xref: /openbmc/qemu/target/hexagon/decode.c (revision 28188253dc26bc3038f30eed0d79798b51f81a94)

/*
 *  Copyright(c) 2019-2023 Qualcomm Innovation Center, Inc. All Rights Reserved.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include "qemu/osdep.h"
#include "iclass.h"
#include "attribs.h"
#include "genptr.h"
#include "decode.h"
#include "insn.h"
#include "printinsn.h"
#include "mmvec/decode_ext_mmvec.h"

#define fZXTN(N, M, VAL) ((VAL) & ((1LL << (N)) - 1))

enum {
    EXT_IDX_noext = 0,
    EXT_IDX_noext_AFTER = 4,
    EXT_IDX_mmvec = 4,
    EXT_IDX_mmvec_AFTER = 8,
    XX_LAST_EXT_IDX
};

/*
 *  Certain operand types represent a non-contiguous set of values.
 *  For example, the compound compare-and-jump instruction can only access
 *  registers R0-R7 and R16-23.
 *  This table represents the mapping from the encoding to the actual values.
 */

#define DEF_REGMAP(NAME, ELEMENTS, ...) \
    static const unsigned int DECODE_REGISTER_##NAME[ELEMENTS] = \
    { __VA_ARGS__ };
        /* Name   Num Table */
DEF_REGMAP(R_16,  16, 0, 1, 2, 3, 4, 5, 6, 7, 16, 17, 18, 19, 20, 21, 22, 23)
DEF_REGMAP(R__8,  8,  0, 2, 4, 6, 16, 18, 20, 22)
DEF_REGMAP(R_8,   8,  0, 1, 2, 3, 4, 5, 6, 7)

#define DECODE_MAPPED_REG(OPNUM, NAME) \
    insn->regno[OPNUM] = DECODE_REGISTER_##NAME[insn->regno[OPNUM]];

/* Helper functions for decode_*_generated.c.inc */
#define DECODE_MAPPED(NAME) \
static int decode_mapped_reg_##NAME(DisasContext *ctx, int x) \
{ \
    return DECODE_REGISTER_##NAME[x]; \
}
DECODE_MAPPED(R_16)
DECODE_MAPPED(R_8)
DECODE_MAPPED(R__8)

/* Helper function for decodetree_trans_funcs_generated.c.inc */
static int shift_left(DisasContext *ctx, int x, int n, int immno)
{
    int ret = x;
    Insn *insn = ctx->insn;
    if (!insn->extension_valid ||
        insn->which_extended != immno) {
        ret <<= n;
    }
    return ret;
}

/* Include the generated decoder for 32 bit insn */
#include "decode_normal_generated.c.inc"
#include "decode_hvx_generated.c.inc"

/* Include the generated decoder for 16 bit insn */
#include "decode_subinsn_a_generated.c.inc"
#include "decode_subinsn_l1_generated.c.inc"
#include "decode_subinsn_l2_generated.c.inc"
#include "decode_subinsn_s1_generated.c.inc"
#include "decode_subinsn_s2_generated.c.inc"

/* Include the generated helpers for the decoder */
#include "decodetree_trans_funcs_generated.c.inc"

void decode_send_insn_to(Packet *packet, int start, int newloc)
{
    Insn tmpinsn;
    int direction;
    int i;
    if (start == newloc) {
        return;
    }
    if (start < newloc) {
        /* Move towards end */
        direction = 1;
    } else {
        /* move towards beginning */
        direction = -1;
    }
    for (i = start; i != newloc; i += direction) {
        tmpinsn = packet->insn[i];
        packet->insn[i] = packet->insn[i + direction];
        packet->insn[i + direction] = tmpinsn;
    }
}

/* Fill newvalue registers with the correct regno */
static void
decode_fill_newvalue_regno(Packet *packet)
{
    int i, use_regidx, offset, def_idx, dst_idx;

    for (i = 1; i < packet->num_insns; i++) {
        if (GET_ATTRIB(packet->insn[i].opcode, A_DOTNEWVALUE) &&
            !GET_ATTRIB(packet->insn[i].opcode, A_EXTENSION)) {

            g_assert(packet->insn[i].new_read_idx != -1);
            use_regidx = packet->insn[i].new_read_idx;

            /*
             * What's encoded at the N-field is the offset to who's producing
             * the value.  Shift off the LSB which indicates odd/even register,
             * then walk backwards and skip over the constant extenders.
             */
            offset = packet->insn[i].regno[use_regidx] >> 1;
            def_idx = i - offset;
            for (int j = 0; j < offset; j++) {
                if (GET_ATTRIB(packet->insn[i - j - 1].opcode, A_IT_EXTENDER)) {
                    def_idx--;
                }
            }

            /*
             * Check for a badly encoded N-field which points to an instruction
             * out-of-range
             */
            g_assert(!((def_idx < 0) || (def_idx > (packet->num_insns - 1))));

            /* Now patch up the consumer with the register number */
            g_assert(packet->insn[def_idx].dest_idx != -1);
            dst_idx = packet->insn[def_idx].dest_idx;
            packet->insn[i].regno[use_regidx] =
                packet->insn[def_idx].regno[dst_idx];
            /*
             * We need to remember who produces this value to later
             * check if it was dynamically cancelled
             */
            packet->insn[i].new_value_producer_slot =
                packet->insn[def_idx].slot;
        }
    }
}

/* Split CJ into a compare and a jump */
static void decode_split_cmpjump(Packet *pkt)
{
    int last, i;
    int numinsns = pkt->num_insns;

    /*
     * First, split all compare-jumps.
     * The compare is sent to the end as a new instruction.
     * Do it this way so we don't reorder dual jumps. Those need to stay in
     * original order.
     */
    for (i = 0; i < numinsns; i++) {
        /* It's a cmp-jump */
        if (GET_ATTRIB(pkt->insn[i].opcode, A_NEWCMPJUMP)) {
            last = pkt->num_insns;
            pkt->insn[last] = pkt->insn[i];    /* copy the instruction */
            pkt->insn[last].part1 = true;      /* last insn does the CMP */
            pkt->insn[i].part1 = false;        /* existing insn does the JUMP */
            pkt->num_insns++;
        }
    }

    /* Now re-shuffle all the compares back to the beginning */
    for (i = 0; i < pkt->num_insns; i++) {
        if (pkt->insn[i].part1) {
            decode_send_insn_to(pkt, i, 0);
        }
    }
}

static bool decode_opcode_can_jump(int opcode)
{
    if ((GET_ATTRIB(opcode, A_JUMP)) ||
        (GET_ATTRIB(opcode, A_CALL)) ||
        (opcode == J2_trap0) ||
        (opcode == J2_pause)) {
        /* Exception to A_JUMP attribute */
        if (opcode == J4_hintjumpr) {
            return false;
        }
        return true;
    }

    return false;
}

static bool decode_opcode_ends_loop(int opcode)
{
    return GET_ATTRIB(opcode, A_HWLOOP0_END) ||
           GET_ATTRIB(opcode, A_HWLOOP1_END);
}

/* Set the is_* fields in each instruction */
static void decode_set_insn_attr_fields(Packet *pkt)
{
    int i;
    int numinsns = pkt->num_insns;
    uint16_t opcode;

    pkt->pkt_has_cof = false;
    pkt->pkt_has_multi_cof = false;
    pkt->pkt_has_endloop = false;
    pkt->pkt_has_dczeroa = false;

    for (i = 0; i < numinsns; i++) {
        opcode = pkt->insn[i].opcode;
        if (pkt->insn[i].part1) {
            continue;    /* Skip compare of cmp-jumps */
        }

        if (GET_ATTRIB(opcode, A_DCZEROA)) {
            pkt->pkt_has_dczeroa = true;
        }

        if (GET_ATTRIB(opcode, A_STORE)) {
            if (GET_ATTRIB(opcode, A_SCALAR_STORE) &&
                !GET_ATTRIB(opcode, A_MEMSIZE_0B)) {
                if (pkt->insn[i].slot == 0) {
                    pkt->pkt_has_store_s0 = true;
                } else {
                    pkt->pkt_has_store_s1 = true;
                }
            }
        }

        if (decode_opcode_can_jump(opcode)) {
            if (pkt->pkt_has_cof) {
                pkt->pkt_has_multi_cof = true;
            }
            pkt->pkt_has_cof = true;
        }

        pkt->insn[i].is_endloop = decode_opcode_ends_loop(opcode);

        pkt->pkt_has_endloop |= pkt->insn[i].is_endloop;

        if (pkt->pkt_has_endloop) {
            if (pkt->pkt_has_cof) {
                pkt->pkt_has_multi_cof = true;
            }
            pkt->pkt_has_cof = true;
        }
    }
}

/*
 * Shuffle for execution
 * Move stores to end (in same order as encoding)
 * Move compares to beginning (for use by .new insns)
 */
static void decode_shuffle_for_execution(Packet *packet)
{
    bool changed = false;
    int i;
    bool flag;    /* flag means we've seen a non-memory instruction */
    int n_mems;
    int last_insn = packet->num_insns - 1;

    /*
     * Skip end loops, somehow an end loop is getting in and messing
     * up the order
     */
    if (decode_opcode_ends_loop(packet->insn[last_insn].opcode)) {
        last_insn--;
    }

    do {
        changed = false;
        /*
         * Stores go last, must not reorder.
         * Cannot shuffle stores past loads, either.
         * Iterate backwards.  If we see a non-memory instruction,
         * then a store, shuffle the store to the front.  Don't shuffle
         * stores wrt each other or a load.
         */
        for (flag = false, n_mems = 0, i = last_insn; i >= 0; i--) {
            int opcode = packet->insn[i].opcode;

            if (flag && GET_ATTRIB(opcode, A_STORE)) {
                decode_send_insn_to(packet, i, last_insn - n_mems);
                n_mems++;
                changed = true;
            } else if (GET_ATTRIB(opcode, A_STORE)) {
                n_mems++;
            } else if (GET_ATTRIB(opcode, A_LOAD)) {
                /*
                 * Don't set flag, since we don't want to shuffle a
                 * store past a load
                 */
                n_mems++;
            } else if (GET_ATTRIB(opcode, A_DOTNEWVALUE)) {
                /*
                 * Don't set flag, since we don't want to shuffle past
                 * a .new value
                 */
            } else {
                flag = true;
            }
        }

        if (changed) {
            continue;
        }
        /* Compares go first, may be reordered wrt each other */
        for (flag = false, i = 0; i < last_insn + 1; i++) {
            int opcode = packet->insn[i].opcode;

            if (packet->insn[i].has_pred_dest &&
                GET_ATTRIB(opcode, A_STORE) == 0) {
                /* This should be a compare (not a store conditional) */
                if (flag) {
                    decode_send_insn_to(packet, i, 0);
                    changed = true;
                    continue;
                }
            } else if (GET_ATTRIB(opcode, A_IMPLICIT_WRITES_P3) &&
                       !decode_opcode_ends_loop(packet->insn[i].opcode)) {
                /*
                 * spNloop instruction
                 * Don't reorder endloops; they are not valid for .new uses,
                 * and we want to match HW
                 */
                if (flag) {
                    decode_send_insn_to(packet, i, 0);
                    changed = true;
                    continue;
                }
            } else if (GET_ATTRIB(opcode, A_IMPLICIT_WRITES_P0) &&
                       !GET_ATTRIB(opcode, A_NEWCMPJUMP)) {
                if (flag) {
                    decode_send_insn_to(packet, i, 0);
                    changed = true;
                    continue;
                }
            } else {
                flag = true;
            }
        }
        if (changed) {
            continue;
        }
    } while (changed);

    /*
     * If we have a .new register compare/branch, move that to the very
     * very end, past stores
     */
    for (i = 0; i < last_insn; i++) {
        if (GET_ATTRIB(packet->insn[i].opcode, A_DOTNEWVALUE)) {
            decode_send_insn_to(packet, i, last_insn);
            break;
        }
    }
}

static void
apply_extender(Packet *pkt, int i, uint32_t extender)
{
    int immed_num;
    uint32_t base_immed;

    immed_num = pkt->insn[i].which_extended;
    base_immed = pkt->insn[i].immed[immed_num];

    pkt->insn[i].immed[immed_num] = extender | fZXTN(6, 32, base_immed);
}

static void decode_apply_extenders(Packet *packet)
{
    int i;
    for (i = 0; i < packet->num_insns; i++) {
        if (GET_ATTRIB(packet->insn[i].opcode, A_IT_EXTENDER)) {
            packet->insn[i + 1].extension_valid = true;
            apply_extender(packet, i + 1, packet->insn[i].immed[0]);
        }
    }
}

static void decode_remove_extenders(Packet *packet)
{
    int i, j;
    for (i = 0; i < packet->num_insns; i++) {
        if (GET_ATTRIB(packet->insn[i].opcode, A_IT_EXTENDER)) {
            /* Remove this one by moving the remaining instructions down */
            for (j = i;
                (j < packet->num_insns - 1) && (j < INSTRUCTIONS_MAX - 1);
                j++) {
                packet->insn[j] = packet->insn[j + 1];
            }
            packet->num_insns--;
        }
    }
}

static SlotMask get_valid_slots(const Packet *pkt, unsigned int slot)
{
    if (GET_ATTRIB(pkt->insn[slot].opcode, A_EXTENSION)) {
        return mmvec_ext_decode_find_iclass_slots(pkt->insn[slot].opcode);
    } else {
        return find_iclass_slots(pkt->insn[slot].opcode,
                                 pkt->insn[slot].iclass);
    }
}

/*
 * Section 10.3 of the Hexagon V73 Programmer's Reference Manual
 *
 * A duplex is encoded as a 32-bit instruction with bits [15:14] set to 00.
 * The sub-instructions that comprise a duplex are encoded as 13-bit fields
 * in the duplex.
 *
 * Per table 10-4, the 4-bit duplex iclass is encoded in bits 31:29, 13
 */
static uint32_t get_duplex_iclass(uint32_t encoding)
{
    uint32_t iclass = extract32(encoding, 13, 1);
    iclass = deposit32(iclass, 1, 3, extract32(encoding, 29, 3));
    return iclass;
}

/*
 * Per table 10-5, the duplex ICLASS field values that specify the group of
 * each sub-instruction in a duplex
 *
 * This table points to the decode instruction for each entry in the table
 */
typedef bool (*subinsn_decode_func)(DisasContext *ctx, uint16_t insn);
typedef struct {
    subinsn_decode_func decode_slot0_subinsn;
    subinsn_decode_func decode_slot1_subinsn;
} subinsn_decode_groups;

static const subinsn_decode_groups decode_groups[16] = {
    [0x0] = { decode_subinsn_l1, decode_subinsn_l1 },
    [0x1] = { decode_subinsn_l2, decode_subinsn_l1 },
    [0x2] = { decode_subinsn_l2, decode_subinsn_l2 },
    [0x3] = { decode_subinsn_a,  decode_subinsn_a },
    [0x4] = { decode_subinsn_l1, decode_subinsn_a },
    [0x5] = { decode_subinsn_l2, decode_subinsn_a },
    [0x6] = { decode_subinsn_s1, decode_subinsn_a },
    [0x7] = { decode_subinsn_s2, decode_subinsn_a },
    [0x8] = { decode_subinsn_s1, decode_subinsn_l1 },
    [0x9] = { decode_subinsn_s1, decode_subinsn_l2 },
    [0xa] = { decode_subinsn_s1, decode_subinsn_s1 },
    [0xb] = { decode_subinsn_s2, decode_subinsn_s1 },
    [0xc] = { decode_subinsn_s2, decode_subinsn_l1 },
    [0xd] = { decode_subinsn_s2, decode_subinsn_l2 },
    [0xe] = { decode_subinsn_s2, decode_subinsn_s2 },
    [0xf] = { NULL,              NULL },              /* Reserved */
};

static uint16_t get_slot0_subinsn(uint32_t encoding)
{
    return extract32(encoding, 0, 13);
}

static uint16_t get_slot1_subinsn(uint32_t encoding)
{
    return extract32(encoding, 16, 13);
}

static unsigned int
decode_insns(DisasContext *ctx, Insn *insn, uint32_t encoding)
{
    if (parse_bits(encoding) != 0) {
        if (decode_normal(ctx, encoding) ||
            decode_hvx(ctx, encoding)) {
            insn->generate = opcode_genptr[insn->opcode];
            insn->iclass = iclass_bits(encoding);
            return 1;
        }
        g_assert_not_reached();
    } else {
        uint32_t iclass = get_duplex_iclass(encoding);
        unsigned int slot0_subinsn = get_slot0_subinsn(encoding);
        unsigned int slot1_subinsn = get_slot1_subinsn(encoding);
        subinsn_decode_func decode_slot0_subinsn =
            decode_groups[iclass].decode_slot0_subinsn;
        subinsn_decode_func decode_slot1_subinsn =
            decode_groups[iclass].decode_slot1_subinsn;

        /* The slot1 subinsn needs to be in the packet first */
        if (decode_slot1_subinsn(ctx, slot1_subinsn)) {
            insn->generate = opcode_genptr[insn->opcode];
            insn->iclass = iclass_bits(encoding);
            ctx->insn = ++insn;
            if (decode_slot0_subinsn(ctx, slot0_subinsn)) {
                insn->generate = opcode_genptr[insn->opcode];
                insn->iclass = iclass_bits(encoding);
                return 2;
            }
        }
        g_assert_not_reached();
    }
}

static void decode_add_endloop_insn(Insn *insn, int loopnum)
{
    if (loopnum == 10) {
        insn->opcode = J2_endloop01;
        insn->generate = opcode_genptr[J2_endloop01];
    } else if (loopnum == 1) {
        insn->opcode = J2_endloop1;
        insn->generate = opcode_genptr[J2_endloop1];
    } else if (loopnum == 0) {
        insn->opcode = J2_endloop0;
        insn->generate = opcode_genptr[J2_endloop0];
    } else {
        g_assert_not_reached();
    }
}

static bool decode_parsebits_is_loopend(uint32_t encoding32)
{
    uint32_t bits = parse_bits(encoding32);
    return bits == 0x2;
}

static bool has_valid_slot_assignment(Packet *pkt)
{
    int used_slots = 0;
    for (int i = 0; i < pkt->num_insns; i++) {
        int slot_mask;
        Insn *insn = &pkt->insn[i];
        if (decode_opcode_ends_loop(insn->opcode)) {
            /* We overload slot 0 for endloop. */
            continue;
        }
        slot_mask = 1 << insn->slot;
        if (used_slots & slot_mask) {
            return false;
        }
        used_slots |= slot_mask;
    }
    return true;
}

static bool
decode_set_slot_number(Packet *pkt)
{
    int slot;
    int i;
    bool hit_mem_insn = false;
    bool hit_duplex = false;
    bool slot0_found = false;
    bool slot1_found = false;
    int slot1_iidx = 0;

    /*
     * The slots are encoded in reverse order
     * For each instruction, count down until you find a suitable slot
     */
    for (i = 0, slot = 3; i < pkt->num_insns; i++) {
        SlotMask valid_slots = get_valid_slots(pkt, i);

        while (!(valid_slots & (1 << slot))) {
            slot--;
        }
        pkt->insn[i].slot = slot;
        if (slot) {
            /* I've assigned the slot, now decrement it for the next insn */
            slot--;
        }
    }

    /* Fix the exceptions - mem insns to slot 0,1 */
    for (i = pkt->num_insns - 1; i >= 0; i--) {
        /* First memory instruction always goes to slot 0 */
        if ((GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE) ||
             GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE_PACKET_RULES)) &&
            !hit_mem_insn) {
            hit_mem_insn = true;
            pkt->insn[i].slot = 0;
            continue;
        }

        /* Next memory instruction always goes to slot 1 */
        if ((GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE) ||
             GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE_PACKET_RULES)) &&
            hit_mem_insn) {
            pkt->insn[i].slot = 1;
        }
    }

    /* Fix the exceptions - duplex always slot 0,1 */
    for (i = pkt->num_insns - 1; i >= 0; i--) {
        /* First subinsn always goes to slot 0 */
        if (GET_ATTRIB(pkt->insn[i].opcode, A_SUBINSN) && !hit_duplex) {
            hit_duplex = true;
            pkt->insn[i].slot = 0;
            continue;
        }

        /* Next subinsn always goes to slot 1 */
        if (GET_ATTRIB(pkt->insn[i].opcode, A_SUBINSN) && hit_duplex) {
            pkt->insn[i].slot = 1;
        }
    }

    /* Fix the exceptions - slot 1 is never empty, always aligns to slot 0 */
    for (i = pkt->num_insns - 1; i >= 0; i--) {
        /* Is slot0 used? */
        if (pkt->insn[i].slot == 0) {
            bool is_endloop = (pkt->insn[i].opcode == J2_endloop01);
            is_endloop |= (pkt->insn[i].opcode == J2_endloop0);
            is_endloop |= (pkt->insn[i].opcode == J2_endloop1);

            /*
             * Make sure it's not endloop since, we're overloading
             * slot0 for endloop
             */
            if (!is_endloop) {
                slot0_found = true;
            }
        }
        /* Is slot1 used? */
        if (pkt->insn[i].slot == 1) {
            slot1_found = true;
            slot1_iidx = i;
        }
    }
    /* Is slot0 empty and slot1 used? */
    if ((!slot0_found) && slot1_found) {
        /* Then push it to slot0 */
        pkt->insn[slot1_iidx].slot = 0;
    }

    return has_valid_slot_assignment(pkt);
}

/*
 * decode_packet
 * Decodes packet with given words
 * Returns 0 on insufficient words,
 * or number of words used on success
 */

int decode_packet(DisasContext *ctx, int max_words, const uint32_t *words,
                  Packet *pkt, bool disas_only)
{
    int num_insns = 0;
    int words_read = 0;
    bool end_of_packet = false;
    int new_insns = 0;
    int i;
    uint32_t encoding32;

    /* Initialize */
    memset(pkt, 0, sizeof(*pkt));
    /* Try to build packet */
    while (!end_of_packet && (words_read < max_words)) {
        Insn *insn = &pkt->insn[num_insns];
        ctx->insn = insn;
        encoding32 = words[words_read];
        end_of_packet = is_packet_end(encoding32);
        new_insns = decode_insns(ctx, insn, encoding32);
        g_assert(new_insns > 0);
        /*
         * If we saw an extender, mark next word extended so immediate
         * decode works
         */
        if (pkt->insn[num_insns].opcode == A4_ext) {
            pkt->insn[num_insns + 1].extension_valid = true;
        }
        num_insns += new_insns;
        words_read++;
    }

    pkt->num_insns = num_insns;
    if (!end_of_packet) {
        /* Ran out of words! */
        return 0;
    }
    pkt->encod_pkt_size_in_bytes = words_read * 4;
    pkt->pkt_has_hvx = false;
    for (i = 0; i < num_insns; i++) {
        pkt->pkt_has_hvx |=
            GET_ATTRIB(pkt->insn[i].opcode, A_CVI);
    }

    /*
     * Check for :endloop in the parse bits
     * Section 10.6 of the Programmer's Reference describes the encoding
     *     The end of hardware loop 0 can be encoded with 2 words
     *     The end of hardware loop 1 needs 3 words
     */
    if ((words_read == 2) && (decode_parsebits_is_loopend(words[0]))) {
        decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 0);
    }
    if (words_read >= 3) {
        bool has_loop0, has_loop1;
        has_loop0 = decode_parsebits_is_loopend(words[0]);
        has_loop1 = decode_parsebits_is_loopend(words[1]);
        if (has_loop0 && has_loop1) {
            decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 10);
        } else if (has_loop1) {
            decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 1);
        } else if (has_loop0) {
            decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 0);
        }
    }

    decode_apply_extenders(pkt);
    if (!disas_only) {
        decode_remove_extenders(pkt);
        if (!decode_set_slot_number(pkt)) {
            /* Invalid packet */
            return 0;
        }
    }
    decode_fill_newvalue_regno(pkt);

    if (pkt->pkt_has_hvx) {
        mmvec_ext_decode_checks(pkt, disas_only);
    }

    if (!disas_only) {
        decode_shuffle_for_execution(pkt);
        decode_split_cmpjump(pkt);
        decode_set_insn_attr_fields(pkt);
    }

    return words_read;
}

/* Used for "-d in_asm" logging */
int disassemble_hexagon(uint32_t *words, int nwords, bfd_vma pc,
                        GString *buf)
{
    DisasContext ctx;
    Packet pkt;

    memset(&ctx, 0, sizeof(DisasContext));
    ctx.pkt = &pkt;

    if (decode_packet(&ctx, nwords, words, &pkt, true) > 0) {
        snprint_a_pkt_disas(buf, &pkt, words, pc);
        return pkt.encod_pkt_size_in_bytes;
    } else {
        g_string_assign(buf, "<invalid>");
        return 0;
    }
}