tccasm.c

一个GNU的C语言编译器源代码,源代码过万行.

            sname[0] = '\0';
            while (tok != ';' && tok != TOK_LINEFEED && tok != ',') {
                if (tok == TOK_STR)
                    pstrcat(sname, sizeof(sname), tokc.cstr->data);
                else
                    pstrcat(sname, sizeof(sname), get_tok_str(tok, NULL));
                next();
            }
            use_section(s1, sname);
        }
        break;
    default:
        error("unknown assembler directive '.%s'", get_tok_str(tok, NULL));
        break;
    }
}


/* assemble a file */
static int tcc_assemble_internal(TCCState *s1, int do_preprocess)
{
    int opcode;

#if 0
    /* print stats about opcodes */
    {
        const ASMInstr *pa;
        int freq[4];
        int op_vals[500];
        int nb_op_vals, i, j;

        nb_op_vals = 0;
        memset(freq, 0, sizeof(freq));
        for(pa = asm_instrs; pa->sym != 0; pa++) {
            freq[pa->nb_ops]++;
            for(i=0;i<pa->nb_ops;i++) {
                for(j=0;j<nb_op_vals;j++) {
                    if (pa->op_type[i] == op_vals[j])
                        goto found;
                }
                op_vals[nb_op_vals++] = pa->op_type[i];
            found: ;
            }
        }
        for(i=0;i<nb_op_vals;i++) {
            int v = op_vals[i];
            if ((v & (v - 1)) != 0)
                printf("%3d: %08x\n", i, v);
        }
        printf("size=%d nb=%d f0=%d f1=%d f2=%d f3=%d\n",
               sizeof(asm_instrs), sizeof(asm_instrs) / sizeof(ASMInstr),
               freq[0], freq[1], freq[2], freq[3]);
    }
#endif

    /* XXX: undefine C labels */

    ch = file->buf_ptr[0];
    tok_flags = TOK_FLAG_BOL | TOK_FLAG_BOF;
    parse_flags = 0;
    if (do_preprocess)
        parse_flags |= PARSE_FLAG_PREPROCESS;
    next();
    for(;;) {
        if (tok == TOK_EOF)
            break;
        parse_flags |= PARSE_FLAG_LINEFEED; /* XXX: suppress that hack */
    redo:
        if (tok == '#') {
            /* horrible gas comment */
            while (tok != TOK_LINEFEED)
                next();
        } else if (tok == '.') {
            asm_parse_directive(s1);
        } else if (tok == TOK_PPNUM) {
            const char *p;
            int n;
            p = tokc.cstr->data;
            n = strtoul(p, (char **)&p, 10);
            if (*p != '\0')
                expect("':'");
            /* new local label */
            asm_new_label(s1, asm_get_local_label_name(s1, n), 1);
            next();
            skip(':');
            goto redo;
        } else if (tok >= TOK_IDENT) {
            /* instruction or label */
            opcode = tok;
            next();
            if (tok == ':') {
                /* new label */
                asm_new_label(s1, opcode, 0);
                next();
                goto redo;
            } else {
                asm_opcode(s1, opcode);
            }
        }
        /* end of line */
        if (tok != ';' && tok != TOK_LINEFEED){
            expect("end of line");
        }
        parse_flags &= ~PARSE_FLAG_LINEFEED; /* XXX: suppress that hack */
        next();
    }

    asm_free_labels(s1);

    return 0;
}

/* Assemble the current file */
static int tcc_assemble(TCCState *s1, int do_preprocess)
{
    int ret;

    preprocess_init(s1);

    /* default section is text */
    cur_text_section = text_section;
    ind = cur_text_section->data_offset;

    ret = tcc_assemble_internal(s1, do_preprocess);

    cur_text_section->data_offset = ind;
    return ret;
}

/********************************************************************/
/* GCC inline asm support */

/* assemble the string 'str' in the current C compilation unit without
   C preprocessing. NOTE: str is modified by modifying the '\0' at the
   end */
static void tcc_assemble_inline(TCCState *s1, char *str, int len)
{
    BufferedFile *bf, *saved_file;
    int saved_parse_flags, *saved_macro_ptr;

    bf = tcc_malloc(sizeof(BufferedFile));
    memset(bf, 0, sizeof(BufferedFile));
    bf->fd = -1;
    bf->buf_ptr = str;
    bf->buf_end = str + len;
    str[len] = CH_EOB;
    /* same name as current file so that errors are correctly
       reported */
    pstrcpy(bf->filename, sizeof(bf->filename), file->filename);
    bf->line_num = file->line_num;
    saved_file = file;
    file = bf;
    saved_parse_flags = parse_flags;
    saved_macro_ptr = macro_ptr;
    macro_ptr = NULL;
    
    tcc_assemble_internal(s1, 0);

    parse_flags = saved_parse_flags;
    macro_ptr = saved_macro_ptr;
    file = saved_file;
    tcc_free(bf);
}

/* find a constraint by its number or id (gcc 3 extended
   syntax). return -1 if not found. Return in *pp in char after the
   constraint */
static int find_constraint(ASMOperand *operands, int nb_operands, 
                           const char *name, const char **pp)
{
    int index;
    TokenSym *ts;
    const char *p;

    if (isnum(*name)) {
        index = 0;
        while (isnum(*name)) {
            index = (index * 10) + (*name) - '0';
            name++;
        }
        if ((unsigned)index >= nb_operands)
            index = -1;
    } else if (*name == '[') {
        name++;
        p = strchr(name, ']');
        if (p) {
            ts = tok_alloc(name, p - name);
            for(index = 0; index < nb_operands; index++) {
                if (operands[index].id == ts->tok)
                    goto found;
            }
            index = -1;
        found:
            name = p + 1;
        } else {
            index = -1;
        }
    } else {
        index = -1;
    }
    if (pp)
        *pp = name;
    return index;
}

static void subst_asm_operands(ASMOperand *operands, int nb_operands, 
                               int nb_outputs,
                               CString *out_str, CString *in_str)
{
    int c, index, modifier;
    const char *str;
    ASMOperand *op;
    SValue sv;

    cstr_new(out_str);
    str = in_str->data;
    for(;;) {
        c = *str++;
        if (c == '%') {
            if (*str == '%') {
                str++;
                goto add_char;
            }
            modifier = 0;
            if (*str == 'c' || *str == 'n' ||
                *str == 'b' || *str == 'w' || *str == 'h')
                modifier = *str++;
            index = find_constraint(operands, nb_operands, str, &str);
            if (index < 0)
                error("invalid operand reference after %%");
            op = &operands[index];
            sv = *op->vt;
            if (op->reg >= 0) {
                sv.r = op->reg;
                if ((op->vt->r & VT_VALMASK) == VT_LLOCAL)
                    sv.r |= VT_LVAL;
            }
            subst_asm_operand(out_str, &sv, modifier);
        } else {
        add_char:
            cstr_ccat(out_str, c);
            if (c == '\0')
                break;
        }
    }
}


static void parse_asm_operands(ASMOperand *operands, int *nb_operands_ptr,
                               int is_output)
{
    ASMOperand *op;
    int nb_operands;

    if (tok != ':') {
        nb_operands = *nb_operands_ptr;
        for(;;) {
            if (nb_operands >= MAX_ASM_OPERANDS)
                error("too many asm operands");
            op = &operands[nb_operands++];
            op->id = 0;
            if (tok == '[') {
                next();
                if (tok < TOK_IDENT)
                    expect("identifier");
                op->id = tok;
                next();
                skip(']');
            }
            if (tok != TOK_STR)
                expect("string constant");
            op->constraint = tcc_malloc(tokc.cstr->size);
            strcpy(op->constraint, tokc.cstr->data);
            next();
            skip('(');
            gexpr();
            if (is_output) {
                test_lvalue();
            } else {
                /* we want to avoid LLOCAL case. note that it may come
                   from register storage, so we need to convert (reg)
                   case */
                if ((vtop->r & VT_LVAL) &&
                    ((vtop->r & VT_VALMASK) == VT_LLOCAL ||
                     (vtop->r & VT_VALMASK) < VT_CONST)) {
                    gv(RC_INT);
                }
            }
            op->vt = vtop;
            skip(')');
            if (tok == ',') {
                next();
            } else {
                break;
            }
        }
        *nb_operands_ptr = nb_operands;
    }
}

/* parse the GCC asm() instruction */
static void asm_instr(void)
{
    CString astr, astr1;
    ASMOperand operands[MAX_ASM_OPERANDS];
    int nb_inputs, nb_outputs, nb_operands, i;
    uint8_t input_regs_allocated[NB_ASM_REGS];
    uint8_t output_regs_allocated[NB_ASM_REGS];
    uint8_t clobber_regs[NB_ASM_REGS];

    next();
    /* since we always generate the asm() instruction, we can ignore
       volatile */
    if (tok == TOK_VOLATILE1 || tok == TOK_VOLATILE2 || tok == TOK_VOLATILE3) {
        next();
    }
    skip('(');
    /* read the string */
    if (tok != TOK_STR)
        expect("string constant");
    cstr_new(&astr);
    while (tok == TOK_STR) {
        /* XXX: add \0 handling too ? */
        cstr_cat(&astr, tokc.cstr->data);
        next();
    }
    cstr_ccat(&astr, '\0');
    nb_operands = 0;
    nb_outputs = 0;
    memset(clobber_regs, 0, sizeof(clobber_regs));
    if (tok == ':') {
        next();
        /* output args */
        parse_asm_operands(operands, &nb_operands, 1);
        nb_outputs = nb_operands;
        if (tok == ':') {
            next();
            /* input args */
            parse_asm_operands(operands, &nb_operands, 0);
            if (tok == ':') {
                /* clobber list */
                /* XXX: handle registers */
                next();
                for(;;) {
                    if (tok != TOK_STR)
                        expect("string constant");
                    asm_clobber(clobber_regs, tokc.cstr->data);
                    next();
                    if (tok == ',') {
                        next();
                    } else {
                        break;
                    }
                }
            }
        }
    }
    skip(')');
    /* NOTE: we do not eat the ';' so that we can restore the current
       token after the assembler parsing */
    if (tok != ';')
        expect("';'");
    nb_inputs = nb_operands - nb_outputs;
    
    /* save all values in the memory */
    save_regs(0);

    /* compute constraints */
    asm_compute_constraints(input_regs_allocated, 
                            operands, nb_operands, nb_outputs, 0, 
                            NULL);
    asm_compute_constraints(output_regs_allocated,
                            operands, nb_operands, nb_outputs, 1, 
                            input_regs_allocated);

    /* substitute the operands in the asm string. No substitution is
       done if no operands (GCC behaviour) */
#ifdef ASM_DEBUG
    printf("asm: \"%s\"\n", (char *)astr.data);
#endif
    if (nb_operands > 0) {
        subst_asm_operands(operands, nb_operands, nb_outputs, &astr1, &astr);
        cstr_free(&astr);
    } else {
        astr1 = astr;
    }
#ifdef ASM_DEBUG
    printf("subst_asm: \"%s\"\n", (char *)astr1.data);
#endif

    /* generate loads */
    asm_gen_code(operands, nb_operands, nb_outputs, 0, clobber_regs);    

    /* assemble the string with tcc internal assembler */
    tcc_assemble_inline(tcc_state, astr1.data, astr1.size - 1);

    /* restore the current C token */
    next();

    /* store the output values if needed */
    asm_gen_code(operands, nb_operands, nb_outputs, 1, clobber_regs);    
    
    /* free everything */
    for(i=0;i<nb_operands;i++) {
        ASMOperand *op;
        op = &operands[i];
        tcc_free(op->constraint);
        vpop();
    }
    cstr_free(&astr1);
}