gcc/regstat.c

   1 /* Scanning of rtl for dataflow analysis.
   2    Copyright (C) 2007-2013 Free Software Foundation, Inc.
   3    Contributed by Kenneth Zadeck (zadeck@naturalbridge.com).
   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 3, 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 COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "rtl.h"
  27 #include "tm_p.h"
  28 #include "flags.h"
  29 #include "regs.h"
  30 #include "except.h"
  31 #include "hard-reg-set.h"
  32 #include "basic-block.h"
  33 #include "timevar.h"
  34 #include "df.h"
  35
  36
  37 struct regstat_n_sets_and_refs_t *regstat_n_sets_and_refs;
  38
  39 /*----------------------------------------------------------------------------
  40    REG_N_SETS and REG_N_REFS.
  41    ----------------------------------------------------------------------------*/
  42
  43 /* If a pass need to change these values in some magical way or the
  44    pass needs to have accurate values for these and is not using
  45    incremental df scanning, then it should use REG_N_SETS and
  46    REG_N_USES.  If the pass is doing incremental scanning then it
  47    should be getting the info from DF_REG_DEF_COUNT and
  48    DF_REG_USE_COUNT.  */
  49
  50 void
  51 regstat_init_n_sets_and_refs (void)
  52 {
  53   unsigned int i;
  54   unsigned int max_regno = max_reg_num ();
  55
  56   timevar_push (TV_REG_STATS);
  57   df_grow_reg_info ();
  58   gcc_assert (!regstat_n_sets_and_refs);
  59
  60   regstat_n_sets_and_refs = XNEWVEC (struct regstat_n_sets_and_refs_t, max_regno);
  61
  62   if (MAY_HAVE_DEBUG_INSNS)
  63     for (i = 0; i < max_regno; i++)
  64       {
  65         int use_count;
  66         df_ref use;
  67
  68         use_count = DF_REG_USE_COUNT (i);
  69         for (use = DF_REG_USE_CHAIN (i); use; use = DF_REF_NEXT_REG (use))
  70           if (DF_REF_INSN_INFO (use) && DEBUG_INSN_P (DF_REF_INSN (use)))
  71             use_count--;
  72
  73
  74         SET_REG_N_SETS (i, DF_REG_DEF_COUNT (i));
  75         SET_REG_N_REFS (i, use_count + REG_N_SETS (i));
  76       }
  77   else
  78     for (i = 0; i < max_regno; i++)
  79       {
  80         SET_REG_N_SETS (i, DF_REG_DEF_COUNT (i));
  81         SET_REG_N_REFS (i, DF_REG_USE_COUNT (i) + REG_N_SETS (i));
  82       }
  83   timevar_pop (TV_REG_STATS);
  84
  85 }
  86
  87
  88 /* Free the array that holds the REG_N_SETS and REG_N_REFS.  */
  89
  90 void
  91 regstat_free_n_sets_and_refs (void)
  92 {
  93   gcc_assert (regstat_n_sets_and_refs);
  94   free (regstat_n_sets_and_refs);
  95   regstat_n_sets_and_refs = NULL;
  96 }
  97
  98
  99 /*----------------------------------------------------------------------------
 100    REGISTER INFORMATION
 101
 102    Process REG_N_DEATHS, REG_LIVE_LENGTH, REG_N_CALLS_CROSSED,
 103    REG_N_THROWING_CALLS_CROSSED and REG_BASIC_BLOCK.
 104
 105    ----------------------------------------------------------------------------*/
 106
 107 static bitmap setjmp_crosses;
 108 struct reg_info_t *reg_info_p;
 109
 110 /* The number allocated elements of reg_info_p.  */
 111 size_t reg_info_p_size;
 112
 113 /* Compute register info: lifetime, bb, and number of defs and uses
 114    for basic block BB.  The three bitvectors are scratch regs used
 115    here.  */
 116
 117 static void
 118 regstat_bb_compute_ri (unsigned int bb_index,
 119                        bitmap live, bitmap artificial_uses,
 120                        bitmap local_live, bitmap local_processed,
 121                        int *local_live_last_luid)
 122 {
 123   basic_block bb = BASIC_BLOCK_FOR_FN (cfun, bb_index);
 124   rtx insn;
 125   df_ref *def_rec;
 126   df_ref *use_rec;
 127   int luid = 0;
 128   bitmap_iterator bi;
 129   unsigned int regno;
 130
 131   bitmap_copy (live, df_get_live_out (bb));
 132   bitmap_clear (artificial_uses);
 133
 134   /* Process the regs live at the end of the block.  Mark them as
 135      not local to any one basic block.  */
 136   EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)
 137     REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
 138
 139   /* Process the artificial defs and uses at the bottom of the block
 140      to begin processing.  */
 141   for (def_rec = df_get_artificial_defs (bb_index); *def_rec; def_rec++)
 142     {
 143       df_ref def = *def_rec;
 144       if ((DF_REF_FLAGS (def) & DF_REF_AT_TOP) == 0)
 145         bitmap_clear_bit (live, DF_REF_REGNO (def));
 146     }
 147
 148   for (use_rec = df_get_artificial_uses (bb_index); *use_rec; use_rec++)
 149     {
 150       df_ref use = *use_rec;
 151       if ((DF_REF_FLAGS (use) & DF_REF_AT_TOP) == 0)
 152         {
 153           regno = DF_REF_REGNO (use);
 154           bitmap_set_bit (live, regno);
 155           bitmap_set_bit (artificial_uses, regno);
 156         }
 157     }
 158
 159   FOR_BB_INSNS_REVERSE (bb, insn)
 160     {
 161       unsigned int uid = INSN_UID (insn);
 162       bitmap_iterator bi;
 163       struct df_mw_hardreg **mws_rec;
 164       rtx link;
 165
 166       if (!NONDEBUG_INSN_P (insn))
 167         continue;
 168
 169       luid++;
 170
 171       link = REG_NOTES (insn);
 172       while (link)
 173         {
 174           if (REG_NOTE_KIND (link) == REG_DEAD)
 175             REG_N_DEATHS (REGNO (XEXP (link, 0)))++;
 176           link = XEXP (link, 1);
 177         }
 178
 179       /* Process the defs.  */
 180       if (CALL_P (insn))
 181         {
 182           bool can_throw = can_throw_internal (insn);
 183           bool set_jump = (find_reg_note (insn, REG_SETJMP, NULL) != NULL);
 184           EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)
 185             {
 186               REG_N_CALLS_CROSSED (regno)++;
 187               REG_FREQ_CALLS_CROSSED (regno) += REG_FREQ_FROM_BB (bb);
 188               REG_FREQ_CALLS_CROSSED (regno) =
 189                 MIN (REG_FREQ_CALLS_CROSSED (regno), REG_FREQ_MAX);
 190               if (can_throw)
 191                 REG_N_THROWING_CALLS_CROSSED (regno)++;
 192
 193               /* We have a problem with any pseudoreg that lives
 194                  across the setjmp.  ANSI says that if a user variable
 195                  does not change in value between the setjmp and the
 196                  longjmp, then the longjmp preserves it.  This
 197                  includes longjmp from a place where the pseudo
 198                  appears dead.  (In principle, the value still exists
 199                  if it is in scope.)  If the pseudo goes in a hard
 200                  reg, some other value may occupy that hard reg where
 201                  this pseudo is dead, thus clobbering the pseudo.
 202                  Conclusion: such a pseudo must not go in a hard
 203                  reg.  */
 204               if (set_jump)
 205                 bitmap_set_bit (setjmp_crosses, regno);
 206             }
 207         }
 208
 209       /* We only care about real sets for calls.  Clobbers cannot
 210          be depended on.
 211          Only do this if the value is totally dead.  */
 212       for (mws_rec = DF_INSN_UID_MWS (uid); *mws_rec; mws_rec++)
 213         {
 214           struct df_mw_hardreg *mws = *mws_rec;
 215           if (DF_MWS_REG_DEF_P (mws))
 216             {
 217               bool all_dead = true;
 218               unsigned int r;
 219
 220               for (r = mws->start_regno; r <= mws->end_regno; r++)
 221                 if (bitmap_bit_p (artificial_uses, r)
 222                     || bitmap_bit_p (live, r))
 223                   {
 224                     all_dead = false;
 225                     break;
 226                   }
 227
 228               if (all_dead)
 229                 {
 230                   regno = mws->start_regno;
 231                   REG_LIVE_LENGTH (regno)++;
 232                 }
 233             }
 234         }
 235
 236       /* All of the defs except the return value are some sort of
 237          clobber.  This code is for the return.  */
 238       for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
 239         {
 240           df_ref def = *def_rec;
 241           if ((!CALL_P (insn))
 242               || (!(DF_REF_FLAGS (def) & (DF_REF_MUST_CLOBBER | DF_REF_MAY_CLOBBER))))
 243             {
 244               unsigned int dregno = DF_REF_REGNO (def);
 245
 246               if (bitmap_bit_p (live, dregno))
 247                 {
 248                   /* If we have seen a use of DREGNO somewhere before (i.e.
 249                      later in this basic block), and DEF is not a subreg
 250                      store or conditional store, then kill the register
 251                      here and add the proper length to its REG_LIVE_LENGTH.
 252
 253                      If we have not seen a use of DREGNO later in this basic
 254                      block, then we need to add the length from here to the
 255                      end of the block to the live length.  */
 256                   if (bitmap_bit_p (local_live, dregno))
 257                     {
 258                       /* Note that LOCAL_LIVE implies LOCAL_PROCESSED, so
 259                          we don't have to set LOCAL_PROCESSED in this clause.  */
 260                       if (!(DF_REF_FLAGS (def) & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))
 261                         {
 262                           REG_LIVE_LENGTH (dregno) +=
 263                             (luid - local_live_last_luid[dregno]);
 264                           local_live_last_luid[dregno] = luid;
 265                           bitmap_clear_bit (local_live, dregno);
 266                         }
 267                     }
 268                   else
 269                     {
 270                       bitmap_set_bit (local_processed, dregno);
 271                       REG_LIVE_LENGTH (dregno) += luid;
 272                       local_live_last_luid[dregno] = luid;
 273                     }
 274
 275                   /* Kill this register if it is not a subreg store or
 276                      conditional store.
 277                      ??? This means that any partial store is live from
 278                      the last use in a basic block to the start of this
 279                      basic block.  This results in poor calculations of
 280                      REG_LIVE_LENGTH in large basic blocks.  */
 281                   if (!(DF_REF_FLAGS (def) & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))
 282                     bitmap_clear_bit (live, dregno);
 283                 }
 284               else if ((!(DF_REF_FLAGS (def) & DF_REF_MW_HARDREG))
 285                        && (!bitmap_bit_p (artificial_uses, dregno)))
 286                 {
 287                   REG_LIVE_LENGTH (dregno)++;
 288                 }
 289
 290               if (dregno >= FIRST_PSEUDO_REGISTER)
 291                 {
 292                   REG_FREQ (dregno) += REG_FREQ_FROM_BB (bb);
 293                   REG_FREQ (dregno) =
 294                     MIN (REG_FREQ (dregno), REG_FREQ_MAX);
 295
 296                   if (REG_BASIC_BLOCK (dregno) == REG_BLOCK_UNKNOWN)
 297                     REG_BASIC_BLOCK (dregno) = bb->index;
 298                   else if (REG_BASIC_BLOCK (dregno) != bb->index)
 299                     REG_BASIC_BLOCK (dregno) = REG_BLOCK_GLOBAL;
 300                 }
 301             }
 302         }
 303
 304       for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)
 305         {
 306           df_ref use = *use_rec;
 307           unsigned int uregno = DF_REF_REGNO (use);
 308
 309           if (uregno >= FIRST_PSEUDO_REGISTER)
 310             {
 311               REG_FREQ (uregno) += REG_FREQ_FROM_BB (bb);
 312               REG_FREQ (uregno) =
 313                 MIN (REG_FREQ (uregno), REG_FREQ_MAX);
 314
 315               if (REG_BASIC_BLOCK (uregno) == REG_BLOCK_UNKNOWN)
 316                 REG_BASIC_BLOCK (uregno) = bb->index;
 317               else if (REG_BASIC_BLOCK (uregno) != bb->index)
 318                 REG_BASIC_BLOCK (uregno) = REG_BLOCK_GLOBAL;
 319             }
 320
 321           if (bitmap_set_bit (live, uregno))
 322             {
 323               /* This register is now live.  Begin to process it locally.
 324
 325                  Note that we don't even get here if the variable was live
 326                  at the end of the block since just a ref inside the block
 327                  does not effect the calculations.  */
 328               REG_LIVE_LENGTH (uregno) ++;
 329               local_live_last_luid[uregno] = luid;
 330               bitmap_set_bit (local_live, uregno);
 331               bitmap_set_bit (local_processed, uregno);
 332             }
 333         }
 334     }
 335
 336   /* Add the liveness length to all registers that were used somewhere
 337      in this bock, but not between that use and the head of this block.  */
 338   EXECUTE_IF_SET_IN_BITMAP (local_live, 0, regno, bi)
 339     {
 340       REG_LIVE_LENGTH (regno) += (luid - local_live_last_luid[regno]);
 341     }
 342
 343   /* Add the length of the block to all of the registers that were not
 344      referenced, but still live in this block.  */
 345   bitmap_and_compl_into (live, local_processed);
 346   EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)
 347     REG_LIVE_LENGTH (regno) += luid;
 348
 349   bitmap_clear (local_processed);
 350   bitmap_clear (local_live);
 351 }
 352
 353
 354 /* Compute register info: lifetime, bb, and number of defs and uses.  */
 355 void
 356 regstat_compute_ri (void)
 357 {
 358   basic_block bb;
 359   bitmap live = BITMAP_ALLOC (&df_bitmap_obstack);
 360   bitmap artificial_uses = BITMAP_ALLOC (&df_bitmap_obstack);
 361   bitmap local_live = BITMAP_ALLOC (&df_bitmap_obstack);
 362   bitmap local_processed = BITMAP_ALLOC (&df_bitmap_obstack);
 363   unsigned int regno;
 364   bitmap_iterator bi;
 365   int *local_live_last_luid;
 366
 367   /* Initialize everything.  */
 368
 369   gcc_assert (!reg_info_p);
 370
 371   timevar_push (TV_REG_STATS);
 372   setjmp_crosses = BITMAP_ALLOC (&df_bitmap_obstack);
 373   max_regno = max_reg_num ();
 374   reg_info_p_size = max_regno;
 375   reg_info_p = XCNEWVEC (struct reg_info_t, max_regno);
 376   local_live_last_luid = XNEWVEC (int, max_regno);
 377
 378   FOR_EACH_BB_FN (bb, cfun)
 379     {
 380       regstat_bb_compute_ri (bb->index, live, artificial_uses,
 381                              local_live, local_processed,
 382                              local_live_last_luid);
 383     }
 384
 385   BITMAP_FREE (live);
 386   BITMAP_FREE (artificial_uses);
 387   BITMAP_FREE (local_live);
 388   BITMAP_FREE (local_processed);
 389   free (local_live_last_luid);
 390
 391   /* See the setjmp comment in regstat_bb_compute_ri.  */
 392   EXECUTE_IF_SET_IN_BITMAP (setjmp_crosses, FIRST_PSEUDO_REGISTER, regno, bi)
 393     {
 394       REG_BASIC_BLOCK (regno) = REG_BLOCK_UNKNOWN;
 395       REG_LIVE_LENGTH (regno) = -1;
 396     }
 397
 398   timevar_pop (TV_REG_STATS);
 399 }
 400
 401
 402 /* Free all storage associated with the problem.  */
 403
 404 void
 405 regstat_free_ri (void)
 406 {
 407   gcc_assert (reg_info_p);
 408   reg_info_p_size = 0;
 409   free (reg_info_p);
 410   reg_info_p = NULL;
 411
 412   BITMAP_FREE (setjmp_crosses);
 413 }
 414
 415
 416 /* Return a bitmap containing the set of registers that cross a setjmp.
 417    The client should not change or delete this bitmap.  */
 418
 419 bitmap
 420 regstat_get_setjmp_crosses (void)
 421 {
 422   return setjmp_crosses;
 423 }
 424
 425 /*----------------------------------------------------------------------------
 426    Process REG_N_CALLS_CROSSED.
 427
 428    This is used by sched_deps.  A good implementation of sched-deps
 429    would really process the blocks directly rather than going through
 430    lists of insns.  If it did this, it could use the exact regs that
 431    cross an individual call rather than using this info that merges
 432    the info for all calls.
 433
 434    ----------------------------------------------------------------------------*/
 435
 436
 437
 438 /* Compute calls crossed for BB. Live is a scratch bitvector.  */
 439
 440 static void
 441 regstat_bb_compute_calls_crossed (unsigned int bb_index, bitmap live)
 442 {
 443   basic_block bb = BASIC_BLOCK_FOR_FN (cfun, bb_index);
 444   rtx insn;
 445   df_ref *def_rec;
 446   df_ref *use_rec;
 447
 448   bitmap_copy (live, df_get_live_out (bb));
 449
 450   /* Process the artificial defs and uses at the bottom of the block
 451      to begin processing.  */
 452   for (def_rec = df_get_artificial_defs (bb_index); *def_rec; def_rec++)
 453     {
 454       df_ref def = *def_rec;
 455       if ((DF_REF_FLAGS (def) & DF_REF_AT_TOP) == 0)
 456         bitmap_clear_bit (live, DF_REF_REGNO (def));
 457     }
 458
 459   for (use_rec = df_get_artificial_uses (bb_index); *use_rec; use_rec++)
 460     {
 461       df_ref use = *use_rec;
 462       if ((DF_REF_FLAGS (use) & DF_REF_AT_TOP) == 0)
 463         bitmap_set_bit (live, DF_REF_REGNO (use));
 464     }
 465
 466   FOR_BB_INSNS_REVERSE (bb, insn)
 467     {
 468       unsigned int uid = INSN_UID (insn);
 469       unsigned int regno;
 470
 471       if (!INSN_P (insn))
 472         continue;
 473
 474       /* Process the defs.  */
 475       if (CALL_P (insn))
 476         {
 477           bitmap_iterator bi;
 478           EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)
 479             {
 480               REG_N_CALLS_CROSSED (regno)++;
 481               REG_FREQ_CALLS_CROSSED (regno) += REG_FREQ_FROM_BB (bb);
 482               REG_FREQ_CALLS_CROSSED (regno) =
 483                 MIN (REG_FREQ_CALLS_CROSSED (regno), REG_FREQ_MAX);
 484             }
 485         }
 486
 487       /* All of the defs except the return value are some sort of
 488          clobber.  This code is for the return.  */
 489       for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
 490         {
 491           df_ref def = *def_rec;
 492           if ((!CALL_P (insn))
 493               || (!(DF_REF_FLAGS (def) & (DF_REF_MUST_CLOBBER | DF_REF_MAY_CLOBBER))))
 494             {
 495               /* Kill this register if it is not a subreg store or conditional store.  */
 496               if (!(DF_REF_FLAGS (def) & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))
 497                 bitmap_clear_bit (live, DF_REF_REGNO (def));
 498             }
 499         }
 500
 501       for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)
 502         {
 503           df_ref use = *use_rec;
 504           bitmap_set_bit (live, DF_REF_REGNO (use));
 505         }
 506     }
 507 }
 508
 509
 510 /* Compute register info: lifetime, bb, and number of defs and uses.  */
 511 void
 512 regstat_compute_calls_crossed (void)
 513 {
 514   basic_block bb;
 515   bitmap live = BITMAP_ALLOC (&df_bitmap_obstack);
 516
 517   /* Initialize everything.  */
 518   gcc_assert (!reg_info_p);
 519
 520   timevar_push (TV_REG_STATS);
 521   max_regno = max_reg_num ();
 522   reg_info_p_size = max_regno;
 523   reg_info_p = XCNEWVEC (struct reg_info_t, max_regno);
 524
 525   FOR_EACH_BB_FN (bb, cfun)
 526     {
 527       regstat_bb_compute_calls_crossed (bb->index, live);
 528     }
 529
 530   BITMAP_FREE (live);
 531   timevar_pop (TV_REG_STATS);
 532 }
 533
 534
 535 /* Free all storage associated with the problem.  */
 536
 537 void
 538 regstat_free_calls_crossed (void)
 539 {
 540   gcc_assert (reg_info_p);
 541   reg_info_p_size = 0;
 542   free (reg_info_p);
 543   reg_info_p = NULL;
 544 }
 545
 546 /* Dump the register info to FILE.  */
 547
 548 void
 549 dump_reg_info (FILE *file)
 550 {
 551   unsigned int i, max = max_reg_num ();
 552   if (reload_completed)
 553     return;
 554
 555   if (reg_info_p_size < max)
 556     max = reg_info_p_size;
 557
 558   fprintf (file, "%d registers.\n", max);
 559   for (i = FIRST_PSEUDO_REGISTER; i < max; i++)
 560     {
 561       enum reg_class rclass, altclass;
 562
 563       if (regstat_n_sets_and_refs)
 564         fprintf (file, "\nRegister %d used %d times across %d insns",
 565                  i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
 566       else if (df)
 567         fprintf (file, "\nRegister %d used %d times across %d insns",
 568                  i, DF_REG_USE_COUNT (i) + DF_REG_DEF_COUNT (i), REG_LIVE_LENGTH (i));
 569
 570       if (REG_BASIC_BLOCK (i) >= NUM_FIXED_BLOCKS)
 571         fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
 572       if (regstat_n_sets_and_refs)
 573         fprintf (file, "; set %d time%s", REG_N_SETS (i),
 574                  (REG_N_SETS (i) == 1) ? "" : "s");
 575       else if (df)
 576         fprintf (file, "; set %d time%s", DF_REG_DEF_COUNT (i),
 577                  (DF_REG_DEF_COUNT (i) == 1) ? "" : "s");
 578       if (regno_reg_rtx[i] != NULL && REG_USERVAR_P (regno_reg_rtx[i]))
 579         fputs ("; user var", file);
 580       if (REG_N_DEATHS (i) != 1)
 581         fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
 582       if (REG_N_CALLS_CROSSED (i) == 1)
 583         fputs ("; crosses 1 call", file);
 584       else if (REG_N_CALLS_CROSSED (i))
 585         fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
 586       if (REG_FREQ_CALLS_CROSSED (i))
 587         fprintf (file, "; crosses call with %d frequency", REG_FREQ_CALLS_CROSSED (i));
 588       if (regno_reg_rtx[i] != NULL
 589           && PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
 590         fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
 591
 592       rclass = reg_preferred_class (i);
 593       altclass = reg_alternate_class (i);
 594       if (rclass != GENERAL_REGS || altclass != ALL_REGS)
 595         {
 596           if (altclass == ALL_REGS || rclass == ALL_REGS)
 597             fprintf (file, "; pref %s", reg_class_names[(int) rclass]);
 598           else if (altclass == NO_REGS)
 599             fprintf (file, "; %s or none", reg_class_names[(int) rclass]);
 600           else
 601             fprintf (file, "; pref %s, else %s",
 602                      reg_class_names[(int) rclass],
 603                      reg_class_names[(int) altclass]);
 604         }
 605
 606       if (regno_reg_rtx[i] != NULL && REG_POINTER (regno_reg_rtx[i]))
 607         fputs ("; pointer", file);
 608       fputs (".\n", file);
 609     }
 610 }
 611