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, attr;
 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         attr = XVEC (desc, 7);
 212         PUT_CODE (desc, DEFINE_INSN);
 213         XVEC (desc, 4) = attr;
 214
 215         /* Queue them.  */
 216         queue_pattern (desc, &define_insn_tail, lineno);
 217         queue_pattern (split, &other_tail, lineno);
 218         break;
 219       }
 220
 221     default:
 222       queue_pattern (desc, &other_tail, lineno);
 223       break;
 224     }
 225 }
 226 \f
 227 /* Return true if attribute PREDICABLE is true for ELEM, which holds
 228    a DEFINE_INSN.  */
 229
 230 static int
 231 is_predicable (elem)
 232      struct queue_elem *elem;
 233 {
 234   rtvec vec = XVEC (elem->data, 4);
 235   const char *value;
 236   int i;
 237
 238   if (! vec)
 239     return predicable_default;
 240
 241   for (i = GET_NUM_ELEM (vec) - 1; i >= 0; --i)
 242     {
 243       rtx sub = RTVEC_ELT (vec, i);
 244       switch (GET_CODE (sub))
 245         {
 246         case SET_ATTR:
 247           if (strcmp (XSTR (sub, 0), "predicable") == 0)
 248             {
 249               value = XSTR (sub, 1);
 250               goto found;
 251             }
 252           break;
 253
 254         case SET_ATTR_ALTERNATIVE:
 255           if (strcmp (XSTR (sub, 0), "predicable") == 0)
 256             {
 257               message_with_line (elem->lineno,
 258                                  "multiple alternatives for `predicable'");
 259               errors = 1;
 260               return 0;
 261             }
 262           break;
 263
 264         case SET:
 265           if (GET_CODE (SET_DEST (sub)) != ATTR
 266               || strcmp (XSTR (SET_DEST (sub), 0), "predicable") != 0)
 267             break;
 268           sub = SET_SRC (sub);
 269           if (GET_CODE (sub) == CONST_STRING)
 270             {
 271               value = XSTR (sub, 0);
 272               goto found;
 273             }
 274
 275           /* ??? It would be possible to handle this if we really tried.
 276              It's not easy though, and I'm not going to bother until it
 277              really proves necessary.  */
 278           message_with_line (elem->lineno,
 279                              "non-constant value for `predicable'");
 280           errors = 1;
 281           return 0;
 282
 283         default:
 284           abort ();
 285         }
 286     }
 287
 288   return predicable_default;
 289
 290  found:
 291   /* Verify that predicability does not vary on the alternative.  */
 292   /* ??? It should be possible to handle this by simply eliminating
 293      the non-predicable alternatives from the insn.  FRV would like
 294      to do this.  Delay this until we've got the basics solid.  */
 295   if (strchr (value, ',') != NULL)
 296     {
 297       message_with_line (elem->lineno,
 298                          "multiple alternatives for `predicable'");
 299       errors = 1;
 300       return 0;
 301     }
 302
 303   /* Find out which value we're looking at.  */
 304   if (strcmp (value, predicable_true) == 0)
 305     return 1;
 306   if (strcmp (value, predicable_false) == 0)
 307     return 0;
 308
 309   message_with_line (elem->lineno,
 310                      "Unknown value `%s' for `predicable' attribute",
 311                      value);
 312   errors = 1;
 313   return 0;
 314 }
 315
 316 /* Examine the attribute "predicable"; discover its boolean values
 317    and its default.  */
 318
 319 static void
 320 identify_predicable_attribute ()
 321 {
 322   struct queue_elem *elem;
 323   char *true, *false;
 324   const char *value;
 325   size_t len;
 326
 327   /* Look for the DEFINE_ATTR for `predicable', which must exist.  */
 328   for (elem = define_attr_queue; elem ; elem = elem->next)
 329     if (strcmp (XSTR (elem->data, 0), "predicable") == 0)
 330       goto found;
 331
 332   message_with_line (define_cond_exec_queue->lineno,
 333                      "Attribute `predicable' not defined");
 334   errors = 1;
 335   return;
 336
 337  found:
 338   value = XSTR (elem->data, 1);
 339   len = strlen (value);
 340   false = (char *) xmalloc (len + 1);
 341   memcpy (false, value, len + 1);
 342
 343   true = strchr (false, ',');
 344   if (true == NULL || strchr (++true, ',') != NULL)
 345     {
 346       message_with_line (elem->lineno,
 347                          "Attribute `predicable' is not a boolean");
 348       errors = 1;
 349       return;
 350     }
 351   true[-1] = '\0';
 352
 353   predicable_true = true;
 354   predicable_false = false;
 355
 356   switch (GET_CODE (XEXP (elem->data, 2)))
 357     {
 358     case CONST_STRING:
 359       value = XSTR (XEXP (elem->data, 2), 0);
 360       break;
 361
 362     case CONST:
 363       message_with_line (elem->lineno,
 364                          "Attribute `predicable' cannot be const");
 365       errors = 1;
 366       return;
 367
 368     default:
 369       message_with_line (elem->lineno,
 370                          "Attribute `predicable' must have a constant default");
 371       errors = 1;
 372       return;
 373     }
 374
 375   if (strcmp (value, true) == 0)
 376     predicable_default = 1;
 377   else if (strcmp (value, false) == 0)
 378     predicable_default = 0;
 379   else
 380     {
 381       message_with_line (elem->lineno,
 382                          "Unknown value `%s' for `predicable' attribute",
 383                          value);
 384       errors = 1;
 385     }
 386 }
 387
 388 /* Return the number of alternatives in constraint S.  */
 389
 390 static int
 391 n_alternatives (s)
 392      const char *s;
 393 {
 394   int n = 1;
 395
 396   if (s)
 397     while (*s)
 398       n += (*s++ == ',');
 399
 400   return n;
 401 }
 402
 403 /* Determine how many alternatives there are in INSN, and how many
 404    operands.  */
 405
 406 static void
 407 collect_insn_data (pattern, palt, pmax)
 408      rtx pattern;
 409      int *palt, *pmax;
 410 {
 411   const char *fmt;
 412   enum rtx_code code;
 413   int i, j, len;
 414
 415   code = GET_CODE (pattern);
 416   switch (code)
 417     {
 418     case MATCH_OPERAND:
 419       i = n_alternatives (XSTR (pattern, 2));
 420       *palt = (i > *palt ? i : *palt);
 421       /* FALLTHRU */
 422
 423     case MATCH_OPERATOR:
 424     case MATCH_SCRATCH:
 425     case MATCH_PARALLEL:
 426     case MATCH_INSN:
 427       i = XINT (pattern, 0);
 428       if (i > *pmax)
 429         *pmax = i;
 430       break;
 431
 432     default:
 433       break;
 434     }
 435
 436   fmt = GET_RTX_FORMAT (code);
 437   len = GET_RTX_LENGTH (code);
 438   for (i = 0; i < len; i++)
 439     {
 440       switch (fmt[i])
 441         {
 442         case 'e': case 'u':
 443           collect_insn_data (XEXP (pattern, i), palt, pmax);
 444           break;
 445
 446         case 'V':
 447           if (XVEC (pattern, i) == NULL)
 448             break;
 449           /* FALLTHRU */
 450         case 'E':
 451           for (j = XVECLEN (pattern, i) - 1; j >= 0; --j)
 452             collect_insn_data (XVECEXP (pattern, i, j), palt, pmax);
 453           break;
 454
 455         case 'i': case 'w': case '0': case 's': case 'S':
 456           break;
 457
 458         default:
 459           abort ();
 460         }
 461     }
 462 }
 463
 464 static rtx
 465 alter_predicate_for_insn (pattern, alt, max_op, lineno)
 466      rtx pattern;
 467      int alt, max_op, lineno;
 468 {
 469   const char *fmt;
 470   enum rtx_code code;
 471   int i, j, len;
 472
 473   code = GET_CODE (pattern);
 474   switch (code)
 475     {
 476     case MATCH_OPERAND:
 477       {
 478         const char *c = XSTR (pattern, 2);
 479
 480         if (n_alternatives (c) != 1)
 481           {
 482             message_with_line (lineno,
 483                                "Too many alternatives for operand %d",
 484                                XINT (pattern, 0));
 485             errors = 1;
 486             return NULL;
 487           }
 488
 489         /* Replicate C as needed to fill out ALT alternatives.  */
 490         if (c && *c && alt > 1)
 491           {
 492             size_t c_len = strlen (c);
 493             size_t len = alt * (c_len + 1);
 494             char *new_c = (char *) xmalloc (len);
 495
 496             memcpy (new_c, c, c_len);
 497             for (i = 1; i < alt; ++i)
 498               {
 499                 new_c[i * (c_len + 1) - 1] = ',';
 500                 memcpy (&new_c[i * (c_len + 1)], c, c_len);
 501               }
 502             new_c[len - 1] = '\0';
 503             XSTR (pattern, 2) = new_c;
 504           }
 505       }
 506       /* FALLTHRU */
 507
 508     case MATCH_OPERATOR:
 509     case MATCH_SCRATCH:
 510     case MATCH_PARALLEL:
 511     case MATCH_INSN:
 512       XINT (pattern, 0) += max_op;
 513       break;
 514
 515     default:
 516       break;
 517     }
 518
 519   fmt = GET_RTX_FORMAT (code);
 520   len = GET_RTX_LENGTH (code);
 521   for (i = 0; i < len; i++)
 522     {
 523       rtx r;
 524
 525       switch (fmt[i])
 526         {
 527         case 'e': case 'u':
 528           r = alter_predicate_for_insn (XEXP (pattern, i), alt,
 529                                         max_op, lineno);
 530           if (r == NULL)
 531             return r;
 532           break;
 533
 534         case 'E':
 535           for (j = XVECLEN (pattern, i) - 1; j >= 0; --j)
 536             {
 537               r = alter_predicate_for_insn (XVECEXP (pattern, i, j),
 538                                             alt, max_op, lineno);
 539               if (r == NULL)
 540                 return r;
 541             }
 542           break;
 543
 544         case 'i': case 'w': case '0': case 's':
 545           break;
 546
 547         default:
 548           abort ();
 549         }
 550     }
 551
 552   return pattern;
 553 }
 554
 555 static const char *
 556 alter_test_for_insn (ce_elem, insn_elem)
 557      struct queue_elem *ce_elem, *insn_elem;
 558 {
 559   const char *ce_test, *insn_test;
 560   char *new_test;
 561   size_t len, ce_len, insn_len;
 562
 563   ce_test = XSTR (ce_elem->data, 1);
 564   insn_test = XSTR (insn_elem->data, 2);
 565   if (!ce_test || *ce_test == '\0')
 566     return insn_test;
 567   if (!insn_test || *insn_test == '\0')
 568     return ce_test;
 569
 570   ce_len = strlen (ce_test);
 571   insn_len = strlen (insn_test);
 572   len = 1 + ce_len + 1 + 4 + 1 + insn_len + 1 + 1;
 573   new_test = (char *) xmalloc (len);
 574
 575   sprintf (new_test, "(%s) && (%s)", ce_test, insn_test);
 576
 577   return new_test;
 578 }
 579
 580 /* Adjust all of the operand numbers in OLD to match the shift they'll
 581    get from an operand displacement of DISP.  Return a pointer after the
 582    adjusted string.  */
 583
 584 static char *
 585 shift_output_template (new, old, disp)
 586      char *new;
 587      const char *old;
 588      int disp;
 589 {
 590   while (*old)
 591     {
 592       char c = *old++;
 593       *new++ = c;
 594       if (c == '%')
 595         {
 596           c = *old++;
 597           if (ISDIGIT ((unsigned char) c))
 598             c += disp;
 599           else if (ISUPPER ((unsigned char) c)
 600                    || ISLOWER ((unsigned char) c))
 601             {
 602               *new++ = c;
 603               c = *old++ + disp;
 604             }
 605           *new++ = c;
 606         }
 607     }
 608
 609   return new;
 610 }
 611
 612 static const char *
 613 alter_output_for_insn (ce_elem, insn_elem, alt, max_op)
 614      struct queue_elem *ce_elem, *insn_elem;
 615      int alt, max_op;
 616 {
 617   const char *ce_out, *insn_out;
 618   char *new, *p;
 619   size_t len, ce_len, insn_len;
 620
 621   /* ??? Could coordinate with genoutput to not duplicate code here.  */
 622
 623   ce_out = XSTR (ce_elem->data, 2);
 624   insn_out = XSTR (insn_elem->data, 3);
 625   if (!ce_out || *ce_out == '\0')
 626     return insn_out;
 627
 628   ce_len = strlen (ce_out);
 629   insn_len = strlen (insn_out);
 630
 631   if (*insn_out == '*')
 632     /* You must take care of the predicate yourself.  */
 633     return insn_out;
 634
 635   if (*insn_out == '@')
 636     {
 637       len = (ce_len + 1) * alt + insn_len + 1;
 638       p = new = xmalloc (len);
 639
 640       do
 641         {
 642           do
 643             *p++ = *insn_out++;
 644           while (ISSPACE ((unsigned char) *insn_out));
 645
 646           if (*insn_out != '#')
 647             {
 648               p = shift_output_template (p, ce_out, max_op);
 649               *p++ = ' ';
 650             }
 651
 652           do
 653             *p++ = *insn_out++;
 654           while (*insn_out && *insn_out != '\n');
 655         }
 656       while (*insn_out);
 657       *p = '\0';
 658     }
 659   else
 660     {
 661       len = ce_len + 1 + insn_len + 1;
 662       new = xmalloc (len);
 663
 664       p = shift_output_template (new, ce_out, max_op);
 665       *p++ = ' ';
 666       memcpy (p, insn_out, insn_len + 1);
 667     }
 668
 669   return new;
 670 }
 671
 672 /* Replicate insns as appropriate for the given DEFINE_COND_EXEC.  */
 673
 674 static void
 675 process_one_cond_exec (ce_elem)
 676      struct queue_elem *ce_elem;
 677 {
 678   struct queue_elem *insn_elem;
 679   for (insn_elem = define_insn_queue; insn_elem ; insn_elem = insn_elem->next)
 680     {
 681       int alternatives, max_operand;
 682       rtx pred, insn, pattern;
 683
 684       if (! is_predicable (insn_elem))
 685         continue;
 686
 687       alternatives = 1;
 688       max_operand = -1;
 689       collect_insn_data (insn_elem->data, &alternatives, &max_operand);
 690       max_operand += 1;
 691
 692       if (XVECLEN (ce_elem->data, 0) != 1)
 693         {
 694           message_with_line (ce_elem->lineno,
 695                              "too many patterns in predicate");
 696           errors = 1;
 697           return;
 698         }
 699
 700       pred = copy_rtx (XVECEXP (ce_elem->data, 0, 0));
 701       pred = alter_predicate_for_insn (pred, alternatives, max_operand,
 702                                        ce_elem->lineno);
 703       if (pred == NULL)
 704         return;
 705
 706       /* Construct a new pattern for the new insn.  */
 707       insn = copy_rtx (insn_elem->data);
 708       XSTR (insn, 0) = "";
 709       pattern = rtx_alloc (COND_EXEC);
 710       XEXP (pattern, 0) = pred;
 711       if (XVECLEN (insn, 1) == 1)
 712         {
 713           XEXP (pattern, 1) = XVECEXP (insn, 1, 0);
 714           XVECEXP (insn, 1, 0) = pattern;
 715           PUT_NUM_ELEM (XVEC (insn, 1), 1);
 716         }
 717       else
 718         {
 719           XEXP (pattern, 1) = rtx_alloc (PARALLEL);
 720           XVEC (XEXP (pattern, 1), 0) = XVEC (insn, 1);
 721           XVEC (insn, 1) = rtvec_alloc (1);
 722           XVECEXP (insn, 1, 0) = pattern;
 723         }
 724
 725       XSTR (insn, 2) = alter_test_for_insn (ce_elem, insn_elem);
 726       XSTR (insn, 3) = alter_output_for_insn (ce_elem, insn_elem,
 727                                               alternatives, max_operand);
 728
 729       /* ??? Set `predicable' to false.  Not crucial since it's really
 730          only used here, and we won't reprocess this new pattern.  */
 731
 732       /* Put the new pattern on the `other' list so that it
 733          (a) is not reprocessed by other define_cond_exec patterns
 734          (b) appears after all normal define_insn patterns.
 735
 736          ??? B is debatable.  If one has normal insns that match
 737          cond_exec patterns, they will be preferred over these
 738          generated patterns.  Whether this matters in practice, or if
 739          it's a good thing, or whether we should thread these new
 740          patterns into the define_insn chain just after their generator
 741          is something we'll have to experiment with.  */
 742
 743       queue_pattern (insn, &other_tail, insn_elem->lineno);
 744     }
 745 }
 746
 747 /* If we have any DEFINE_COND_EXEC patterns, expand the DEFINE_INSN
 748    patterns appropriately.  */
 749
 750 static void
 751 process_define_cond_exec ()
 752 {
 753   struct queue_elem *elem;
 754
 755   identify_predicable_attribute ();
 756   if (errors)
 757     return;
 758
 759   for (elem = define_cond_exec_queue; elem ; elem = elem->next)
 760     process_one_cond_exec (elem);
 761 }
 762 \f
 763 /* The entry point for initializing the reader.  */
 764
 765 int
 766 init_md_reader (filename)
 767      const char *filename;
 768 {
 769   FILE *input_file;
 770   int c;
 771
 772   read_rtx_filename = filename;
 773   input_file = fopen (filename, "r");
 774   if (input_file == 0)
 775     {
 776       perror (filename);
 777       return FATAL_EXIT_CODE;
 778     }
 779
 780   obstack_init (rtl_obstack);
 781   errors = 0;
 782   sequence_num = 0;
 783
 784   /* Read the entire file.  */
 785   while (1)
 786     {
 787       rtx desc;
 788       int lineno;
 789
 790       c = read_skip_spaces (input_file);
 791       if (c == EOF)
 792         break;
 793
 794       ungetc (c, input_file);
 795       lineno = read_rtx_lineno;
 796       desc = read_rtx (input_file);
 797       process_rtx (desc, lineno);
 798     }
 799   fclose (input_file);
 800
 801   /* Process define_cond_exec patterns.  */
 802   if (define_cond_exec_queue != NULL)
 803     process_define_cond_exec ();
 804
 805   return errors ? FATAL_EXIT_CODE : SUCCESS_EXIT_CODE;
 806 }
 807
 808 /* The entry point for reading a single rtx from an md file.  */
 809
 810 rtx
 811 read_md_rtx (lineno, seqnr)
 812      int *lineno;
 813      int *seqnr;
 814 {
 815   struct queue_elem **queue, *elem;
 816   rtx desc;
 817
 818   /* Read all patterns from a given queue before moving on to the next.  */
 819   if (define_attr_queue != NULL)
 820     queue = &define_attr_queue;
 821   else if (define_insn_queue != NULL)
 822     queue = &define_insn_queue;
 823   else if (other_queue != NULL)
 824     queue = &other_queue;
 825   else
 826     return NULL_RTX;
 827
 828   elem = *queue;
 829   *queue = elem->next;
 830   desc = elem->data;
 831   *lineno = elem->lineno;
 832   *seqnr = sequence_num;
 833
 834   free (elem);
 835
 836   switch (GET_CODE (desc))
 837     {
 838     case DEFINE_INSN:
 839     case DEFINE_EXPAND:
 840     case DEFINE_SPLIT:
 841     case DEFINE_PEEPHOLE:
 842     case DEFINE_PEEPHOLE2:
 843       sequence_num++;
 844       break;
 845
 846     default:
 847       break;
 848     }
 849
 850   return desc;
 851 }
 852
 853 /* Until we can use the versions in libiberty.  */
 854 char *
 855 xstrdup (input)
 856   const char *input;
 857 {
 858   register size_t len = strlen (input) + 1;
 859   register char *output = xmalloc (len);
 860   memcpy (output, input, len);
 861   return output;
 862 }
 863
 864 PTR
 865 xrealloc (old, size)
 866   PTR old;
 867   size_t size;
 868 {
 869   register PTR ptr;
 870   if (old)
 871     ptr = (PTR) realloc (old, size);
 872   else
 873     ptr = (PTR) malloc (size);
 874   if (!ptr)
 875     fatal ("virtual memory exhausted");
 876   return ptr;
 877 }
 878
 879 PTR
 880 xmalloc (size)
 881   size_t size;
 882 {
 883   register PTR val = (PTR) malloc (size);
 884
 885   if (val == 0)
 886     fatal ("virtual memory exhausted");
 887   return val;
 888 }