          0.00 11110 .... ... 10000 1 ..... .....     @q_shri_b
+SHRN_v          0.00 11110 .... ... 10000 1 ..... .....     @q_shri_h
+SHRN_v          0.00 11110 .... ... 10000 1 ..... .....     @q_shri_s
+
+RSHRN_v         0.00 11110 .... ... 10001 1 ..... .....     @q_shri_b
+RSHRN_v         0.00 11110 .... ... 10001 1 ..... .....     @q_shri_h
+RSHRN_v         0.00 11110 .... ... 10001 1 ..... .....     @q_shri_s

target/arm/tcg/translate-a64.c

@@ -7091,6 +7091,51 @@ static void gen_urshr_d(TCGv_i64 dst, TCGv_i64 src, int64_t shift)
     }
 }
 
+static bool do_vec_shift_imm_narrow(DisasContext *s, arg_qrri_e *a,
+                                    WideShiftImmFn * const fns[3], MemOp sign)
+{
+    TCGv_i64 tcg_rn, tcg_rd;
+    int esz = a->esz;
+    int esize;
+    WideShiftImmFn *fn;
+
+    tcg_debug_assert(esz >= MO_8 && esz <= MO_32);
+
+    if (!fp_access_check(s)) {
+        return true;
+    }
+
+    tcg_rn = tcg_temp_new_i64();
+    tcg_rd = tcg_temp_new_i64();
+    tcg_gen_movi_i64(tcg_rd, 0);
+
+    fn = fns[esz];
+    esize = 8 << esz;
+    for (int i = 0, elements = 8 >> esz; i < elements; i++) {
+        read_vec_element(s, tcg_rn, a->rn, i, (esz + 1) | sign);
+        fn(tcg_rn, tcg_rn, a->imm);
+        tcg_gen_deposit_i64(tcg_rd, tcg_rd, tcg_rn, esize * i, esize);
+    }
+
+    write_vec_element(s, tcg_rd, a->rd, a->q, MO_64);
+    clear_vec_high(s, a->q, a->rd);
+    return true;
+}
+
+static WideShiftImmFn * const shrn_fns[] = {
+    tcg_gen_shri_i64,
+    tcg_gen_shri_i64,
+    gen_ushr_d,
+};
+TRANS(SHRN_v, do_vec_shift_imm_narrow, a, shrn_fns, 0)
+
+static WideShiftImmFn * const rshrn_fns[] = {
+    gen_urshr_bhs,
+    gen_urshr_bhs,
+    gen_urshr_d,
+};
+TRANS(RSHRN_v, do_vec_shift_imm_narrow, a, rshrn_fns, 0)
+
 /* Shift a TCGv src by TCGv shift_amount, put result in dst.
  * Note that it is the caller's responsibility to ensure that the
  * shift amount is in range (ie 0..31 or 0..63) and provide the ARM
@@ -10496,52 +10541,6 @@ static void disas_simd_scalar_two_reg_misc(DisasContext *s, uint32_t insn)
     }
 }
 
-/* SHRN/RSHRN - Shift right with narrowing (and potential rounding) */
-static void handle_vec_simd_shrn(DisasContext *s, bool is_q,
-                                 int immh, int immb, int opcode, int rn, int rd)
-{
-    int immhb = immh << 3 | immb;
-    int size = 32 - clz32(immh) - 1;
-    int dsize = 64;
-    int esize = 8 << size;
-    int elements = dsize/esize;
-    int shift = (2 * esize) - immhb;
-    bool round = extract32(opcode, 0, 1);
-    TCGv_i64 tcg_rn, tcg_rd, tcg_final;
-    int i;
-
-    if (extract32(immh, 3, 1)) {
-        unallocated_encoding(s);
-        return;
-    }
-
-    if (!fp_access_check(s)) {
-        return;
-    }
-
-    tcg_rn = tcg_temp_new_i64();
-    tcg_rd = tcg_temp_new_i64();
-    tcg_final = tcg_temp_new_i64();
-    read_vec_element(s, tcg_final, rd, is_q ? 1 : 0, MO_64);
-
-    for (i = 0; i < elements; i++) {
-        read_vec_element(s, tcg_rn, rn, i, size+1);
-        handle_shri_with_rndacc(tcg_rd, tcg_rn, round,
-                                false, true, size+1, shift);
-
-        tcg_gen_deposit_i64(tcg_final, tcg_final, tcg_rd, esize * i, esize);
-    }
-
-    if (!is_q) {
-        write_vec_element(s, tcg_final, rd, 0, MO_64);
-    } else {
-        write_vec_element(s, tcg_final, rd, 1, MO_64);
-    }
-
-    clear_vec_high(s, is_q, rd);
-}
-
-
 /* AdvSIMD shift by immediate
  *  31  30   29 28         23 22  19 18  16 15    11  10 9    5 4    0
  * +---+---+---+-------------+------+------+--------+---+------+------+
@@ -10564,13 +10563,13 @@ static void disas_simd_shift_imm(DisasContext *s, uint32_t insn)
     }
 
     switch (opcode) {
-    case 0x10: /* SHRN */
+    case 0x10: /* SHRN / SQSHRUN */
     case 0x11: /* RSHRN / SQRSHRUN */
         if (is_u) {
             handle_vec_simd_sqshrn(s, false, is_q, false, true, immh, immb,
                                    opcode, rn, rd);
         } else {
-            handle_vec_simd_shrn(s, is_q, immh, immb, opcode, rn, rd);
+            unallocated_encoding(s);
         }
         break;
     case 0x12: /* SQSHRN / UQSHRN */