tccasm.c

   1 /*
   2  *  GAS like assembler for TCC
   3  *
   4  *  Copyright (c) 2001-2004 Fabrice Bellard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "tcc.h"
  22
  23 ST_FUNC int asm_get_local_label_name(TCCState *s1, unsigned int n)
  24 {
  25     char buf[64];
  26     TokenSym *ts;
  27
  28     snprintf(buf, sizeof(buf), "L..%u", n);
  29     ts = tok_alloc(buf, strlen(buf));
  30     return ts->tok;
  31 }
  32
  33 ST_FUNC void asm_expr(TCCState *s1, ExprValue *pe);
  34
  35 /* We do not use the C expression parser to handle symbols. Maybe the
  36    C expression parser could be tweaked to do so. */
  37
  38 static void asm_expr_unary(TCCState *s1, ExprValue *pe)
  39 {
  40     Sym *sym;
  41     int op, n, label;
  42     const char *p;
  43
  44     switch(tok) {
  45     case TOK_PPNUM:
  46         p = tokc.cstr->data;
  47         n = strtoul(p, (char **)&p, 0);
  48         if (*p == 'b' || *p == 'f') {
  49             /* backward or forward label */
  50             label = asm_get_local_label_name(s1, n);
  51             sym = label_find(label);
  52             if (*p == 'b') {
  53                 /* backward : find the last corresponding defined label */
  54                 if (sym && sym->r == 0)
  55                     sym = sym->prev_tok;
  56                 if (!sym)
  57                     error("local label '%d' not found backward", n);
  58             } else {
  59                 /* forward */
  60                 if (!sym || sym->r) {
  61                     /* if the last label is defined, then define a new one */
  62                     sym = label_push(&s1->asm_labels, label, 0);
  63                     sym->type.t = VT_STATIC | VT_VOID;
  64                 }
  65             }
  66             pe->v = 0;
  67             pe->sym = sym;
  68         } else if (*p == '\0') {
  69             pe->v = n;
  70             pe->sym = NULL;
  71         } else {
  72             error("invalid number syntax");
  73         }
  74         next();
  75         break;
  76     case '+':
  77         next();
  78         asm_expr_unary(s1, pe);
  79         break;
  80     case '-':
  81     case '~':
  82         op = tok;
  83         next();
  84         asm_expr_unary(s1, pe);
  85         if (pe->sym)
  86             error("invalid operation with label");
  87         if (op == '-')
  88             pe->v = -pe->v;
  89         else
  90             pe->v = ~pe->v;
  91         break;
  92     case TOK_CCHAR:
  93     case TOK_LCHAR:
  94         pe->v = tokc.i;
  95         pe->sym = NULL;
  96         next();
  97         break;
  98     case '(':
  99         next();
 100         asm_expr(s1, pe);
 101         skip(')');
 102         break;
 103     default:
 104         if (tok >= TOK_IDENT) {
 105             /* label case : if the label was not found, add one */
 106             sym = label_find(tok);
 107             if (!sym) {
 108                 sym = label_push(&s1->asm_labels, tok, 0);
 109                 /* NOTE: by default, the symbol is global */
 110                 sym->type.t = VT_VOID;
 111             }
 112             if (sym->r == SHN_ABS) {
 113                 /* if absolute symbol, no need to put a symbol value */
 114                 pe->v = sym->jnext;
 115                 pe->sym = NULL;
 116             } else {
 117                 pe->v = 0;
 118                 pe->sym = sym;
 119             }
 120             next();
 121         } else {
 122             error("bad expression syntax [%s]", get_tok_str(tok, &tokc));
 123         }
 124         break;
 125     }
 126 }
 127
 128 static void asm_expr_prod(TCCState *s1, ExprValue *pe)
 129 {
 130     int op;
 131     ExprValue e2;
 132
 133     asm_expr_unary(s1, pe);
 134     for(;;) {
 135         op = tok;
 136         if (op != '*' && op != '/' && op != '%' &&
 137             op != TOK_SHL && op != TOK_SAR)
 138             break;
 139         next();
 140         asm_expr_unary(s1, &e2);
 141         if (pe->sym || e2.sym)
 142             error("invalid operation with label");
 143         switch(op) {
 144         case '*':
 145             pe->v *= e2.v;
 146             break;
 147         case '/':
 148             if (e2.v == 0) {
 149             div_error:
 150                 error("division by zero");
 151             }
 152             pe->v /= e2.v;
 153             break;
 154         case '%':
 155             if (e2.v == 0)
 156                 goto div_error;
 157             pe->v %= e2.v;
 158             break;
 159         case TOK_SHL:
 160             pe->v <<= e2.v;
 161             break;
 162         default:
 163         case TOK_SAR:
 164             pe->v >>= e2.v;
 165             break;
 166         }
 167     }
 168 }
 169
 170 static void asm_expr_logic(TCCState *s1, ExprValue *pe)
 171 {
 172     int op;
 173     ExprValue e2;
 174
 175     asm_expr_prod(s1, pe);
 176     for(;;) {
 177         op = tok;
 178         if (op != '&' && op != '|' && op != '^')
 179             break;
 180         next();
 181         asm_expr_prod(s1, &e2);
 182         if (pe->sym || e2.sym)
 183             error("invalid operation with label");
 184         switch(op) {
 185         case '&':
 186             pe->v &= e2.v;
 187             break;
 188         case '|':
 189             pe->v |= e2.v;
 190             break;
 191         default:
 192         case '^':
 193             pe->v ^= e2.v;
 194             break;
 195         }
 196     }
 197 }
 198
 199 static inline void asm_expr_sum(TCCState *s1, ExprValue *pe)
 200 {
 201     int op;
 202     ExprValue e2;
 203
 204     asm_expr_logic(s1, pe);
 205     for(;;) {
 206         op = tok;
 207         if (op != '+' && op != '-')
 208             break;
 209         next();
 210         asm_expr_logic(s1, &e2);
 211         if (op == '+') {
 212             if (pe->sym != NULL && e2.sym != NULL)
 213                 goto cannot_relocate;
 214             pe->v += e2.v;
 215             if (pe->sym == NULL && e2.sym != NULL)
 216                 pe->sym = e2.sym;
 217         } else {
 218             pe->v -= e2.v;
 219             /* NOTE: we are less powerful than gas in that case
 220                because we store only one symbol in the expression */
 221             if (!pe->sym && !e2.sym) {
 222                 /* OK */
 223             } else if (pe->sym && !e2.sym) {
 224                 /* OK */
 225             } else if (pe->sym && e2.sym) {
 226                 if (pe->sym == e2.sym) {
 227                     /* OK */
 228                 } else if (pe->sym->r == e2.sym->r && pe->sym->r != 0) {
 229                     /* we also accept defined symbols in the same section */
 230                     pe->v += pe->sym->jnext - e2.sym->jnext;
 231                 } else {
 232                     goto cannot_relocate;
 233                 }
 234                 pe->sym = NULL; /* same symbols can be substracted to NULL */
 235             } else {
 236             cannot_relocate:
 237                 error("invalid operation with label");
 238             }
 239         }
 240     }
 241 }
 242
 243 ST_FUNC void asm_expr(TCCState *s1, ExprValue *pe)
 244 {
 245     asm_expr_sum(s1, pe);
 246 }
 247
 248 ST_FUNC int asm_int_expr(TCCState *s1)
 249 {
 250     ExprValue e;
 251     asm_expr(s1, &e);
 252     if (e.sym)
 253         expect("constant");
 254     return e.v;
 255 }
 256
 257 /* NOTE: the same name space as C labels is used to avoid using too
 258    much memory when storing labels in TokenStrings */
 259 static void asm_new_label1(TCCState *s1, int label, int is_local,
 260                            int sh_num, int value)
 261 {
 262     Sym *sym;
 263
 264     sym = label_find(label);
 265     if (sym) {
 266         if (sym->r) {
 267             /* the label is already defined */
 268             if (!is_local) {
 269                 error("assembler label '%s' already defined",
 270                       get_tok_str(label, NULL));
 271             } else {
 272                 /* redefinition of local labels is possible */
 273                 goto new_label;
 274             }
 275         }
 276     } else {
 277     new_label:
 278         sym = label_push(&s1->asm_labels, label, 0);
 279         sym->type.t = VT_STATIC | VT_VOID;
 280     }
 281     sym->r = sh_num;
 282     sym->jnext = value;
 283 }
 284
 285 static void asm_new_label(TCCState *s1, int label, int is_local)
 286 {
 287     asm_new_label1(s1, label, is_local, cur_text_section->sh_num, ind);
 288 }
 289
 290 static void asm_free_labels(TCCState *st)
 291 {
 292     Sym *s, *s1;
 293     Section *sec;
 294
 295     for(s = st->asm_labels; s != NULL; s = s1) {
 296         s1 = s->prev;
 297         /* define symbol value in object file */
 298         if (s->r) {
 299             if (s->r == SHN_ABS)
 300                 sec = SECTION_ABS;
 301             else
 302                 sec = st->sections[s->r];
 303             put_extern_sym2(s, sec, s->jnext, 0, 0);
 304         }
 305         /* remove label */
 306         table_ident[s->v - TOK_IDENT]->sym_label = NULL;
 307         sym_free(s);
 308     }
 309     st->asm_labels = NULL;
 310 }
 311
 312 static void use_section1(TCCState *s1, Section *sec)
 313 {
 314     cur_text_section->data_offset = ind;
 315     cur_text_section = sec;
 316     ind = cur_text_section->data_offset;
 317 }
 318
 319 static void use_section(TCCState *s1, const char *name)
 320 {
 321     Section *sec;
 322     sec = find_section(s1, name);
 323     use_section1(s1, sec);
 324 }
 325
 326 static void asm_parse_directive(TCCState *s1)
 327 {
 328     int n, offset, v, size, tok1;
 329     Section *sec;
 330     uint8_t *ptr;
 331
 332     /* assembler directive */
 333     next();
 334     sec = cur_text_section;
 335     switch(tok) {
 336     case TOK_ASM_align:
 337     case TOK_ASM_skip:
 338     case TOK_ASM_space:
 339         tok1 = tok;
 340         next();
 341         n = asm_int_expr(s1);
 342         if (tok1 == TOK_ASM_align) {
 343             if (n < 0 || (n & (n-1)) != 0)
 344                 error("alignment must be a positive power of two");
 345             offset = (ind + n - 1) & -n;
 346             size = offset - ind;
 347             /* the section must have a compatible alignment */
 348             if (sec->sh_addralign < n)
 349                 sec->sh_addralign = n;
 350         } else {
 351             size = n;
 352         }
 353         v = 0;
 354         if (tok == ',') {
 355             next();
 356             v = asm_int_expr(s1);
 357         }
 358     zero_pad:
 359         if (sec->sh_type != SHT_NOBITS) {
 360             sec->data_offset = ind;
 361             ptr = section_ptr_add(sec, size);
 362             memset(ptr, v, size);
 363         }
 364         ind += size;
 365         break;
 366     case TOK_ASM_quad:
 367         next();
 368         for(;;) {
 369             uint64_t vl;
 370             const char *p;
 371
 372             p = tokc.cstr->data;
 373             if (tok != TOK_PPNUM) {
 374             error_constant:
 375                 error("64 bit constant");
 376             }
 377             vl = strtoll(p, (char **)&p, 0);
 378             if (*p != '\0')
 379                 goto error_constant;
 380             next();
 381             if (sec->sh_type != SHT_NOBITS) {
 382                 /* XXX: endianness */
 383                 gen_le32(vl);
 384                 gen_le32(vl >> 32);
 385             } else {
 386                 ind += 8;
 387             }
 388             if (tok != ',')
 389                 break;
 390             next();
 391         }
 392         break;
 393     case TOK_ASM_byte:
 394         size = 1;
 395         goto asm_data;
 396     case TOK_ASM_word:
 397     case TOK_SHORT:
 398         size = 2;
 399         goto asm_data;
 400     case TOK_LONG:
 401     case TOK_INT:
 402         size = 4;
 403     asm_data:
 404         next();
 405         for(;;) {
 406             ExprValue e;
 407             asm_expr(s1, &e);
 408             if (sec->sh_type != SHT_NOBITS) {
 409                 if (size == 4) {
 410                     gen_expr32(&e);
 411                 } else {
 412                     if (e.sym)
 413                         expect("constant");
 414                     if (size == 1)
 415                         g(e.v);
 416                     else
 417                         gen_le16(e.v);
 418                 }
 419             } else {
 420                 ind += size;
 421             }
 422             if (tok != ',')
 423                 break;
 424             next();
 425         }
 426         break;
 427     case TOK_ASM_fill:
 428         {
 429             int repeat, size, val, i, j;
 430             uint8_t repeat_buf[8];
 431             next();
 432             repeat = asm_int_expr(s1);
 433             if (repeat < 0) {
 434                 error("repeat < 0; .fill ignored");
 435                 break;
 436             }
 437             size = 1;
 438             val = 0;
 439             if (tok == ',') {
 440                 next();
 441                 size = asm_int_expr(s1);
 442                 if (size < 0) {
 443                     error("size < 0; .fill ignored");
 444                     break;
 445                 }
 446                 if (size > 8)
 447                     size = 8;
 448                 if (tok == ',') {
 449                     next();
 450                     val = asm_int_expr(s1);
 451                 }
 452             }
 453             /* XXX: endianness */
 454             repeat_buf[0] = val;
 455             repeat_buf[1] = val >> 8;
 456             repeat_buf[2] = val >> 16;
 457             repeat_buf[3] = val >> 24;
 458             repeat_buf[4] = 0;
 459             repeat_buf[5] = 0;
 460             repeat_buf[6] = 0;
 461             repeat_buf[7] = 0;
 462             for(i = 0; i < repeat; i++) {
 463                 for(j = 0; j < size; j++) {
 464                     g(repeat_buf[j]);
 465                 }
 466             }
 467         }
 468         break;
 469     case TOK_ASM_org:
 470         {
 471             unsigned long n;
 472             next();
 473             /* XXX: handle section symbols too */
 474             n = asm_int_expr(s1);
 475             if (n < ind)
 476                 error("attempt to .org backwards");
 477             v = 0;
 478             size = n - ind;
 479             goto zero_pad;
 480         }
 481         break;
 482     case TOK_ASM_globl:
 483     case TOK_ASM_global:
 484     case TOK_ASM_weak:
 485     tok1 = tok;
 486         do {
 487             Sym *sym;
 488
 489             next();
 490             sym = label_find(tok);
 491             if (!sym) {
 492                 sym = label_push(&s1->asm_labels, tok, 0);
 493                 sym->type.t = VT_VOID;
 494             }
 495             sym->type.t &= ~VT_STATIC;
 496             if (tok1 == TOK_ASM_weak)
 497                 sym->type.t |= VT_WEAK;
 498             next();
 499         } while (tok == ',');
 500         break;
 501     case TOK_ASM_string:
 502     case TOK_ASM_ascii:
 503     case TOK_ASM_asciz:
 504         {
 505             const uint8_t *p;
 506             int i, size, t;
 507
 508             t = tok;
 509             next();
 510             for(;;) {
 511                 if (tok != TOK_STR)
 512                     expect("string constant");
 513                 p = tokc.cstr->data;
 514                 size = tokc.cstr->size;
 515                 if (t == TOK_ASM_ascii && size > 0)
 516                     size--;
 517                 for(i = 0; i < size; i++)
 518                     g(p[i]);
 519                 next();
 520                 if (tok == ',') {
 521                     next();
 522                 } else if (tok != TOK_STR) {
 523                     break;
 524                 }
 525             }
 526         }
 527         break;
 528     case TOK_ASM_text:
 529     case TOK_ASM_data:
 530     case TOK_ASM_bss:
 531         {
 532             char sname[64];
 533             tok1 = tok;
 534             n = 0;
 535             next();
 536             if (tok != ';' && tok != TOK_LINEFEED) {
 537                 n = asm_int_expr(s1);
 538                 next();
 539             }
 540             sprintf(sname, (n?".%s%d":".%s"), get_tok_str(tok1, NULL), n);
 541             use_section(s1, sname);
 542         }
 543         break;
 544     case TOK_ASM_file:
 545         {
 546             char filename[512];
 547
 548             filename[0] = '\0';
 549             next();
 550
 551             if (tok == TOK_STR)
 552                 pstrcat(filename, sizeof(filename), tokc.cstr->data);
 553             else
 554                 pstrcat(filename, sizeof(filename), get_tok_str(tok, NULL));
 555
 556             if (s1->warn_unsupported)
 557                 warning("ignoring .file %s", filename);
 558
 559             next();
 560         }
 561         break;
 562     case TOK_ASM_ident:
 563         {
 564             char ident[256];
 565
 566             ident[0] = '\0';
 567             next();
 568
 569             if (tok == TOK_STR)
 570                 pstrcat(ident, sizeof(ident), tokc.cstr->data);
 571             else
 572                 pstrcat(ident, sizeof(ident), get_tok_str(tok, NULL));
 573
 574             if (s1->warn_unsupported)
 575                 warning("ignoring .ident %s", ident);
 576
 577             next();
 578         }
 579         break;
 580     case TOK_ASM_size:
 581         {
 582             Sym *sym;
 583
 584             next();
 585             sym = label_find(tok);
 586             if (!sym) {
 587                 error("label not found: %s", get_tok_str(tok, NULL));
 588             }
 589
 590             next();
 591             skip(',');
 592             /* XXX .size name,label2-label1 */
 593             if (s1->warn_unsupported)
 594                 warning("ignoring .size %s,*", get_tok_str(tok, NULL));
 595
 596             while (tok != '\n' && tok != CH_EOF) {
 597                 next();
 598             }
 599         }
 600         break;
 601     case TOK_ASM_type:
 602         {
 603             Sym *sym;
 604             char newtype[64];
 605             newtype[0] = 0;
 606
 607             next();
 608             sym = label_find(tok);
 609             if (!sym) {
 610                 sym = label_push(&s1->asm_labels, tok, 0);
 611                 sym->type.t = VT_VOID;
 612             }
 613
 614             next();
 615             skip(',');
 616             skip('@');
 617             if (tok == TOK_STR)
 618                 pstrcat(newtype, sizeof(newtype), tokc.cstr->data);
 619             else
 620                 pstrcat(newtype, sizeof(newtype), get_tok_str(tok, NULL));
 621
 622             if (!strcmp(newtype, "function")) {
 623                 sym->type.t = VT_FUNC;
 624             }
 625             else if (s1->warn_unsupported)
 626                 warning("change type of '%s' from 0x%x to '%s' ignored",
 627                     get_tok_str(sym->v, NULL), sym->type.t, newtype);
 628
 629             next();
 630         }
 631         break;
 632     case TOK_SECTION1:
 633         {
 634             char sname[256];
 635
 636             /* XXX: support more options */
 637             next();
 638             sname[0] = '\0';
 639             while (tok != ';' && tok != TOK_LINEFEED && tok != ',') {
 640                 if (tok == TOK_STR)
 641                     pstrcat(sname, sizeof(sname), tokc.cstr->data);
 642                 else
 643                     pstrcat(sname, sizeof(sname), get_tok_str(tok, NULL));
 644                 next();
 645             }
 646             if (tok == ',') {
 647                 /* skip section options */
 648                 next();
 649                 if (tok != TOK_STR)
 650                     expect("string constant");
 651                 next();
 652             }
 653             last_text_section = cur_text_section;
 654             use_section(s1, sname);
 655         }
 656         break;
 657     case TOK_ASM_previous:
 658         {
 659             Section *sec;
 660             next();
 661             if (!last_text_section)
 662                 error("no previous section referenced");
 663             sec = cur_text_section;
 664             use_section1(s1, last_text_section);
 665             last_text_section = sec;
 666         }
 667         break;
 668 #ifdef TCC_TARGET_I386
 669     case TOK_ASM_code16:
 670         {
 671             next();
 672             s1->seg_size = 16;
 673         }
 674         break;
 675     case TOK_ASM_code32:
 676         {
 677             next();
 678             s1->seg_size = 32;
 679         }
 680         break;
 681 #endif
 682 #ifdef TCC_TARGET_X86_64
 683     /* added for compatibility with GAS */
 684     case TOK_ASM_code64:
 685         next();
 686         break;
 687 #endif
 688     default:
 689         error("unknown assembler directive '.%s'", get_tok_str(tok, NULL));
 690         break;
 691     }
 692 }
 693
 694
 695 /* assemble a file */
 696 static int tcc_assemble_internal(TCCState *s1, int do_preprocess)
 697 {
 698     int opcode;
 699
 700 #if 0
 701     /* print stats about opcodes */
 702     {
 703         const ASMInstr *pa;
 704         int freq[4];
 705         int op_vals[500];
 706         int nb_op_vals, i, j;
 707
 708         nb_op_vals = 0;
 709         memset(freq, 0, sizeof(freq));
 710         for(pa = asm_instrs; pa->sym != 0; pa++) {
 711             freq[pa->nb_ops]++;
 712             for(i=0;i<pa->nb_ops;i++) {
 713                 for(j=0;j<nb_op_vals;j++) {
 714                     if (pa->op_type[i] == op_vals[j])
 715                         goto found;
 716                 }
 717                 op_vals[nb_op_vals++] = pa->op_type[i];
 718             found: ;
 719             }
 720         }
 721         for(i=0;i<nb_op_vals;i++) {
 722             int v = op_vals[i];
 723             if ((v & (v - 1)) != 0)
 724                 printf("%3d: %08x\n", i, v);
 725         }
 726         printf("size=%d nb=%d f0=%d f1=%d f2=%d f3=%d\n",
 727                sizeof(asm_instrs), sizeof(asm_instrs) / sizeof(ASMInstr),
 728                freq[0], freq[1], freq[2], freq[3]);
 729     }
 730 #endif
 731
 732     /* XXX: undefine C labels */
 733
 734     ch = file->buf_ptr[0];
 735     tok_flags = TOK_FLAG_BOL | TOK_FLAG_BOF;
 736     parse_flags = PARSE_FLAG_ASM_COMMENTS;
 737     if (do_preprocess)
 738         parse_flags |= PARSE_FLAG_PREPROCESS;
 739     next();
 740     for(;;) {
 741         if (tok == TOK_EOF)
 742             break;
 743         parse_flags |= PARSE_FLAG_LINEFEED; /* XXX: suppress that hack */
 744     redo:
 745         if (tok == '#') {
 746             /* horrible gas comment */
 747             while (tok != TOK_LINEFEED)
 748                 next();
 749         } else if (tok == '.') {
 750             asm_parse_directive(s1);
 751         } else if (tok == TOK_PPNUM) {
 752             const char *p;
 753             int n;
 754             p = tokc.cstr->data;
 755             n = strtoul(p, (char **)&p, 10);
 756             if (*p != '\0')
 757                 expect("':'");
 758             /* new local label */
 759             asm_new_label(s1, asm_get_local_label_name(s1, n), 1);
 760             next();
 761             skip(':');
 762             goto redo;
 763         } else if (tok >= TOK_IDENT) {
 764             /* instruction or label */
 765             opcode = tok;
 766             next();
 767             if (tok == ':') {
 768                 /* new label */
 769                 asm_new_label(s1, opcode, 0);
 770                 next();
 771                 goto redo;
 772             } else if (tok == '=') {
 773                 int n;
 774                 next();
 775                 n = asm_int_expr(s1);
 776                 asm_new_label1(s1, opcode, 0, SHN_ABS, n);
 777                 goto redo;
 778             } else {
 779                 asm_opcode(s1, opcode);
 780             }
 781         }
 782         /* end of line */
 783         if (tok != ';' && tok != TOK_LINEFEED){
 784             expect("end of line");
 785         }
 786         parse_flags &= ~PARSE_FLAG_LINEFEED; /* XXX: suppress that hack */
 787         next();
 788     }
 789
 790     asm_free_labels(s1);
 791
 792     return 0;
 793 }
 794
 795 /* Assemble the current file */
 796 ST_FUNC int tcc_assemble(TCCState *s1, int do_preprocess)
 797 {
 798     Sym *define_start;
 799     int ret;
 800
 801     preprocess_init(s1);
 802
 803     /* default section is text */
 804     cur_text_section = text_section;
 805     ind = cur_text_section->data_offset;
 806
 807     define_start = define_stack;
 808
 809     /* an elf symbol of type STT_FILE must be put so that STB_LOCAL
 810        symbols can be safely used */
 811     put_elf_sym(symtab_section, 0, 0,
 812                 ELFW(ST_INFO)(STB_LOCAL, STT_FILE), 0,
 813                 SHN_ABS, file->filename);
 814
 815     ret = tcc_assemble_internal(s1, do_preprocess);
 816
 817     cur_text_section->data_offset = ind;
 818
 819     free_defines(define_start);
 820
 821     return ret;
 822 }
 823
 824 /********************************************************************/
 825 /* GCC inline asm support */
 826
 827 /* assemble the string 'str' in the current C compilation unit without
 828    C preprocessing. NOTE: str is modified by modifying the '\0' at the
 829    end */
 830 static void tcc_assemble_inline(TCCState *s1, char *str, int len)
 831 {
 832     int saved_parse_flags;
 833     const int *saved_macro_ptr;
 834
 835     saved_parse_flags = parse_flags;
 836     saved_macro_ptr = macro_ptr;
 837
 838     tcc_open_bf(s1, file->filename, len);
 839     file->line_num = file->prev->line_num;
 840     memcpy(file->buffer, str, len);
 841
 842     macro_ptr = NULL;
 843     tcc_assemble_internal(s1, 0);
 844     tcc_close();
 845
 846     parse_flags = saved_parse_flags;
 847     macro_ptr = saved_macro_ptr;
 848 }
 849
 850 /* find a constraint by its number or id (gcc 3 extended
 851    syntax). return -1 if not found. Return in *pp in char after the
 852    constraint */
 853 ST_FUNC int find_constraint(ASMOperand *operands, int nb_operands,
 854                            const char *name, const char **pp)
 855 {
 856     int index;
 857     TokenSym *ts;
 858     const char *p;
 859
 860     if (isnum(*name)) {
 861         index = 0;
 862         while (isnum(*name)) {
 863             index = (index * 10) + (*name) - '0';
 864             name++;
 865         }
 866         if ((unsigned)index >= nb_operands)
 867             index = -1;
 868     } else if (*name == '[') {
 869         name++;
 870         p = strchr(name, ']');
 871         if (p) {
 872             ts = tok_alloc(name, p - name);
 873             for(index = 0; index < nb_operands; index++) {
 874                 if (operands[index].id == ts->tok)
 875                     goto found;
 876             }
 877             index = -1;
 878         found:
 879             name = p + 1;
 880         } else {
 881             index = -1;
 882         }
 883     } else {
 884         index = -1;
 885     }
 886     if (pp)
 887         *pp = name;
 888     return index;
 889 }
 890
 891 static void subst_asm_operands(ASMOperand *operands, int nb_operands,
 892                                int nb_outputs,
 893                                CString *out_str, CString *in_str)
 894 {
 895     int c, index, modifier;
 896     const char *str;
 897     ASMOperand *op;
 898     SValue sv;
 899
 900     cstr_new(out_str);
 901     str = in_str->data;
 902     for(;;) {
 903         c = *str++;
 904         if (c == '%') {
 905             if (*str == '%') {
 906                 str++;
 907                 goto add_char;
 908             }
 909             modifier = 0;
 910             if (*str == 'c' || *str == 'n' ||
 911                 *str == 'b' || *str == 'w' || *str == 'h')
 912                 modifier = *str++;
 913             index = find_constraint(operands, nb_operands, str, &str);
 914             if (index < 0)
 915                 error("invalid operand reference after %%");
 916             op = &operands[index];
 917             sv = *op->vt;
 918             if (op->reg >= 0) {
 919                 sv.r = op->reg;
 920                 if ((op->vt->r & VT_VALMASK) == VT_LLOCAL && op->is_memory)
 921                     sv.r |= VT_LVAL;
 922             }
 923             subst_asm_operand(out_str, &sv, modifier);
 924         } else {
 925         add_char:
 926             cstr_ccat(out_str, c);
 927             if (c == '\0')
 928                 break;
 929         }
 930     }
 931 }
 932
 933
 934 static void parse_asm_operands(ASMOperand *operands, int *nb_operands_ptr,
 935                                int is_output)
 936 {
 937     ASMOperand *op;
 938     int nb_operands;
 939
 940     if (tok != ':') {
 941         nb_operands = *nb_operands_ptr;
 942         for(;;) {
 943             if (nb_operands >= MAX_ASM_OPERANDS)
 944                 error("too many asm operands");
 945             op = &operands[nb_operands++];
 946             op->id = 0;
 947             if (tok == '[') {
 948                 next();
 949                 if (tok < TOK_IDENT)
 950                     expect("identifier");
 951                 op->id = tok;
 952                 next();
 953                 skip(']');
 954             }
 955             if (tok != TOK_STR)
 956                 expect("string constant");
 957             op->constraint = tcc_malloc(tokc.cstr->size);
 958             strcpy(op->constraint, tokc.cstr->data);
 959             next();
 960             skip('(');
 961             gexpr();
 962             if (is_output) {
 963                 test_lvalue();
 964             } else {
 965                 /* we want to avoid LLOCAL case, except when the 'm'
 966                    constraint is used. Note that it may come from
 967                    register storage, so we need to convert (reg)
 968                    case */
 969                 if ((vtop->r & VT_LVAL) &&
 970                     ((vtop->r & VT_VALMASK) == VT_LLOCAL ||
 971                      (vtop->r & VT_VALMASK) < VT_CONST) &&
 972                     !strchr(op->constraint, 'm')) {
 973                     gv(RC_INT);
 974                 }
 975             }
 976             op->vt = vtop;
 977             skip(')');
 978             if (tok == ',') {
 979                 next();
 980             } else {
 981                 break;
 982             }
 983         }
 984         *nb_operands_ptr = nb_operands;
 985     }
 986 }
 987
 988 /* parse the GCC asm() instruction */
 989 ST_FUNC void asm_instr(void)
 990 {
 991     CString astr, astr1;
 992     ASMOperand operands[MAX_ASM_OPERANDS];
 993     int nb_inputs, nb_outputs, nb_operands, i, must_subst, out_reg;
 994     uint8_t clobber_regs[NB_ASM_REGS];
 995
 996     next();
 997     /* since we always generate the asm() instruction, we can ignore
 998        volatile */
 999     if (tok == TOK_VOLATILE1 || tok == TOK_VOLATILE2 || tok == TOK_VOLATILE3) {
1000         next();
1001     }
1002     parse_asm_str(&astr);
1003     nb_operands = 0;
1004     nb_outputs = 0;
1005     must_subst = 0;
1006     memset(clobber_regs, 0, sizeof(clobber_regs));
1007     if (tok == ':') {
1008         next();
1009         must_subst = 1;
1010         /* output args */
1011         parse_asm_operands(operands, &nb_operands, 1);
1012         nb_outputs = nb_operands;
1013         if (tok == ':') {
1014             next();
1015             if (tok != ')') {
1016                 /* input args */
1017                 parse_asm_operands(operands, &nb_operands, 0);
1018                 if (tok == ':') {
1019                     /* clobber list */
1020                     /* XXX: handle registers */
1021                     next();
1022                     for(;;) {
1023                         if (tok != TOK_STR)
1024                             expect("string constant");
1025                         asm_clobber(clobber_regs, tokc.cstr->data);
1026                         next();
1027                         if (tok == ',') {
1028                             next();
1029                         } else {
1030                             break;
1031                         }
1032                     }
1033                 }
1034             }
1035         }
1036     }
1037     skip(')');
1038     /* NOTE: we do not eat the ';' so that we can restore the current
1039        token after the assembler parsing */
1040     if (tok != ';')
1041         expect("';'");
1042     nb_inputs = nb_operands - nb_outputs;
1043
1044     /* save all values in the memory */
1045     save_regs(0);
1046
1047     /* compute constraints */
1048     asm_compute_constraints(operands, nb_operands, nb_outputs,
1049                             clobber_regs, &out_reg);
1050
1051     /* substitute the operands in the asm string. No substitution is
1052        done if no operands (GCC behaviour) */
1053 #ifdef ASM_DEBUG
1054     printf("asm: \"%s\"\n", (char *)astr.data);
1055 #endif
1056     if (must_subst) {
1057         subst_asm_operands(operands, nb_operands, nb_outputs, &astr1, &astr);
1058         cstr_free(&astr);
1059     } else {
1060         astr1 = astr;
1061     }
1062 #ifdef ASM_DEBUG
1063     printf("subst_asm: \"%s\"\n", (char *)astr1.data);
1064 #endif
1065
1066     /* generate loads */
1067     asm_gen_code(operands, nb_operands, nb_outputs, 0,
1068                  clobber_regs, out_reg);
1069
1070     /* assemble the string with tcc internal assembler */
1071     tcc_assemble_inline(tcc_state, astr1.data, astr1.size - 1);
1072
1073     /* restore the current C token */
1074     next();
1075
1076     /* store the output values if needed */
1077     asm_gen_code(operands, nb_operands, nb_outputs, 1,
1078                  clobber_regs, out_reg);
1079
1080     /* free everything */
1081     for(i=0;i<nb_operands;i++) {
1082         ASMOperand *op;
1083         op = &operands[i];
1084         tcc_free(op->constraint);
1085         vpop();
1086     }
1087     cstr_free(&astr1);
1088 }
1089
1090 ST_FUNC void asm_global_instr(void)
1091 {
1092     CString astr;
1093
1094     next();
1095     parse_asm_str(&astr);
1096     skip(')');
1097     /* NOTE: we do not eat the ';' so that we can restore the current
1098        token after the assembler parsing */
1099     if (tok != ';')
1100         expect("';'");
1101
1102 #ifdef ASM_DEBUG
1103     printf("asm_global: \"%s\"\n", (char *)astr.data);
1104 #endif
1105     cur_text_section = text_section;
1106     ind = cur_text_section->data_offset;
1107
1108     /* assemble the string with tcc internal assembler */
1109     tcc_assemble_inline(tcc_state, astr.data, astr.size - 1);
1110
1111     cur_text_section->data_offset = ind;
1112
1113     /* restore the current C token */
1114     next();
1115
1116     cstr_free(&astr);
1117 }