gcc/cselib.c

   1 /* Common subexpression elimination library for GNU compiler.
   2    Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24
  25 #include "rtl.h"
  26 #include "tm_p.h"
  27 #include "regs.h"
  28 #include "hard-reg-set.h"
  29 #include "flags.h"
  30 #include "real.h"
  31 #include "insn-config.h"
  32 #include "recog.h"
  33 #include "function.h"
  34 #include "expr.h"
  35 #include "toplev.h"
  36 #include "output.h"
  37 #include "ggc.h"
  38 #include "hashtab.h"
  39 #include "cselib.h"
  40
  41 static int entry_and_rtx_equal_p        PARAMS ((const void *, const void *));
  42 static unsigned int get_value_hash      PARAMS ((const void *));
  43 static struct elt_list *new_elt_list    PARAMS ((struct elt_list *,
  44                                                  cselib_val *));
  45 static struct elt_loc_list *new_elt_loc_list PARAMS ((struct elt_loc_list *,
  46                                                       rtx));
  47 static void unchain_one_value           PARAMS ((cselib_val *));
  48 static void unchain_one_elt_list        PARAMS ((struct elt_list **));
  49 static void unchain_one_elt_loc_list    PARAMS ((struct elt_loc_list **));
  50 static void clear_table                 PARAMS ((int));
  51 static int discard_useless_locs         PARAMS ((void **, void *));
  52 static int discard_useless_values       PARAMS ((void **, void *));
  53 static void remove_useless_values       PARAMS ((void));
  54 static rtx wrap_constant                PARAMS ((enum machine_mode, rtx));
  55 static unsigned int hash_rtx            PARAMS ((rtx, enum machine_mode, int));
  56 static cselib_val *new_cselib_val       PARAMS ((unsigned int,
  57                                                  enum machine_mode));
  58 static void add_mem_for_addr            PARAMS ((cselib_val *, cselib_val *,
  59                                                  rtx));
  60 static cselib_val *cselib_lookup_mem    PARAMS ((rtx, int));
  61 static void cselib_invalidate_regno     PARAMS ((unsigned int,
  62                                                  enum machine_mode));
  63 static int cselib_mem_conflict_p        PARAMS ((rtx, rtx));
  64 static int cselib_invalidate_mem_1      PARAMS ((void **, void *));
  65 static void cselib_invalidate_mem       PARAMS ((rtx));
  66 static void cselib_invalidate_rtx       PARAMS ((rtx, rtx, void *));
  67 static void cselib_record_set           PARAMS ((rtx, cselib_val *,
  68                                                  cselib_val *));
  69 static void cselib_record_sets          PARAMS ((rtx));
  70
  71 /* There are three ways in which cselib can look up an rtx:
  72    - for a REG, the reg_values table (which is indexed by regno) is used
  73    - for a MEM, we recursively look up its address and then follow the
  74      addr_list of that value
  75    - for everything else, we compute a hash value and go through the hash
  76      table.  Since different rtx's can still have the same hash value,
  77      this involves walking the table entries for a given value and comparing
  78      the locations of the entries with the rtx we are looking up.  */
  79
  80 /* A table that enables us to look up elts by their value.  */
  81 static GTY((param_is (cselib_val))) htab_t hash_table;
  82
  83 /* This is a global so we don't have to pass this through every function.
  84    It is used in new_elt_loc_list to set SETTING_INSN.  */
  85 static rtx cselib_current_insn;
  86
  87 /* Every new unknown value gets a unique number.  */
  88 static unsigned int next_unknown_value;
  89
  90 /* The number of registers we had when the varrays were last resized.  */
  91 static unsigned int cselib_nregs;
  92
  93 /* Count values without known locations.  Whenever this grows too big, we
  94    remove these useless values from the table.  */
  95 static int n_useless_values;
  96
  97 /* Number of useless values before we remove them from the hash table.  */
  98 #define MAX_USELESS_VALUES 32
  99
 100 /* This table maps from register number to values.  It does not contain
 101    pointers to cselib_val structures, but rather elt_lists.  The purpose is
 102    to be able to refer to the same register in different modes.  */
 103 static GTY(()) varray_type reg_values;
 104 static GTY((deletable (""))) varray_type reg_values_old;
 105 #define REG_VALUES(I) VARRAY_ELT_LIST (reg_values, (I))
 106
 107 /* The largest number of hard regs used by any entry added to the
 108    REG_VALUES table.  Cleared on each clear_table() invocation.  */
 109 static unsigned int max_value_regs;
 110
 111 /* Here the set of indices I with REG_VALUES(I) != 0 is saved.  This is used
 112    in clear_table() for fast emptying.  */
 113 static GTY(()) varray_type used_regs;
 114 static GTY((deletable (""))) varray_type used_regs_old;
 115
 116 /* We pass this to cselib_invalidate_mem to invalidate all of
 117    memory for a non-const call instruction.  */
 118 static GTY(()) rtx callmem;
 119
 120 /* Caches for unused structures.  */
 121 static GTY((deletable (""))) cselib_val *empty_vals;
 122 static GTY((deletable (""))) struct elt_list *empty_elt_lists;
 123 static GTY((deletable (""))) struct elt_loc_list *empty_elt_loc_lists;
 124
 125 /* Set by discard_useless_locs if it deleted the last location of any
 126    value.  */
 127 static int values_became_useless;
 128 \f
 129
 130 /* Allocate a struct elt_list and fill in its two elements with the
 131    arguments.  */
 132
 133 static struct elt_list *
 134 new_elt_list (next, elt)
 135      struct elt_list *next;
 136      cselib_val *elt;
 137 {
 138   struct elt_list *el = empty_elt_lists;
 139
 140   if (el)
 141     empty_elt_lists = el->next;
 142   else
 143     el = (struct elt_list *) ggc_alloc (sizeof (struct elt_list));
 144   el->next = next;
 145   el->elt = elt;
 146   return el;
 147 }
 148
 149 /* Allocate a struct elt_loc_list and fill in its two elements with the
 150    arguments.  */
 151
 152 static struct elt_loc_list *
 153 new_elt_loc_list (next, loc)
 154      struct elt_loc_list *next;
 155      rtx loc;
 156 {
 157   struct elt_loc_list *el = empty_elt_loc_lists;
 158
 159   if (el)
 160     empty_elt_loc_lists = el->next;
 161   else
 162     el = (struct elt_loc_list *) ggc_alloc (sizeof (struct elt_loc_list));
 163   el->next = next;
 164   el->loc = loc;
 165   el->setting_insn = cselib_current_insn;
 166   return el;
 167 }
 168
 169 /* The elt_list at *PL is no longer needed.  Unchain it and free its
 170    storage.  */
 171
 172 static void
 173 unchain_one_elt_list (pl)
 174      struct elt_list **pl;
 175 {
 176   struct elt_list *l = *pl;
 177
 178   *pl = l->next;
 179   l->next = empty_elt_lists;
 180   empty_elt_lists = l;
 181 }
 182
 183 /* Likewise for elt_loc_lists.  */
 184
 185 static void
 186 unchain_one_elt_loc_list (pl)
 187      struct elt_loc_list **pl;
 188 {
 189   struct elt_loc_list *l = *pl;
 190
 191   *pl = l->next;
 192   l->next = empty_elt_loc_lists;
 193   empty_elt_loc_lists = l;
 194 }
 195
 196 /* Likewise for cselib_vals.  This also frees the addr_list associated with
 197    V.  */
 198
 199 static void
 200 unchain_one_value (v)
 201      cselib_val *v;
 202 {
 203   while (v->addr_list)
 204     unchain_one_elt_list (&v->addr_list);
 205
 206   v->u.next_free = empty_vals;
 207   empty_vals = v;
 208 }
 209
 210 /* Remove all entries from the hash table.  Also used during
 211    initialization.  If CLEAR_ALL isn't set, then only clear the entries
 212    which are known to have been used.  */
 213
 214 static void
 215 clear_table (clear_all)
 216      int clear_all;
 217 {
 218   unsigned int i;
 219
 220   if (clear_all)
 221     for (i = 0; i < cselib_nregs; i++)
 222       REG_VALUES (i) = 0;
 223   else
 224     for (i = 0; i < VARRAY_ACTIVE_SIZE (used_regs); i++)
 225       REG_VALUES (VARRAY_UINT (used_regs, i)) = 0;
 226
 227   max_value_regs = 0;
 228
 229   VARRAY_POP_ALL (used_regs);
 230
 231   htab_empty (hash_table);
 232
 233   n_useless_values = 0;
 234
 235   next_unknown_value = 0;
 236 }
 237
 238 /* The equality test for our hash table.  The first argument ENTRY is a table
 239    element (i.e. a cselib_val), while the second arg X is an rtx.  We know
 240    that all callers of htab_find_slot_with_hash will wrap CONST_INTs into a
 241    CONST of an appropriate mode.  */
 242
 243 static int
 244 entry_and_rtx_equal_p (entry, x_arg)
 245      const void *entry, *x_arg;
 246 {
 247   struct elt_loc_list *l;
 248   const cselib_val *v = (const cselib_val *) entry;
 249   rtx x = (rtx) x_arg;
 250   enum machine_mode mode = GET_MODE (x);
 251
 252   if (GET_CODE (x) == CONST_INT
 253       || (mode == VOIDmode && GET_CODE (x) == CONST_DOUBLE))
 254     abort ();
 255   if (mode != GET_MODE (v->u.val_rtx))
 256     return 0;
 257
 258   /* Unwrap X if necessary.  */
 259   if (GET_CODE (x) == CONST
 260       && (GET_CODE (XEXP (x, 0)) == CONST_INT
 261           || GET_CODE (XEXP (x, 0)) == CONST_DOUBLE))
 262     x = XEXP (x, 0);
 263
 264   /* We don't guarantee that distinct rtx's have different hash values,
 265      so we need to do a comparison.  */
 266   for (l = v->locs; l; l = l->next)
 267     if (rtx_equal_for_cselib_p (l->loc, x))
 268       return 1;
 269
 270   return 0;
 271 }
 272
 273 /* The hash function for our hash table.  The value is always computed with
 274    hash_rtx when adding an element; this function just extracts the hash
 275    value from a cselib_val structure.  */
 276
 277 static unsigned int
 278 get_value_hash (entry)
 279      const void *entry;
 280 {
 281   const cselib_val *v = (const cselib_val *) entry;
 282   return v->value;
 283 }
 284
 285 /* Return true if X contains a VALUE rtx.  If ONLY_USELESS is set, we
 286    only return true for values which point to a cselib_val whose value
 287    element has been set to zero, which implies the cselib_val will be
 288    removed.  */
 289
 290 int
 291 references_value_p (x, only_useless)
 292      rtx x;
 293      int only_useless;
 294 {
 295   enum rtx_code code = GET_CODE (x);
 296   const char *fmt = GET_RTX_FORMAT (code);
 297   int i, j;
 298
 299   if (GET_CODE (x) == VALUE
 300       && (! only_useless || CSELIB_VAL_PTR (x)->locs == 0))
 301     return 1;
 302
 303   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
 304     {
 305       if (fmt[i] == 'e' && references_value_p (XEXP (x, i), only_useless))
 306         return 1;
 307       else if (fmt[i] == 'E')
 308         for (j = 0; j < XVECLEN (x, i); j++)
 309           if (references_value_p (XVECEXP (x, i, j), only_useless))
 310             return 1;
 311     }
 312
 313   return 0;
 314 }
 315
 316 /* For all locations found in X, delete locations that reference useless
 317    values (i.e. values without any location).  Called through
 318    htab_traverse.  */
 319
 320 static int
 321 discard_useless_locs (x, info)
 322      void **x;
 323      void *info ATTRIBUTE_UNUSED;
 324 {
 325   cselib_val *v = (cselib_val *)*x;
 326   struct elt_loc_list **p = &v->locs;
 327   int had_locs = v->locs != 0;
 328
 329   while (*p)
 330     {
 331       if (references_value_p ((*p)->loc, 1))
 332         unchain_one_elt_loc_list (p);
 333       else
 334         p = &(*p)->next;
 335     }
 336
 337   if (had_locs && v->locs == 0)
 338     {
 339       n_useless_values++;
 340       values_became_useless = 1;
 341     }
 342   return 1;
 343 }
 344
 345 /* If X is a value with no locations, remove it from the hashtable.  */
 346
 347 static int
 348 discard_useless_values (x, info)
 349      void **x;
 350      void *info ATTRIBUTE_UNUSED;
 351 {
 352   cselib_val *v = (cselib_val *)*x;
 353
 354   if (v->locs == 0)
 355     {
 356       htab_clear_slot (hash_table, x);
 357       unchain_one_value (v);
 358       n_useless_values--;
 359     }
 360
 361   return 1;
 362 }
 363
 364 /* Clean out useless values (i.e. those which no longer have locations
 365    associated with them) from the hash table.  */
 366
 367 static void
 368 remove_useless_values ()
 369 {
 370   /* First pass: eliminate locations that reference the value.  That in
 371      turn can make more values useless.  */
 372   do
 373     {
 374       values_became_useless = 0;
 375       htab_traverse (hash_table, discard_useless_locs, 0);
 376     }
 377   while (values_became_useless);
 378
 379   /* Second pass: actually remove the values.  */
 380   htab_traverse (hash_table, discard_useless_values, 0);
 381
 382   if (n_useless_values != 0)
 383     abort ();
 384 }
 385
 386 /* Return nonzero if we can prove that X and Y contain the same value, taking
 387    our gathered information into account.  */
 388
 389 int
 390 rtx_equal_for_cselib_p (x, y)
 391      rtx x, y;
 392 {
 393   enum rtx_code code;
 394   const char *fmt;
 395   int i;
 396
 397   if (GET_CODE (x) == REG || GET_CODE (x) == MEM)
 398     {
 399       cselib_val *e = cselib_lookup (x, GET_MODE (x), 0);
 400
 401       if (e)
 402         x = e->u.val_rtx;
 403     }
 404
 405   if (GET_CODE (y) == REG || GET_CODE (y) == MEM)
 406     {
 407       cselib_val *e = cselib_lookup (y, GET_MODE (y), 0);
 408
 409       if (e)
 410         y = e->u.val_rtx;
 411     }
 412
 413   if (x == y)
 414     return 1;
 415
 416   if (GET_CODE (x) == VALUE && GET_CODE (y) == VALUE)
 417     return CSELIB_VAL_PTR (x) == CSELIB_VAL_PTR (y);
 418
 419   if (GET_CODE (x) == VALUE)
 420     {
 421       cselib_val *e = CSELIB_VAL_PTR (x);
 422       struct elt_loc_list *l;
 423
 424       for (l = e->locs; l; l = l->next)
 425         {
 426           rtx t = l->loc;
 427
 428           /* Avoid infinite recursion.  */
 429           if (GET_CODE (t) == REG || GET_CODE (t) == MEM)
 430             continue;
 431           else if (rtx_equal_for_cselib_p (t, y))
 432             return 1;
 433         }
 434
 435       return 0;
 436     }
 437
 438   if (GET_CODE (y) == VALUE)
 439     {
 440       cselib_val *e = CSELIB_VAL_PTR (y);
 441       struct elt_loc_list *l;
 442
 443       for (l = e->locs; l; l = l->next)
 444         {
 445           rtx t = l->loc;
 446
 447           if (GET_CODE (t) == REG || GET_CODE (t) == MEM)
 448             continue;
 449           else if (rtx_equal_for_cselib_p (x, t))
 450             return 1;
 451         }
 452
 453       return 0;
 454     }
 455
 456   if (GET_CODE (x) != GET_CODE (y) || GET_MODE (x) != GET_MODE (y))
 457     return 0;
 458
 459   /* This won't be handled correctly by the code below.  */
 460   if (GET_CODE (x) == LABEL_REF)
 461     return XEXP (x, 0) == XEXP (y, 0);
 462
 463   code = GET_CODE (x);
 464   fmt = GET_RTX_FORMAT (code);
 465
 466   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
 467     {
 468       int j;
 469
 470       switch (fmt[i])
 471         {
 472         case 'w':
 473           if (XWINT (x, i) != XWINT (y, i))
 474             return 0;
 475           break;
 476
 477         case 'n':
 478         case 'i':
 479           if (XINT (x, i) != XINT (y, i))
 480             return 0;
 481           break;
 482
 483         case 'V':
 484         case 'E':
 485           /* Two vectors must have the same length.  */
 486           if (XVECLEN (x, i) != XVECLEN (y, i))
 487             return 0;
 488
 489           /* And the corresponding elements must match.  */
 490           for (j = 0; j < XVECLEN (x, i); j++)
 491             if (! rtx_equal_for_cselib_p (XVECEXP (x, i, j),
 492                                           XVECEXP (y, i, j)))
 493               return 0;
 494           break;
 495
 496         case 'e':
 497           if (! rtx_equal_for_cselib_p (XEXP (x, i), XEXP (y, i)))
 498             return 0;
 499           break;
 500
 501         case 'S':
 502         case 's':
 503           if (strcmp (XSTR (x, i), XSTR (y, i)))
 504             return 0;
 505           break;
 506
 507         case 'u':
 508           /* These are just backpointers, so they don't matter.  */
 509           break;
 510
 511         case '0':
 512         case 't':
 513           break;
 514
 515           /* It is believed that rtx's at this level will never
 516              contain anything but integers and other rtx's,
 517              except for within LABEL_REFs and SYMBOL_REFs.  */
 518         default:
 519           abort ();
 520         }
 521     }
 522   return 1;
 523 }
 524
 525 /* We need to pass down the mode of constants through the hash table
 526    functions.  For that purpose, wrap them in a CONST of the appropriate
 527    mode.  */
 528 static rtx
 529 wrap_constant (mode, x)
 530      enum machine_mode mode;
 531      rtx x;
 532 {
 533   if (GET_CODE (x) != CONST_INT
 534       && (GET_CODE (x) != CONST_DOUBLE || GET_MODE (x) != VOIDmode))
 535     return x;
 536   if (mode == VOIDmode)
 537     abort ();
 538   return gen_rtx_CONST (mode, x);
 539 }
 540
 541 /* Hash an rtx.  Return 0 if we couldn't hash the rtx.
 542    For registers and memory locations, we look up their cselib_val structure
 543    and return its VALUE element.
 544    Possible reasons for return 0 are: the object is volatile, or we couldn't
 545    find a register or memory location in the table and CREATE is zero.  If
 546    CREATE is nonzero, table elts are created for regs and mem.
 547    MODE is used in hashing for CONST_INTs only;
 548    otherwise the mode of X is used.  */
 549
 550 static unsigned int
 551 hash_rtx (x, mode, create)
 552      rtx x;
 553      enum machine_mode mode;
 554      int create;
 555 {
 556   cselib_val *e;
 557   int i, j;
 558   enum rtx_code code;
 559   const char *fmt;
 560   unsigned int hash = 0;
 561
 562   code = GET_CODE (x);
 563   hash += (unsigned) code + (unsigned) GET_MODE (x);
 564
 565   switch (code)
 566     {
 567     case MEM:
 568     case REG:
 569       e = cselib_lookup (x, GET_MODE (x), create);
 570       if (! e)
 571         return 0;
 572
 573       return e->value;
 574
 575     case CONST_INT:
 576       hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + INTVAL (x);
 577       return hash ? hash : (unsigned int) CONST_INT;
 578
 579     case CONST_DOUBLE:
 580       /* This is like the general case, except that it only counts
 581          the integers representing the constant.  */
 582       hash += (unsigned) code + (unsigned) GET_MODE (x);
 583       if (GET_MODE (x) != VOIDmode)
 584         for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
 585           hash += XWINT (x, i);
 586       else
 587         hash += ((unsigned) CONST_DOUBLE_LOW (x)
 588                  + (unsigned) CONST_DOUBLE_HIGH (x));
 589       return hash ? hash : (unsigned int) CONST_DOUBLE;
 590
 591     case CONST_VECTOR:
 592       {
 593         int units;
 594         rtx elt;
 595
 596         units = CONST_VECTOR_NUNITS (x);
 597
 598         for (i = 0; i < units; ++i)
 599           {
 600             elt = CONST_VECTOR_ELT (x, i);
 601             hash += hash_rtx (elt, GET_MODE (elt), 0);
 602           }
 603
 604         return hash;
 605       }
 606
 607       /* Assume there is only one rtx object for any given label.  */
 608     case LABEL_REF:
 609       hash
 610         += ((unsigned) LABEL_REF << 7) + (unsigned long) XEXP (x, 0);
 611       return hash ? hash : (unsigned int) LABEL_REF;
 612
 613     case SYMBOL_REF:
 614       hash
 615         += ((unsigned) SYMBOL_REF << 7) + (unsigned long) XSTR (x, 0);
 616       return hash ? hash : (unsigned int) SYMBOL_REF;
 617
 618     case PRE_DEC:
 619     case PRE_INC:
 620     case POST_DEC:
 621     case POST_INC:
 622     case POST_MODIFY:
 623     case PRE_MODIFY:
 624     case PC:
 625     case CC0:
 626     case CALL:
 627     case UNSPEC_VOLATILE:
 628       return 0;
 629
 630     case ASM_OPERANDS:
 631       if (MEM_VOLATILE_P (x))
 632         return 0;
 633
 634       break;
 635
 636     default:
 637       break;
 638     }
 639
 640   i = GET_RTX_LENGTH (code) - 1;
 641   fmt = GET_RTX_FORMAT (code);
 642   for (; i >= 0; i--)
 643     {
 644       if (fmt[i] == 'e')
 645         {
 646           rtx tem = XEXP (x, i);
 647           unsigned int tem_hash = hash_rtx (tem, 0, create);
 648
 649           if (tem_hash == 0)
 650             return 0;
 651
 652           hash += tem_hash;
 653         }
 654       else if (fmt[i] == 'E')
 655         for (j = 0; j < XVECLEN (x, i); j++)
 656           {
 657             unsigned int tem_hash = hash_rtx (XVECEXP (x, i, j), 0, create);
 658
 659             if (tem_hash == 0)
 660               return 0;
 661
 662             hash += tem_hash;
 663           }
 664       else if (fmt[i] == 's')
 665         {
 666           const unsigned char *p = (const unsigned char *) XSTR (x, i);
 667
 668           if (p)
 669             while (*p)
 670               hash += *p++;
 671         }
 672       else if (fmt[i] == 'i')
 673         hash += XINT (x, i);
 674       else if (fmt[i] == '0' || fmt[i] == 't')
 675         /* unused */;
 676       else
 677         abort ();
 678     }
 679
 680   return hash ? hash : 1 + (unsigned int) GET_CODE (x);
 681 }
 682
 683 /* Create a new value structure for VALUE and initialize it.  The mode of the
 684    value is MODE.  */
 685
 686 static cselib_val *
 687 new_cselib_val (value, mode)
 688      unsigned int value;
 689      enum machine_mode mode;
 690 {
 691   cselib_val *e = empty_vals;
 692
 693   if (e)
 694     empty_vals = e->u.next_free;
 695   else
 696     e = (cselib_val *) ggc_alloc (sizeof (cselib_val));
 697
 698   if (value == 0)
 699     abort ();
 700
 701   e->value = value;
 702   e->u.val_rtx = gen_rtx_VALUE (mode);
 703   CSELIB_VAL_PTR (e->u.val_rtx) = e;
 704   e->addr_list = 0;
 705   e->locs = 0;
 706   return e;
 707 }
 708
 709 /* ADDR_ELT is a value that is used as address.  MEM_ELT is the value that
 710    contains the data at this address.  X is a MEM that represents the
 711    value.  Update the two value structures to represent this situation.  */
 712
 713 static void
 714 add_mem_for_addr (addr_elt, mem_elt, x)
 715      cselib_val *addr_elt, *mem_elt;
 716      rtx x;
 717 {
 718   struct elt_loc_list *l;
 719
 720   /* Avoid duplicates.  */
 721   for (l = mem_elt->locs; l; l = l->next)
 722     if (GET_CODE (l->loc) == MEM
 723         && CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt)
 724       return;
 725
 726   addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt);
 727   mem_elt->locs
 728     = new_elt_loc_list (mem_elt->locs,
 729                         replace_equiv_address_nv (x, addr_elt->u.val_rtx));
 730 }
 731
 732 /* Subroutine of cselib_lookup.  Return a value for X, which is a MEM rtx.
 733    If CREATE, make a new one if we haven't seen it before.  */
 734
 735 static cselib_val *
 736 cselib_lookup_mem (x, create)
 737      rtx x;
 738      int create;
 739 {
 740   enum machine_mode mode = GET_MODE (x);
 741   void **slot;
 742   cselib_val *addr;
 743   cselib_val *mem_elt;
 744   struct elt_list *l;
 745
 746   if (MEM_VOLATILE_P (x) || mode == BLKmode
 747       || (FLOAT_MODE_P (mode) && flag_float_store))
 748     return 0;
 749
 750   /* Look up the value for the address.  */
 751   addr = cselib_lookup (XEXP (x, 0), mode, create);
 752   if (! addr)
 753     return 0;
 754
 755   /* Find a value that describes a value of our mode at that address.  */
 756   for (l = addr->addr_list; l; l = l->next)
 757     if (GET_MODE (l->elt->u.val_rtx) == mode)
 758       return l->elt;
 759
 760   if (! create)
 761     return 0;
 762
 763   mem_elt = new_cselib_val (++next_unknown_value, mode);
 764   add_mem_for_addr (addr, mem_elt, x);
 765   slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
 766                                    mem_elt->value, INSERT);
 767   *slot = mem_elt;
 768   return mem_elt;
 769 }
 770
 771 /* Walk rtx X and replace all occurrences of REG and MEM subexpressions
 772    with VALUE expressions.  This way, it becomes independent of changes
 773    to registers and memory.
 774    X isn't actually modified; if modifications are needed, new rtl is
 775    allocated.  However, the return value can share rtl with X.  */
 776
 777 rtx
 778 cselib_subst_to_values (x)
 779      rtx x;
 780 {
 781   enum rtx_code code = GET_CODE (x);
 782   const char *fmt = GET_RTX_FORMAT (code);
 783   cselib_val *e;
 784   struct elt_list *l;
 785   rtx copy = x;
 786   int i;
 787
 788   switch (code)
 789     {
 790     case REG:
 791       for (l = REG_VALUES (REGNO (x)); l; l = l->next)
 792         if (GET_MODE (l->elt->u.val_rtx) == GET_MODE (x))
 793           return l->elt->u.val_rtx;
 794
 795       abort ();
 796
 797     case MEM:
 798       e = cselib_lookup_mem (x, 0);
 799       if (! e)
 800         {
 801           /* This happens for autoincrements.  Assign a value that doesn't
 802              match any other.  */
 803           e = new_cselib_val (++next_unknown_value, GET_MODE (x));
 804         }
 805       return e->u.val_rtx;
 806
 807     case CONST_DOUBLE:
 808     case CONST_VECTOR:
 809     case CONST_INT:
 810       return x;
 811
 812     case POST_INC:
 813     case PRE_INC:
 814     case POST_DEC:
 815     case PRE_DEC:
 816     case POST_MODIFY:
 817     case PRE_MODIFY:
 818       e = new_cselib_val (++next_unknown_value, GET_MODE (x));
 819       return e->u.val_rtx;
 820
 821     default:
 822       break;
 823     }
 824
 825   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
 826     {
 827       if (fmt[i] == 'e')
 828         {
 829           rtx t = cselib_subst_to_values (XEXP (x, i));
 830
 831           if (t != XEXP (x, i) && x == copy)
 832             copy = shallow_copy_rtx (x);
 833
 834           XEXP (copy, i) = t;
 835         }
 836       else if (fmt[i] == 'E')
 837         {
 838           int j, k;
 839
 840           for (j = 0; j < XVECLEN (x, i); j++)
 841             {
 842               rtx t = cselib_subst_to_values (XVECEXP (x, i, j));
 843
 844               if (t != XVECEXP (x, i, j) && XVEC (x, i) == XVEC (copy, i))
 845                 {
 846                   if (x == copy)
 847                     copy = shallow_copy_rtx (x);
 848
 849                   XVEC (copy, i) = rtvec_alloc (XVECLEN (x, i));
 850                   for (k = 0; k < j; k++)
 851                     XVECEXP (copy, i, k) = XVECEXP (x, i, k);
 852                 }
 853
 854               XVECEXP (copy, i, j) = t;
 855             }
 856         }
 857     }
 858
 859   return copy;
 860 }
 861
 862 /* Look up the rtl expression X in our tables and return the value it has.
 863    If CREATE is zero, we return NULL if we don't know the value.  Otherwise,
 864    we create a new one if possible, using mode MODE if X doesn't have a mode
 865    (i.e. because it's a constant).  */
 866
 867 cselib_val *
 868 cselib_lookup (x, mode, create)
 869      rtx x;
 870      enum machine_mode mode;
 871      int create;
 872 {
 873   void **slot;
 874   cselib_val *e;
 875   unsigned int hashval;
 876
 877   if (GET_MODE (x) != VOIDmode)
 878     mode = GET_MODE (x);
 879
 880   if (GET_CODE (x) == VALUE)
 881     return CSELIB_VAL_PTR (x);
 882
 883   if (GET_CODE (x) == REG)
 884     {
 885       struct elt_list *l;
 886       unsigned int i = REGNO (x);
 887
 888       for (l = REG_VALUES (i); l; l = l->next)
 889         if (mode == GET_MODE (l->elt->u.val_rtx))
 890           return l->elt;
 891
 892       if (! create)
 893         return 0;
 894
 895       if (i < FIRST_PSEUDO_REGISTER)
 896         {
 897           unsigned int n = HARD_REGNO_NREGS (i, mode);
 898
 899           if (n > max_value_regs)
 900             max_value_regs = n;
 901         }
 902
 903       e = new_cselib_val (++next_unknown_value, GET_MODE (x));
 904       e->locs = new_elt_loc_list (e->locs, x);
 905       if (REG_VALUES (i) == 0)
 906         VARRAY_PUSH_UINT (used_regs, i);
 907       REG_VALUES (i) = new_elt_list (REG_VALUES (i), e);
 908       slot = htab_find_slot_with_hash (hash_table, x, e->value, INSERT);
 909       *slot = e;
 910       return e;
 911     }
 912
 913   if (GET_CODE (x) == MEM)
 914     return cselib_lookup_mem (x, create);
 915
 916   hashval = hash_rtx (x, mode, create);
 917   /* Can't even create if hashing is not possible.  */
 918   if (! hashval)
 919     return 0;
 920
 921   slot = htab_find_slot_with_hash (hash_table, wrap_constant (mode, x),
 922                                    hashval, create ? INSERT : NO_INSERT);
 923   if (slot == 0)
 924     return 0;
 925
 926   e = (cselib_val *) *slot;
 927   if (e)
 928     return e;
 929
 930   e = new_cselib_val (hashval, mode);
 931
 932   /* We have to fill the slot before calling cselib_subst_to_values:
 933      the hash table is inconsistent until we do so, and
 934      cselib_subst_to_values will need to do lookups.  */
 935   *slot = (void *) e;
 936   e->locs = new_elt_loc_list (e->locs, cselib_subst_to_values (x));
 937   return e;
 938 }
 939
 940 /* Invalidate any entries in reg_values that overlap REGNO.  This is called
 941    if REGNO is changing.  MODE is the mode of the assignment to REGNO, which
 942    is used to determine how many hard registers are being changed.  If MODE
 943    is VOIDmode, then only REGNO is being changed; this is used when
 944    invalidating call clobbered registers across a call.  */
 945
 946 static void
 947 cselib_invalidate_regno (regno, mode)
 948      unsigned int regno;
 949      enum machine_mode mode;
 950 {
 951   unsigned int endregno;
 952   unsigned int i;
 953
 954   /* If we see pseudos after reload, something is _wrong_.  */
 955   if (reload_completed && regno >= FIRST_PSEUDO_REGISTER
 956       && reg_renumber[regno] >= 0)
 957     abort ();
 958
 959   /* Determine the range of registers that must be invalidated.  For
 960      pseudos, only REGNO is affected.  For hard regs, we must take MODE
 961      into account, and we must also invalidate lower register numbers
 962      if they contain values that overlap REGNO.  */
 963   if (regno < FIRST_PSEUDO_REGISTER && mode != VOIDmode)
 964     {
 965       if (regno < max_value_regs)
 966         i = 0;
 967       else
 968         i = regno - max_value_regs;
 969
 970       endregno = regno + HARD_REGNO_NREGS (regno, mode);
 971     }
 972   else
 973     {
 974       i = regno;
 975       endregno = regno + 1;
 976     }
 977
 978   for (; i < endregno; i++)
 979     {
 980       struct elt_list **l = &REG_VALUES (i);
 981
 982       /* Go through all known values for this reg; if it overlaps the range
 983          we're invalidating, remove the value.  */
 984       while (*l)
 985         {
 986           cselib_val *v = (*l)->elt;
 987           struct elt_loc_list **p;
 988           unsigned int this_last = i;
 989
 990           if (i < FIRST_PSEUDO_REGISTER)
 991             this_last += HARD_REGNO_NREGS (i, GET_MODE (v->u.val_rtx)) - 1;
 992
 993           if (this_last < regno)
 994             {
 995               l = &(*l)->next;
 996               continue;
 997             }
 998
 999           /* We have an overlap.  */
1000           unchain_one_elt_list (l);
1001
1002           /* Now, we clear the mapping from value to reg.  It must exist, so
1003              this code will crash intentionally if it doesn't.  */
1004           for (p = &v->locs; ; p = &(*p)->next)
1005             {
1006               rtx x = (*p)->loc;
1007
1008               if (GET_CODE (x) == REG && REGNO (x) == i)
1009                 {
1010                   unchain_one_elt_loc_list (p);
1011                   break;
1012                 }
1013             }
1014           if (v->locs == 0)
1015             n_useless_values++;
1016         }
1017     }
1018 }
1019
1020 /* The memory at address MEM_BASE is being changed.
1021    Return whether this change will invalidate VAL.  */
1022
1023 static int
1024 cselib_mem_conflict_p (mem_base, val)
1025      rtx mem_base;
1026      rtx val;
1027 {
1028   enum rtx_code code;
1029   const char *fmt;
1030   int i, j;
1031
1032   code = GET_CODE (val);
1033   switch (code)
1034     {
1035       /* Get rid of a few simple cases quickly.  */
1036     case REG:
1037     case PC:
1038     case CC0:
1039     case SCRATCH:
1040     case CONST:
1041     case CONST_INT:
1042     case CONST_DOUBLE:
1043     case CONST_VECTOR:
1044     case SYMBOL_REF:
1045     case LABEL_REF:
1046       return 0;
1047
1048     case MEM:
1049       if (GET_MODE (mem_base) == BLKmode
1050           || GET_MODE (val) == BLKmode
1051           || anti_dependence (val, mem_base))
1052         return 1;
1053
1054       /* The address may contain nested MEMs.  */
1055       break;
1056
1057     default:
1058       break;
1059     }
1060
1061   fmt = GET_RTX_FORMAT (code);
1062   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1063     {
1064       if (fmt[i] == 'e')
1065         {
1066           if (cselib_mem_conflict_p (mem_base, XEXP (val, i)))
1067             return 1;
1068         }
1069       else if (fmt[i] == 'E')
1070         for (j = 0; j < XVECLEN (val, i); j++)
1071           if (cselib_mem_conflict_p (mem_base, XVECEXP (val, i, j)))
1072             return 1;
1073     }
1074
1075   return 0;
1076 }
1077
1078 /* For the value found in SLOT, walk its locations to determine if any overlap
1079    INFO (which is a MEM rtx).  */
1080
1081 static int
1082 cselib_invalidate_mem_1 (slot, info)
1083      void **slot;
1084      void *info;
1085 {
1086   cselib_val *v = (cselib_val *) *slot;
1087   rtx mem_rtx = (rtx) info;
1088   struct elt_loc_list **p = &v->locs;
1089   int had_locs = v->locs != 0;
1090
1091   while (*p)
1092     {
1093       rtx x = (*p)->loc;
1094       cselib_val *addr;
1095       struct elt_list **mem_chain;
1096
1097       /* MEMs may occur in locations only at the top level; below
1098          that every MEM or REG is substituted by its VALUE.  */
1099       if (GET_CODE (x) != MEM
1100           || ! cselib_mem_conflict_p (mem_rtx, x))
1101         {
1102           p = &(*p)->next;
1103           continue;
1104         }
1105
1106       /* This one overlaps.  */
1107       /* We must have a mapping from this MEM's address to the
1108          value (E).  Remove that, too.  */
1109       addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0);
1110       mem_chain = &addr->addr_list;
1111       for (;;)
1112         {
1113           if ((*mem_chain)->elt == v)
1114             {
1115               unchain_one_elt_list (mem_chain);
1116               break;
1117             }
1118
1119           mem_chain = &(*mem_chain)->next;
1120         }
1121
1122       unchain_one_elt_loc_list (p);
1123     }
1124
1125   if (had_locs && v->locs == 0)
1126     n_useless_values++;
1127
1128   return 1;
1129 }
1130
1131 /* Invalidate any locations in the table which are changed because of a
1132    store to MEM_RTX.  If this is called because of a non-const call
1133    instruction, MEM_RTX is (mem:BLK const0_rtx).  */
1134
1135 static void
1136 cselib_invalidate_mem (mem_rtx)
1137      rtx mem_rtx;
1138 {
1139   htab_traverse (hash_table, cselib_invalidate_mem_1, mem_rtx);
1140 }
1141
1142 /* Invalidate DEST, which is being assigned to or clobbered.  The second and
1143    the third parameter exist so that this function can be passed to
1144    note_stores; they are ignored.  */
1145
1146 static void
1147 cselib_invalidate_rtx (dest, ignore, data)
1148      rtx dest;
1149      rtx ignore ATTRIBUTE_UNUSED;
1150      void *data ATTRIBUTE_UNUSED;
1151 {
1152   while (GET_CODE (dest) == STRICT_LOW_PART || GET_CODE (dest) == SIGN_EXTRACT
1153          || GET_CODE (dest) == ZERO_EXTRACT || GET_CODE (dest) == SUBREG)
1154     dest = XEXP (dest, 0);
1155
1156   if (GET_CODE (dest) == REG)
1157     cselib_invalidate_regno (REGNO (dest), GET_MODE (dest));
1158   else if (GET_CODE (dest) == MEM)
1159     cselib_invalidate_mem (dest);
1160
1161   /* Some machines don't define AUTO_INC_DEC, but they still use push
1162      instructions.  We need to catch that case here in order to
1163      invalidate the stack pointer correctly.  Note that invalidating
1164      the stack pointer is different from invalidating DEST.  */
1165   if (push_operand (dest, GET_MODE (dest)))
1166     cselib_invalidate_rtx (stack_pointer_rtx, NULL_RTX, NULL);
1167 }
1168
1169 /* Record the result of a SET instruction.  DEST is being set; the source
1170    contains the value described by SRC_ELT.  If DEST is a MEM, DEST_ADDR_ELT
1171    describes its address.  */
1172
1173 static void
1174 cselib_record_set (dest, src_elt, dest_addr_elt)
1175      rtx dest;
1176      cselib_val *src_elt, *dest_addr_elt;
1177 {
1178   int dreg = GET_CODE (dest) == REG ? (int) REGNO (dest) : -1;
1179
1180   if (src_elt == 0 || side_effects_p (dest))
1181     return;
1182
1183   if (dreg >= 0)
1184     {
1185       if (REG_VALUES (dreg) == 0)
1186         VARRAY_PUSH_UINT (used_regs, dreg);
1187
1188       if (dreg < FIRST_PSEUDO_REGISTER)
1189         {
1190           unsigned int n = HARD_REGNO_NREGS (dreg, GET_MODE (dest));
1191
1192           if (n > max_value_regs)
1193             max_value_regs = n;
1194         }
1195
1196       REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt);
1197       if (src_elt->locs == 0)
1198         n_useless_values--;
1199       src_elt->locs = new_elt_loc_list (src_elt->locs, dest);
1200     }
1201   else if (GET_CODE (dest) == MEM && dest_addr_elt != 0)
1202     {
1203       if (src_elt->locs == 0)
1204         n_useless_values--;
1205       add_mem_for_addr (dest_addr_elt, src_elt, dest);
1206     }
1207 }
1208
1209 /* Describe a single set that is part of an insn.  */
1210 struct set
1211 {
1212   rtx src;
1213   rtx dest;
1214   cselib_val *src_elt;
1215   cselib_val *dest_addr_elt;
1216 };
1217
1218 /* There is no good way to determine how many elements there can be
1219    in a PARALLEL.  Since it's fairly cheap, use a really large number.  */
1220 #define MAX_SETS (FIRST_PSEUDO_REGISTER * 2)
1221
1222 /* Record the effects of any sets in INSN.  */
1223 static void
1224 cselib_record_sets (insn)
1225      rtx insn;
1226 {
1227   int n_sets = 0;
1228   int i;
1229   struct set sets[MAX_SETS];
1230   rtx body = PATTERN (insn);
1231   rtx cond = 0;
1232
1233   body = PATTERN (insn);
1234   if (GET_CODE (body) == COND_EXEC)
1235     {
1236       cond = COND_EXEC_TEST (body);
1237       body = COND_EXEC_CODE (body);
1238     }
1239
1240   /* Find all sets.  */
1241   if (GET_CODE (body) == SET)
1242     {
1243       sets[0].src = SET_SRC (body);
1244       sets[0].dest = SET_DEST (body);
1245       n_sets = 1;
1246     }
1247   else if (GET_CODE (body) == PARALLEL)
1248     {
1249       /* Look through the PARALLEL and record the values being
1250          set, if possible.  Also handle any CLOBBERs.  */
1251       for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
1252         {
1253           rtx x = XVECEXP (body, 0, i);
1254
1255           if (GET_CODE (x) == SET)
1256             {
1257               sets[n_sets].src = SET_SRC (x);
1258               sets[n_sets].dest = SET_DEST (x);
1259               n_sets++;
1260             }
1261         }
1262     }
1263
1264   /* Look up the values that are read.  Do this before invalidating the
1265      locations that are written.  */
1266   for (i = 0; i < n_sets; i++)
1267     {
1268       rtx dest = sets[i].dest;
1269
1270       /* A STRICT_LOW_PART can be ignored; we'll record the equivalence for
1271          the low part after invalidating any knowledge about larger modes.  */
1272       if (GET_CODE (sets[i].dest) == STRICT_LOW_PART)
1273         sets[i].dest = dest = XEXP (dest, 0);
1274
1275       /* We don't know how to record anything but REG or MEM.  */
1276       if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
1277         {
1278           rtx src = sets[i].src;
1279           if (cond)
1280             src = gen_rtx_IF_THEN_ELSE (GET_MODE (src), cond, src, dest);
1281           sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1);
1282           if (GET_CODE (dest) == MEM)
1283             sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0), Pmode, 1);
1284           else
1285             sets[i].dest_addr_elt = 0;
1286         }
1287     }
1288
1289   /* Invalidate all locations written by this insn.  Note that the elts we
1290      looked up in the previous loop aren't affected, just some of their
1291      locations may go away.  */
1292   note_stores (body, cselib_invalidate_rtx, NULL);
1293
1294   /* Now enter the equivalences in our tables.  */
1295   for (i = 0; i < n_sets; i++)
1296     {
1297       rtx dest = sets[i].dest;
1298       if (GET_CODE (dest) == REG || GET_CODE (dest) == MEM)
1299         cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt);
1300     }
1301 }
1302
1303 /* Record the effects of INSN.  */
1304
1305 void
1306 cselib_process_insn (insn)
1307      rtx insn;
1308 {
1309   int i;
1310   rtx x;
1311
1312   cselib_current_insn = insn;
1313
1314   /* Forget everything at a CODE_LABEL, a volatile asm, or a setjmp.  */
1315   if (GET_CODE (insn) == CODE_LABEL
1316       || (GET_CODE (insn) == CALL_INSN
1317           && find_reg_note (insn, REG_SETJMP, NULL))
1318       || (GET_CODE (insn) == INSN
1319           && GET_CODE (PATTERN (insn)) == ASM_OPERANDS
1320           && MEM_VOLATILE_P (PATTERN (insn))))
1321     {
1322       clear_table (0);
1323       return;
1324     }
1325
1326   if (! INSN_P (insn))
1327     {
1328       cselib_current_insn = 0;
1329       return;
1330     }
1331
1332   /* If this is a call instruction, forget anything stored in a
1333      call clobbered register, or, if this is not a const call, in
1334      memory.  */
1335   if (GET_CODE (insn) == CALL_INSN)
1336     {
1337       for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1338         if (call_used_regs[i])
1339           cselib_invalidate_regno (i, VOIDmode);
1340
1341       if (! CONST_OR_PURE_CALL_P (insn))
1342         cselib_invalidate_mem (callmem);
1343     }
1344
1345   cselib_record_sets (insn);
1346
1347 #ifdef AUTO_INC_DEC
1348   /* Clobber any registers which appear in REG_INC notes.  We
1349      could keep track of the changes to their values, but it is
1350      unlikely to help.  */
1351   for (x = REG_NOTES (insn); x; x = XEXP (x, 1))
1352     if (REG_NOTE_KIND (x) == REG_INC)
1353       cselib_invalidate_rtx (XEXP (x, 0), NULL_RTX, NULL);
1354 #endif
1355
1356   /* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only
1357      after we have processed the insn.  */
1358   if (GET_CODE (insn) == CALL_INSN)
1359     for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
1360       if (GET_CODE (XEXP (x, 0)) == CLOBBER)
1361         cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0), NULL_RTX, NULL);
1362
1363   cselib_current_insn = 0;
1364
1365   if (n_useless_values > MAX_USELESS_VALUES)
1366     remove_useless_values ();
1367 }
1368
1369 /* Make sure our varrays are big enough.  Not called from any cselib routines;
1370    it must be called by the user if it allocated new registers.  */
1371
1372 void
1373 cselib_update_varray_sizes ()
1374 {
1375   unsigned int nregs = max_reg_num ();
1376
1377   if (nregs == cselib_nregs)
1378     return;
1379
1380   cselib_nregs = nregs;
1381   VARRAY_GROW (reg_values, nregs);
1382   VARRAY_GROW (used_regs, nregs);
1383 }
1384
1385 /* Initialize cselib for one pass.  The caller must also call
1386    init_alias_analysis.  */
1387
1388 void
1389 cselib_init ()
1390 {
1391   /* This is only created once.  */
1392   if (! callmem)
1393     callmem = gen_rtx_MEM (BLKmode, const0_rtx);
1394
1395   cselib_nregs = max_reg_num ();
1396   if (reg_values_old != NULL && VARRAY_SIZE (reg_values_old) >= cselib_nregs)
1397     {
1398       reg_values = reg_values_old;
1399       used_regs = used_regs_old;
1400       VARRAY_CLEAR (reg_values);
1401       VARRAY_CLEAR (used_regs);
1402     }
1403   else
1404     {
1405       VARRAY_ELT_LIST_INIT (reg_values, cselib_nregs, "reg_values");
1406       VARRAY_UINT_INIT (used_regs, cselib_nregs, "used_regs");
1407     }
1408   hash_table = htab_create_ggc (31, get_value_hash, entry_and_rtx_equal_p,
1409                                 NULL);
1410   clear_table (1);
1411 }
1412
1413 /* Called when the current user is done with cselib.  */
1414
1415 void
1416 cselib_finish ()
1417 {
1418   reg_values_old = reg_values;
1419   reg_values = 0;
1420   used_regs_old = used_regs;
1421   used_regs = 0;
1422   hash_table = 0;
1423   n_useless_values = 0;
1424   next_unknown_value = 0;
1425 }
1426
1427 #include "gt-cselib.h"