target-arm: A64: Add SIMD TBL/TBLX

Add support for the SIMD TBL/TBLX instructions (group C3.6.2).

Signed-off-by: Michael Matz <matz@suse.de>
[PMM: rewritten to do more of the decode in translate-a64.c,
 and to do only one 64 bit pass at a time in the helper]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>

1 files changed, 54 insertions, 1 deletions

diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 75b00392bc..7a6b00a938 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -4742,7 +4742,60 @@ static void disas_simd_ext(DisasContext *s, uint32_t insn)
  */
 static void disas_simd_tb(DisasContext *s, uint32_t insn)
 {
-    unsupported_encoding(s, insn);
+    int op2 = extract32(insn, 22, 2);
+    int is_q = extract32(insn, 30, 1);
+    int rm = extract32(insn, 16, 5);
+    int rn = extract32(insn, 5, 5);
+    int rd = extract32(insn, 0, 5);
+    int is_tblx = extract32(insn, 12, 1);
+    int len = extract32(insn, 13, 2);
+    TCGv_i64 tcg_resl, tcg_resh, tcg_idx;
+    TCGv_i32 tcg_regno, tcg_numregs;
+
+    if (op2 != 0) {
+        unallocated_encoding(s);
+        return;
+    }
+
+    /* This does a table lookup: for every byte element in the input
+     * we index into a table formed from up to four vector registers,
+     * and then the output is the result of the lookups. Our helper
+     * function does the lookup operation for a single 64 bit part of
+     * the input.
+     */
+    tcg_resl = tcg_temp_new_i64();
+    tcg_resh = tcg_temp_new_i64();
+
+    if (is_tblx) {
+        read_vec_element(s, tcg_resl, rd, 0, MO_64);
+    } else {
+        tcg_gen_movi_i64(tcg_resl, 0);
+    }
+    if (is_tblx && is_q) {
+        read_vec_element(s, tcg_resh, rd, 1, MO_64);
+    } else {
+        tcg_gen_movi_i64(tcg_resh, 0);
+    }
+
+    tcg_idx = tcg_temp_new_i64();
+    tcg_regno = tcg_const_i32(rn);
+    tcg_numregs = tcg_const_i32(len + 1);
+    read_vec_element(s, tcg_idx, rm, 0, MO_64);
+    gen_helper_simd_tbl(tcg_resl, cpu_env, tcg_resl, tcg_idx,
+                        tcg_regno, tcg_numregs);
+    if (is_q) {
+        read_vec_element(s, tcg_idx, rm, 1, MO_64);
+        gen_helper_simd_tbl(tcg_resh, cpu_env, tcg_resh, tcg_idx,
+                            tcg_regno, tcg_numregs);
+    }
+    tcg_temp_free_i64(tcg_idx);
+    tcg_temp_free_i32(tcg_regno);
+    tcg_temp_free_i32(tcg_numregs);
+
+    write_vec_element(s, tcg_resl, rd, 0, MO_64);
+    tcg_temp_free_i64(tcg_resl);
+    write_vec_element(s, tcg_resh, rd, 1, MO_64);
+    tcg_temp_free_i64(tcg_resh);
 }
 
 /* C3.6.3 ZIP/UZP/TRN