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         int i;
 178
 179         /* Create a split with values from the insn_and_split. */
 180         split = rtx_alloc (DEFINE_SPLIT);
 181
 182         i = XVECLEN (desc, 1);
 183         XVEC (split, 0) = rtvec_alloc (i);
 184         while (--i >= 0)
 185           {
 186             XVECEXP (split, 0, i) = copy_rtx (XVECEXP (desc, 1, i));
 187             remove_constraints (XVECEXP (split, 0, i));
 188           }
 189
 190         /* If the split condition starts with "&&", append it to the
 191            insn condition to create the new split condition.  */
 192         split_cond = XSTR (desc, 4);
 193         if (split_cond[0] == '&' && split_cond[1] == '&')
 194           {
 195             const char *insn_cond = XSTR (desc, 2);
 196             size_t insn_cond_len = strlen (insn_cond);
 197             size_t split_cond_len = strlen (split_cond);
 198             char *combined;
 199
 200             combined = (char *) xmalloc (insn_cond_len + split_cond_len + 1);
 201             memcpy (combined, insn_cond, insn_cond_len);
 202             memcpy (combined + insn_cond_len, split_cond, split_cond_len + 1);
 203
 204             split_cond = combined;
 205           }
 206         XSTR (split, 1) = split_cond;
 207         XVEC (split, 2) = XVEC (desc, 5);
 208         XSTR (split, 3) = XSTR (desc, 6);
 209
 210         /* Fix up the DEFINE_INSN.  */
 211         PUT_CODE (desc, DEFINE_INSN);
 212         XVEC (desc, 4) = XVEC (desc, 7);
 213
 214         /* Queue them.  */
 215         queue_pattern (desc, &define_insn_tail, lineno);
 216         queue_pattern (split, &other_tail, lineno);
 217         break;
 218       }
 219
 220     default:
 221       queue_pattern (desc, &other_tail, lineno);
 222       break;
 223     }
 224 }
 225 \f
 226 /* Return true if attribute PREDICABLE is true for ELEM, which holds
 227    a DEFINE_INSN.  */
 228
 229 static int
 230 is_predicable (elem)
 231      struct queue_elem *elem;
 232 {
 233   rtvec vec = XVEC (elem->data, 4);
 234   const char *value;
 235   int i;
 236
 237   if (! vec)
 238     return predicable_default;
 239
 240   for (i = GET_NUM_ELEM (vec) - 1; i >= 0; --i)
 241     {
 242       rtx sub = RTVEC_ELT (vec, i);
 243       switch (GET_CODE (sub))
 244         {
 245         case SET_ATTR:
 246           if (strcmp (XSTR (sub, 0), "predicable") == 0)
 247             {
 248               value = XSTR (sub, 1);
 249               goto found;
 250             }
 251           break;
 252
 253         case SET_ATTR_ALTERNATIVE:
 254           if (strcmp (XSTR (sub, 0), "predicable") == 0)
 255             {
 256               message_with_line (elem->lineno,
 257                                  "multiple alternatives for `predicable'");
 258               errors = 1;
 259               return 0;
 260             }
 261           break;
 262
 263         case SET:
 264           if (GET_CODE (SET_DEST (sub)) != ATTR
 265               || strcmp (XSTR (SET_DEST (sub), 0), "predicable") != 0)
 266             break;
 267           sub = SET_SRC (sub);
 268           if (GET_CODE (sub) == CONST_STRING)
 269             {
 270               value = XSTR (sub, 0);
 271               goto found;
 272             }
 273
 274           /* ??? It would be possible to handle this if we really tried.
 275              It's not easy though, and I'm not going to bother until it
 276              really proves necessary.  */
 277           message_with_line (elem->lineno,
 278                              "non-constant value for `predicable'");
 279           errors = 1;
 280           return 0;
 281
 282         default:
 283           abort ();
 284         }
 285     }
 286
 287   return predicable_default;
 288
 289  found:
 290   /* Verify that predicability does not vary on the alternative.  */
 291   /* ??? It should be possible to handle this by simply eliminating
 292      the non-predicable alternatives from the insn.  FRV would like
 293      to do this.  Delay this until we've got the basics solid.  */
 294   if (strchr (value, ',') != NULL)
 295     {
 296       message_with_line (elem->lineno,
 297                          "multiple alternatives for `predicable'");
 298       errors = 1;
 299       return 0;
 300     }
 301
 302   /* Find out which value we're looking at.  */
 303   if (strcmp (value, predicable_true) == 0)
 304     return 1;
 305   if (strcmp (value, predicable_false) == 0)
 306     return 0;
 307
 308   message_with_line (elem->lineno,
 309                      "Unknown value `%s' for `predicable' attribute",
 310                      value);
 311   errors = 1;
 312   return 0;
 313 }
 314
 315 /* Examine the attribute "predicable"; discover its boolean values
 316    and its default.  */
 317
 318 static void
 319 identify_predicable_attribute ()
 320 {
 321   struct queue_elem *elem;
 322   char *true, *false;
 323   const char *value;
 324   size_t len;
 325
 326   /* Look for the DEFINE_ATTR for `predicable', which must exist.  */
 327   for (elem = define_attr_queue; elem ; elem = elem->next)
 328     if (strcmp (XSTR (elem->data, 0), "predicable") == 0)
 329       goto found;
 330
 331   message_with_line (define_cond_exec_queue->lineno,
 332                      "Attribute `predicable' not defined");
 333   errors = 1;
 334   return;
 335
 336  found:
 337   value = XSTR (elem->data, 1);
 338   len = strlen (value);
 339   false = (char *) xmalloc (len + 1);
 340   memcpy (false, value, len + 1);
 341
 342   true = strchr (false, ',');
 343   if (true == NULL || strchr (++true, ',') != NULL)
 344     {
 345       message_with_line (elem->lineno,
 346                          "Attribute `predicable' is not a boolean");
 347       errors = 1;
 348       return;
 349     }
 350   true[-1] = '\0';
 351
 352   predicable_true = true;
 353   predicable_false = false;
 354
 355   switch (GET_CODE (XEXP (elem->data, 2)))
 356     {
 357     case CONST_STRING:
 358       value = XSTR (XEXP (elem->data, 2), 0);
 359       break;
 360
 361     case CONST:
 362       message_with_line (elem->lineno,
 363                          "Attribute `predicable' cannot be const");
 364       errors = 1;
 365       return;
 366
 367     default:
 368       message_with_line (elem->lineno,
 369                          "Attribute `predicable' must have a constant default");
 370       errors = 1;
 371       return;
 372     }
 373
 374   if (strcmp (value, true) == 0)
 375     predicable_default = 1;
 376   else if (strcmp (value, false) == 0)
 377     predicable_default = 0;
 378   else
 379     {
 380       message_with_line (elem->lineno,
 381                          "Unknown value `%s' for `predicable' attribute",
 382                          value);
 383       errors = 1;
 384     }
 385 }
 386
 387 /* Return the number of alternatives in constraint S.  */
 388
 389 static int
 390 n_alternatives (s)
 391      const char *s;
 392 {
 393   int n = 1;
 394
 395   if (s)
 396     while (*s)
 397       n += (*s++ == ',');
 398
 399   return n;
 400 }
 401
 402 /* Determine how many alternatives there are in INSN, and how many
 403    operands.  */
 404
 405 static void
 406 collect_insn_data (pattern, palt, pmax)
 407      rtx pattern;
 408      int *palt, *pmax;
 409 {
 410   const char *fmt;
 411   enum rtx_code code;
 412   int i, j, len;
 413
 414   code = GET_CODE (pattern);
 415   switch (code)
 416     {
 417     case MATCH_OPERAND:
 418       *palt = n_alternatives (XSTR (pattern, 2));
 419       /* FALLTHRU */
 420
 421     case MATCH_OPERATOR:
 422     case MATCH_SCRATCH:
 423     case MATCH_PARALLEL:
 424     case MATCH_INSN:
 425       i = XINT (pattern, 0);
 426       if (i > *pmax)
 427         *pmax = i;
 428       break;
 429
 430     default:
 431       break;
 432     }
 433
 434   fmt = GET_RTX_FORMAT (code);
 435   len = GET_RTX_LENGTH (code);
 436   for (i = 0; i < len; i++)
 437     {
 438       switch (fmt[i])
 439         {
 440         case 'e': case 'u':
 441           collect_insn_data (XEXP (pattern, i), palt, pmax);
 442           break;
 443
 444         case 'V':
 445           if (XVEC (pattern, i) == NULL)
 446             break;
 447           /* FALLTHRU */
 448         case 'E':
 449           for (j = XVECLEN (pattern, i) - 1; j >= 0; --j)
 450             collect_insn_data (XVECEXP (pattern, i, j), palt, pmax);
 451           break;
 452
 453         case 'i': case 'w': case '0': case 's': case 'S':
 454           break;
 455
 456         default:
 457           abort ();
 458         }
 459     }
 460 }
 461
 462 static rtx
 463 alter_predicate_for_insn (pattern, alt, max_op, lineno)
 464      rtx pattern;
 465      int alt, max_op, lineno;
 466 {
 467   const char *fmt;
 468   enum rtx_code code;
 469   int i, j, len;
 470
 471   code = GET_CODE (pattern);
 472   switch (code)
 473     {
 474     case MATCH_OPERAND:
 475       {
 476         const char *c = XSTR (pattern, 2);
 477
 478         if (n_alternatives (c) != 1)
 479           {
 480             message_with_line (lineno,
 481                                "Too many alternatives for operand %d",
 482                                XINT (pattern, 0));
 483             errors = 1;
 484             return NULL;
 485           }
 486
 487         /* Replicate C as needed to fill out ALT alternatives.  */
 488         if (c && *c && alt > 1)
 489           {
 490             size_t c_len = strlen (c);
 491             size_t len = alt * (c_len + 1);
 492             char *new_c = (char *) xmalloc (len);
 493
 494             memcpy (new_c, c, c_len);
 495             for (i = 1; i < alt; ++i)
 496               {
 497                 new_c[i * (c_len + 1) - 1] = ',';
 498                 memcpy (&new_c[i * (c_len + 1)], c, c_len);
 499               }
 500             new_c[len - 1] = '\0';
 501             XSTR (pattern, 2) = new_c;
 502           }
 503       }
 504       /* FALLTHRU */
 505
 506     case MATCH_OPERATOR:
 507     case MATCH_SCRATCH:
 508     case MATCH_PARALLEL:
 509     case MATCH_INSN:
 510       XINT (pattern, 0) += max_op;
 511       break;
 512
 513     default:
 514       break;
 515     }
 516
 517   fmt = GET_RTX_FORMAT (code);
 518   len = GET_RTX_LENGTH (code);
 519   for (i = 0; i < len; i++)
 520     {
 521       rtx r;
 522
 523       switch (fmt[i])
 524         {
 525         case 'e': case 'u':
 526           r = alter_predicate_for_insn (XEXP (pattern, i), alt,
 527                                         max_op, lineno);
 528           if (r == NULL)
 529             return r;
 530           break;
 531
 532         case 'E':
 533           for (j = XVECLEN (pattern, i) - 1; j >= 0; --j)
 534             {
 535               r = alter_predicate_for_insn (XVECEXP (pattern, i, j),
 536                                             alt, max_op, lineno);
 537               if (r == NULL)
 538                 return r;
 539             }
 540           break;
 541
 542         case 'i': case 'w': case '0': case 's':
 543           break;
 544
 545         default:
 546           abort ();
 547         }
 548     }
 549
 550   return pattern;
 551 }
 552
 553 static const char *
 554 alter_test_for_insn (ce_elem, insn_elem)
 555      struct queue_elem *ce_elem, *insn_elem;
 556 {
 557   const char *ce_test, *insn_test;
 558   char *new_test;
 559   size_t len, ce_len, insn_len;
 560
 561   ce_test = XSTR (ce_elem->data, 1);
 562   insn_test = XSTR (insn_elem->data, 2);
 563   if (!ce_test || *ce_test == '\0')
 564     return insn_test;
 565   if (!insn_test || *insn_test == '\0')
 566     return ce_test;
 567
 568   ce_len = strlen (ce_test);
 569   insn_len = strlen (insn_test);
 570   len = 1 + ce_len + 1 + 4 + 1 + insn_len + 1 + 1;
 571   new_test = (char *) xmalloc (len);
 572
 573   sprintf (new_test, "(%s) && (%s)", ce_test, insn_test);
 574
 575   return new_test;
 576 }
 577
 578 /* Adjust all of the operand numbers in OLD to match the shift they'll
 579    get from an operand displacement of DISP.  Return a pointer after the
 580    adjusted string.  */
 581
 582 static char *
 583 shift_output_template (new, old, disp)
 584      char *new;
 585      const char *old;
 586      int disp;
 587 {
 588   while (*old)
 589     {
 590       char c = *old++;
 591       *new++ = c;
 592       if (c == '%')
 593         {
 594           c = *old++;
 595           if (ISDIGIT ((unsigned char) c))
 596             c += disp;
 597           else if (ISUPPER ((unsigned char) c)
 598                    || ISLOWER ((unsigned char) c))
 599             {
 600               *new++ = c;
 601               c = *old++ + disp;
 602             }
 603           *new++ = c;
 604         }
 605     }
 606
 607   return new;
 608 }
 609
 610 static const char *
 611 alter_output_for_insn (ce_elem, insn_elem, alt, max_op)
 612      struct queue_elem *ce_elem, *insn_elem;
 613      int alt, max_op;
 614 {
 615   const char *ce_out, *insn_out;
 616   char *new, *p;
 617   size_t len, ce_len, insn_len;
 618
 619   /* ??? Could coordinate with genoutput to not duplicate code here.  */
 620
 621   ce_out = XSTR (ce_elem->data, 2);
 622   insn_out = XSTR (insn_elem->data, 3);
 623   if (!ce_out || *ce_out == '\0')
 624     return insn_out;
 625
 626   ce_len = strlen (ce_out);
 627   insn_len = strlen (insn_out);
 628
 629   if (*insn_out == '*')
 630     /* You must take care of the predicate yourself.  */
 631     return insn_out;
 632
 633   if (*insn_out == '@')
 634     {
 635       len = (ce_len + 1) * alt + insn_len + 1;
 636       p = new = xmalloc (len);
 637
 638       do
 639         {
 640           do
 641             *p++ = *insn_out++;
 642           while (ISSPACE ((unsigned char) *insn_out));
 643
 644           if (*insn_out != '#')
 645             {
 646               p = shift_output_template (p, ce_out, max_op);
 647               *p++ = ' ';
 648             }
 649
 650           do
 651             *p++ = *insn_out++;
 652           while (*insn_out && *insn_out != '\n');
 653         }
 654       while (*insn_out);
 655       *p = '\0';
 656     }
 657   else
 658     {
 659       len = ce_len + 1 + insn_len + 1;
 660       new = xmalloc (len);
 661
 662       p = shift_output_template (new, ce_out, max_op);
 663       *p++ = ' ';
 664       memcpy (p, insn_out, insn_len + 1);
 665     }
 666
 667   return new;
 668 }
 669
 670 /* Replicate insns as appropriate for the given DEFINE_COND_EXEC.  */
 671
 672 static void
 673 process_one_cond_exec (ce_elem)
 674      struct queue_elem *ce_elem;
 675 {
 676   struct queue_elem *insn_elem;
 677   for (insn_elem = define_insn_queue; insn_elem ; insn_elem = insn_elem->next)
 678     {
 679       int alternatives, max_operand;
 680       rtx pred, insn, pattern;
 681
 682       if (! is_predicable (insn_elem))
 683         continue;
 684
 685       alternatives = 1;
 686       max_operand = -1;
 687       collect_insn_data (insn_elem->data, &alternatives, &max_operand);
 688       max_operand += 1;
 689
 690       if (XVECLEN (ce_elem->data, 0) != 1)
 691         {
 692           message_with_line (ce_elem->lineno,
 693                              "too many patterns in predicate");
 694           errors = 1;
 695           return;
 696         }
 697
 698       pred = copy_rtx (XVECEXP (ce_elem->data, 0, 0));
 699       pred = alter_predicate_for_insn (pred, alternatives, max_operand,
 700                                        ce_elem->lineno);
 701       if (pred == NULL)
 702         return;
 703
 704       /* Construct a new pattern for the new insn.  */
 705       insn = copy_rtx (insn_elem->data);
 706       XSTR (insn, 0) = "";
 707       pattern = rtx_alloc (COND_EXEC);
 708       XEXP (pattern, 0) = pred;
 709       if (XVECLEN (insn, 1) == 1)
 710         {
 711           XEXP (pattern, 1) = XVECEXP (insn, 1, 0);
 712           XVECEXP (insn, 1, 0) = pattern;
 713           PUT_NUM_ELEM (XVEC (insn, 1), 1);
 714         }
 715       else
 716         {
 717           XEXP (pattern, 1) = rtx_alloc (PARALLEL);
 718           XVEC (XEXP (pattern, 1), 0) = XVEC (insn, 1);
 719           XVEC (insn, 1) = rtvec_alloc (1);
 720           XVECEXP (insn, 1, 0) = pattern;
 721         }
 722
 723       XSTR (insn, 2) = alter_test_for_insn (ce_elem, insn_elem);
 724       XSTR (insn, 3) = alter_output_for_insn (ce_elem, insn_elem,
 725                                               alternatives, max_operand);
 726
 727       /* ??? Set `predicable' to false.  Not crucial since it's really
 728          only used here, and we won't reprocess this new pattern.  */
 729
 730       /* Put the new pattern on the `other' list so that it
 731          (a) is not reprocessed by other define_cond_exec patterns
 732          (b) appears after all normal define_insn patterns.
 733
 734          ??? B is debatable.  If one has normal insns that match
 735          cond_exec patterns, they will be preferred over these
 736          generated patterns.  Whether this matters in practice, or if
 737          it's a good thing, or whether we should thread these new
 738          patterns into the define_insn chain just after their generator
 739          is something we'll have to experiment with.  */
 740
 741       queue_pattern (insn, &other_tail, insn_elem->lineno);
 742     }
 743 }
 744
 745 /* If we have any DEFINE_COND_EXEC patterns, expand the DEFINE_INSN
 746    patterns appropriately.  */
 747
 748 static void
 749 process_define_cond_exec ()
 750 {
 751   struct queue_elem *elem;
 752
 753   identify_predicable_attribute ();
 754   if (errors)
 755     return;
 756
 757   for (elem = define_cond_exec_queue; elem ; elem = elem->next)
 758     process_one_cond_exec (elem);
 759 }
 760 \f
 761 /* The entry point for initializing the reader.  */
 762
 763 int
 764 init_md_reader (filename)
 765      const char *filename;
 766 {
 767   FILE *input_file;
 768   int c;
 769
 770   read_rtx_filename = filename;
 771   input_file = fopen (filename, "r");
 772   if (input_file == 0)
 773     {
 774       perror (filename);
 775       return FATAL_EXIT_CODE;
 776     }
 777
 778   obstack_init (rtl_obstack);
 779   errors = 0;
 780   sequence_num = 0;
 781
 782   /* Read the entire file.  */
 783   while (1)
 784     {
 785       rtx desc;
 786       int lineno;
 787
 788       c = read_skip_spaces (input_file);
 789       if (c == EOF)
 790         break;
 791
 792       ungetc (c, input_file);
 793       lineno = read_rtx_lineno;
 794       desc = read_rtx (input_file);
 795       process_rtx (desc, lineno);
 796     }
 797   fclose (input_file);
 798
 799   /* Process define_cond_exec patterns.  */
 800   if (define_cond_exec_queue != NULL)
 801     process_define_cond_exec ();
 802
 803   return errors ? FATAL_EXIT_CODE : SUCCESS_EXIT_CODE;
 804 }
 805
 806 /* The entry point for reading a single rtx from an md file.  */
 807
 808 rtx
 809 read_md_rtx (lineno, seqnr)
 810      int *lineno;
 811      int *seqnr;
 812 {
 813   struct queue_elem **queue, *elem;
 814   rtx desc;
 815
 816   /* Read all patterns from a given queue before moving on to the next.  */
 817   if (define_attr_queue != NULL)
 818     queue = &define_attr_queue;
 819   else if (define_insn_queue != NULL)
 820     queue = &define_insn_queue;
 821   else if (other_queue != NULL)
 822     queue = &other_queue;
 823   else
 824     return NULL_RTX;
 825
 826   elem = *queue;
 827   *queue = elem->next;
 828   desc = elem->data;
 829   *lineno = elem->lineno;
 830   *seqnr = sequence_num;
 831
 832   free (elem);
 833
 834   switch (GET_CODE (desc))
 835     {
 836     case DEFINE_INSN:
 837     case DEFINE_EXPAND:
 838     case DEFINE_SPLIT:
 839     case DEFINE_PEEPHOLE:
 840     case DEFINE_PEEPHOLE2:
 841       sequence_num++;
 842       break;
 843
 844     default:
 845       break;
 846     }
 847
 848   return desc;
 849 }
 850
 851 /* Until we can use the versions in libiberty.  */
 852 char *
 853 xstrdup (input)
 854   const char *input;
 855 {
 856   register size_t len = strlen (input) + 1;
 857   register char *output = xmalloc (len);
 858   memcpy (output, input, len);
 859   return output;
 860 }
 861
 862 PTR
 863 xrealloc (old, size)
 864   PTR old;
 865   size_t size;
 866 {
 867   register PTR ptr;
 868   if (old)
 869     ptr = (PTR) realloc (old, size);
 870   else
 871     ptr = (PTR) malloc (size);
 872   if (!ptr)
 873     fatal ("virtual memory exhausted");
 874   return ptr;
 875 }
 876
 877 PTR
 878 xmalloc (size)
 879   size_t size;
 880 {
 881   register PTR val = (PTR) malloc (size);
 882
 883   if (val == 0)
 884     fatal ("virtual memory exhausted");
 885   return val;
 886 }