tcg-target.c

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/*
 * 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.
 */
const char *tcg_target_reg_names[TCG_TARGET_NB_REGS] = {
    "%eax",
    "%ecx",
    "%edx",
    "%ebx",
    "%esp",
    "%ebp",
    "%esi",
    "%edi",
};

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,
    TCG_REG_ESP,
};

const int tcg_target_call_iarg_regs[3] = { TCG_REG_EAX, TCG_REG_EDX, TCG_REG_ECX };
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;
    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 */
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_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)
{
    if (val == (int8_t)val) {
        tcg_out_modrm(s, 0x83, c, r0);
        tcg_out8(s, val);
    } else {
        tcg_out_modrm(s, 0x81, c, r0);
        tcg_out32(s, val);
    }
}

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

static void tcg_out_jxx(TCGContext *s, int opc, int label_index)
{
    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 (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 (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_brcond(TCGContext *s, int cond, 
                           TCGArg arg1, TCGArg arg2, int const_arg2,
                           int label_index)
{
    int c;
    if (const_arg2) {
        if (arg2 == 0) {
            /* use test */
            switch(cond) {
            case TCG_COND_EQ:
                c = JCC_JE;
                break;
            case TCG_COND_NE:
                c = JCC_JNE;
                break;
            case TCG_COND_LT:
                c = JCC_JS;
                break;
            case TCG_COND_GE:
                c = JCC_JNS;
                break;
            default:
                goto do_cmpi;
            }
            /* test r, r */
            tcg_out_modrm(s, 0x85, arg1, arg1);
            tcg_out_jxx(s, c, label_index);
        } else {
        do_cmpi:
            tgen_arithi(s, ARITH_CMP, arg1, arg2);
            tcg_out_jxx(s, tcg_cond_to_jcc[cond], label_index);
        }
    } else {
        tcg_out_modrm(s, 0x01 | (ARITH_CMP << 3), arg2, arg1);
        tcg_out_jxx(s, tcg_cond_to_jcc[cond], label_index);
    }
}

/* 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 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);
        tcg_out_brcond(s, TCG_COND_EQ, args[1], args[3], const_args[3], args[5]);
        break;
    case TCG_COND_NE:
        tcg_out_brcond(s, TCG_COND_NE, args[0], args[2], const_args[2], args[5]);
        tcg_out_brcond(s, TCG_COND_NE, args[1], args[3], const_args[3], args[5]);
        break;
    case TCG_COND_LT:
        tcg_out_brcond(s, TCG_COND_LT, args[1], args[3], const_args[3], args[5]);
        tcg_out_brcond(s, TCG_COND_NE, args[1], args[3], const_args[3], label_next);
        tcg_out_brcond(s, TCG_COND_LT, args[0], args[2], const_args[2], args[5]);
        break;
    case TCG_COND_LE:
        tcg_out_brcond(s, TCG_COND_LT, args[1], args[3], const_args[3], args[5]);
        tcg_out_brcond(s, TCG_COND_NE, args[1], args[3], const_args[3], label_next);
        tcg_out_brcond(s, TCG_COND_LE, args[0], args[2], const_args[2], args[5]);
        break;
    case TCG_COND_GT:
        tcg_out_brcond(s, TCG_COND_GT, args[1], args[3], const_args[3], args[5]);
        tcg_out_brcond(s, TCG_COND_NE, args[1], args[3], const_args[3], label_next);
        tcg_out_brcond(s, TCG_COND_GT, args[0], args[2], const_args[2], args[5]);
        break;
    case TCG_COND_GE:
        tcg_out_brcond(s, TCG_COND_GT, args[1], args[3], const_args[3], args[5]);
        tcg_out_brcond(s, TCG_COND_NE, args[1], args[3], const_args[3], label_next);
        tcg_out_brcond(s, TCG_COND_GE, args[0], args[2], const_args[2], args[5]);
        break;
    case TCG_COND_LTU:
        tcg_out_brcond(s, TCG_COND_LTU, args[1], args[3], const_args[3], args[5]);
        tcg_out_brcond(s, TCG_COND_NE, args[1], args[3], const_args[3], label_next);
        tcg_out_brcond(s, TCG_COND_LTU, args[0], args[2], const_args[2], args[5]);