target-arm/translate-a64.c

/*
 *  AArch64 translation
 *
 *  Copyright (c) 2013 Alexander Graf <agraf@suse.de>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <inttypes.h>

#include "cpu.h"
#include "tcg-op.h"
#include "qemu/log.h"
#include "translate.h"
#include "qemu/host-utils.h"

#include "exec/gen-icount.h"

#include "helper.h"
#define GEN_HELPER 1
#include "helper.h"

static TCGv_i64 cpu_X[32];
static TCGv_i64 cpu_pc;
static TCGv_i32 cpu_NF, cpu_ZF, cpu_CF, cpu_VF;

static const char *regnames[] = {
    "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
    "x8", "x9", "x10", "x11", "x12", "x13", "x14", "x15",
    "x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
    "x24", "x25", "x26", "x27", "x28", "x29", "lr", "sp"
};

enum a64_shift_type {
    A64_SHIFT_TYPE_LSL = 0,
    A64_SHIFT_TYPE_LSR = 1,
    A64_SHIFT_TYPE_ASR = 2,
    A64_SHIFT_TYPE_ROR = 3
};

/* initialize TCG globals.  */
void a64_translate_init(void)
{
    int i;

    cpu_pc = tcg_global_mem_new_i64(TCG_AREG0,
                                    offsetof(CPUARMState, pc),
                                    "pc");
    for (i = 0; i < 32; i++) {
        cpu_X[i] = tcg_global_mem_new_i64(TCG_AREG0,
                                          offsetof(CPUARMState, xregs[i]),
                                          regnames[i]);
    }

    cpu_NF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, NF), "NF");
    cpu_ZF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, ZF), "ZF");
    cpu_CF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, CF), "CF");
    cpu_VF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, VF), "VF");
}

void aarch64_cpu_dump_state(CPUState *cs, FILE *f,
                            fprintf_function cpu_fprintf, int flags)
{
    ARMCPU *cpu = ARM_CPU(cs);
    CPUARMState *env = &cpu->env;
    uint32_t psr = pstate_read(env);
    int i;

    cpu_fprintf(f, "PC=%016"PRIx64"  SP=%016"PRIx64"\n",
            env->pc, env->xregs[31]);
    for (i = 0; i < 31; i++) {
        cpu_fprintf(f, "X%02d=%016"PRIx64, i, env->xregs[i]);
        if ((i % 4) == 3) {
            cpu_fprintf(f, "\n");
        } else {
            cpu_fprintf(f, " ");
        }
    }
    cpu_fprintf(f, "PSTATE=%08x (flags %c%c%c%c)\n",
                psr,
                psr & PSTATE_N ? 'N' : '-',
                psr & PSTATE_Z ? 'Z' : '-',
                psr & PSTATE_C ? 'C' : '-',
                psr & PSTATE_V ? 'V' : '-');
    cpu_fprintf(f, "\n");
}

void gen_a64_set_pc_im(uint64_t val)
{
    tcg_gen_movi_i64(cpu_pc, val);
}

static void gen_exception(int excp)
{
    TCGv_i32 tmp = tcg_temp_new_i32();
    tcg_gen_movi_i32(tmp, excp);
    gen_helper_exception(cpu_env, tmp);
    tcg_temp_free_i32(tmp);
}

static void gen_exception_insn(DisasContext *s, int offset, int excp)
{
    gen_a64_set_pc_im(s->pc - offset);
    gen_exception(excp);
    s->is_jmp = DISAS_EXC;
}

static inline bool use_goto_tb(DisasContext *s, int n, uint64_t dest)
{
    /* No direct tb linking with singlestep or deterministic io */
    if (s->singlestep_enabled || (s->tb->cflags & CF_LAST_IO)) {
        return false;
    }

    /* Only link tbs from inside the same guest page */
    if ((s->tb->pc & TARGET_PAGE_MASK) != (dest & TARGET_PAGE_MASK)) {
        return false;
    }

    return true;
}

static inline void gen_goto_tb(DisasContext *s, int n, uint64_t dest)
{
    TranslationBlock *tb;

    tb = s->tb;
    if (use_goto_tb(s, n, dest)) {
        tcg_gen_goto_tb(n);
        gen_a64_set_pc_im(dest);
        tcg_gen_exit_tb((tcg_target_long)tb + n);
        s->is_jmp = DISAS_TB_JUMP;
    } else {
        gen_a64_set_pc_im(dest);
        if (s->singlestep_enabled) {
            gen_exception(EXCP_DEBUG);
        }
        tcg_gen_exit_tb(0);
        s->is_jmp = DISAS_JUMP;
    }
}

static void unallocated_encoding(DisasContext *s)
{
    gen_exception_insn(s, 4, EXCP_UDEF);
}

#define unsupported_encoding(s, insn)                                    \
    do {                                                                 \
        qemu_log_mask(LOG_UNIMP,                                         \
                      "%s:%d: unsupported instruction encoding 0x%08x "  \
                      "at pc=%016" PRIx64 "\n",                          \
                      __FILE__, __LINE__, insn, s->pc - 4);              \
        unallocated_encoding(s);                                         \
    } while (0);

static void init_tmp_a64_array(DisasContext *s)
{
#ifdef CONFIG_DEBUG_TCG
    int i;
    for (i = 0; i < ARRAY_SIZE(s->tmp_a64); i++) {
        TCGV_UNUSED_I64(s->tmp_a64[i]);
    }
#endif
    s->tmp_a64_count = 0;
}

static void free_tmp_a64(DisasContext *s)
{
    int i;
    for (i = 0; i < s->tmp_a64_count; i++) {
        tcg_temp_free_i64(s->tmp_a64[i]);
    }
    init_tmp_a64_array(s);
}

static TCGv_i64 new_tmp_a64(DisasContext *s)
{
    assert(s->tmp_a64_count < TMP_A64_MAX);
    return s->tmp_a64[s->tmp_a64_count++] = tcg_temp_new_i64();
}

static TCGv_i64 new_tmp_a64_zero(DisasContext *s)
{
    TCGv_i64 t = new_tmp_a64(s);
    tcg_gen_movi_i64(t, 0);
    return t;
}

static TCGv_i64 cpu_reg(DisasContext *s, int reg)
{
    if (reg == 31) {
        return new_tmp_a64_zero(s);
    } else {
        return cpu_X[reg];
    }
}

/* read a cpu register in 32bit/64bit mode. Returns a TCGv_i64
 * representing the register contents. This TCGv is an auto-freed
 * temporary so it need not be explicitly freed, and may be modified.
 */
static TCGv_i64 read_cpu_reg(DisasContext *s, int reg, int sf)
{
    TCGv_i64 v = new_tmp_a64(s);
    if (reg != 31) {
        if (sf) {
            tcg_gen_mov_i64(v, cpu_X[reg]);
        } else {
            tcg_gen_ext32u_i64(v, cpu_X[reg]);
        }
    } else {
        tcg_gen_movi_i64(v, 0);
    }
    return v;
}

/* Set ZF and NF based on a 64 bit result. This is alas fiddlier
 * than the 32 bit equivalent.
 */
static inline void gen_set_NZ64(TCGv_i64 result)
{
    TCGv_i64 flag = tcg_temp_new_i64();

    tcg_gen_setcondi_i64(TCG_COND_NE, flag, result, 0);
    tcg_gen_trunc_i64_i32(cpu_ZF, flag);
    tcg_gen_shri_i64(flag, result, 32);
    tcg_gen_trunc_i64_i32(cpu_NF, flag);
    tcg_temp_free_i64(flag);
}

/* Set NZCV as for a logical operation: NZ as per result, CV cleared. */
static inline void gen_logic_CC(int sf, TCGv_i64 result)
{
    if (sf) {
        gen_set_NZ64(result);
    } else {
        tcg_gen_trunc_i64_i32(cpu_ZF, result);
        tcg_gen_trunc_i64_i32(cpu_NF, result);
    }
    tcg_gen_movi_i32(cpu_CF, 0);
    tcg_gen_movi_i32(cpu_VF, 0);
}

/*
 * the instruction disassembly implemented here matches
 * the instruction encoding classifications in chapter 3 (C3)
 * of the ARM Architecture Reference Manual (DDI0487A_a)
 */

/* C3.2.7 Unconditional branch (immediate)
 *   31  30       26 25                                  0
 * +----+-----------+-------------------------------------+
 * | op | 0 0 1 0 1 |                 imm26               |
 * +----+-----------+-------------------------------------+
 */
static void disas_uncond_b_imm(DisasContext *s, uint32_t insn)
{
    uint64_t addr = s->pc + sextract32(insn, 0, 26) * 4 - 4;

    if (insn & (1 << 31)) {
        /* C5.6.26 BL Branch with link */
        tcg_gen_movi_i64(cpu_reg(s, 30), s->pc);
    }

    /* C5.6.20 B Branch / C5.6.26 BL Branch with link */
    gen_goto_tb(s, 0, addr);
}

/* C3.2.1 Compare & branch (immediate)
 *   31  30         25  24  23                  5 4      0
 * +----+-------------+----+---------------------+--------+
 * | sf | 0 1 1 0 1 0 | op |         imm19       |   Rt   |
 * +----+-------------+----+---------------------+--------+
 */
static void disas_comp_b_imm(DisasContext *s, uint32_t insn)
{
    unsigned int sf, op, rt;
    uint64_t addr;
    int label_match;
    TCGv_i64 tcg_cmp;

    sf = extract32(insn, 31, 1);
    op = extract32(insn, 24, 1); /* 0: CBZ; 1: CBNZ */
    rt = extract32(insn, 0, 5);
    addr = s->pc + sextract32(insn, 5, 19) * 4 - 4;

    tcg_cmp = read_cpu_reg(s, rt, sf);
    label_match = gen_new_label();

    tcg_gen_brcondi_i64(op ? TCG_COND_NE : TCG_COND_EQ,
                        tcg_cmp, 0, label_match);

    gen_goto_tb(s, 0, s->pc);
    gen_set_label(label_match);
    gen_goto_tb(s, 1, addr);
}

/* C3.2.5 Test & branch (immediate)
 *   31  30         25  24  23   19 18          5 4    0
 * +----+-------------+----+-------+-------------+------+
 * | b5 | 0 1 1 0 1 1 | op |  b40  |    imm14    |  Rt  |
 * +----+-------------+----+-------+-------------+------+
 */
static void disas_test_b_imm(DisasContext *s, uint32_t insn)
{
    unsigned int bit_pos, op, rt;
    uint64_t addr;
    int label_match;
    TCGv_i64 tcg_cmp;

    bit_pos = (extract32(insn, 31, 1) << 5) | extract32(insn, 19, 5);
    op = extract32(insn, 24, 1); /* 0: TBZ; 1: TBNZ */
    addr = s->pc + sextract32(insn, 5, 14) * 4 - 4;
    rt = extract32(insn, 0, 5);

    tcg_cmp = tcg_temp_new_i64();
    tcg_gen_andi_i64(tcg_cmp, cpu_reg(s, rt), (1ULL << bit_pos));
    label_match = gen_new_label();
    tcg_gen_brcondi_i64(op ? TCG_COND_NE : TCG_COND_EQ,
                        tcg_cmp, 0, label_match);
    tcg_temp_free_i64(tcg_cmp);
    gen_goto_tb(s, 0, s->pc);
    gen_set_label(label_match);
    gen_goto_tb(s, 1, addr);
}

/* C3.2.2 / C5.6.19 Conditional branch (immediate)
 *  31           25  24  23                  5   4  3    0
 * +---------------+----+---------------------+----+------+
 * | 0 1 0 1 0 1 0 | o1 |         imm19       | o0 | cond |
 * +---------------+----+---------------------+----+------+
 */
static void disas_cond_b_imm(DisasContext *s, uint32_t insn)
{
    unsigned int cond;
    uint64_t addr;

    if ((insn & (1 << 4)) || (insn & (1 << 24))) {
        unallocated_encoding(s);
        return;
    }
    addr = s->pc + sextract32(insn, 5, 19) * 4 - 4;
    cond = extract32(insn, 0, 4);

    if (cond < 0x0e) {
        /* genuinely conditional branches */
        int label_match = gen_new_label();
        arm_gen_test_cc(cond, label_match);
        gen_goto_tb(s, 0, s->pc);
        gen_set_label(label_match);
        gen_goto_tb(s, 1, addr);
    } else {
        /* 0xe and 0xf are both "always" conditions */
        gen_goto_tb(s, 0, addr);
    }
}

/* C5.6.68 HINT */
static void handle_hint(DisasContext *s, uint32_t insn,
                        unsigned int op1, unsigned int op2, unsigned int crm)
{
    unsigned int selector = crm << 3 | op2;

    if (op1 != 3) {
        unallocated_encoding(s);
        return;
    }

    switch (selector) {
    case 0: /* NOP */
        return;
    case 1: /* YIELD */
    case 2: /* WFE */
    case 3: /* WFI */
    case 4: /* SEV */
    case 5: /* SEVL */
        /* we treat all as NOP at least for now */
        return;
    default:
        /* default specified as NOP equivalent */
        return;
    }
}

/* CLREX, DSB, DMB, ISB */
static void handle_sync(DisasContext *s, uint32_t insn,
                        unsigned int op1, unsigned int op2, unsigned int crm)
{
    if (op1 != 3) {
        unallocated_encoding(s);
        return;
    }

    switch (op2) {
    case 2: /* CLREX */
        unsupported_encoding(s, insn);
        return;
    case 4: /* DSB */
    case 5: /* DMB */
    case 6: /* ISB */
        /* We don't emulate caches so barriers are no-ops */
        return;
    default:
        unallocated_encoding(s);
        return;
    }
}

/* C5.6.130 MSR (immediate) - move immediate to processor state field */
static void handle_msr_i(DisasContext *s, uint32_t insn,
                         unsigned int op1, unsigned int op2, unsigned int crm)
{
    unsupported_encoding(s, insn);
}

/* C5.6.204 SYS */
static void handle_sys(DisasContext *s, uint32_t insn, unsigned int l,
                       unsigned int op1, unsigned int op2,
                       unsigned int crn, unsigned int crm, unsigned int rt)
{
    unsupported_encoding(s, insn);
}

/* C5.6.129 MRS - move from system register */
static void handle_mrs(DisasContext *s, uint32_t insn, unsigned int op0,
                       unsigned int op1, unsigned int op2,
                       unsigned int crn, unsigned int crm, unsigned int rt)
{
    unsupported_encoding(s, insn);
}

/* C5.6.131 MSR (register) - move to system register */
static void handle_msr(DisasContext *s, uint32_t insn, unsigned int op0,
                       unsigned int op1, unsigned int op2,
                       unsigned int crn, unsigned int crm, unsigned int rt)
{
    unsupported_encoding(s, insn);
}

/* C3.2.4 System
 *  31                 22 21  20 19 18 16 15   12 11    8 7   5 4    0
 * +---------------------+---+-----+-----+-------+-------+-----+------+
 * | 1 1 0 1 0 1 0 1 0 0 | L | op0 | op1 |  CRn  |  CRm  | op2 |  Rt  |
 * +---------------------+---+-----+-----+-------+-------+-----+------+
 */
static void disas_system(DisasContext *s, uint32_t insn)
{
    unsigned int l, op0, op1, crn, crm, op2, rt;
    l = extract32(insn, 21, 1);
    op0 = extract32(insn, 19, 2);
    op1 = extract32(insn, 16, 3);
    crn = extract32(insn, 12, 4);
    crm = extract32(insn, 8, 4);
    op2 = extract32(insn, 5, 3);
    rt = extract32(insn, 0, 5);

    if (op0 == 0) {
        if (l || rt != 31) {
            unallocated_encoding(s);
            return;
        }
        switch (crn) {
        case 2: /* C5.6.68 HINT */
            handle_hint(s, insn, op1, op2, crm);
            break;
        case 3: /* CLREX, DSB, DMB, ISB */
            handle_sync(s, insn, op1, op2, crm);
            break;
        case 4: /* C5.6.130 MSR (immediate) */
            handle_msr_i(s, insn, op1, op2, crm);
            break;
        default:
            unallocated_encoding(s);
            break;
        }
        return;
    }

    if (op0 == 1) {
        /* C5.6.204 SYS */
        handle_sys(s, insn, l, op1, op2, crn, crm, rt);
    } else if (l) { /* op0 > 1 */
        /* C5.6.129 MRS - move from system register */
        handle_mrs(s, insn, op0, op1, op2, crn, crm, rt);
    } else {
        /* C5.6.131 MSR (register) - move to system register */
        handle_msr(s, insn, op0, op1, op2, crn, crm, rt);
    }
}

/* Exception generation */
static void disas_exc(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* C3.2.7 Unconditional branch (register)
 *  31           25 24   21 20   16 15   10 9    5 4     0
 * +---------------+-------+-------+-------+------+-------+
 * | 1 1 0 1 0 1 1 |  opc  |  op2  |  op3  |  Rn  |  op4  |
 * +---------------+-------+-------+-------+------+-------+
 */
static void disas_uncond_b_reg(DisasContext *s, uint32_t insn)
{
    unsigned int opc, op2, op3, rn, op4;

    opc = extract32(insn, 21, 4);
    op2 = extract32(insn, 16, 5);
    op3 = extract32(insn, 10, 6);
    rn = extract32(insn, 5, 5);
    op4 = extract32(insn, 0, 5);

    if (op4 != 0x0 || op3 != 0x0 || op2 != 0x1f) {
        unallocated_encoding(s);
        return;
    }

    switch (opc) {
    case 0: /* BR */
    case 2: /* RET */
        break;
    case 1: /* BLR */
        tcg_gen_movi_i64(cpu_reg(s, 30), s->pc);
        break;
    case 4: /* ERET */
    case 5: /* DRPS */
        if (rn != 0x1f) {
            unallocated_encoding(s);
        } else {
            unsupported_encoding(s, insn);
        }
        return;
    default:
        unallocated_encoding(s);
        return;
    }

    tcg_gen_mov_i64(cpu_pc, cpu_reg(s, rn));
    s->is_jmp = DISAS_JUMP;
}

/* C3.2 Branches, exception generating and system instructions */
static void disas_b_exc_sys(DisasContext *s, uint32_t insn)
{
    switch (extract32(insn, 25, 7)) {
    case 0x0a: case 0x0b:
    case 0x4a: case 0x4b: /* Unconditional branch (immediate) */
        disas_uncond_b_imm(s, insn);
        break;
    case 0x1a: case 0x5a: /* Compare & branch (immediate) */
        disas_comp_b_imm(s, insn);
        break;
    case 0x1b: case 0x5b: /* Test & branch (immediate) */
        disas_test_b_imm(s, insn);
        break;
    case 0x2a: /* Conditional branch (immediate) */
        disas_cond_b_imm(s, insn);
        break;
    case 0x6a: /* Exception generation / System */
        if (insn & (1 << 24)) {
            disas_system(s, insn);
        } else {
            disas_exc(s, insn);
        }
        break;
    case 0x6b: /* Unconditional branch (register) */
        disas_uncond_b_reg(s, insn);
        break;
    default:
        unallocated_encoding(s);
        break;
    }
}

/* Load/store exclusive */
static void disas_ldst_excl(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Load register (literal) */
static void disas_ld_lit(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Load/store pair (all forms) */
static void disas_ldst_pair(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Load/store register (all forms) */
static void disas_ldst_reg(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* AdvSIMD load/store multiple structures */
static void disas_ldst_multiple_struct(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* AdvSIMD load/store single structure */
static void disas_ldst_single_struct(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* C3.3 Loads and stores */
static void disas_ldst(DisasContext *s, uint32_t insn)
{
    switch (extract32(insn, 24, 6)) {
    case 0x08: /* Load/store exclusive */
        disas_ldst_excl(s, insn);
        break;
    case 0x18: case 0x1c: /* Load register (literal) */
        disas_ld_lit(s, insn);
        break;
    case 0x28: case 0x29:
    case 0x2c: case 0x2d: /* Load/store pair (all forms) */
        disas_ldst_pair(s, insn);
        break;
    case 0x38: case 0x39:
    case 0x3c: case 0x3d: /* Load/store register (all forms) */
        disas_ldst_reg(s, insn);
        break;
    case 0x0c: /* AdvSIMD load/store multiple structures */
        disas_ldst_multiple_struct(s, insn);
        break;
    case 0x0d: /* AdvSIMD load/store single structure */
        disas_ldst_single_struct(s, insn);
        break;
    default:
        unallocated_encoding(s);
        break;
    }
}

/* C3.4.6 PC-rel. addressing
 *   31  30   29 28       24 23                5 4    0
 * +----+-------+-----------+-------------------+------+
 * | op | immlo | 1 0 0 0 0 |       immhi       |  Rd  |
 * +----+-------+-----------+-------------------+------+
 */
static void disas_pc_rel_adr(DisasContext *s, uint32_t insn)
{
    unsigned int page, rd;
    uint64_t base;
    int64_t offset;

    page = extract32(insn, 31, 1);
    /* SignExtend(immhi:immlo) -> offset */
    offset = ((int64_t)sextract32(insn, 5, 19) << 2) | extract32(insn, 29, 2);
    rd = extract32(insn, 0, 5);
    base = s->pc - 4;

    if (page) {
        /* ADRP (page based) */
        base &= ~0xfff;
        offset <<= 12;
    }

    tcg_gen_movi_i64(cpu_reg(s, rd), base + offset);
}

/* Add/subtract (immediate) */
static void disas_add_sub_imm(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Logical (immediate) */
static void disas_logic_imm(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Move wide (immediate) */
static void disas_movw_imm(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Bitfield */
static void disas_bitfield(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* C3.4.3 Extract
 *   31  30  29 28         23 22   21  20  16 15    10 9    5 4    0
 * +----+------+-------------+---+----+------+--------+------+------+
 * | sf | op21 | 1 0 0 1 1 1 | N | o0 |  Rm  |  imms  |  Rn  |  Rd  |
 * +----+------+-------------+---+----+------+--------+------+------+
 */
static void disas_extract(DisasContext *s, uint32_t insn)
{
    unsigned int sf, n, rm, imm, rn, rd, bitsize, op21, op0;

    sf = extract32(insn, 31, 1);
    n = extract32(insn, 22, 1);
    rm = extract32(insn, 16, 5);
    imm = extract32(insn, 10, 6);
    rn = extract32(insn, 5, 5);
    rd = extract32(insn, 0, 5);
    op21 = extract32(insn, 29, 2);
    op0 = extract32(insn, 21, 1);
    bitsize = sf ? 64 : 32;

    if (sf != n || op21 || op0 || imm >= bitsize) {
        unallocated_encoding(s);
    } else {
        TCGv_i64 tcg_rd, tcg_rm, tcg_rn;

        tcg_rd = cpu_reg(s, rd);

        if (imm) {
            /* OPTME: we can special case rm==rn as a rotate */
            tcg_rm = read_cpu_reg(s, rm, sf);
            tcg_rn = read_cpu_reg(s, rn, sf);
            tcg_gen_shri_i64(tcg_rm, tcg_rm, imm);
            tcg_gen_shli_i64(tcg_rn, tcg_rn, bitsize - imm);
            tcg_gen_or_i64(tcg_rd, tcg_rm, tcg_rn);
            if (!sf) {
                tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
            }
        } else {
            /* tcg shl_i32/shl_i64 is undefined for 32/64 bit shifts,
             * so an extract from bit 0 is a special case.
             */
            if (sf) {
                tcg_gen_mov_i64(tcg_rd, cpu_reg(s, rm));
            } else {
                tcg_gen_ext32u_i64(tcg_rd, cpu_reg(s, rm));
            }
        }

    }
}

/* C3.4 Data processing - immediate */
static void disas_data_proc_imm(DisasContext *s, uint32_t insn)
{
    switch (extract32(insn, 23, 6)) {
    case 0x20: case 0x21: /* PC-rel. addressing */
        disas_pc_rel_adr(s, insn);
        break;
    case 0x22: case 0x23: /* Add/subtract (immediate) */
        disas_add_sub_imm(s, insn);
        break;
    case 0x24: /* Logical (immediate) */
        disas_logic_imm(s, insn);
        break;
    case 0x25: /* Move wide (immediate) */
        disas_movw_imm(s, insn);
        break;
    case 0x26: /* Bitfield */
        disas_bitfield(s, insn);
        break;
    case 0x27: /* Extract */
        disas_extract(s, insn);
        break;
    default:
        unallocated_encoding(s);
        break;
    }
}

/* 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
 * mandated semantics for out of range shifts.
 */
static void shift_reg(TCGv_i64 dst, TCGv_i64 src, int sf,
                      enum a64_shift_type shift_type, TCGv_i64 shift_amount)
{
    switch (shift_type) {
    case A64_SHIFT_TYPE_LSL:
        tcg_gen_shl_i64(dst, src, shift_amount);
        break;
    case A64_SHIFT_TYPE_LSR:
        tcg_gen_shr_i64(dst, src, shift_amount);
        break;
    case A64_SHIFT_TYPE_ASR:
        if (!sf) {
            tcg_gen_ext32s_i64(dst, src);
        }
        tcg_gen_sar_i64(dst, sf ? src : dst, shift_amount);
        break;
    case A64_SHIFT_TYPE_ROR:
        if (sf) {
            tcg_gen_rotr_i64(dst, src, shift_amount);
        } else {
            TCGv_i32 t0, t1;
            t0 = tcg_temp_new_i32();
            t1 = tcg_temp_new_i32();
            tcg_gen_trunc_i64_i32(t0, src);
            tcg_gen_trunc_i64_i32(t1, shift_amount);
            tcg_gen_rotr_i32(t0, t0, t1);
            tcg_gen_extu_i32_i64(dst, t0);
            tcg_temp_free_i32(t0);
            tcg_temp_free_i32(t1);
        }
        break;
    default:
        assert(FALSE); /* all shift types should be handled */
        break;
    }

    if (!sf) { /* zero extend final result */
        tcg_gen_ext32u_i64(dst, dst);
    }
}

/* Shift a TCGv src by immediate, put result in dst.
 * The shift amount must be in range (this should always be true as the
 * relevant instructions will UNDEF on bad shift immediates).
 */
static void shift_reg_imm(TCGv_i64 dst, TCGv_i64 src, int sf,
                          enum a64_shift_type shift_type, unsigned int shift_i)
{
    assert(shift_i < (sf ? 64 : 32));

    if (shift_i == 0) {
        tcg_gen_mov_i64(dst, src);
    } else {
        TCGv_i64 shift_const;

        shift_const = tcg_const_i64(shift_i);
        shift_reg(dst, src, sf, shift_type, shift_const);
        tcg_temp_free_i64(shift_const);
    }
}

/* C3.5.10 Logical (shifted register)
 *   31  30 29 28       24 23   22 21  20  16 15    10 9    5 4    0
 * +----+-----+-----------+-------+---+------+--------+------+------+
 * | sf | opc | 0 1 0 1 0 | shift | N |  Rm  |  imm6  |  Rn  |  Rd  |
 * +----+-----+-----------+-------+---+------+--------+------+------+
 */
static void disas_logic_reg(DisasContext *s, uint32_t insn)
{
    TCGv_i64 tcg_rd, tcg_rn, tcg_rm;
    unsigned int sf, opc, shift_type, invert, rm, shift_amount, rn, rd;

    sf = extract32(insn, 31, 1);
    opc = extract32(insn, 29, 2);
    shift_type = extract32(insn, 22, 2);
    invert = extract32(insn, 21, 1);
    rm = extract32(insn, 16, 5);
    shift_amount = extract32(insn, 10, 6);
    rn = extract32(insn, 5, 5);
    rd = extract32(insn, 0, 5);

    if (!sf && (shift_amount & (1 << 5))) {
        unallocated_encoding(s);
        return;
    }

    tcg_rd = cpu_reg(s, rd);

    if (opc == 1 && shift_amount == 0 && shift_type == 0 && rn == 31) {
        /* Unshifted ORR and ORN with WZR/XZR is the standard encoding for
         * register-register MOV and MVN, so it is worth special casing.
         */
        tcg_rm = cpu_reg(s, rm);
        if (invert) {
            tcg_gen_not_i64(tcg_rd, tcg_rm);
            if (!sf) {
                tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
            }
        } else {
            if (sf) {
                tcg_gen_mov_i64(tcg_rd, tcg_rm);
            } else {
                tcg_gen_ext32u_i64(tcg_rd, tcg_rm);
            }
        }
        return;
    }

    tcg_rm = read_cpu_reg(s, rm, sf);

    if (shift_amount) {
        shift_reg_imm(tcg_rm, tcg_rm, sf, shift_type, shift_amount);
    }

    tcg_rn = cpu_reg(s, rn);

    switch (opc | (invert << 2)) {
    case 0: /* AND */
    case 3: /* ANDS */
        tcg_gen_and_i64(tcg_rd, tcg_rn, tcg_rm);
        break;
    case 1: /* ORR */
        tcg_gen_or_i64(tcg_rd, tcg_rn, tcg_rm);
        break;
    case 2: /* EOR */
        tcg_gen_xor_i64(tcg_rd, tcg_rn, tcg_rm);
        break;
    case 4: /* BIC */
    case 7: /* BICS */
        tcg_gen_andc_i64(tcg_rd, tcg_rn, tcg_rm);
        break;
    case 5: /* ORN */
        tcg_gen_orc_i64(tcg_rd, tcg_rn, tcg_rm);
        break;
    case 6: /* EON */
        tcg_gen_eqv_i64(tcg_rd, tcg_rn, tcg_rm);
        break;
    default:
        assert(FALSE);
        break;
    }

    if (!sf) {
        tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
    }

    if (opc == 3) {
        gen_logic_CC(sf, tcg_rd);
    }
}

/* Add/subtract (extended register) */
static void disas_add_sub_ext_reg(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Add/subtract (shifted register) */
static void disas_add_sub_reg(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Data-processing (3 source) */
static void disas_data_proc_3src(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Add/subtract (with carry) */
static void disas_adc_sbc(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Conditional compare (immediate) */
static void disas_cc_imm(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* Conditional compare (register) */
static void disas_cc_reg(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* C3.5.6 Conditional select
 *   31   30  29  28             21 20  16 15  12 11 10 9    5 4    0
 * +----+----+---+-----------------+------+------+-----+------+------+
 * | sf | op | S | 1 1 0 1 0 1 0 0 |  Rm  | cond | op2 |  Rn  |  Rd  |
 * +----+----+---+-----------------+------+------+-----+------+------+
 */
static void disas_cond_select(DisasContext *s, uint32_t insn)
{
    unsigned int sf, else_inv, rm, cond, else_inc, rn, rd;
    TCGv_i64 tcg_rd, tcg_src;

    if (extract32(insn, 29, 1) || extract32(insn, 11, 1)) {
        /* S == 1 or op2<1> == 1 */
        unallocated_encoding(s);
        return;
    }
    sf = extract32(insn, 31, 1);
    else_inv = extract32(insn, 30, 1);
    rm = extract32(insn, 16, 5);
    cond = extract32(insn, 12, 4);
    else_inc = extract32(insn, 10, 1);
    rn = extract32(insn, 5, 5);
    rd = extract32(insn, 0, 5);

    if (rd == 31) {
        /* silly no-op write; until we use movcond we must special-case
         * this to avoid a dead temporary across basic blocks.
         */
        return;
    }

    tcg_rd = cpu_reg(s, rd);

    if (cond >= 0x0e) { /* condition "always" */
        tcg_src = read_cpu_reg(s, rn, sf);
        tcg_gen_mov_i64(tcg_rd, tcg_src);
    } else {
        /* OPTME: we could use movcond here, at the cost of duplicating
         * a lot of the arm_gen_test_cc() logic.
         */
        int label_match = gen_new_label();
        int label_continue = gen_new_label();

        arm_gen_test_cc(cond, label_match);
        /* nomatch: */
        tcg_src = cpu_reg(s, rm);

        if (else_inv && else_inc) {
            tcg_gen_neg_i64(tcg_rd, tcg_src);
        } else if (else_inv) {
            tcg_gen_not_i64(tcg_rd, tcg_src);
        } else if (else_inc) {
            tcg_gen_addi_i64(tcg_rd, tcg_src, 1);
        } else {
            tcg_gen_mov_i64(tcg_rd, tcg_src);
        }
        if (!sf) {
            tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
        }
        tcg_gen_br(label_continue);
        /* match: */
        gen_set_label(label_match);
        tcg_src = read_cpu_reg(s, rn, sf);
        tcg_gen_mov_i64(tcg_rd, tcg_src);
        /* continue: */
        gen_set_label(label_continue);
    }
}

static void handle_clz(DisasContext *s, unsigned int sf,
                       unsigned int rn, unsigned int rd)
{
    TCGv_i64 tcg_rd, tcg_rn;
    tcg_rd = cpu_reg(s, rd);
    tcg_rn = cpu_reg(s, rn);

    if (sf) {
        gen_helper_clz64(tcg_rd, tcg_rn);
    } else {
        TCGv_i32 tcg_tmp32 = tcg_temp_new_i32();
        tcg_gen_trunc_i64_i32(tcg_tmp32, tcg_rn);
        gen_helper_clz(tcg_tmp32, tcg_tmp32);
        tcg_gen_extu_i32_i64(tcg_rd, tcg_tmp32);
        tcg_temp_free_i32(tcg_tmp32);
    }
}

static void handle_rbit(DisasContext *s, unsigned int sf,
                        unsigned int rn, unsigned int rd)
{
    TCGv_i64 tcg_rd, tcg_rn;
    tcg_rd = cpu_reg(s, rd);
    tcg_rn = cpu_reg(s, rn);

    if (sf) {
        gen_helper_rbit64(tcg_rd, tcg_rn);
    } else {
        TCGv_i32 tcg_tmp32 = tcg_temp_new_i32();
        tcg_gen_trunc_i64_i32(tcg_tmp32, tcg_rn);
        gen_helper_rbit(tcg_tmp32, tcg_tmp32);
        tcg_gen_extu_i32_i64(tcg_rd, tcg_tmp32);
        tcg_temp_free_i32(tcg_tmp32);
    }
}

/* C5.6.149 REV with sf==1, opcode==3 ("REV64") */
static void handle_rev64(DisasContext *s, unsigned int sf,
                         unsigned int rn, unsigned int rd)
{
    if (!sf) {
        unallocated_encoding(s);
        return;
    }
    tcg_gen_bswap64_i64(cpu_reg(s, rd), cpu_reg(s, rn));
}

/* C5.6.149 REV with sf==0, opcode==2
 * C5.6.151 REV32 (sf==1, opcode==2)
 */
static void handle_rev32(DisasContext *s, unsigned int sf,
                         unsigned int rn, unsigned int rd)
{
    TCGv_i64 tcg_rd = cpu_reg(s, rd);

    if (sf) {
        TCGv_i64 tcg_tmp = tcg_temp_new_i64();
        TCGv_i64 tcg_rn = read_cpu_reg(s, rn, sf);

        /* bswap32_i64 requires zero high word */
        tcg_gen_ext32u_i64(tcg_tmp, tcg_rn);
        tcg_gen_bswap32_i64(tcg_rd, tcg_tmp);
        tcg_gen_shri_i64(tcg_tmp, tcg_rn, 32);
        tcg_gen_bswap32_i64(tcg_tmp, tcg_tmp);
        tcg_gen_concat32_i64(tcg_rd, tcg_rd, tcg_tmp);

        tcg_temp_free_i64(tcg_tmp);
    } else {
        tcg_gen_ext32u_i64(tcg_rd, cpu_reg(s, rn));
        tcg_gen_bswap32_i64(tcg_rd, tcg_rd);
    }
}

/* C5.6.150 REV16 (opcode==1) */
static void handle_rev16(DisasContext *s, unsigned int sf,
                         unsigned int rn, unsigned int rd)
{
    TCGv_i64 tcg_rd = cpu_reg(s, rd);
    TCGv_i64 tcg_tmp = tcg_temp_new_i64();
    TCGv_i64 tcg_rn = read_cpu_reg(s, rn, sf);

    tcg_gen_andi_i64(tcg_tmp, tcg_rn, 0xffff);
    tcg_gen_bswap16_i64(tcg_rd, tcg_tmp);

    tcg_gen_shri_i64(tcg_tmp, tcg_rn, 16);
    tcg_gen_andi_i64(tcg_tmp, tcg_tmp, 0xffff);
    tcg_gen_bswap16_i64(tcg_tmp, tcg_tmp);
    tcg_gen_deposit_i64(tcg_rd, tcg_rd, tcg_tmp, 16, 16);

    if (sf) {
        tcg_gen_shri_i64(tcg_tmp, tcg_rn, 32);
        tcg_gen_andi_i64(tcg_tmp, tcg_tmp, 0xffff);
        tcg_gen_bswap16_i64(tcg_tmp, tcg_tmp);
        tcg_gen_deposit_i64(tcg_rd, tcg_rd, tcg_tmp, 32, 16);

        tcg_gen_shri_i64(tcg_tmp, tcg_rn, 48);
        tcg_gen_bswap16_i64(tcg_tmp, tcg_tmp);
        tcg_gen_deposit_i64(tcg_rd, tcg_rd, tcg_tmp, 48, 16);
    }

    tcg_temp_free_i64(tcg_tmp);
}

/* C3.5.7 Data-processing (1 source)
 *   31  30  29  28             21 20     16 15    10 9    5 4    0
 * +----+---+---+-----------------+---------+--------+------+------+
 * | sf | 1 | S | 1 1 0 1 0 1 1 0 | opcode2 | opcode |  Rn  |  Rd  |
 * +----+---+---+-----------------+---------+--------+------+------+
 */
static void disas_data_proc_1src(DisasContext *s, uint32_t insn)
{
    unsigned int sf, opcode, rn, rd;

    if (extract32(insn, 29, 1) || extract32(insn, 16, 5)) {
        unallocated_encoding(s);
        return;
    }

    sf = extract32(insn, 31, 1);
    opcode = extract32(insn, 10, 6);
    rn = extract32(insn, 5, 5);
    rd = extract32(insn, 0, 5);

    switch (opcode) {
    case 0: /* RBIT */
        handle_rbit(s, sf, rn, rd);
        break;
    case 1: /* REV16 */
        handle_rev16(s, sf, rn, rd);
        break;
    case 2: /* REV32 */
        handle_rev32(s, sf, rn, rd);
        break;
    case 3: /* REV64 */
        handle_rev64(s, sf, rn, rd);
        break;
    case 4: /* CLZ */
        handle_clz(s, sf, rn, rd);
        break;
    case 5: /* CLS */
        unsupported_encoding(s, insn);
        break;
    }
}

static void handle_div(DisasContext *s, bool is_signed, unsigned int sf,
                       unsigned int rm, unsigned int rn, unsigned int rd)
{
    TCGv_i64 tcg_n, tcg_m, tcg_rd;
    tcg_rd = cpu_reg(s, rd);

    if (!sf && is_signed) {
        tcg_n = new_tmp_a64(s);
        tcg_m = new_tmp_a64(s);
        tcg_gen_ext32s_i64(tcg_n, cpu_reg(s, rn));
        tcg_gen_ext32s_i64(tcg_m, cpu_reg(s, rm));
    } else {
        tcg_n = read_cpu_reg(s, rn, sf);
        tcg_m = read_cpu_reg(s, rm, sf);
    }

    if (is_signed) {
        gen_helper_sdiv64(tcg_rd, tcg_n, tcg_m);
    } else {
        gen_helper_udiv64(tcg_rd, tcg_n, tcg_m);
    }

    if (!sf) { /* zero extend final result */
        tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
    }
}

/* C5.6.115 LSLV, C5.6.118 LSRV, C5.6.17 ASRV, C5.6.154 RORV */
static void handle_shift_reg(DisasContext *s,
                             enum a64_shift_type shift_type, unsigned int sf,
                             unsigned int rm, unsigned int rn, unsigned int rd)
{
    TCGv_i64 tcg_shift = tcg_temp_new_i64();
    TCGv_i64 tcg_rd = cpu_reg(s, rd);
    TCGv_i64 tcg_rn = read_cpu_reg(s, rn, sf);

    tcg_gen_andi_i64(tcg_shift, cpu_reg(s, rm), sf ? 63 : 31);
    shift_reg(tcg_rd, tcg_rn, sf, shift_type, tcg_shift);
    tcg_temp_free_i64(tcg_shift);
}

/* C3.5.8 Data-processing (2 source)
 *   31   30  29 28             21 20  16 15    10 9    5 4    0
 * +----+---+---+-----------------+------+--------+------+------+
 * | sf | 0 | S | 1 1 0 1 0 1 1 0 |  Rm  | opcode |  Rn  |  Rd  |
 * +----+---+---+-----------------+------+--------+------+------+
 */
static void disas_data_proc_2src(DisasContext *s, uint32_t insn)
{
    unsigned int sf, rm, opcode, rn, rd;
    sf = extract32(insn, 31, 1);
    rm = extract32(insn, 16, 5);
    opcode = extract32(insn, 10, 6);
    rn = extract32(insn, 5, 5);
    rd = extract32(insn, 0, 5);

    if (extract32(insn, 29, 1)) {
        unallocated_encoding(s);
        return;
    }

    switch (opcode) {
    case 2: /* UDIV */
        handle_div(s, false, sf, rm, rn, rd);
        break;
    case 3: /* SDIV */
        handle_div(s, true, sf, rm, rn, rd);
        break;
    case 8: /* LSLV */
        handle_shift_reg(s, A64_SHIFT_TYPE_LSL, sf, rm, rn, rd);
        break;
    case 9: /* LSRV */
        handle_shift_reg(s, A64_SHIFT_TYPE_LSR, sf, rm, rn, rd);
        break;
    case 10: /* ASRV */
        handle_shift_reg(s, A64_SHIFT_TYPE_ASR, sf, rm, rn, rd);
        break;
    case 11: /* RORV */
        handle_shift_reg(s, A64_SHIFT_TYPE_ROR, sf, rm, rn, rd);
        break;
    case 16:
    case 17:
    case 18:
    case 19:
    case 20:
    case 21:
    case 22:
    case 23: /* CRC32 */
        unsupported_encoding(s, insn);
        break;
    default:
        unallocated_encoding(s);
        break;
    }
}

/* C3.5 Data processing - register */
static void disas_data_proc_reg(DisasContext *s, uint32_t insn)
{
    switch (extract32(insn, 24, 5)) {
    case 0x0a: /* Logical (shifted register) */
        disas_logic_reg(s, insn);
        break;
    case 0x0b: /* Add/subtract */
        if (insn & (1 << 21)) { /* (extended register) */
            disas_add_sub_ext_reg(s, insn);
        } else {
            disas_add_sub_reg(s, insn);
        }
        break;
    case 0x1b: /* Data-processing (3 source) */
        disas_data_proc_3src(s, insn);
        break;
    case 0x1a:
        switch (extract32(insn, 21, 3)) {
        case 0x0: /* Add/subtract (with carry) */
            disas_adc_sbc(s, insn);
            break;
        case 0x2: /* Conditional compare */
            if (insn & (1 << 11)) { /* (immediate) */
                disas_cc_imm(s, insn);
            } else {            /* (register) */
                disas_cc_reg(s, insn);
            }
            break;
        case 0x4: /* Conditional select */
            disas_cond_select(s, insn);
            break;
        case 0x6: /* Data-processing */
            if (insn & (1 << 30)) { /* (1 source) */
                disas_data_proc_1src(s, insn);
            } else {            /* (2 source) */
                disas_data_proc_2src(s, insn);
            }
            break;
        default:
            unallocated_encoding(s);
            break;
        }
        break;
    default:
        unallocated_encoding(s);
        break;
    }
}

/* C3.6 Data processing - SIMD and floating point */
static void disas_data_proc_simd_fp(DisasContext *s, uint32_t insn)
{
    unsupported_encoding(s, insn);
}

/* C3.1 A64 instruction index by encoding */
static void disas_a64_insn(CPUARMState *env, DisasContext *s)
{
    uint32_t insn;

    insn = arm_ldl_code(env, s->pc, s->bswap_code);
    s->insn = insn;
    s->pc += 4;

    switch (extract32(insn, 25, 4)) {
    case 0x0: case 0x1: case 0x2: case 0x3: /* UNALLOCATED */
        unallocated_encoding(s);
        break;
    case 0x8: case 0x9: /* Data processing - immediate */
        disas_data_proc_imm(s, insn);
        break;
    case 0xa: case 0xb: /* Branch, exception generation and system insns */
        disas_b_exc_sys(s, insn);
        break;
    case 0x4:
    case 0x6:
    case 0xc:
    case 0xe:      /* Loads and stores */
        disas_ldst(s, insn);
        break;
    case 0x5:
    case 0xd:      /* Data processing - register */
        disas_data_proc_reg(s, insn);
        break;
    case 0x7:
    case 0xf:      /* Data processing - SIMD and floating point */
        disas_data_proc_simd_fp(s, insn);
        break;
    default:
        assert(FALSE); /* all 15 cases should be handled above */
        break;
    }

    /* if we allocated any temporaries, free them here */
    free_tmp_a64(s);
}

void gen_intermediate_code_internal_a64(ARMCPU *cpu,
                                        TranslationBlock *tb,
                                        bool search_pc)
{
    CPUState *cs = CPU(cpu);
    CPUARMState *env = &cpu->env;
    DisasContext dc1, *dc = &dc1;
    CPUBreakpoint *bp;
    uint16_t *gen_opc_end;
    int j, lj;
    target_ulong pc_start;
    target_ulong next_page_start;
    int num_insns;
    int max_insns;

    pc_start = tb->pc;

    dc->tb = tb;

    gen_opc_end = tcg_ctx.gen_opc_buf + OPC_MAX_SIZE;

    dc->is_jmp = DISAS_NEXT;
    dc->pc = pc_start;
    dc->singlestep_enabled = cs->singlestep_enabled;
    dc->condjmp = 0;

    dc->aarch64 = 1;
    dc->thumb = 0;
    dc->bswap_code = 0;
    dc->condexec_mask = 0;
    dc->condexec_cond = 0;
#if !defined(CONFIG_USER_ONLY)
    dc->user = 0;
#endif
    dc->vfp_enabled = 0;
    dc->vec_len = 0;
    dc->vec_stride = 0;

    init_tmp_a64_array(dc);

    next_page_start = (pc_start & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
    lj = -1;
    num_insns = 0;
    max_insns = tb->cflags & CF_COUNT_MASK;
    if (max_insns == 0) {
        max_insns = CF_COUNT_MASK;
    }

    gen_tb_start();

    tcg_clear_temp_count();

    do {
        if (unlikely(!QTAILQ_EMPTY(&env->breakpoints))) {
            QTAILQ_FOREACH(bp, &env->breakpoints, entry) {
                if (bp->pc == dc->pc) {
                    gen_exception_insn(dc, 0, EXCP_DEBUG);
                    /* Advance PC so that clearing the breakpoint will
                       invalidate this TB.  */
                    dc->pc += 2;
                    goto done_generating;
                }
            }
        }

        if (search_pc) {
            j = tcg_ctx.gen_opc_ptr - tcg_ctx.gen_opc_buf;
            if (lj < j) {
                lj++;
                while (lj < j) {
                    tcg_ctx.gen_opc_instr_start[lj++] = 0;
                }
            }
            tcg_ctx.gen_opc_pc[lj] = dc->pc;
            tcg_ctx.gen_opc_instr_start[lj] = 1;
            tcg_ctx.gen_opc_icount[lj] = num_insns;
        }

        if (num_insns + 1 == max_insns && (tb->cflags & CF_LAST_IO)) {
            gen_io_start();
        }

        if (unlikely(qemu_loglevel_mask(CPU_LOG_TB_OP | CPU_LOG_TB_OP_OPT))) {
            tcg_gen_debug_insn_start(dc->pc);
        }

        disas_a64_insn(env, dc);

        if (tcg_check_temp_count()) {
            fprintf(stderr, "TCG temporary leak before "TARGET_FMT_lx"\n",
                    dc->pc);
        }

        /* Translation stops when a conditional branch is encountered.
         * Otherwise the subsequent code could get translated several times.
         * Also stop translation when a page boundary is reached.  This
         * ensures prefetch aborts occur at the right place.
         */
        num_insns++;
    } while (!dc->is_jmp && tcg_ctx.gen_opc_ptr < gen_opc_end &&
             !cs->singlestep_enabled &&
             !singlestep &&
             dc->pc < next_page_start &&
             num_insns < max_insns);

    if (tb->cflags & CF_LAST_IO) {
        gen_io_end();
    }

    if (unlikely(cs->singlestep_enabled) && dc->is_jmp != DISAS_EXC) {
        /* Note that this means single stepping WFI doesn't halt the CPU.
         * For conditional branch insns this is harmless unreachable code as
         * gen_goto_tb() has already handled emitting the debug exception
         * (and thus a tb-jump is not possible when singlestepping).
         */
        assert(dc->is_jmp != DISAS_TB_JUMP);
        if (dc->is_jmp != DISAS_JUMP) {
            gen_a64_set_pc_im(dc->pc);
        }
        gen_exception(EXCP_DEBUG);
    } else {
        switch (dc->is_jmp) {
        case DISAS_NEXT:
            gen_goto_tb(dc, 1, dc->pc);
            break;
        default:
        case DISAS_JUMP:
        case DISAS_UPDATE:
            /* indicate that the hash table must be used to find the next TB */
            tcg_gen_exit_tb(0);
            break;
        case DISAS_TB_JUMP:
        case DISAS_EXC:
        case DISAS_SWI:
            break;
        case DISAS_WFI:
            /* This is a special case because we don't want to just halt the CPU
             * if trying to debug across a WFI.
             */
            gen_helper_wfi(cpu_env);
            break;
        }
    }

done_generating:
    gen_tb_end(tb, num_insns);
    *tcg_ctx.gen_opc_ptr = INDEX_op_end;

#ifdef DEBUG_DISAS
    if (qemu_loglevel_mask(CPU_LOG_TB_IN_ASM)) {
        qemu_log("----------------\n");
        qemu_log("IN: %s\n", lookup_symbol(pc_start));
        log_target_disas(env, pc_start, dc->pc - pc_start,
                         dc->thumb | (dc->bswap_code << 1));
        qemu_log("\n");
    }
#endif
    if (search_pc) {
        j = tcg_ctx.gen_opc_ptr - tcg_ctx.gen_opc_buf;
        lj++;
        while (lj <= j) {
            tcg_ctx.gen_opc_instr_start[lj++] = 0;
        }
    } else {
        tb->size = dc->pc - pc_start;
        tb->icount = num_insns;
    }
}