[Qemu-devel] [PULL 03/38] target-arm: A64: Add decode skeleton for SIMD data processing insns

[Peter Maydell <peter.maydell@linaro.org>]

From: Alex Bennée <alex.bennee@linaro.org>

Add decode skeleton and function placeholders for all the SIMD data
processing instructions. Due to the complexity of this part of the
table the normal extract and switch approach gets very messy very
quickly, so we use a simple data-driven pattern-and-mask approach.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
---
 target-arm/translate-a64.c | 306 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 305 insertions(+), 1 deletion(-)

diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 6e31740..8060c9f 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -61,6 +61,17 @@ enum a64_shift_type {
     A64_SHIFT_TYPE_ROR = 3
 };
 
+/* Table based decoder typedefs - used when the relevant bits for decode
+ * are too awkwardly scattered across the instruction (eg SIMD).
+ */
+typedef void AArch64DecodeFn(DisasContext *s, uint32_t insn);
+
+typedef struct AArch64DecodeTable {
+    uint32_t pattern;
+    uint32_t mask;
+    AArch64DecodeFn *disas_fn;
+} AArch64DecodeTable;
+
 /* initialize TCG globals.  */
 void a64_translate_init(void)
 {
@@ -846,6 +857,31 @@ static inline void gen_check_sp_alignment(DisasContext *s)
 }
 
 /*
+ * This provides a simple table based table lookup decoder. It is
+ * intended to be used when the relevant bits for decode are too
+ * awkwardly placed and switch/if based logic would be confusing and
+ * deeply nested. Since it's a linear search through the table, tables
+ * should be kept small.
+ *
+ * It returns the first handler where insn & mask == pattern, or
+ * NULL if there is no match.
+ * The table is terminated by an empty mask (i.e. 0)
+ */
+static inline AArch64DecodeFn *lookup_disas_fn(const AArch64DecodeTable *table,
+                                               uint32_t insn)
+{
+    const AArch64DecodeTable *tptr = table;
+
+    while (tptr->mask) {
+        if ((insn & tptr->mask) == tptr->pattern) {
+            return tptr->disas_fn;
+        }
+        tptr++;
+    }
+    return NULL;
+}
+
+/*
  * the instruction disassembly implemented here matches
  * the instruction encoding classifications in chapter 3 (C3)
  * of the ARM Architecture Reference Manual (DDI0487A_a)
@@ -4610,13 +4646,281 @@ static void disas_data_proc_fp(DisasContext *s, uint32_t insn)
     }
 }
 
+/* C3.6.1 EXT
+ *   31  30 29         24 23 22  21 20  16 15  14  11 10  9    5 4    0
+ * +---+---+-------------+-----+---+------+---+------+---+------+------+
+ * | 0 | Q | 1 0 1 1 1 0 | op2 | 0 |  Rm  | 0 | imm4 | 0 |  Rn  |  Rd  |
+ * +---+---+-------------+-----+---+------+---+------+---+------+------+
+ */
+static void disas_simd_ext(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.2 TBL/TBX
+ *   31  30 29         24 23 22  21 20  16 15  14 13  12  11 10 9    5 4    0
+ * +---+---+-------------+-----+---+------+---+-----+----+-----+------+------+
+ * | 0 | Q | 0 0 1 1 1 0 | op2 | 0 |  Rm  | 0 | len | op | 0 0 |  Rn  |  Rd  |
+ * +---+---+-------------+-----+---+------+---+-----+----+-----+------+------+
+ */
+static void disas_simd_tb(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.3 ZIP/UZP/TRN
+ *   31  30 29         24 23  22  21 20   16 15 14 12 11 10 9    5 4    0
+ * +---+---+-------------+------+---+------+---+------------------+------+
+ * | 0 | Q | 0 0 1 1 1 0 | size | 0 |  Rm  | 0 | opc | 1 0 |  Rn  |  Rd  |
+ * +---+---+-------------+------+---+------+---+------------------+------+
+ */
+static void disas_simd_zip_trn(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.4 AdvSIMD across lanes
+ *   31  30  29 28       24 23  22 21       17 16    12 11 10 9    5 4    0
+ * +---+---+---+-----------+------+-----------+--------+-----+------+------+
+ * | 0 | Q | U | 0 1 1 1 0 | size | 1 1 0 0 0 | opcode | 1 0 |  Rn  |  Rd  |
+ * +---+---+---+-----------+------+-----------+--------+-----+------+------+
+ */
+static void disas_simd_across_lanes(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.5 AdvSIMD copy
+ *   31  30  29  28             21 20  16 15  14  11 10  9    5 4    0
+ * +---+---+----+-----------------+------+---+------+---+------+------+
+ * | 0 | Q | op | 0 1 1 1 0 0 0 0 | imm5 | 0 | imm4 | 1 |  Rn  |  Rd  |
+ * +---+---+----+-----------------+------+---+------+---+------+------+
+ */
+static void disas_simd_copy(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.6 AdvSIMD modified immediate
+ *  31  30   29  28                 19 18 16 15   12  11  10  9     5 4    0
+ * +---+---+----+---------------------+-----+-------+----+---+-------+------+
+ * | 0 | Q | op | 0 1 1 1 1 0 0 0 0 0 | abc | cmode | o2 | 1 | defgh |  Rd  |
+ * +---+---+----+---------------------+-----+-------+----+---+-------+------+
+ */
+static void disas_simd_mod_imm(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.7 AdvSIMD scalar copy
+ *  31 30  29  28             21 20  16 15  14  11 10  9    5 4    0
+ * +-----+----+-----------------+------+---+------+---+------+------+
+ * | 0 1 | op | 1 1 1 1 0 0 0 0 | imm5 | 0 | imm4 | 1 |  Rn  |  Rd  |
+ * +-----+----+-----------------+------+---+------+---+------+------+
+ */
+static void disas_simd_scalar_copy(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.8 AdvSIMD scalar pairwise
+ *  31 30  29 28       24 23  22 21       17 16    12 11 10 9    5 4    0
+ * +-----+---+-----------+------+-----------+--------+-----+------+------+
+ * | 0 1 | U | 1 1 1 1 0 | size | 1 1 0 0 0 | opcode | 1 0 |  Rn  |  Rd  |
+ * +-----+---+-----------+------+-----------+--------+-----+------+------+
+ */
+static void disas_simd_scalar_pairwise(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.9 AdvSIMD scalar shift by immediate
+ *  31 30  29 28         23 22  19 18  16 15    11  10 9    5 4    0
+ * +-----+---+-------------+------+------+--------+---+------+------+
+ * | 0 1 | U | 1 1 1 1 1 0 | immh | immb | opcode | 1 |  Rn  |  Rd  |
+ * +-----+---+-------------+------+------+--------+---+------+------+
+ */
+static void disas_simd_scalar_shift_imm(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.10 AdvSIMD scalar three different
+ *  31 30  29 28       24 23  22  21 20  16 15    12 11 10 9    5 4    0
+ * +-----+---+-----------+------+---+------+--------+-----+------+------+
+ * | 0 1 | U | 1 1 1 1 0 | size | 1 |  Rm  | opcode | 0 0 |  Rn  |  Rd  |
+ * +-----+---+-----------+------+---+------+--------+-----+------+------+
+ */
+static void disas_simd_scalar_three_reg_diff(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.11 AdvSIMD scalar three same
+ *  31 30  29 28       24 23  22  21 20  16 15    11  10 9    5 4    0
+ * +-----+---+-----------+------+---+------+--------+---+------+------+
+ * | 0 1 | U | 1 1 1 1 0 | size | 1 |  Rm  | opcode | 1 |  Rn  |  Rd  |
+ * +-----+---+-----------+------+---+------+--------+---+------+------+
+ */
+static void disas_simd_scalar_three_reg_same(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.12 AdvSIMD scalar two reg misc
+ *  31 30  29 28       24 23  22 21       17 16    12 11 10 9    5 4    0
+ * +-----+---+-----------+------+-----------+--------+-----+------+------+
+ * | 0 1 | U | 1 1 1 1 0 | size | 1 0 0 0 0 | opcode | 1 0 |  Rn  |  Rd  |
+ * +-----+---+-----------+------+-----------+--------+-----+------+------+
+ */
+static void disas_simd_scalar_two_reg_misc(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.13 AdvSIMD scalar x indexed element
+ *  31 30  29 28       24 23  22 21  20  19  16 15 12  11  10 9    5 4    0
+ * +-----+---+-----------+------+---+---+------+-----+---+---+------+------+
+ * | 0 1 | U | 1 1 1 1 1 | size | L | M |  Rm  | opc | H | 0 |  Rn  |  Rd  |
+ * +-----+---+-----------+------+---+---+------+-----+---+---+------+------+
+ */
+static void disas_simd_scalar_indexed(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.14 AdvSIMD shift by immediate
+ *  31  30   29 28         23 22  19 18  16 15    11  10 9    5 4    0
+ * +---+---+---+-------------+------+------+--------+---+------+------+
+ * | 0 | Q | U | 0 1 1 1 1 0 | immh | immb | opcode | 1 |  Rn  |  Rd  |
+ * +---+---+---+-------------+------+------+--------+---+------+------+
+ */
+static void disas_simd_shift_imm(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.15 AdvSIMD three different
+ *   31  30  29 28       24 23  22  21 20  16 15    12 11 10 9    5 4    0
+ * +---+---+---+-----------+------+---+------+--------+-----+------+------+
+ * | 0 | Q | U | 0 1 1 1 0 | size | 1 |  Rm  | opcode | 0 0 |  Rn  |  Rd  |
+ * +---+---+---+-----------+------+---+------+--------+-----+------+------+
+ */
+static void disas_simd_three_reg_diff(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.16 AdvSIMD three same
+ *  31  30  29  28       24 23  22  21 20  16 15    11  10 9    5 4    0
+ * +---+---+---+-----------+------+---+------+--------+---+------+------+
+ * | 0 | Q | U | 0 1 1 1 0 | size | 1 |  Rm  | opcode | 1 |  Rn  |  Rd  |
+ * +---+---+---+-----------+------+---+------+--------+---+------+------+
+ */
+static void disas_simd_three_reg_same(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.17 AdvSIMD two reg misc
+ *   31  30  29 28       24 23  22 21       17 16    12 11 10 9    5 4    0
+ * +---+---+---+-----------+------+-----------+--------+-----+------+------+
+ * | 0 | Q | U | 0 1 1 1 0 | size | 1 0 0 0 0 | opcode | 1 0 |  Rn  |  Rd  |
+ * +---+---+---+-----------+------+-----------+--------+-----+------+------+
+ */
+static void disas_simd_two_reg_misc(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.18 AdvSIMD vector x indexed element
+ *   31  30  29 28       24 23  22 21  20  19  16 15 12  11  10 9    5 4    0
+ * +---+---+---+-----------+------+---+---+------+-----+---+---+------+------+
+ * | 0 | Q | U | 0 1 1 1 1 | size | L | M |  Rm  | opc | H | 0 |  Rn  |  Rd  |
+ * +---+---+---+-----------+------+---+---+------+-----+---+---+------+------+
+ */
+static void disas_simd_indexed_vector(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.19 Crypto AES
+ *  31             24 23  22 21       17 16    12 11 10 9    5 4    0
+ * +-----------------+------+-----------+--------+-----+------+------+
+ * | 0 1 0 0 1 1 1 0 | size | 1 0 1 0 0 | opcode | 1 0 |  Rn  |  Rd  |
+ * +-----------------+------+-----------+--------+-----+------+------+
+ */
+static void disas_crypto_aes(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.20 Crypto three-reg SHA
+ *  31             24 23  22  21 20  16  15 14    12 11 10 9    5 4    0
+ * +-----------------+------+---+------+---+--------+-----+------+------+
+ * | 0 1 0 1 1 1 1 0 | size | 0 |  Rm  | 0 | opcode | 0 0 |  Rn  |  Rd  |
+ * +-----------------+------+---+------+---+--------+-----+------+------+
+ */
+static void disas_crypto_three_reg_sha(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6.21 Crypto two-reg SHA
+ *  31             24 23  22 21       17 16    12 11 10 9    5 4    0
+ * +-----------------+------+-----------+--------+-----+------+------+
+ * | 0 1 0 1 1 1 1 0 | size | 1 0 1 0 0 | opcode | 1 0 |  Rn  |  Rd  |
+ * +-----------------+------+-----------+--------+-----+------+------+
+ */
+static void disas_crypto_two_reg_sha(DisasContext *s, uint32_t insn)
+{
+    unsupported_encoding(s, insn);
+}
+
+/* C3.6 Data processing - SIMD, inc Crypto
+ *
+ * As the decode gets a little complex we are using a table based
+ * approach for this part of the decode.
+ */
+static const AArch64DecodeTable data_proc_simd[] = {
+    /* pattern  ,  mask     ,  fn                        */
+    { 0x0e200400, 0x9f200400, disas_simd_three_reg_same },
+    { 0x0e200000, 0x9f200c00, disas_simd_three_reg_diff },
+    { 0x0e200800, 0x9f3e0c00, disas_simd_two_reg_misc },
+    { 0x0e300800, 0x9f3e0c00, disas_simd_across_lanes },
+    { 0x0e000400, 0x9fe08400, disas_simd_copy },
+    { 0x0f000000, 0x9f000400, disas_simd_indexed_vector },
+    /* simd_mod_imm decode is a subset of simd_shift_imm, so must precede it */
+    { 0x0f000400, 0x9ff80400, disas_simd_mod_imm },
+    { 0x0f000400, 0x9f800400, disas_simd_shift_imm },
+    { 0x0e000000, 0xbf208c00, disas_simd_tb },
+    { 0x0e000800, 0xbf208c00, disas_simd_zip_trn },
+    { 0x2e000000, 0xbf208400, disas_simd_ext },
+    { 0x5e200400, 0xdf200400, disas_simd_scalar_three_reg_same },
+    { 0x5e200000, 0xdf200c00, disas_simd_scalar_three_reg_diff },
+    { 0x5e200800, 0xdf3e0c00, disas_simd_scalar_two_reg_misc },
+    { 0x5e300800, 0xdf3e0c00, disas_simd_scalar_pairwise },
+    { 0x5e000400, 0xdfe08400, disas_simd_scalar_copy },
+    { 0x5f000000, 0xdf000400, disas_simd_scalar_indexed },
+    { 0x5f000400, 0xdf800400, disas_simd_scalar_shift_imm },
+    { 0x4e280800, 0xff3e0c00, disas_crypto_aes },
+    { 0x5e000000, 0xff208c00, disas_crypto_three_reg_sha },
+    { 0x5e280800, 0xff3e0c00, disas_crypto_two_reg_sha },
+    { 0x00000000, 0x00000000, NULL }
+};
+
 static void disas_data_proc_simd(DisasContext *s, uint32_t insn)
 {
     /* Note that this is called with all non-FP cases from
      * table C3-6 so it must UNDEF for entries not specifically
      * allocated to instructions in that table.
      */
-    unsupported_encoding(s, insn);
+    AArch64DecodeFn *fn = lookup_disas_fn(&data_proc_simd[0], insn);
+    if (fn) {
+        fn(s, insn);
+    } else {
+        unallocated_encoding(s);
+    }
 }
 
 /* C3.6 Data processing - SIMD and floating point */
-- 
1.8.5