[qemu.git] / tcg / i386 / tcg-target.c

/*
 * Tiny Code Generator for QEMU
 *
 * Copyright (c) 2008 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#ifndef NDEBUG
static const char * const tcg_target_reg_names[TCG_TARGET_NB_REGS] = {
    "%eax",
    "%ecx",
    "%edx",
    "%ebx",
    "%esp",
    "%ebp",
    "%esi",
    "%edi",
};
#endif

static const int tcg_target_reg_alloc_order[] = {
    TCG_REG_EAX,
    TCG_REG_EDX,
    TCG_REG_ECX,
    TCG_REG_EBX,
    TCG_REG_ESI,
    TCG_REG_EDI,
    TCG_REG_EBP,
};

static const int tcg_target_call_iarg_regs[3] = { TCG_REG_EAX, TCG_REG_EDX, TCG_REG_ECX };
static const int tcg_target_call_oarg_regs[2] = { TCG_REG_EAX, TCG_REG_EDX };

static uint8_t *tb_ret_addr;

static void patch_reloc(uint8_t *code_ptr, int type, 
                        tcg_target_long value, tcg_target_long addend)
{
    value += addend;
    switch(type) {
    case R_386_32:
        *(uint32_t *)code_ptr = value;
        break;
    case R_386_PC32:
        *(uint32_t *)code_ptr = value - (long)code_ptr;
        break;
    case R_386_PC8:
        value -= (long)code_ptr;
        if (value != (int8_t)value) {
            tcg_abort();
        }
        *(uint8_t *)code_ptr = value;
        break;
    default:
        tcg_abort();
    }
}

/* maximum number of register used for input function arguments */
static inline int tcg_target_get_call_iarg_regs_count(int flags)
{
    flags &= TCG_CALL_TYPE_MASK;
    switch(flags) {
    case TCG_CALL_TYPE_STD:
        return 0;
    case TCG_CALL_TYPE_REGPARM_1:
    case TCG_CALL_TYPE_REGPARM_2:
    case TCG_CALL_TYPE_REGPARM:
        return flags - TCG_CALL_TYPE_REGPARM_1 + 1;
    default:
        tcg_abort();
    }
}

/* parse target specific constraints */
static int target_parse_constraint(TCGArgConstraint *ct, const char **pct_str)
{
    const char *ct_str;

    ct_str = *pct_str;
    switch(ct_str[0]) {
    case 'a':
        ct->ct |= TCG_CT_REG;
        tcg_regset_set_reg(ct->u.regs, TCG_REG_EAX);
        break;
    case 'b':
        ct->ct |= TCG_CT_REG;
        tcg_regset_set_reg(ct->u.regs, TCG_REG_EBX);
        break;
    case 'c':
        ct->ct |= TCG_CT_REG;
        tcg_regset_set_reg(ct->u.regs, TCG_REG_ECX);
        break;
    case 'd':
        ct->ct |= TCG_CT_REG;
        tcg_regset_set_reg(ct->u.regs, TCG_REG_EDX);
        break;
    case 'S':
        ct->ct |= TCG_CT_REG;
        tcg_regset_set_reg(ct->u.regs, TCG_REG_ESI);
        break;
    case 'D':
        ct->ct |= TCG_CT_REG;
        tcg_regset_set_reg(ct->u.regs, TCG_REG_EDI);
        break;
    case 'q':
        ct->ct |= TCG_CT_REG;
        tcg_regset_set32(ct->u.regs, 0, 0xf);
        break;
    case 'r':
        ct->ct |= TCG_CT_REG;
        tcg_regset_set32(ct->u.regs, 0, 0xff);
        break;

        /* qemu_ld/st address constraint */
    case 'L':
        ct->ct |= TCG_CT_REG;
        tcg_regset_set32(ct->u.regs, 0, 0xff);
        tcg_regset_reset_reg(ct->u.regs, TCG_REG_EAX);
        tcg_regset_reset_reg(ct->u.regs, TCG_REG_EDX);
        break;
    default:
        return -1;
    }
    ct_str++;
    *pct_str = ct_str;
    return 0;
}

/* test if a constant matches the constraint */
static inline int tcg_target_const_match(tcg_target_long val,
                                         const TCGArgConstraint *arg_ct)
{
    int ct;
    ct = arg_ct->ct;
    if (ct & TCG_CT_CONST)
        return 1;
    else
        return 0;
}

#define ARITH_ADD 0
#define ARITH_OR  1
#define ARITH_ADC 2
#define ARITH_SBB 3
#define ARITH_AND 4
#define ARITH_SUB 5
#define ARITH_XOR 6
#define ARITH_CMP 7

#define SHIFT_ROL 0
#define SHIFT_ROR 1
#define SHIFT_SHL 4
#define SHIFT_SHR 5
#define SHIFT_SAR 7

#define JCC_JMP (-1)
#define JCC_JO  0x0
#define JCC_JNO 0x1
#define JCC_JB  0x2
#define JCC_JAE 0x3
#define JCC_JE  0x4
#define JCC_JNE 0x5
#define JCC_JBE 0x6
#define JCC_JA  0x7
#define JCC_JS  0x8
#define JCC_JNS 0x9
#define JCC_JP  0xa
#define JCC_JNP 0xb
#define JCC_JL  0xc
#define JCC_JGE 0xd
#define JCC_JLE 0xe
#define JCC_JG  0xf

#define P_EXT   0x100 /* 0x0f opcode prefix */

static const uint8_t tcg_cond_to_jcc[10] = {
    [TCG_COND_EQ] = JCC_JE,
    [TCG_COND_NE] = JCC_JNE,
    [TCG_COND_LT] = JCC_JL,
    [TCG_COND_GE] = JCC_JGE,
    [TCG_COND_LE] = JCC_JLE,
    [TCG_COND_GT] = JCC_JG,
    [TCG_COND_LTU] = JCC_JB,
    [TCG_COND_GEU] = JCC_JAE,
    [TCG_COND_LEU] = JCC_JBE,
    [TCG_COND_GTU] = JCC_JA,
};

static inline void tcg_out_opc(TCGContext *s, int opc)
{
    if (opc & P_EXT)
        tcg_out8(s, 0x0f);
    tcg_out8(s, opc);
}

static inline void tcg_out_modrm(TCGContext *s, int opc, int r, int rm)
{
    tcg_out_opc(s, opc);
    tcg_out8(s, 0xc0 | (r << 3) | rm);
}

/* rm == -1 means no register index */
static inline void tcg_out_modrm_offset(TCGContext *s, int opc, int r, int rm, 
                                        int32_t offset)
{
    tcg_out_opc(s, opc);
    if (rm == -1) {
        tcg_out8(s, 0x05 | (r << 3));
        tcg_out32(s, offset);
    } else if (offset == 0 && rm != TCG_REG_EBP) {
        if (rm == TCG_REG_ESP) {
            tcg_out8(s, 0x04 | (r << 3));
            tcg_out8(s, 0x24);
        } else {
            tcg_out8(s, 0x00 | (r << 3) | rm);
        }
    } else if ((int8_t)offset == offset) {
        if (rm == TCG_REG_ESP) {
            tcg_out8(s, 0x44 | (r << 3));
            tcg_out8(s, 0x24);
        } else {
            tcg_out8(s, 0x40 | (r << 3) | rm);
        }
        tcg_out8(s, offset);
    } else {
        if (rm == TCG_REG_ESP) {
            tcg_out8(s, 0x84 | (r << 3));
            tcg_out8(s, 0x24);
        } else {
            tcg_out8(s, 0x80 | (r << 3) | rm);
        }
        tcg_out32(s, offset);
    }
}

static inline void tcg_out_mov(TCGContext *s, int ret, int arg)
{
    if (arg != ret)
        tcg_out_modrm(s, 0x8b, ret, arg);
}

static inline void tcg_out_movi(TCGContext *s, TCGType type,
                                int ret, int32_t arg)
{
    if (arg == 0) {
        /* xor r0,r0 */
        tcg_out_modrm(s, 0x01 | (ARITH_XOR << 3), ret, ret);
    } else {
        tcg_out8(s, 0xb8 + ret);
        tcg_out32(s, arg);
    }
}

static inline void tcg_out_ld(TCGContext *s, TCGType type, int ret,
                              int arg1, tcg_target_long arg2)
{
    /* movl */
    tcg_out_modrm_offset(s, 0x8b, ret, arg1, arg2);
}

static inline void tcg_out_st(TCGContext *s, TCGType type, int arg,
                              int arg1, tcg_target_long arg2)
{
    /* movl */
    tcg_out_modrm_offset(s, 0x89, arg, arg1, arg2);
}

static inline void tgen_arithi(TCGContext *s, int c, int r0, int32_t val, int cf)
{
    if (!cf && ((c == ARITH_ADD && val == 1) || (c == ARITH_SUB && val == -1))) {
        /* inc */
        tcg_out_opc(s, 0x40 + r0);
    } else if (!cf && ((c == ARITH_ADD && val == -1) || (c == ARITH_SUB && val == 1))) {
        /* dec */
        tcg_out_opc(s, 0x48 + r0);
    } else if (val == (int8_t)val) {
        tcg_out_modrm(s, 0x83, c, r0);
        tcg_out8(s, val);
    } else if (c == ARITH_AND && val == 0xffu && r0 < 4) {
        /* movzbl */
        tcg_out_modrm(s, 0xb6 | P_EXT, r0, r0);
    } else if (c == ARITH_AND && val == 0xffffu) {
        /* movzwl */
        tcg_out_modrm(s, 0xb7 | P_EXT, r0, r0);
    } else {
        tcg_out_modrm(s, 0x81, c, r0);
        tcg_out32(s, val);
    }
}

static void tcg_out_addi(TCGContext *s, int reg, tcg_target_long val)
{
    if (val != 0)
        tgen_arithi(s, ARITH_ADD, reg, val, 0);
}

/* Use SMALL != 0 to force a short forward branch.  */
static void tcg_out_jxx(TCGContext *s, int opc, int label_index, int small)
{
    int32_t val, val1;
    TCGLabel *l = &s->labels[label_index];
    
    if (l->has_value) {
        val = l->u.value - (tcg_target_long)s->code_ptr;
        val1 = val - 2;
        if ((int8_t)val1 == val1) {
            if (opc == -1) {
                tcg_out8(s, 0xeb);
            } else {
                tcg_out8(s, 0x70 + opc);
            }
            tcg_out8(s, val1);
        } else {
            if (small) {
                tcg_abort();
            }
            if (opc == -1) {
                tcg_out8(s, 0xe9);
                tcg_out32(s, val - 5);
            } else {
                tcg_out8(s, 0x0f);
                tcg_out8(s, 0x80 + opc);
                tcg_out32(s, val - 6);
            }
        }
    } else if (small) {
        if (opc == -1) {
            tcg_out8(s, 0xeb);
        } else {
            tcg_out8(s, 0x70 + opc);
        }
        tcg_out_reloc(s, s->code_ptr, R_386_PC8, label_index, -1);
        s->code_ptr += 1;
    } else {
        if (opc == -1) {
            tcg_out8(s, 0xe9);
        } else {
            tcg_out8(s, 0x0f);
            tcg_out8(s, 0x80 + opc);
        }
        tcg_out_reloc(s, s->code_ptr, R_386_PC32, label_index, -4);
        s->code_ptr += 4;
    }
}

static void tcg_out_cmp(TCGContext *s, TCGArg arg1, TCGArg arg2,
                        int const_arg2)
{
    if (const_arg2) {
        if (arg2 == 0) {
            /* test r, r */
            tcg_out_modrm(s, 0x85, arg1, arg1);
        } else {
            tgen_arithi(s, ARITH_CMP, arg1, arg2, 0);
        }
    } else {
        tcg_out_modrm(s, 0x01 | (ARITH_CMP << 3), arg2, arg1);
    }
}

static void tcg_out_brcond(TCGContext *s, int cond,
                           TCGArg arg1, TCGArg arg2, int const_arg2,
                           int label_index, int small)
{
    tcg_out_cmp(s, arg1, arg2, const_arg2);
    tcg_out_jxx(s, tcg_cond_to_jcc[cond], label_index, small);
}

/* XXX: we implement it at the target level to avoid having to
   handle cross basic blocks temporaries */
static void tcg_out_brcond2(TCGContext *s, const TCGArg *args,
                            const int *const_args, int small)
{
    int label_next;
    label_next = gen_new_label();
    switch(args[4]) {
    case TCG_COND_EQ:
        tcg_out_brcond(s, TCG_COND_NE, args[0], args[2], const_args[2],
                       label_next, 1);
        tcg_out_brcond(s, TCG_COND_EQ, args[1], args[3], const_args[3],
                       args[5], small);
        break;
    case TCG_COND_NE:
        tcg_out_brcond(s, TCG_COND_NE, args[0], args[2], const_args[2],
                       args[5], small);
        tcg_out_brcond(s, TCG_COND_NE, args[1], args[3], const_args[3],
                       args[5], small);
        break;
    case TCG_COND_LT:
        tcg_out_brcond(s, TCG_COND_LT, args[1], args[3], const_args[3],
                       args[5], small);
        tcg_out_jxx(s, JCC_JNE, label_next, 1);
        tcg_out_brcond(s, TCG_COND_LTU, args[0], args[2], const_args[2],
                       args[5], small);
        break;
    case TCG_COND_LE:
        tcg_out_brcond(s, TCG_COND_LT, args[1], args[3], const_args[3],
                       args[5], small);
        tcg_out_jxx(s, JCC_JNE, label_next, 1);
        tcg_out_brcond(s, TCG_COND_LEU, args[0], args[2], const_args[2],
                       args[5], small);
        break;
    case TCG_COND_GT:
        tcg_out_brcond(s, TCG_COND_GT, args[1], args[3], const_args[3],
                       args[5], small);
        tcg_out_jxx(s, JCC_JNE, label_next, 1);
        tcg_out_brcond(s, TCG_COND_GTU, args[0], args[2], const_args[2],
                       args[5], small);
        break;
    case TCG_COND_GE:
        tcg_out_brcond(s, TCG_COND_GT, args[1], args[3], const_args[3],
                       args[5], small);
        tcg_out_jxx(s, JCC_JNE, label_next, 1);
        tcg_out_brcond(s, TCG_COND_GEU, args[0], args[2], const_args[2],
                       args[5], small);
        break;
    case TCG_COND_LTU:
        tcg_out_brcond(s, TCG_COND_LTU, args[1], args[3], const_args[3],
                       args[5], small);
        tcg_out_jxx(s, JCC_JNE, label_next, 1);
        tcg_out_brcond(s, TCG_COND_LTU, args[0], args[2], const_args[2],
                       args[5], small);
        break;
    case TCG_COND_LEU:
        tcg_out_brcond(s, TCG_COND_LTU, args[1], args[3], const_args[3],
                       args[5], small);
        tcg_out_jxx(s, JCC_JNE, label_next, 1);
        tcg_out_brcond(s, TCG_COND_LEU, args[0], args[2], const_args[2],
                       args[5], small);
        break;
    case TCG_COND_GTU:
        tcg_out_brcond(s, TCG_COND_GTU, args[1], args[3], const_args[3],
                       args[5], small);
        tcg_out_jxx(s, JCC_JNE, label_next, 1);
        tcg_out_brcond(s, TCG_COND_GTU, args[0], args[2], const_args[2],
                       args[5], small);
        break;
    case TCG_COND_GEU:
        tcg_out_brcond(s, TCG_COND_GTU, args[1], args[3], const_args[3],
                       args[5], small);
        tcg_out_jxx(s, JCC_JNE, label_next, 1);
        tcg_out_brcond(s, TCG_COND_GEU, args[0], args[2], const_args[2],
                       args[5], small);
        break;
    default:
        tcg_abort();
    }
    tcg_out_label(s, label_next, (tcg_target_long)s->code_ptr);
}

static void tcg_out_setcond(TCGContext *s, int cond, TCGArg dest,
                            TCGArg arg1, TCGArg arg2, int const_arg2)
{
    tcg_out_cmp(s, arg1, arg2, const_arg2);
    /* setcc */
    tcg_out_modrm(s, 0x90 | tcg_cond_to_jcc[cond] | P_EXT, 0, dest);
    tgen_arithi(s, ARITH_AND, dest, 0xff, 0);
}

static void tcg_out_setcond2(TCGContext *s, const TCGArg *args,
                             const int *const_args)
{
    TCGArg new_args[6];
    int label_true, label_over;

    memcpy(new_args, args+1, 5*sizeof(TCGArg));

    if (args[0] == args[1] || args[0] == args[2]
        || (!const_args[3] && args[0] == args[3])
        || (!const_args[4] && args[0] == args[4])) {
        /* When the destination overlaps with one of the argument
           registers, don't do anything tricky.  */
        label_true = gen_new_label();
        label_over = gen_new_label();

        new_args[5] = label_true;
        tcg_out_brcond2(s, new_args, const_args+1, 1);

        tcg_out_movi(s, TCG_TYPE_I32, args[0], 0);
        tcg_out_jxx(s, JCC_JMP, label_over, 1);
        tcg_out_label(s, label_true, (tcg_target_long)s->code_ptr);

        tcg_out_movi(s, TCG_TYPE_I32, args[0], 1);
        tcg_out_label(s, label_over, (tcg_target_long)s->code_ptr);
    } else {
        /* When the destination does not overlap one of the arguments,
           clear the destination first, jump if cond false, and emit an
           increment in the true case.  This results in smaller code.  */

        tcg_out_movi(s, TCG_TYPE_I32, args[0], 0);

        label_over = gen_new_label();
        new_args[4] = tcg_invert_cond(new_args[4]);
        new_args[5] = label_over;
        tcg_out_brcond2(s, new_args, const_args+1, 1);

        tgen_arithi(s, ARITH_ADD, args[0], 1, 0);
        tcg_out_label(s, label_over, (tcg_target_long)s->code_ptr);
    }
}

#if defined(CONFIG_SOFTMMU)

#include "../../softmmu_defs.h"

static void *qemu_ld_helpers[4] = {
    __ldb_mmu,
    __ldw_mmu,
    __ldl_mmu,
    __ldq_mmu,
};

static void *qemu_st_helpers[4] = {
    __stb_mmu,
    __stw_mmu,
    __stl_mmu,
    __stq_mmu,
};
#endif

#ifndef CONFIG_USER_ONLY
#define GUEST_BASE 0
#endif

/* XXX: qemu_ld and qemu_st could be modified to clobber only EDX and
   EAX. It will be useful once fixed registers globals are less
   common. */
static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args,
                            int opc)
{
    int addr_reg, data_reg, data_reg2, r0, r1, mem_index, s_bits, bswap;
#if defined(CONFIG_SOFTMMU)
    uint8_t *label1_ptr, *label2_ptr;
#endif
#if TARGET_LONG_BITS == 64
#if defined(CONFIG_SOFTMMU)
    uint8_t *label3_ptr;
#endif
    int addr_reg2;
#endif

    data_reg = *args++;
    if (opc == 3)
        data_reg2 = *args++;
    else
        data_reg2 = 0;
    addr_reg = *args++;
#if TARGET_LONG_BITS == 64
    addr_reg2 = *args++;
#endif
    mem_index = *args;
    s_bits = opc & 3;

    r0 = TCG_REG_EAX;
    r1 = TCG_REG_EDX;

#if defined(CONFIG_SOFTMMU)
    tcg_out_mov(s, r1, addr_reg); 

    tcg_out_mov(s, r0, addr_reg); 
 
    tcg_out_modrm(s, 0xc1, 5, r1); /* shr $x, r1 */
    tcg_out8(s, TARGET_PAGE_BITS - CPU_TLB_ENTRY_BITS); 
    
    tcg_out_modrm(s, 0x81, 4, r0); /* andl $x, r0 */
    tcg_out32(s, TARGET_PAGE_MASK | ((1 << s_bits) - 1));
    
    tcg_out_modrm(s, 0x81, 4, r1); /* andl $x, r1 */
    tcg_out32(s, (CPU_TLB_SIZE - 1) << CPU_TLB_ENTRY_BITS);

    tcg_out_opc(s, 0x8d); /* lea offset(r1, %ebp), r1 */
    tcg_out8(s, 0x80 | (r1 << 3) | 0x04);
    tcg_out8(s, (5 << 3) | r1);
    tcg_out32(s, offsetof(CPUState, tlb_table[mem_index][0].addr_read));

    /* cmp 0(r1), r0 */
    tcg_out_modrm_offset(s, 0x3b, r0, r1, 0);
    
    tcg_out_mov(s, r0, addr_reg);
    
#if TARGET_LONG_BITS == 32
    /* je label1 */
    tcg_out8(s, 0x70 + JCC_JE);
    label1_ptr = s->code_ptr;
    s->code_ptr++;
#else
    /* jne label3 */
    tcg_out8(s, 0x70 + JCC_JNE);
    label3_ptr = s->code_ptr;
    s->code_ptr++;
    
    /* cmp 4(r1), addr_reg2 */
    tcg_out_modrm_offset(s, 0x3b, addr_reg2, r1, 4);

    /* je label1 */
    tcg_out8(s, 0x70 + JCC_JE);
    label1_ptr = s->code_ptr;
    s->code_ptr++;
    
    /* label3: */
    *label3_ptr = s->code_ptr - label3_ptr - 1;
#endif

    /* XXX: move that code at the end of the TB */
#if TARGET_LONG_BITS == 32
    tcg_out_movi(s, TCG_TYPE_I32, TCG_REG_EDX, mem_index);
#else
    tcg_out_mov(s, TCG_REG_EDX, addr_reg2);
    tcg_out_movi(s, TCG_TYPE_I32, TCG_REG_ECX, mem_index);
#endif
    tcg_out8(s, 0xe8);
    tcg_out32(s, (tcg_target_long)qemu_ld_helpers[s_bits] - 
              (tcg_target_long)s->code_ptr - 4);

    switch(opc) {
    case 0 | 4:
        /* movsbl */
        tcg_out_modrm(s, 0xbe | P_EXT, data_reg, TCG_REG_EAX);
        break;
    case 1 | 4:
        /* movswl */
        tcg_out_modrm(s, 0xbf | P_EXT, data_reg, TCG_REG_EAX);
        break;
    case 0:
        /* movzbl */
        tcg_out_modrm(s, 0xb6 | P_EXT, data_reg, TCG_REG_EAX);
        break;
    case 1:
        /* movzwl */
        tcg_out_modrm(s, 0xb7 | P_EXT, data_reg, TCG_REG_EAX);
        break;
    case 2:
    default:
        tcg_out_mov(s, data_reg, TCG_REG_EAX);
        break;
    case 3:
        if (data_reg == TCG_REG_EDX) {
            tcg_out_opc(s, 0x90 + TCG_REG_EDX); /* xchg %edx, %eax */
            tcg_out_mov(s, data_reg2, TCG_REG_EAX);
        } else {
            tcg_out_mov(s, data_reg, TCG_REG_EAX);
            tcg_out_mov(s, data_reg2, TCG_REG_EDX);
        }
        break;
    }

    /* jmp label2 */
    tcg_out8(s, 0xeb);
    label2_ptr = s->code_ptr;
    s->code_ptr++;
    
    /* label1: */
    *label1_ptr = s->code_ptr - label1_ptr - 1;

    /* add x(r1), r0 */
    tcg_out_modrm_offset(s, 0x03, r0, r1, offsetof(CPUTLBEntry, addend) - 
                         offsetof(CPUTLBEntry, addr_read));
#else
    r0 = addr_reg;
#endif

#ifdef TARGET_WORDS_BIGENDIAN
    bswap = 1;
#else
    bswap = 0;
#endif
    switch(opc) {
    case 0:
        /* movzbl */
        tcg_out_modrm_offset(s, 0xb6 | P_EXT, data_reg, r0, GUEST_BASE);
        break;
    case 0 | 4:
        /* movsbl */
        tcg_out_modrm_offset(s, 0xbe | P_EXT, data_reg, r0, GUEST_BASE);
        break;
    case 1:
        /* movzwl */
        tcg_out_modrm_offset(s, 0xb7 | P_EXT, data_reg, r0, GUEST_BASE);
        if (bswap) {
            /* rolw $8, data_reg */
            tcg_out8(s, 0x66); 
            tcg_out_modrm(s, 0xc1, 0, data_reg);
            tcg_out8(s, 8);
        }
        break;
    case 1 | 4:
        /* movswl */
        tcg_out_modrm_offset(s, 0xbf | P_EXT, data_reg, r0, GUEST_BASE);
        if (bswap) {
            /* rolw $8, data_reg */
            tcg_out8(s, 0x66); 
            tcg_out_modrm(s, 0xc1, 0, data_reg);
            tcg_out8(s, 8);

            /* movswl data_reg, data_reg */
            tcg_out_modrm(s, 0xbf | P_EXT, data_reg, data_reg);
        }
        break;
    case 2:
        /* movl (r0), data_reg */
        tcg_out_modrm_offset(s, 0x8b, data_reg, r0, GUEST_BASE);
        if (bswap) {
            /* bswap */
            tcg_out_opc(s, (0xc8 + data_reg) | P_EXT);
        }
        break;
    case 3:
        /* XXX: could be nicer */
        if (r0 == data_reg) {
            r1 = TCG_REG_EDX;
            if (r1 == data_reg)
                r1 = TCG_REG_EAX;
            tcg_out_mov(s, r1, r0);
            r0 = r1;
        }
        if (!bswap) {
            tcg_out_modrm_offset(s, 0x8b, data_reg, r0, GUEST_BASE);
            tcg_out_modrm_offset(s, 0x8b, data_reg2, r0, GUEST_BASE + 4);
        } else {
            tcg_out_modrm_offset(s, 0x8b, data_reg, r0, GUEST_BASE + 4);
            tcg_out_opc(s, (0xc8 + data_reg) | P_EXT);

            tcg_out_modrm_offset(s, 0x8b, data_reg2, r0, GUEST_BASE);
            /* bswap */
            tcg_out_opc(s, (0xc8 + data_reg2) | P_EXT);
        }
        break;
    default:
        tcg_abort();
    }

#if defined(CONFIG_SOFTMMU)
    /* label2: */
    *label2_ptr = s->code_ptr - label2_ptr - 1;
#endif
}


static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args,
                            int opc)
{
    int addr_reg, data_reg, data_reg2, r0, r1, mem_index, s_bits, bswap;
#if defined(CONFIG_SOFTMMU)
    uint8_t *label1_ptr, *label2_ptr;
#endif
#if TARGET_LONG_BITS == 64
#if defined(CONFIG_SOFTMMU)
    uint8_t *label3_ptr;
#endif
    int addr_reg2;
#endif

    data_reg = *args++;
    if (opc == 3)
        data_reg2 = *args++;
    else
        data_reg2 = 0;
    addr_reg = *args++;
#if TARGET_LONG_BITS == 64
    addr_reg2 = *args++;
#endif
    mem_index = *args;

    s_bits = opc;

    r0 = TCG_REG_EAX;
    r1 = TCG_REG_EDX;

#if defined(CONFIG_SOFTMMU)
    tcg_out_mov(s, r1, addr_reg); 

    tcg_out_mov(s, r0, addr_reg); 
 
    tcg_out_modrm(s, 0xc1, 5, r1); /* shr $x, r1 */
    tcg_out8(s, TARGET_PAGE_BITS - CPU_TLB_ENTRY_BITS); 
    
    tcg_out_modrm(s, 0x81, 4, r0); /* andl $x, r0 */
    tcg_out32(s, TARGET_PAGE_MASK | ((1 << s_bits) - 1));
    
    tcg_out_modrm(s, 0x81, 4, r1); /* andl $x, r1 */
    tcg_out32(s, (CPU_TLB_SIZE - 1) << CPU_TLB_ENTRY_BITS);

    tcg_out_opc(s, 0x8d); /* lea offset(r1, %ebp), r1 */
    tcg_out8(s, 0x80 | (r1 << 3) | 0x04);
    tcg_out8(s, (5 << 3) | r1);
    tcg_out32(s, offsetof(CPUState, tlb_table[mem_index][0].addr_write));

    /* cmp 0(r1), r0 */
    tcg_out_modrm_offset(s, 0x3b, r0, r1, 0);
    
    tcg_out_mov(s, r0, addr_reg);
    
#if TARGET_LONG_BITS == 32
    /* je label1 */
    tcg_out8(s, 0x70 + JCC_JE);
    label1_ptr = s->code_ptr;
    s->code_ptr++;
#else
    /* jne label3 */
    tcg_out8(s, 0x70 + JCC_JNE);
    label3_ptr = s->code_ptr;
    s->code_ptr++;
    
    /* cmp 4(r1), addr_reg2 */
    tcg_out_modrm_offset(s, 0x3b, addr_reg2, r1, 4);

    /* je label1 */
    tcg_out8(s, 0x70 + JCC_JE);
    label1_ptr = s->code_ptr;
    s->code_ptr++;
    
    /* label3: */
    *label3_ptr = s->code_ptr - label3_ptr - 1;
#endif

    /* XXX: move that code at the end of the TB */
#if TARGET_LONG_BITS == 32
    if (opc == 3) {
        tcg_out_mov(s, TCG_REG_EDX, data_reg);
        tcg_out_mov(s, TCG_REG_ECX, data_reg2);
        tcg_out8(s, 0x6a); /* push Ib */
        tcg_out8(s, mem_index);
        tcg_out8(s, 0xe8);
        tcg_out32(s, (tcg_target_long)qemu_st_helpers[s_bits] - 
                  (tcg_target_long)s->code_ptr - 4);
        tcg_out_addi(s, TCG_REG_ESP, 4);
    } else {
        switch(opc) {
        case 0:
            /* movzbl */
            tcg_out_modrm(s, 0xb6 | P_EXT, TCG_REG_EDX, data_reg);
            break;
        case 1:
            /* movzwl */
            tcg_out_modrm(s, 0xb7 | P_EXT, TCG_REG_EDX, data_reg);
            break;
        case 2:
            tcg_out_mov(s, TCG_REG_EDX, data_reg);
            break;
        }
        tcg_out_movi(s, TCG_TYPE_I32, TCG_REG_ECX, mem_index);
        tcg_out8(s, 0xe8);
        tcg_out32(s, (tcg_target_long)qemu_st_helpers[s_bits] - 
                  (tcg_target_long)s->code_ptr - 4);
    }
#else
    if (opc == 3) {
        tcg_out_mov(s, TCG_REG_EDX, addr_reg2);
        tcg_out8(s, 0x6a); /* push Ib */
        tcg_out8(s, mem_index);
        tcg_out_opc(s, 0x50 + data_reg2); /* push */
        tcg_out_opc(s, 0x50 + data_reg); /* push */
        tcg_out8(s, 0xe8);
        tcg_out32(s, (tcg_target_long)qemu_st_helpers[s_bits] - 
                  (tcg_target_long)s->code_ptr - 4);
        tcg_out_addi(s, TCG_REG_ESP, 12);
    } else {
        tcg_out_mov(s, TCG_REG_EDX, addr_reg2);
        switch(opc) {
        case 0:
            /* movzbl */
            tcg_out_modrm(s, 0xb6 | P_EXT, TCG_REG_ECX, data_reg);
            break;
        case 1:
            /* movzwl */
            tcg_out_modrm(s, 0xb7 | P_EXT, TCG_REG_ECX, data_reg);
            break;
        case 2:
            tcg_out_mov(s, TCG_REG_ECX, data_reg);
            break;
        }
        tcg_out8(s, 0x6a); /* push Ib */
        tcg_out8(s, mem_index);
        tcg_out8(s, 0xe8);
        tcg_out32(s, (tcg_target_long)qemu_st_helpers[s_bits] - 
                  (tcg_target_long)s->code_ptr - 4);
        tcg_out_addi(s, TCG_REG_ESP, 4);
    }
#endif
    
    /* jmp label2 */
    tcg_out8(s, 0xeb);
    label2_ptr = s->code_ptr;
    s->code_ptr++;
    
    /* label1: */
    *label1_ptr = s->code_ptr - label1_ptr - 1;

    /* add x(r1), r0 */
    tcg_out_modrm_offset(s, 0x03, r0, r1, offsetof(CPUTLBEntry, addend) - 
                         offsetof(CPUTLBEntry, addr_write));
#else
    r0 = addr_reg;
#endif

#ifdef TARGET_WORDS_BIGENDIAN
    bswap = 1;
#else
    bswap = 0;
#endif
    switch(opc) {
    case 0:
        /* movb */
        tcg_out_modrm_offset(s, 0x88, data_reg, r0, GUEST_BASE);
        break;
    case 1:
        if (bswap) {
            tcg_out_mov(s, r1, data_reg);
            tcg_out8(s, 0x66); /* rolw $8, %ecx */
            tcg_out_modrm(s, 0xc1, 0, r1);
            tcg_out8(s, 8);
            data_reg = r1;
        }
        /* movw */
        tcg_out8(s, 0x66);
        tcg_out_modrm_offset(s, 0x89, data_reg, r0, GUEST_BASE);
        break;
    case 2:
        if (bswap) {
            tcg_out_mov(s, r1, data_reg);
            /* bswap data_reg */
            tcg_out_opc(s, (0xc8 + r1) | P_EXT);
            data_reg = r1;
        }
        /* movl */
        tcg_out_modrm_offset(s, 0x89, data_reg, r0, GUEST_BASE);
        break;
    case 3:
        if (bswap) {
            tcg_out_mov(s, r1, data_reg2);
            /* bswap data_reg */
            tcg_out_opc(s, (0xc8 + r1) | P_EXT);
            tcg_out_modrm_offset(s, 0x89, r1, r0, GUEST_BASE);
            tcg_out_mov(s, r1, data_reg);
            /* bswap data_reg */
            tcg_out_opc(s, (0xc8 + r1) | P_EXT);
            tcg_out_modrm_offset(s, 0x89, r1, r0, GUEST_BASE + 4);
        } else {
            tcg_out_modrm_offset(s, 0x89, data_reg, r0, GUEST_BASE);
            tcg_out_modrm_offset(s, 0x89, data_reg2, r0, GUEST_BASE + 4);
        }
        break;
    default:
        tcg_abort();
    }

#if defined(CONFIG_SOFTMMU)
    /* label2: */
    *label2_ptr = s->code_ptr - label2_ptr - 1;
#endif
}

static inline void tcg_out_op(TCGContext *s, int opc, 
                              const TCGArg *args, const int *const_args)
{
    int c;
    
    switch(opc) {
    case INDEX_op_exit_tb:
        tcg_out_movi(s, TCG_TYPE_I32, TCG_REG_EAX, args[0]);
        tcg_out8(s, 0xe9); /* jmp tb_ret_addr */
        tcg_out32(s, tb_ret_addr - s->code_ptr - 4);
        break;
    case INDEX_op_goto_tb:
        if (s->tb_jmp_offset) {
            /* direct jump method */
            tcg_out8(s, 0xe9); /* jmp im */
            s->tb_jmp_offset[args[0]] = s->code_ptr - s->code_buf;
            tcg_out32(s, 0);
        } else {
            /* indirect jump method */
            /* jmp Ev */
            tcg_out_modrm_offset(s, 0xff, 4, -1, 
                                 (tcg_target_long)(s->tb_next + args[0]));
        }
        s->tb_next_offset[args[0]] = s->code_ptr - s->code_buf;
        break;
    case INDEX_op_call:
        if (const_args[0]) {
            tcg_out8(s, 0xe8);
            tcg_out32(s, args[0] - (tcg_target_long)s->code_ptr - 4);
        } else {
            tcg_out_modrm(s, 0xff, 2, args[0]);
        }
        break;
    case INDEX_op_jmp:
        if (const_args[0]) {
            tcg_out8(s, 0xe9);
            tcg_out32(s, args[0] - (tcg_target_long)s->code_ptr - 4);
        } else {
            tcg_out_modrm(s, 0xff, 4, args[0]);
        }
        break;
    case INDEX_op_br:
        tcg_out_jxx(s, JCC_JMP, args[0], 0);
        break;
    case INDEX_op_movi_i32:
        tcg_out_movi(s, TCG_TYPE_I32, args[0], args[1]);
        break;
    case INDEX_op_ld8u_i32:
        /* movzbl */
        tcg_out_modrm_offset(s, 0xb6 | P_EXT, args[0], args[1], args[2]);
        break;
    case INDEX_op_ld8s_i32:
        /* movsbl */
        tcg_out_modrm_offset(s, 0xbe | P_EXT, args[0], args[1], args[2]);
        break;
    case INDEX_op_ld16u_i32:
        /* movzwl */
        tcg_out_modrm_offset(s, 0xb7 | P_EXT, args[0], args[1], args[2]);
        break;
    case INDEX_op_ld16s_i32:
        /* movswl */
        tcg_out_modrm_offset(s, 0xbf | P_EXT, args[0], args[1], args[2]);
        break;
    case INDEX_op_ld_i32:
        /* movl */
        tcg_out_modrm_offset(s, 0x8b, args[0], args[1], args[2]);
        break;
    case INDEX_op_st8_i32:
        /* movb */
        tcg_out_modrm_offset(s, 0x88, args[0], args[1], args[2]);
        break;
    case INDEX_op_st16_i32:
        /* movw */
        tcg_out8(s, 0x66);
        tcg_out_modrm_offset(s, 0x89, args[0], args[1], args[2]);
        break;
    case INDEX_op_st_i32:
        /* movl */
        tcg_out_modrm_offset(s, 0x89, args[0], args[1], args[2]);
        break;
    case INDEX_op_sub_i32:
        c = ARITH_SUB;
        goto gen_arith;
    case INDEX_op_and_i32:
        c = ARITH_AND;
        goto gen_arith;
    case INDEX_op_or_i32:
        c = ARITH_OR;
        goto gen_arith;
    case INDEX_op_xor_i32:
        c = ARITH_XOR;
        goto gen_arith;
    case INDEX_op_add_i32:
        c = ARITH_ADD;
    gen_arith:
        if (const_args[2]) {
            tgen_arithi(s, c, args[0], args[2], 0);
        } else {
            tcg_out_modrm(s, 0x01 | (c << 3), args[2], args[0]);
        }
        break;
    case INDEX_op_mul_i32:
        if (const_args[2]) {
            int32_t val;
            val = args[2];
            if (val == (int8_t)val) {
                tcg_out_modrm(s, 0x6b, args[0], args[0]);
                tcg_out8(s, val);
            } else {
                tcg_out_modrm(s, 0x69, args[0], args[0]);
                tcg_out32(s, val);
            }
        } else {
            tcg_out_modrm(s, 0xaf | P_EXT, args[0], args[2]);
        }
        break;
    case INDEX_op_mulu2_i32:
        tcg_out_modrm(s, 0xf7, 4, args[3]);
        break;
    case INDEX_op_div2_i32:
        tcg_out_modrm(s, 0xf7, 7, args[4]);
        break;
    case INDEX_op_divu2_i32:
        tcg_out_modrm(s, 0xf7, 6, args[4]);
        break;
    case INDEX_op_shl_i32:
        c = SHIFT_SHL;
    gen_shift32:
        if (const_args[2]) {
            if (args[2] == 1) {
                tcg_out_modrm(s, 0xd1, c, args[0]);
            } else {
                tcg_out_modrm(s, 0xc1, c, args[0]);
                tcg_out8(s, args[2]);
            }
        } else {
            tcg_out_modrm(s, 0xd3, c, args[0]);
        }
        break;
    case INDEX_op_shr_i32:
        c = SHIFT_SHR;
        goto gen_shift32;
    case INDEX_op_sar_i32:
        c = SHIFT_SAR;
        goto gen_shift32;
    case INDEX_op_rotl_i32:
        c = SHIFT_ROL;
        goto gen_shift32;
    case INDEX_op_rotr_i32:
        c = SHIFT_ROR;
        goto gen_shift32;

    case INDEX_op_add2_i32:
        if (const_args[4]) 
            tgen_arithi(s, ARITH_ADD, args[0], args[4], 1);
        else
            tcg_out_modrm(s, 0x01 | (ARITH_ADD << 3), args[4], args[0]);
        if (const_args[5]) 
            tgen_arithi(s, ARITH_ADC, args[1], args[5], 1);
        else
            tcg_out_modrm(s, 0x01 | (ARITH_ADC << 3), args[5], args[1]);
        break;
    case INDEX_op_sub2_i32:
        if (const_args[4]) 
            tgen_arithi(s, ARITH_SUB, args[0], args[4], 1);
        else
            tcg_out_modrm(s, 0x01 | (ARITH_SUB << 3), args[4], args[0]);
        if (const_args[5]) 
            tgen_arithi(s, ARITH_SBB, args[1], args[5], 1);
        else
            tcg_out_modrm(s, 0x01 | (ARITH_SBB << 3), args[5], args[1]);
        break;
    case INDEX_op_brcond_i32:
        tcg_out_brcond(s, args[2], args[0], args[1], const_args[1],
                       args[3], 0);
        break;
    case INDEX_op_brcond2_i32:
        tcg_out_brcond2(s, args, const_args, 0);
        break;

    case INDEX_op_bswap16_i32:
        tcg_out8(s, 0x66);
        tcg_out_modrm(s, 0xc1, SHIFT_ROL, args[0]);
        tcg_out8(s, 8);
        break;
    case INDEX_op_bswap32_i32:
        tcg_out_opc(s, (0xc8 + args[0]) | P_EXT);
        break;

    case INDEX_op_neg_i32:
        tcg_out_modrm(s, 0xf7, 3, args[0]);
        break;

    case INDEX_op_not_i32:
        tcg_out_modrm(s, 0xf7, 2, args[0]);
        break;

    case INDEX_op_ext8s_i32:
        tcg_out_modrm(s, 0xbe | P_EXT, args[0], args[1]);
        break;
    case INDEX_op_ext16s_i32:
        tcg_out_modrm(s, 0xbf | P_EXT, args[0], args[1]);
        break;
    case INDEX_op_ext8u_i32:
        tcg_out_modrm(s, 0xb6 | P_EXT, args[0], args[1]);
        break;
    case INDEX_op_ext16u_i32:
        tcg_out_modrm(s, 0xb7 | P_EXT, args[0], args[1]);
        break;

    case INDEX_op_setcond_i32:
        tcg_out_setcond(s, args[3], args[0], args[1], args[2], const_args[2]);
        break;
    case INDEX_op_setcond2_i32:
        tcg_out_setcond2(s, args, const_args);
        break;

    case INDEX_op_qemu_ld8u:
        tcg_out_qemu_ld(s, args, 0);
        break;
    case INDEX_op_qemu_ld8s:
        tcg_out_qemu_ld(s, args, 0 | 4);
        break;
    case INDEX_op_qemu_ld16u:
        tcg_out_qemu_ld(s, args, 1);
        break;
    case INDEX_op_qemu_ld16s:
        tcg_out_qemu_ld(s, args, 1 | 4);
        break;
    case INDEX_op_qemu_ld32u:
        tcg_out_qemu_ld(s, args, 2);
        break;
    case INDEX_op_qemu_ld64:
        tcg_out_qemu_ld(s, args, 3);
        break;
        
    case INDEX_op_qemu_st8:
        tcg_out_qemu_st(s, args, 0);
        break;
    case INDEX_op_qemu_st16:
        tcg_out_qemu_st(s, args, 1);
        break;
    case INDEX_op_qemu_st32:
        tcg_out_qemu_st(s, args, 2);
        break;
    case INDEX_op_qemu_st64:
        tcg_out_qemu_st(s, args, 3);
        break;

    default:
        tcg_abort();
    }
}

static const TCGTargetOpDef x86_op_defs[] = {
    { INDEX_op_exit_tb, { } },
    { INDEX_op_goto_tb, { } },
    { INDEX_op_call, { "ri" } },
    { INDEX_op_jmp, { "ri" } },
    { INDEX_op_br, { } },
    { INDEX_op_mov_i32, { "r", "r" } },
    { INDEX_op_movi_i32, { "r" } },
    { INDEX_op_ld8u_i32, { "r", "r" } },
    { INDEX_op_ld8s_i32, { "r", "r" } },
    { INDEX_op_ld16u_i32, { "r", "r" } },
    { INDEX_op_ld16s_i32, { "r", "r" } },
    { INDEX_op_ld_i32, { "r", "r" } },
    { INDEX_op_st8_i32, { "q", "r" } },
    { INDEX_op_st16_i32, { "r", "r" } },
    { INDEX_op_st_i32, { "r", "r" } },

    { INDEX_op_add_i32, { "r", "0", "ri" } },
    { INDEX_op_sub_i32, { "r", "0", "ri" } },
    { INDEX_op_mul_i32, { "r", "0", "ri" } },
    { INDEX_op_mulu2_i32, { "a", "d", "a", "r" } },
    { INDEX_op_div2_i32, { "a", "d", "0", "1", "r" } },
    { INDEX_op_divu2_i32, { "a", "d", "0", "1", "r" } },
    { INDEX_op_and_i32, { "r", "0", "ri" } },
    { INDEX_op_or_i32, { "r", "0", "ri" } },
    { INDEX_op_xor_i32, { "r", "0", "ri" } },

    { INDEX_op_shl_i32, { "r", "0", "ci" } },
    { INDEX_op_shr_i32, { "r", "0", "ci" } },
    { INDEX_op_sar_i32, { "r", "0", "ci" } },
    { INDEX_op_rotl_i32, { "r", "0", "ci" } },
    { INDEX_op_rotr_i32, { "r", "0", "ci" } },

    { INDEX_op_brcond_i32, { "r", "ri" } },

    { INDEX_op_add2_i32, { "r", "r", "0", "1", "ri", "ri" } },
    { INDEX_op_sub2_i32, { "r", "r", "0", "1", "ri", "ri" } },
    { INDEX_op_brcond2_i32, { "r", "r", "ri", "ri" } },

    { INDEX_op_bswap16_i32, { "r", "0" } },
    { INDEX_op_bswap32_i32, { "r", "0" } },

    { INDEX_op_neg_i32, { "r", "0" } },

    { INDEX_op_not_i32, { "r", "0" } },

    { INDEX_op_ext8s_i32, { "r", "q" } },
    { INDEX_op_ext16s_i32, { "r", "r" } },
    { INDEX_op_ext8u_i32, { "r", "q"} },
    { INDEX_op_ext16u_i32, { "r", "r"} },

    { INDEX_op_setcond_i32, { "q", "r", "ri" } },
    { INDEX_op_setcond2_i32, { "r", "r", "r", "ri", "ri" } },

#if TARGET_LONG_BITS == 32
    { INDEX_op_qemu_ld8u, { "r", "L" } },
    { INDEX_op_qemu_ld8s, { "r", "L" } },
    { INDEX_op_qemu_ld16u, { "r", "L" } },
    { INDEX_op_qemu_ld16s, { "r", "L" } },
    { INDEX_op_qemu_ld32u, { "r", "L" } },
    { INDEX_op_qemu_ld64, { "r", "r", "L" } },

    { INDEX_op_qemu_st8, { "cb", "L" } },
    { INDEX_op_qemu_st16, { "L", "L" } },
    { INDEX_op_qemu_st32, { "L", "L" } },
    { INDEX_op_qemu_st64, { "L", "L", "L" } },
#else
    { INDEX_op_qemu_ld8u, { "r", "L", "L" } },
    { INDEX_op_qemu_ld8s, { "r", "L", "L" } },
    { INDEX_op_qemu_ld16u, { "r", "L", "L" } },
    { INDEX_op_qemu_ld16s, { "r", "L", "L" } },
    { INDEX_op_qemu_ld32u, { "r", "L", "L" } },
    { INDEX_op_qemu_ld64, { "r", "r", "L", "L" } },

    { INDEX_op_qemu_st8, { "cb", "L", "L" } },
    { INDEX_op_qemu_st16, { "L", "L", "L" } },
    { INDEX_op_qemu_st32, { "L", "L", "L" } },
    { INDEX_op_qemu_st64, { "L", "L", "L", "L" } },
#endif
    { -1 },
};

static int tcg_target_callee_save_regs[] = {
    /*    TCG_REG_EBP, */ /* currently used for the global env, so no
                             need to save */
    TCG_REG_EBX,
    TCG_REG_ESI,
    TCG_REG_EDI,
};

static inline void tcg_out_push(TCGContext *s, int reg)
{
    tcg_out_opc(s, 0x50 + reg);
}

static inline void tcg_out_pop(TCGContext *s, int reg)
{
    tcg_out_opc(s, 0x58 + reg);
}

/* Generate global QEMU prologue and epilogue code */
void tcg_target_qemu_prologue(TCGContext *s)
{
    int i, frame_size, push_size, stack_addend;
    
    /* TB prologue */
    /* save all callee saved registers */
    for(i = 0; i < ARRAY_SIZE(tcg_target_callee_save_regs); i++) {
        tcg_out_push(s, tcg_target_callee_save_regs[i]);
    }
    /* reserve some stack space */
    push_size = 4 + ARRAY_SIZE(tcg_target_callee_save_regs) * 4;
    frame_size = push_size + TCG_STATIC_CALL_ARGS_SIZE;
    frame_size = (frame_size + TCG_TARGET_STACK_ALIGN - 1) & 
        ~(TCG_TARGET_STACK_ALIGN - 1);
    stack_addend = frame_size - push_size;
    tcg_out_addi(s, TCG_REG_ESP, -stack_addend);

    tcg_out_modrm(s, 0xff, 4, TCG_REG_EAX); /* jmp *%eax */
    
    /* TB epilogue */
    tb_ret_addr = s->code_ptr;
    tcg_out_addi(s, TCG_REG_ESP, stack_addend);
    for(i = ARRAY_SIZE(tcg_target_callee_save_regs) - 1; i >= 0; i--) {
        tcg_out_pop(s, tcg_target_callee_save_regs[i]);
    }
    tcg_out8(s, 0xc3); /* ret */
}

void tcg_target_init(TCGContext *s)
{
    /* fail safe */
    if ((1 << CPU_TLB_ENTRY_BITS) != sizeof(CPUTLBEntry))
        tcg_abort();

    tcg_regset_set32(tcg_target_available_regs[TCG_TYPE_I32], 0, 0xff);
    tcg_regset_set32(tcg_target_call_clobber_regs, 0,
                     (1 << TCG_REG_EAX) | 
                     (1 << TCG_REG_EDX) | 
                     (1 << TCG_REG_ECX));
    
    tcg_regset_clear(s->reserved_regs);
    tcg_regset_set_reg(s->reserved_regs, TCG_REG_ESP);

    tcg_add_target_add_op_defs(x86_op_defs);
}