gcc/gensupport.c

   1 /* Support routines for the various generation passes.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3
   4    This file is part of GNU CC.
   5
   6    GNU CC is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    GNU CC 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
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GNU CC; see the file COPYING.  If not, write to
  18    the Free Software Foundation, 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include "hconfig.h"
  22 #include "system.h"
  23 #include "rtl.h"
  24 #include "obstack.h"
  25 #include "errors.h"
  26 #include "gensupport.h"
  27
  28
  29 static struct obstack obstack;
  30 struct obstack *rtl_obstack = &obstack;
  31
  32 #define obstack_chunk_alloc xmalloc
  33 #define obstack_chunk_free free
  34
  35 static int sequence_num;
  36 static int errors;
  37
  38 static int predicable_default;
  39 static const char *predicable_true;
  40 static const char *predicable_false;
  41
  42 /* We initially queue all patterns, process the define_insn and
  43    define_cond_exec patterns, then return them one at a time.  */
  44
  45 struct queue_elem
  46 {
  47   rtx data;
  48   int lineno;
  49   struct queue_elem *next;
  50 };
  51
  52 static struct queue_elem *define_attr_queue;
  53 static struct queue_elem **define_attr_tail = &define_attr_queue;
  54 static struct queue_elem *define_insn_queue;
  55 static struct queue_elem **define_insn_tail = &define_insn_queue;
  56 static struct queue_elem *define_cond_exec_queue;
  57 static struct queue_elem **define_cond_exec_tail = &define_cond_exec_queue;
  58 static struct queue_elem *other_queue;
  59 static struct queue_elem **other_tail = &other_queue;
  60
  61 static void queue_pattern PARAMS ((rtx, struct queue_elem ***, int));
  62 static void remove_constraints PARAMS ((rtx));
  63 static void process_rtx PARAMS ((rtx, int));
  64
  65 static int is_predicable PARAMS ((struct queue_elem *));
  66 static void identify_predicable_attribute PARAMS ((void));
  67 static int n_alternatives PARAMS ((const char *));
  68 static void collect_insn_data PARAMS ((rtx, int *, int *));
  69 static rtx alter_predicate_for_insn PARAMS ((rtx, int, int, int));
  70 static const char *alter_test_for_insn PARAMS ((struct queue_elem *,
  71                                                 struct queue_elem *));
  72 static char *shift_output_template PARAMS ((char *, const char *, int));
  73 static const char *alter_output_for_insn PARAMS ((struct queue_elem *,
  74                                                   struct queue_elem *,
  75                                                   int, int));
  76 static void process_one_cond_exec PARAMS ((struct queue_elem *));
  77 static void process_define_cond_exec PARAMS ((void));
  78 \f
  79 void
  80 message_with_line VPARAMS ((int lineno, const char *msg, ...))
  81 {
  82 #ifndef ANSI_PROTOTYPES
  83   int lineno;
  84   const char *msg;
  85 #endif
  86   va_list ap;
  87
  88   VA_START (ap, msg);
  89
  90 #ifndef ANSI_PROTOTYPES
  91   lineno = va_arg (ap, int);
  92   msg = va_arg (ap, const char *);
  93 #endif
  94
  95   fprintf (stderr, "%s:%d: ", read_rtx_filename, lineno);
  96   vfprintf (stderr, msg, ap);
  97   fputc ('\n', stderr);
  98
  99   va_end (ap);
 100 }
 101 \f
 102 /* Queue PATTERN on LIST_TAIL.  */
 103
 104 static void
 105 queue_pattern (pattern, list_tail, lineno)
 106      rtx pattern;
 107      struct queue_elem ***list_tail;
 108      int lineno;
 109 {
 110   struct queue_elem *e = (struct queue_elem *) xmalloc (sizeof (*e));
 111   e->data = pattern;
 112   e->lineno = lineno;
 113   e->next = NULL;
 114   **list_tail = e;
 115   *list_tail = &e->next;
 116 }
 117
 118 /* Recursively remove constraints from an rtx.  */
 119
 120 static void
 121 remove_constraints (part)
 122      rtx part;
 123 {
 124   register int i, j;
 125   register const char *format_ptr;
 126
 127   if (part == 0)
 128     return;
 129
 130   if (GET_CODE (part) == MATCH_OPERAND)
 131     XSTR (part, 2) = "";
 132   else if (GET_CODE (part) == MATCH_SCRATCH)
 133     XSTR (part, 1) = "";
 134
 135   format_ptr = GET_RTX_FORMAT (GET_CODE (part));
 136
 137   for (i = 0; i < GET_RTX_LENGTH (GET_CODE (part)); i++)
 138     switch (*format_ptr++)
 139       {
 140       case 'e':
 141       case 'u':
 142         remove_constraints (XEXP (part, i));
 143         break;
 144       case 'E':
 145         if (XVEC (part, i) != NULL)
 146           for (j = 0; j < XVECLEN (part, i); j++)
 147             remove_constraints (XVECEXP (part, i, j));
 148         break;
 149       }
 150 }
 151
 152 /* Process a top level rtx in some way, queueing as appropriate.  */
 153
 154 static void
 155 process_rtx (desc, lineno)
 156      rtx desc;
 157      int lineno;
 158 {
 159   switch (GET_CODE (desc))
 160     {
 161     case DEFINE_INSN:
 162       queue_pattern (desc, &define_insn_tail, lineno);
 163       break;
 164
 165     case DEFINE_COND_EXEC:
 166       queue_pattern (desc, &define_cond_exec_tail, lineno);
 167       break;
 168
 169     case DEFINE_ATTR:
 170       queue_pattern (desc, &define_attr_tail, lineno);
 171       break;
 172
 173     case DEFINE_INSN_AND_SPLIT:
 174       {
 175         const char *split_cond;
 176         rtx split;
 177
 178         /* Create a split with values from the insn_and_split. */
 179         split = rtx_alloc (DEFINE_SPLIT);
 180         XEXP (split, 0) = copy_rtx (XEXP (desc, 1));
 181         remove_constraints (XEXP (split, 0));
 182
 183         /* If the split condition starts with "&&", append it to the
 184            insn condition to create the new split condition.  */
 185         split_cond = XSTR (desc, 4);
 186         if (split_cond[0] == '&' && split_cond[1] == '&')
 187           {
 188             const char *insn_cond = XSTR (desc, 2);
 189             size_t insn_cond_len = strlen (insn_cond);
 190             size_t split_cond_len = strlen (split_cond);
 191             char *combined;
 192
 193             combined = (char *) xmalloc (insn_cond_len + split_cond_len + 1);
 194             memcpy (combined, insn_cond, insn_cond_len);
 195             memcpy (combined + insn_cond_len, split_cond, split_cond_len + 1);
 196
 197             split_cond = combined;
 198           }
 199         XSTR (split, 1) = split_cond;
 200         XVEC (split, 2) = XVEC (desc, 5);
 201         XSTR (split, 3) = XSTR (desc, 6);
 202
 203         /* Fix up the DEFINE_INSN.  */
 204         PUT_CODE (desc, DEFINE_INSN);
 205         XVEC (desc, 4) = XVEC (desc, 7);
 206
 207         /* Queue them.  */
 208         queue_pattern (desc, &define_insn_tail, lineno);
 209         queue_pattern (split, &other_tail, lineno);
 210         break;
 211       }
 212
 213     default:
 214       queue_pattern (desc, &other_tail, lineno);
 215       break;
 216     }
 217 }
 218 \f
 219 /* Return true if attribute PREDICABLE is true for ELEM, which holds
 220    a DEFINE_INSN.  */
 221
 222 static int
 223 is_predicable (elem)
 224      struct queue_elem *elem;
 225 {
 226   rtvec vec = XVEC (elem->data, 4);
 227   const char *value;
 228   int i;
 229
 230   if (! vec)
 231     return predicable_default;
 232
 233   for (i = GET_NUM_ELEM (vec) - 1; i >= 0; --i)
 234     {
 235       rtx sub = RTVEC_ELT (vec, i);
 236       switch (GET_CODE (sub))
 237         {
 238         case SET_ATTR:
 239           if (strcmp (XSTR (sub, 0), "predicable") == 0)
 240             {
 241               value = XSTR (sub, 1);
 242               goto found;
 243             }
 244           break;
 245
 246         case SET_ATTR_ALTERNATIVE:
 247           if (strcmp (XSTR (sub, 0), "predicable") == 0)
 248             {
 249               message_with_line (elem->lineno,
 250                                  "multiple alternatives for `predicable'");
 251               errors = 1;
 252               return 0;
 253             }
 254           break;
 255
 256         case SET:
 257           if (GET_CODE (SET_DEST (sub)) != ATTR
 258               || strcmp (XSTR (SET_DEST (sub), 0), "predicable") != 0)
 259             break;
 260           sub = SET_SRC (sub);
 261           if (GET_CODE (sub) == CONST_STRING)
 262             {
 263               value = XSTR (sub, 0);
 264               goto found;
 265             }
 266
 267           /* ??? It would be possible to handle this if we really tried.
 268              It's not easy though, and I'm not going to bother until it
 269              really proves necessary.  */
 270           message_with_line (elem->lineno,
 271                              "non-constant value for `predicable'");
 272           errors = 1;
 273           return 0;
 274
 275         default:
 276           abort ();
 277         }
 278     }
 279
 280   return predicable_default;
 281
 282  found:
 283   /* Verify that predicability does not vary on the alternative.  */
 284   /* ??? It should be possible to handle this by simply eliminating
 285      the non-predicable alternatives from the insn.  FRV would like
 286      to do this.  Delay this until we've got the basics solid.  */
 287   if (strchr (value, ',') != NULL)
 288     {
 289       message_with_line (elem->lineno,
 290                          "multiple alternatives for `predicable'");
 291       errors = 1;
 292       return 0;
 293     }
 294
 295   /* Find out which value we're looking at.  */
 296   if (strcmp (value, predicable_true) == 0)
 297     return 1;
 298   if (strcmp (value, predicable_false) == 0)
 299     return 0;
 300
 301   message_with_line (elem->lineno,
 302                      "Unknown value `%s' for `predicable' attribute",
 303                      value);
 304   errors = 1;
 305   return 0;
 306 }
 307
 308 /* Examine the attribute "predicable"; discover its boolean values
 309    and its default.  */
 310
 311 static void
 312 identify_predicable_attribute ()
 313 {
 314   struct queue_elem *elem;
 315   char *true, *false;
 316   const char *value;
 317   size_t len;
 318
 319   /* Look for the DEFINE_ATTR for `predicable', which must exist.  */
 320   for (elem = define_attr_queue; elem ; elem = elem->next)
 321     if (strcmp (XSTR (elem->data, 0), "predicable") == 0)
 322       goto found;
 323
 324   message_with_line (define_cond_exec_queue->lineno,
 325                      "Attribute `predicable' not defined");
 326   errors = 1;
 327   return;
 328
 329  found:
 330   value = XSTR (elem->data, 1);
 331   len = strlen (value);
 332   false = (char *) xmalloc (len + 1);
 333   memcpy (false, value, len + 1);
 334
 335   true = strchr (false, ',');
 336   if (true == NULL || strchr (++true, ',') != NULL)
 337     {
 338       message_with_line (elem->lineno,
 339                          "Attribute `predicable' is not a boolean");
 340       errors = 1;
 341       return;
 342     }
 343   true[-1] = '\0';
 344
 345   predicable_true = true;
 346   predicable_false = false;
 347
 348   switch (GET_CODE (XEXP (elem->data, 2)))
 349     {
 350     case CONST_STRING:
 351       value = XSTR (XEXP (elem->data, 2), 0);
 352       break;
 353
 354     case CONST:
 355       message_with_line (elem->lineno,
 356                          "Attribute `predicable' cannot be const");
 357       errors = 1;
 358       return;
 359
 360     default:
 361       message_with_line (elem->lineno,
 362                          "Attribute `predicable' must have a constant default");
 363       errors = 1;
 364       return;
 365     }
 366
 367   if (strcmp (value, true) == 0)
 368     predicable_default = 1;
 369   else if (strcmp (value, false) == 0)
 370     predicable_default = 0;
 371   else
 372     {
 373       message_with_line (elem->lineno,
 374                          "Unknown value `%s' for `predicable' attribute",
 375                          value);
 376       errors = 1;
 377     }
 378 }
 379
 380 /* Return the number of alternatives in constraint S.  */
 381
 382 static int
 383 n_alternatives (s)
 384      const char *s;
 385 {
 386   int n = 1;
 387
 388   if (s)
 389     while (*s)
 390       n += (*s++ == ',');
 391
 392   return n;
 393 }
 394
 395 /* Determine how many alternatives there are in INSN, and how many
 396    operands.  */
 397
 398 static void
 399 collect_insn_data (pattern, palt, pmax)
 400      rtx pattern;
 401      int *palt, *pmax;
 402 {
 403   const char *fmt;
 404   enum rtx_code code;
 405   int i, j, len;
 406
 407   code = GET_CODE (pattern);
 408   switch (code)
 409     {
 410     case MATCH_OPERAND:
 411       *palt = n_alternatives (XSTR (pattern, 2));
 412       /* FALLTHRU */
 413
 414     case MATCH_OPERATOR:
 415     case MATCH_SCRATCH:
 416     case MATCH_PARALLEL:
 417     case MATCH_INSN:
 418       i = XINT (pattern, 0);
 419       if (i > *pmax)
 420         *pmax = i;
 421       break;
 422
 423     default:
 424       break;
 425     }
 426
 427   fmt = GET_RTX_FORMAT (code);
 428   len = GET_RTX_LENGTH (code);
 429   for (i = 0; i < len; i++)
 430     {
 431       switch (fmt[i])
 432         {
 433         case 'e': case 'u':
 434           collect_insn_data (XEXP (pattern, i), palt, pmax);
 435           break;
 436
 437         case 'V':
 438           if (XVEC (pattern, i) == NULL)
 439             break;
 440           /* FALLTHRU */
 441         case 'E':
 442           for (j = XVECLEN (pattern, i) - 1; j >= 0; --j)
 443             collect_insn_data (XVECEXP (pattern, i, j), palt, pmax);
 444           break;
 445
 446         case 'i': case 'w': case '0': case 's': case 'S':
 447           break;
 448
 449         default:
 450           abort ();
 451         }
 452     }
 453 }
 454
 455 static rtx
 456 alter_predicate_for_insn (pattern, alt, max_op, lineno)
 457      rtx pattern;
 458      int alt, max_op, lineno;
 459 {
 460   const char *fmt;
 461   enum rtx_code code;
 462   int i, j, len;
 463
 464   code = GET_CODE (pattern);
 465   switch (code)
 466     {
 467     case MATCH_OPERAND:
 468       {
 469         const char *c = XSTR (pattern, 2);
 470
 471         if (n_alternatives (c) != 1)
 472           {
 473             message_with_line (lineno,
 474                                "Too many alternatives for operand %d",
 475                                XINT (pattern, 0));
 476             errors = 1;
 477             return NULL;
 478           }
 479
 480         /* Replicate C as needed to fill out ALT alternatives.  */
 481         if (c && *c && alt > 1)
 482           {
 483             size_t c_len = strlen (c);
 484             size_t len = alt * (c_len + 1);
 485             char *new_c = (char *) xmalloc (len);
 486
 487             memcpy (new_c, c, c_len);
 488             for (i = 1; i < alt; ++i)
 489               {
 490                 new_c[i * (c_len + 1) - 1] = ',';
 491                 memcpy (&new_c[i * (c_len + 1)], c, c_len);
 492               }
 493             new_c[len - 1] = '\0';
 494             XSTR (pattern, 2) = new_c;
 495           }
 496       }
 497       /* FALLTHRU */
 498
 499     case MATCH_OPERATOR:
 500     case MATCH_SCRATCH:
 501     case MATCH_PARALLEL:
 502     case MATCH_INSN:
 503       XINT (pattern, 0) += max_op;
 504       break;
 505
 506     default:
 507       break;
 508     }
 509
 510   fmt = GET_RTX_FORMAT (code);
 511   len = GET_RTX_LENGTH (code);
 512   for (i = 0; i < len; i++)
 513     {
 514       rtx r;
 515
 516       switch (fmt[i])
 517         {
 518         case 'e': case 'u':
 519           r = alter_predicate_for_insn (XEXP (pattern, i), alt,
 520                                         max_op, lineno);
 521           if (r == NULL)
 522             return r;
 523           break;
 524
 525         case 'E':
 526           for (j = XVECLEN (pattern, i) - 1; j >= 0; --j)
 527             {
 528               r = alter_predicate_for_insn (XVECEXP (pattern, i, j),
 529                                             alt, max_op, lineno);
 530               if (r == NULL)
 531                 return r;
 532             }
 533           break;
 534
 535         case 'i': case 'w': case '0': case 's':
 536           break;
 537
 538         default:
 539           abort ();
 540         }
 541     }
 542
 543   return pattern;
 544 }
 545
 546 static const char *
 547 alter_test_for_insn (ce_elem, insn_elem)
 548      struct queue_elem *ce_elem, *insn_elem;
 549 {
 550   const char *ce_test, *insn_test;
 551   char *new_test;
 552   size_t len, ce_len, insn_len;
 553
 554   ce_test = XSTR (ce_elem->data, 1);
 555   insn_test = XSTR (insn_elem->data, 2);
 556   if (!ce_test || *ce_test == '\0')
 557     return insn_test;
 558   if (!insn_test || *insn_test == '\0')
 559     return ce_test;
 560
 561   ce_len = strlen (ce_test);
 562   insn_len = strlen (insn_test);
 563   len = 1 + ce_len + 1 + 4 + 1 + insn_len + 1 + 1;
 564   new_test = (char *) xmalloc (len);
 565
 566   sprintf (new_test, "(%s) && (%s)", ce_test, insn_test);
 567
 568   return new_test;
 569 }
 570
 571 /* Adjust all of the operand numbers in OLD to match the shift they'll
 572    get from an operand displacement of DISP.  Return a pointer after the
 573    adjusted string.  */
 574
 575 static char *
 576 shift_output_template (new, old, disp)
 577      char *new;
 578      const char *old;
 579      int disp;
 580 {
 581   while (*old)
 582     {
 583       char c = *old++;
 584       *new++ = c;
 585       if (c == '%')
 586         {
 587           c = *old++;
 588           if (ISDIGIT ((unsigned char) c))
 589             c += disp;
 590           else if (ISUPPER ((unsigned char) c)
 591                    || ISLOWER ((unsigned char) c))
 592             {
 593               *new++ = c;
 594               c = *old++ + disp;
 595             }
 596           *new++ = c;
 597         }
 598     }
 599
 600   return new;
 601 }
 602
 603 static const char *
 604 alter_output_for_insn (ce_elem, insn_elem, alt, max_op)
 605      struct queue_elem *ce_elem, *insn_elem;
 606      int alt, max_op;
 607 {
 608   const char *ce_out, *insn_out;
 609   char *new, *p;
 610   size_t len, ce_len, insn_len;
 611
 612   /* ??? Could coordinate with genoutput to not duplicate code here.  */
 613
 614   ce_out = XSTR (ce_elem->data, 2);
 615   insn_out = XSTR (insn_elem->data, 3);
 616   if (!ce_out || *ce_out == '\0')
 617     return insn_out;
 618
 619   ce_len = strlen (ce_out);
 620   insn_len = strlen (insn_out);
 621
 622   if (*insn_out == '*')
 623     /* You must take care of the predicate yourself.  */
 624     return insn_out;
 625
 626   if (*insn_out == '@')
 627     {
 628       len = (ce_len + 1) * alt + insn_len + 1;
 629       p = new = xmalloc (len);
 630
 631       do
 632         {
 633           do
 634             *p++ = *insn_out++;
 635           while (ISSPACE ((unsigned char) *insn_out));
 636
 637           if (*insn_out != '#')
 638             {
 639               p = shift_output_template (p, ce_out, max_op);
 640               *p++ = ' ';
 641             }
 642
 643           do
 644             *p++ = *insn_out++;
 645           while (*insn_out && *insn_out != '\n');
 646         }
 647       while (*insn_out);
 648       *p = '\0';
 649     }
 650   else
 651     {
 652       len = ce_len + 1 + insn_len + 1;
 653       new = xmalloc (len);
 654
 655       p = shift_output_template (new, ce_out, max_op);
 656       *p++ = ' ';
 657       memcpy (p, insn_out, insn_len + 1);
 658     }
 659
 660   return new;
 661 }
 662
 663 /* Replicate insns as appropriate for the given DEFINE_COND_EXEC.  */
 664
 665 static void
 666 process_one_cond_exec (ce_elem)
 667      struct queue_elem *ce_elem;
 668 {
 669   struct queue_elem *insn_elem;
 670   for (insn_elem = define_insn_queue; insn_elem ; insn_elem = insn_elem->next)
 671     {
 672       int alternatives, max_operand;
 673       rtx pred, insn, pattern;
 674
 675       if (! is_predicable (insn_elem))
 676         continue;
 677
 678       alternatives = 1;
 679       max_operand = -1;
 680       collect_insn_data (insn_elem->data, &alternatives, &max_operand);
 681       max_operand += 1;
 682
 683       if (XVECLEN (ce_elem->data, 0) != 1)
 684         {
 685           message_with_line (ce_elem->lineno,
 686                              "too many patterns in predicate");
 687           errors = 1;
 688           return;
 689         }
 690
 691       pred = copy_rtx (XVECEXP (ce_elem->data, 0, 0));
 692       pred = alter_predicate_for_insn (pred, alternatives, max_operand,
 693                                        ce_elem->lineno);
 694       if (pred == NULL)
 695         return;
 696
 697       /* Construct a new pattern for the new insn.  */
 698       insn = copy_rtx (insn_elem->data);
 699       XSTR (insn, 0) = "";
 700       pattern = rtx_alloc (COND_EXEC);
 701       XEXP (pattern, 0) = pred;
 702       if (XVECLEN (insn, 1) == 1)
 703         {
 704           XEXP (pattern, 1) = XVECEXP (insn, 1, 0);
 705           XVECEXP (insn, 1, 0) = pattern;
 706           PUT_NUM_ELEM (XVEC (insn, 1), 1);
 707         }
 708       else
 709         {
 710           XEXP (pattern, 1) = rtx_alloc (PARALLEL);
 711           XVEC (XEXP (pattern, 1), 0) = XVEC (insn, 1);
 712           XVEC (insn, 1) = rtvec_alloc (1);
 713           XVECEXP (insn, 1, 0) = pattern;
 714         }
 715
 716       XSTR (insn, 2) = alter_test_for_insn (ce_elem, insn_elem);
 717       XSTR (insn, 3) = alter_output_for_insn (ce_elem, insn_elem,
 718                                               alternatives, max_operand);
 719
 720       /* ??? Set `predicable' to false.  Not crucial since it's really
 721          only used here, and we won't reprocess this new pattern.  */
 722
 723       /* Put the new pattern on the `other' list so that it
 724          (a) is not reprocessed by other define_cond_exec patterns
 725          (b) appears after all normal define_insn patterns.
 726
 727          ??? B is debatable.  If one has normal insns that match
 728          cond_exec patterns, they will be preferred over these
 729          generated patterns.  Whether this matters in practice, or if
 730          it's a good thing, or whether we should thread these new
 731          patterns into the define_insn chain just after their generator
 732          is something we'll have to experiment with.  */
 733
 734       queue_pattern (insn, &other_tail, insn_elem->lineno);
 735     }
 736 }
 737
 738 /* If we have any DEFINE_COND_EXEC patterns, expand the DEFINE_INSN
 739    patterns appropriately.  */
 740
 741 static void
 742 process_define_cond_exec ()
 743 {
 744   struct queue_elem *elem;
 745
 746   identify_predicable_attribute ();
 747   if (errors)
 748     return;
 749
 750   for (elem = define_cond_exec_queue; elem ; elem = elem->next)
 751     process_one_cond_exec (elem);
 752 }
 753 \f
 754 /* The entry point for initializing the reader.  */
 755
 756 int
 757 init_md_reader (filename)
 758      const char *filename;
 759 {
 760   FILE *input_file;
 761   int c;
 762
 763   read_rtx_filename = filename;
 764   input_file = fopen (filename, "r");
 765   if (input_file == 0)
 766     {
 767       perror (filename);
 768       return FATAL_EXIT_CODE;
 769     }
 770
 771   obstack_init (rtl_obstack);
 772   errors = 0;
 773   sequence_num = 0;
 774
 775   /* Read the entire file.  */
 776   while (1)
 777     {
 778       rtx desc;
 779       int lineno;
 780
 781       c = read_skip_spaces (input_file);
 782       if (c == EOF)
 783         break;
 784
 785       ungetc (c, input_file);
 786       lineno = read_rtx_lineno;
 787       desc = read_rtx (input_file);
 788       process_rtx (desc, lineno);
 789     }
 790   fclose (input_file);
 791
 792   /* Process define_cond_exec patterns.  */
 793   if (define_cond_exec_queue != NULL)
 794     process_define_cond_exec ();
 795
 796   return errors ? FATAL_EXIT_CODE : SUCCESS_EXIT_CODE;
 797 }
 798
 799 /* The entry point for reading a single rtx from an md file.  */
 800
 801 rtx
 802 read_md_rtx (lineno, seqnr)
 803      int *lineno;
 804      int *seqnr;
 805 {
 806   struct queue_elem **queue, *elem;
 807   rtx desc;
 808
 809   /* Read all patterns from a given queue before moving on to the next.  */
 810   if (define_attr_queue != NULL)
 811     queue = &define_attr_queue;
 812   else if (define_insn_queue != NULL)
 813     queue = &define_insn_queue;
 814   else if (other_queue != NULL)
 815     queue = &other_queue;
 816   else
 817     return NULL_RTX;
 818
 819   elem = *queue;
 820   *queue = elem->next;
 821   desc = elem->data;
 822   *lineno = elem->lineno;
 823   *seqnr = sequence_num;
 824
 825   free (elem);
 826
 827   switch (GET_CODE (desc))
 828     {
 829     case DEFINE_INSN:
 830     case DEFINE_EXPAND:
 831     case DEFINE_SPLIT:
 832     case DEFINE_PEEPHOLE:
 833     case DEFINE_PEEPHOLE2:
 834       sequence_num++;
 835       break;
 836
 837     default:
 838       break;
 839     }
 840
 841   return desc;
 842 }