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