tccasm.c

一个GNU的C语言编译器源代码,源代码过万行.

/*
 *  GAS like assembler for TCC
 * 
 *  Copyright (c) 2001, 2002 Fabrice Bellard
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

static int asm_get_local_label_name(TCCState *s1, unsigned int n)
{
    char buf[64];
    TokenSym *ts;

    snprintf(buf, sizeof(buf), "L..%u", n);
    ts = tok_alloc(buf, strlen(buf));
    return ts->tok;
}

/* We do not use the C expression parser to handle symbols. Maybe the
   C expression parser could be tweaked to do so. */

static void asm_expr_unary(TCCState *s1, ExprValue *pe)
{
    Sym *sym;
    int op, n, label;
    const char *p;

    switch(tok) {
    case TOK_PPNUM:
        p = tokc.cstr->data;
        n = strtoul(p, (char **)&p, 0);
        if (*p == 'b' || *p == 'f') {
            /* backward or forward label */
            label = asm_get_local_label_name(s1, n);
            sym = label_find(label);
            if (*p == 'b') {
                /* backward : find the last corresponding defined label */
                if (sym && sym->r == 0)
                    sym = sym->prev_tok;
                if (!sym)
                    error("local label '%d' not found backward", n);
            } else {
                /* forward */
                if (!sym || sym->r) {
                    /* if the last label is defined, then define a new one */
                    sym = label_push(&s1->asm_labels, label, 0);
                    sym->type.t = VT_STATIC | VT_VOID;
                }
            }
            pe->v = 0;
            pe->sym = sym;
        } else if (*p == '\0') {
            pe->v = n;
            pe->sym = NULL;
        } else {
            error("invalid number syntax");
        }
        next();
        break;
    case '+':
        next();
        asm_expr_unary(s1, pe);
        break;
    case '-':
    case '~':
        op = tok;
        next();
        asm_expr_unary(s1, pe);
        if (pe->sym)
            error("invalid operation with label");
        if (op == '-')
            pe->v = -pe->v;
        else
            pe->v = ~pe->v;
        break;
    case TOK_CCHAR:
    case TOK_LCHAR:
	pe->v = tokc.i;
	pe->sym = NULL;
	next();
	break;
    default:
        if (tok >= TOK_IDENT) {
            /* label case : if the label was not found, add one */
            sym = label_find(tok);
            if (!sym) {
                sym = label_push(&s1->asm_labels, tok, 0);
                /* NOTE: by default, the symbol is global */
                sym->type.t = VT_VOID;
            }
            pe->v = 0;
            pe->sym = sym;
            next();
        } else {
            error("bad expression syntax [%s]", get_tok_str(tok, &tokc));
        }
        break;
    }
}
    
static void asm_expr_prod(TCCState *s1, ExprValue *pe)
{
    int op;
    ExprValue e2;

    asm_expr_unary(s1, pe);
    for(;;) {
        op = tok;
        if (op != '*' && op != '/' && op != '%' && 
            op != TOK_SHL && op != TOK_SAR)
            break;
        next();
        asm_expr_unary(s1, &e2);
        if (pe->sym || e2.sym)
            error("invalid operation with label");
        switch(op) {
        case '*':
            pe->v *= e2.v;
            break;
        case '/':  
            if (e2.v == 0) {
            div_error:
                error("division by zero");
            }
            pe->v /= e2.v;
            break;
        case '%':  
            if (e2.v == 0)
                goto div_error;
            pe->v %= e2.v;
            break;
        case TOK_SHL:
            pe->v <<= e2.v;
            break;
        default:
        case TOK_SAR:
            pe->v >>= e2.v;
            break;
        }
    }
}

static void asm_expr_logic(TCCState *s1, ExprValue *pe)
{
    int op;
    ExprValue e2;

    asm_expr_prod(s1, pe);
    for(;;) {
        op = tok;
        if (op != '&' && op != '|' && op != '^')
            break;
        next();
        asm_expr_prod(s1, &e2);
        if (pe->sym || e2.sym)
            error("invalid operation with label");
        switch(op) {
        case '&':
            pe->v &= e2.v;
            break;
        case '|':  
            pe->v |= e2.v;
            break;
        default:
        case '^':
            pe->v ^= e2.v;
            break;
        }
    }
}

static inline void asm_expr_sum(TCCState *s1, ExprValue *pe)
{
    int op;
    ExprValue e2;

    asm_expr_logic(s1, pe);
    for(;;) {
        op = tok;
        if (op != '+' && op != '-')
            break;
        next();
        asm_expr_logic(s1, &e2);
        if (op == '+') {
            if (pe->sym != NULL && e2.sym != NULL)
                goto cannot_relocate;
            pe->v += e2.v;
            if (pe->sym == NULL && e2.sym != NULL)
                pe->sym = e2.sym;
        } else {
            pe->v -= e2.v;
            /* NOTE: we are less powerful than gas in that case
               because we store only one symbol in the expression */
            if (!pe->sym && !e2.sym) {
                /* OK */
            } else if (pe->sym && !e2.sym) {
                /* OK */
            } else if (pe->sym && e2.sym) {
                if (pe->sym == e2.sym) { 
                    /* OK */
                } else if (pe->sym->r == e2.sym->r && pe->sym->r != 0) {
                    /* we also accept defined symbols in the same section */
                    pe->v += (long)pe->sym->next - (long)e2.sym->next;
                } else {
                    goto cannot_relocate;
                }
                pe->sym = NULL; /* same symbols can be substracted to NULL */
            } else {
            cannot_relocate:
                error("invalid operation with label");
            }
        }
    }
}

static void asm_expr(TCCState *s1, ExprValue *pe)
{
    asm_expr_sum(s1, pe);
}

static int asm_int_expr(TCCState *s1)
{
    ExprValue e;
    asm_expr(s1, &e);
    if (e.sym)
        expect("constant");
    return e.v;
}

/* NOTE: the same name space as C labels is used to avoid using too
   much memory when storing labels in TokenStrings */
static void asm_new_label(TCCState *s1, int label, int is_local)
{
    Sym *sym;

    sym = label_find(label);
    if (sym) {
        if (sym->r) {
            /* the label is already defined */
            if (!is_local) {
                error("assembler label '%s' already defined", 
                      get_tok_str(label, NULL));
            } else {
                /* redefinition of local labels is possible */
                goto new_label;
            }
        }
    } else {
    new_label:
        sym = label_push(&s1->asm_labels, label, 0);
        sym->type.t = VT_STATIC | VT_VOID;
    }
    sym->r = cur_text_section->sh_num;
    sym->next = (void *)ind;
}

static void asm_free_labels(TCCState *st)
{
    Sym *s, *s1;
    for(s = st->asm_labels; s != NULL; s = s1) {
        s1 = s->prev;
        /* define symbol value in object file */
        if (s->r) {
            put_extern_sym(s, st->sections[s->r], (long)s->next, 0);
        }
        /* remove label */
        table_ident[s->v - TOK_IDENT]->sym_label = NULL;
        tcc_free(s);
    }
    st->asm_labels = NULL;
}

static void use_section(TCCState *s1, const char *name)
{
    Section *sec;
    sec = find_section(s1, name);
    cur_text_section->data_offset = ind;
    cur_text_section = sec;
    ind = cur_text_section->data_offset;
}

static void asm_parse_directive(TCCState *s1)
{
    int n, offset, v, size, tok1;
    Section *sec;
    uint8_t *ptr;

    /* assembler directive */
    next();
    sec = cur_text_section;
    switch(tok) {
    case TOK_ASM_align:
    case TOK_ASM_skip:
    case TOK_ASM_space:
        tok1 = tok;
        next();
        n = asm_int_expr(s1);
        if (tok1 == TOK_ASM_align) {
            if (n < 0 || (n & (n-1)) != 0)
                error("alignment must be a positive power of two");
            offset = (ind + n - 1) & -n;
            size = offset - ind;
        } else {
            size = n;
        }
        v = 0;
        if (tok == ',') {
            next();
            v = asm_int_expr(s1);
        }
        if (sec->sh_type != SHT_NOBITS) {
            sec->data_offset = ind;
            ptr = section_ptr_add(sec, size);
            memset(ptr, v, size);
        }
        ind += size;
        break;
    case TOK_ASM_byte:
        size = 1;
        goto asm_data;
    case TOK_ASM_word:
    case TOK_SHORT:
        size = 2;
        goto asm_data;
    case TOK_LONG:
    case TOK_INT:
        size = 4;
    asm_data:
        next();
        for(;;) {
            ExprValue e;
            asm_expr(s1, &e);
            if (sec->sh_type != SHT_NOBITS) {
                if (size == 4) {
                    gen_expr32(&e);
                } else {
                    if (e.sym)
                        expect("constant");
                    if (size == 1)
                        g(e.v);
                    else
                        gen_le16(e.v);
                }
            } else {
                ind += size;
            }
            if (tok != ',')
                break;
            next();
        }
        break;
    case TOK_ASM_globl:
	{ 
            Sym *sym;

            next();
            sym = label_find(tok);
            if (!sym) {
                sym = label_push(&s1->asm_labels, tok, 0);
                sym->type.t = VT_VOID;
            }
            sym->type.t &= ~VT_STATIC;
            next();
	}
	break;
    case TOK_ASM_string:
        {
            const uint8_t *p;
            int i;

            next();
            if (tok != TOK_STR)
                expect("string constant");
            p = tokc.cstr->data;
            for(i = 0; i < tokc.cstr->size; i++)
                g(p[i]);
            next();
	}
	break;
    case TOK_ASM_text:
    case TOK_ASM_data:
    case TOK_ASM_bss:
	{ 
            char sname[64];
            tok1 = tok;
            n = 0;
            next();
            if (tok != ';' && tok != TOK_LINEFEED) {
		n = asm_int_expr(s1);
		next();
            }
            sprintf(sname, (n?".%s%d":".%s"), get_tok_str(tok1, NULL), n);
            use_section(s1, sname);
	}
	break;
    case TOK_SECTION1:
        {
            char sname[256];

            /* XXX: support more options */
            next();