gcc/bc-optab.c

   1 /* Bytecode conversion definitions for GNU C-compiler.
   2    Copyright (C) 1993, 1994 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, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20
  21 #include "config.h"
  22 #include "tree.h"
  23 #include "rtl.h"
  24 #include "machmode.h"
  25 #include "obstack.h"
  26 #include "bytecode.h"
  27 #include "bc-typecd.h"
  28 #include "bc-opcode.h"
  29 #include "bc-optab.h"
  30
  31 #define obstack_chunk_alloc xmalloc
  32 #define obstack_chunk_free free
  33
  34 extern char *xmalloc ();
  35 extern void free ();
  36
  37 /* Table relating interpreter typecodes to machine modes.  */
  38 #define GET_TYPECODE_MODE(CODE) (typecode_mode[((int) CODE)])
  39 enum machine_mode typecode_mode[] = {
  40 #define DEFTYPECODE(CODE, NAME, MODE, TYPE) MODE,
  41 #include "bc-typecd.def"
  42 #undef DEFTYPECODE
  43 };
  44
  45 /* Machine mode to type code map */
  46 static enum typecode signed_mode_to_code_map[MAX_MACHINE_MODE+1];
  47 static enum typecode unsigned_mode_to_code_map[MAX_MACHINE_MODE+1];
  48
  49 #define GET_TYPECODE_SIZE(CODE) GET_MODE_SIZE (GET_TYPECODE_MODE (CODE))
  50
  51 #define BIG_ARBITRARY_NUMBER 100000
  52
  53 /* Table of recipes for conversions among scalar types, to be filled
  54    in as needed at run time.  */
  55 static struct conversion_recipe
  56 {
  57   unsigned char *opcodes;       /* Bytecodes to emit in order.  */
  58   int nopcodes;                 /* Count of bytecodes. */
  59   int cost;                     /* A rather arbitrary cost function. */
  60 } conversion_recipe[NUM_TYPECODES][NUM_TYPECODES];
  61
  62 /* Binary operator tables.  */
  63 struct binary_operator optab_plus_expr[] = {
  64   { addSI, SIcode, SIcode, SIcode },
  65   { addDI, DIcode, DIcode, DIcode },
  66   { addSF, SFcode, SFcode, SFcode },
  67   { addDF, DFcode, DFcode, DFcode },
  68   { addXF, XFcode, XFcode, XFcode },
  69   { addPSI, Pcode, Pcode, SIcode },
  70   { -1, -1, -1, -1 },
  71 };
  72
  73 struct binary_operator optab_minus_expr[] = {
  74   { subSI, SIcode, SIcode, SIcode },
  75   { subDI, DIcode, DIcode, DIcode },
  76   { subSF, SFcode, SFcode, SFcode },
  77   { subDF, DFcode, DFcode, DFcode },
  78   { subXF, XFcode, XFcode, XFcode },
  79   { subPP, SIcode, Pcode, Pcode },
  80   { -1, -1, -1, -1 },
  81 };
  82
  83 /* The ordering of the tables for multiplicative operators
  84    is such that unsigned operations will be preferred to signed
  85    operations when one argument is unsigned.  */
  86
  87 struct binary_operator optab_mult_expr[] = {
  88   { mulSU, SUcode, SUcode, SUcode },
  89   { mulDU, DUcode, DUcode, DUcode },
  90   { mulSI, SIcode, SIcode, SIcode },
  91   { mulDI, DIcode, DIcode, DIcode },
  92   { mulSF, SFcode, SFcode, SFcode },
  93   { mulDF, DFcode, DFcode, DFcode },
  94   { mulXF, XFcode, XFcode, XFcode },
  95   { -1, -1, -1, -1 },
  96 };
  97
  98 struct binary_operator optab_trunc_div_expr[] = {
  99   { divSU, SUcode, SUcode, SUcode },
 100   { divDU, DUcode, DUcode, DUcode },
 101   { divSI, SIcode, SIcode, SIcode },
 102   { divDI, DIcode, DIcode, DIcode },
 103   { -1, -1, -1, -1 },
 104 };
 105
 106 struct binary_operator optab_trunc_mod_expr[] = {
 107   { modSU, SUcode, SUcode, SUcode },
 108   { modDU, DUcode, DUcode, DUcode },
 109   { modSI, SIcode, SIcode, SIcode },
 110   { modDI, DIcode, DIcode, DIcode },
 111   { -1, -1, -1, -1 },
 112 };
 113
 114 struct binary_operator optab_rdiv_expr[] = {
 115   { divSF, SFcode, SFcode, SFcode },
 116   { divDF, DFcode, DFcode, DFcode },
 117   { divXF, XFcode, XFcode, XFcode },
 118   { -1, -1, -1, -1 },
 119 };
 120
 121 struct binary_operator optab_bit_and_expr[] = {
 122   { andSI, SIcode, SIcode, SIcode },
 123   { andDI, DIcode, DIcode, DIcode },
 124   { -1, -1, -1, -1 },
 125 };
 126
 127 struct binary_operator optab_bit_ior_expr[] = {
 128   { iorSI, SIcode, SIcode, SIcode },
 129   { iorDI, DIcode, DIcode, DIcode },
 130   { -1, -1, -1, -1 },
 131 };
 132
 133 struct binary_operator optab_bit_xor_expr[] = {
 134   { xorSI, SIcode, SIcode, SIcode },
 135   { xorDI, DIcode, DIcode, DIcode },
 136   { -1, -1, -1, -1 },
 137 };
 138
 139 struct binary_operator optab_lshift_expr[] = {
 140   { lshiftSI, SIcode, SIcode, SIcode },
 141   { lshiftSU, SUcode, SUcode, SIcode },
 142   { lshiftDI, DIcode, DIcode, SIcode },
 143   { lshiftDU, DUcode, DUcode, SIcode },
 144   { -1, -1, -1, -1 },
 145 };
 146
 147 struct binary_operator optab_rshift_expr[] = {
 148   { rshiftSI, SIcode, SIcode, SIcode },
 149   { rshiftSU, SUcode, SUcode, SIcode },
 150   { rshiftDI, DIcode, DIcode, SIcode },
 151   { rshiftDU, DUcode, DUcode, SIcode },
 152   { -1, -1, -1, -1 },
 153 };
 154
 155 struct binary_operator optab_truth_and_expr[] = {
 156   { andSI, SIcode, Tcode, Tcode },
 157   { -1, -1, -1, -1 },
 158 };
 159
 160 struct binary_operator optab_truth_or_expr[] = {
 161   { iorSI, SIcode, Tcode, Tcode },
 162   { -1, -1, -1, -1 },
 163 };
 164
 165 struct binary_operator optab_lt_expr[] = {
 166   { ltSI, Tcode, SIcode, SIcode },
 167   { ltSU, Tcode, SUcode, SUcode },
 168   { ltDI, Tcode, DIcode, DIcode },
 169   { ltDU, Tcode, DUcode, DUcode },
 170   { ltSF, Tcode, SFcode, SFcode },
 171   { ltDF, Tcode, DFcode, DFcode },
 172   { ltXF, Tcode, XFcode, XFcode },
 173   { ltP, Tcode, Pcode, Pcode },
 174   { -1, -1, -1, -1 },
 175 };
 176
 177 struct binary_operator optab_le_expr[] = {
 178   { leSI, Tcode, SIcode, SIcode },
 179   { leSU, Tcode, SUcode, SUcode },
 180   { leDI, Tcode, DIcode, DIcode },
 181   { leDU, Tcode, DUcode, DUcode },
 182   { leSF, Tcode, SFcode, SFcode },
 183   { leDF, Tcode, DFcode, DFcode },
 184   { leXF, Tcode, XFcode, XFcode },
 185   { leP, Tcode, Pcode, Pcode },
 186   { -1, -1, -1, -1 },
 187 };
 188
 189 struct binary_operator optab_ge_expr[] = {
 190   { geSI, Tcode, SIcode, SIcode },
 191   { geSU, Tcode, SUcode, SUcode },
 192   { geDI, Tcode, DIcode, DIcode },
 193   { geDU, Tcode, DUcode, DUcode },
 194   { geSF, Tcode, SFcode, SFcode },
 195   { geDF, Tcode, DFcode, DFcode },
 196   { geXF, Tcode, XFcode, XFcode },
 197   { geP, Tcode, Pcode, Pcode },
 198   { -1, -1, -1, -1 },
 199 };
 200
 201 struct binary_operator optab_gt_expr[] = {
 202   { gtSI, Tcode, SIcode, SIcode },
 203   { gtSU, Tcode, SUcode, SUcode },
 204   { gtDI, Tcode, DIcode, DIcode },
 205   { gtDU, Tcode, DUcode, DUcode },
 206   { gtSF, Tcode, SFcode, SFcode },
 207   { gtDF, Tcode, DFcode, DFcode },
 208   { gtXF, Tcode, XFcode, XFcode },
 209   { gtP, Tcode, Pcode, Pcode },
 210   { -1, -1, -1, -1 },
 211 };
 212
 213 struct binary_operator optab_eq_expr[] = {
 214   { eqSI, Tcode, SIcode, SIcode },
 215   { eqDI, Tcode, DIcode, DIcode },
 216   { eqSF, Tcode, SFcode, SFcode },
 217   { eqDF, Tcode, DFcode, DFcode },
 218   { eqXF, Tcode, XFcode, XFcode },
 219   { eqP, Tcode, Pcode, Pcode },
 220   { -1, -1, -1, -1 },
 221 };
 222
 223 struct binary_operator optab_ne_expr[] = {
 224   { neSI, Tcode, SIcode, SIcode },
 225   { neDI, Tcode, DIcode, DIcode },
 226   { neSF, Tcode, SFcode, SFcode },
 227   { neDF, Tcode, DFcode, DFcode },
 228   { neXF, Tcode, XFcode, XFcode },
 229   { neP, Tcode, Pcode, Pcode },
 230   { -1, -1, -1, -1 },
 231 };
 232
 233 /* Unary operator tables.  */
 234 struct unary_operator optab_negate_expr[] = {
 235   { negSI, SIcode, SIcode },
 236   { negDI, DIcode, DIcode },
 237   { negSF, SFcode, SFcode },
 238   { negDF, DFcode, DFcode },
 239   { negXF, XFcode, XFcode },
 240   { -1, -1, -1 },
 241 };
 242
 243 struct unary_operator optab_bit_not_expr[] = {
 244   { notSI, SIcode, SIcode },
 245   { notDI, DIcode, DIcode },
 246   { -1, -1, -1 },
 247 };
 248
 249 struct unary_operator optab_truth_not_expr[] = {
 250   { notT, SIcode, SIcode },
 251   { -1, -1, -1 },
 252 };
 253
 254 /* Increment operator tables.  */
 255 struct increment_operator optab_predecrement_expr[] = {
 256   { predecQI, QIcode },
 257   { predecQI, QUcode },
 258   { predecHI, HIcode },
 259   { predecHI, HUcode },
 260   { predecSI, SIcode },
 261   { predecSI, SUcode },
 262   { predecDI, DIcode },
 263   { predecDI, DUcode },
 264   { predecP, Pcode },
 265   { predecSF, SFcode },
 266   { predecDF, DFcode },
 267   { predecXF, XFcode },
 268   { -1, -1 },
 269 };
 270
 271 struct increment_operator optab_preincrement_expr[] = {
 272   { preincQI, QIcode },
 273   { preincQI, QUcode },
 274   { preincHI, HIcode },
 275   { preincHI, HUcode },
 276   { preincSI, SIcode },
 277   { preincSI, SUcode },
 278   { preincDI, DIcode },
 279   { preincDI, DUcode },
 280   { preincP, Pcode },
 281   { preincSF, SFcode },
 282   { preincDF, DFcode },
 283   { preincXF, XFcode },
 284   { -1, -1 },
 285 };
 286
 287 struct increment_operator optab_postdecrement_expr[] = {
 288   { postdecQI, QIcode },
 289   { postdecQI, QUcode },
 290   { postdecHI, HIcode },
 291   { postdecHI, HUcode },
 292   { postdecSI, SIcode },
 293   { postdecSI, SUcode },
 294   { postdecDI, DIcode },
 295   { postdecDI, DUcode },
 296   { postdecP, Pcode },
 297   { postdecSF, SFcode },
 298   { postdecDF, DFcode },
 299   { postdecXF, XFcode },
 300   { -1, -1 },
 301 };
 302
 303 struct increment_operator optab_postincrement_expr[] = {
 304   { postincQI, QIcode },
 305   { postincQI, QUcode },
 306   { postincHI, HIcode },
 307   { postincHI, HUcode },
 308   { postincSI, SIcode },
 309   { postincSI, SUcode },
 310   { postincDI, DIcode },
 311   { postincDI, DUcode },
 312   { postincP, Pcode },
 313   { postincSF, SFcode },
 314   { postincDF, DFcode },
 315   { postincXF, XFcode },
 316   { -1, -1 },
 317 };
 318
 319 /* Table of conversions supported by the interpreter.  */
 320 static struct conversion_info
 321 {
 322   enum bytecode_opcode opcode;  /*  here indicates the conversion needs no opcode.  */
 323   enum typecode from;
 324   enum typecode to;
 325   int cost;                     /* 1 for no-op conversions, 2 for widening conversions,
 326                                    4 for int/float conversions, 8 for narrowing conversions.  */
 327 } conversion_info[] = {
 328   { -1, QIcode, QUcode, 1 },
 329   { -1, HIcode, HUcode, 1 },
 330   { -1, SIcode, SUcode, 1 },
 331   { -1, DIcode, DUcode, 1 },
 332   { -1, QUcode, QIcode, 1 },
 333   { -1, HUcode, HIcode, 1 },
 334   { -1, SUcode, SIcode, 1 },
 335   { -1, DUcode, DIcode, 1 },
 336   { -1, Tcode, SIcode, 1 },
 337   { convertQIHI, QIcode, HIcode, 2 },
 338   { convertQUHU, QUcode, HUcode, 2 },
 339   { convertQUSU, QUcode, SUcode, 2 },
 340   { convertHISI, HIcode, SIcode, 2 },
 341   { convertHUSU, HUcode, SUcode, 2 },
 342   { convertSIDI, SIcode, DIcode, 2 },
 343   { convertSUDU, SUcode, DUcode, 2 },
 344   { convertSFDF, SFcode, DFcode, 2 },
 345   { convertDFXF, DFcode, XFcode, 2 },
 346   { convertHIQI, HIcode, QIcode, 8 },
 347   { convertSIQI, SIcode, QIcode, 8 },
 348   { convertSIHI, SIcode, HIcode, 8 },
 349   { convertSUQU, SUcode, QUcode, 8 },
 350   { convertDISI, DIcode, SIcode, 8 },
 351   { convertDFSF, DFcode, SFcode, 8 },
 352   { convertXFDF, XFcode, DFcode, 8 },
 353   { convertPSI, Pcode, SIcode, 2 },
 354   { convertSIP, SIcode, Pcode, 2 },
 355   { convertSIT, SIcode, Tcode, 2 },
 356   { convertDIT, DIcode, Tcode, 2 },
 357   { convertSFT, SFcode, Tcode, 2 },
 358   { convertDFT, DFcode, Tcode, 2 },
 359   { convertXFT, XFcode, Tcode, 2 },
 360   { convertQISI, QIcode, SIcode, 2 },
 361   { convertPT, Pcode, Tcode, 2 },
 362   { convertSISF, SIcode, SFcode, 4 },
 363   { convertSIDF, SIcode, DFcode, 4 },
 364   { convertSIXF, SIcode, XFcode, 4 },
 365   { convertSUSF, SUcode, SFcode, 4 },
 366   { convertSUDF, SUcode, DFcode, 4 },
 367   { convertSUXF, SUcode, XFcode, 4 },
 368   { convertDISF, DIcode, SFcode, 4 },
 369   { convertDIDF, DIcode, DFcode, 4 },
 370   { convertDIXF, DIcode, XFcode, 4 },
 371   { convertDUSF, DUcode, SFcode, 4 },
 372   { convertDUDF, DUcode, DFcode, 4 },
 373   { convertDUXF, DUcode, XFcode, 4 },
 374   { convertSFSI, SFcode, SIcode, 4 },
 375   { convertDFSI, DFcode, SIcode, 4 },
 376   { convertXFSI, XFcode, SIcode, 4 },
 377   { convertSFSU, SFcode, SUcode, 4 },
 378   { convertDFSU, DFcode, SUcode, 4 },
 379   { convertXFSU, XFcode, SUcode, 4 },
 380   { convertSFDI, SFcode, DIcode, 4 },
 381   { convertDFDI, DFcode, DIcode, 4 },
 382   { convertXFDI, XFcode, DIcode, 4 },
 383   { convertSFDU, SFcode, DUcode, 4 },
 384   { convertDFDU, DFcode, DUcode, 4 },
 385   { convertXFDU, XFcode, DUcode, 4 },
 386   { convertSIQI, SIcode, QIcode, 8 },
 387 };
 388
 389 #define NUM_CONVERSIONS (sizeof conversion_info / sizeof (struct conversion_info))
 390
 391 /* List form of a conversion recipe.  */
 392 struct conversion_list
 393 {
 394   enum bytecode_opcode opcode;
 395   enum typecode to;
 396   int cost;
 397   struct conversion_list *prev;
 398 };
 399
 400 /* Determine if it is "reasonable" to add a given conversion to
 401    a given list of conversions.  The following criteria define
 402    "reasonable" conversion lists:
 403    * No typecode appears more than once in the sequence (no loops).
 404    * At most one conversion from integer to float or vice versa is present.
 405    * Either sign extensions or zero extensions may be present, but not both.
 406    * No widening conversions occur after a signed/unsigned conversion.
 407    * The sequence of sizes must be strict nonincreasing or nondecreasing.  */
 408 static int
 409 conversion_reasonable_p (conversion, list)
 410      struct conversion_info *conversion;
 411      struct conversion_list *list;
 412 {
 413   struct conversion_list *curr;
 414   int curr_size, prev_size;
 415   int has_int_float, has_float_int;
 416   int has_sign_extend, has_zero_extend;
 417   int has_signed_unsigned, has_unsigned_signed;
 418
 419   has_int_float = 0;
 420   has_float_int = 0;
 421   has_sign_extend = 0;
 422   has_zero_extend = 0;
 423   has_signed_unsigned = 0;
 424   has_unsigned_signed = 0;
 425
 426   /* Make sure the destination typecode doesn't already appear in
 427      the list.  */
 428   for (curr = list; curr; curr = curr->prev)
 429     if (conversion->to == curr->to)
 430       return 0;
 431
 432   /* Check for certain kinds of conversions.  */
 433   if (TYPECODE_INTEGER_P (conversion->from)
 434       && TYPECODE_FLOAT_P (conversion->to))
 435     has_int_float = 1;
 436   if (TYPECODE_FLOAT_P (conversion->from)
 437       && TYPECODE_INTEGER_P (conversion->to))
 438     has_float_int = 1;
 439   if (TYPECODE_SIGNED_P (conversion->from)
 440       && TYPECODE_SIGNED_P (conversion->to)
 441       && GET_TYPECODE_SIZE (conversion->from)
 442       < GET_TYPECODE_SIZE (conversion->to))
 443     has_sign_extend = 1;
 444   if (TYPECODE_UNSIGNED_P (conversion->from)
 445       && TYPECODE_UNSIGNED_P (conversion->to)
 446       && GET_TYPECODE_SIZE (conversion->from)
 447       < GET_TYPECODE_SIZE (conversion->to))
 448     has_zero_extend = 1;
 449
 450   for (curr = list; curr && curr->prev; curr = curr->prev)
 451     {
 452       if (TYPECODE_INTEGER_P (curr->prev->to)
 453           && TYPECODE_FLOAT_P (curr->to))
 454         has_int_float = 1;
 455       if (TYPECODE_FLOAT_P (curr->prev->to)
 456           && TYPECODE_INTEGER_P (curr->to))
 457         has_float_int = 1;
 458       if (TYPECODE_SIGNED_P (curr->prev->to)
 459           && TYPECODE_SIGNED_P (curr->to)
 460           && GET_TYPECODE_SIZE (curr->prev->to)
 461           < GET_TYPECODE_SIZE (curr->to))
 462         has_sign_extend = 1;
 463       if (TYPECODE_UNSIGNED_P (curr->prev->to)
 464           && TYPECODE_UNSIGNED_P (curr->to)
 465           && GET_TYPECODE_SIZE (curr->prev->to)
 466           < GET_TYPECODE_SIZE (curr->to))
 467         has_zero_extend = 1;
 468       if (TYPECODE_SIGNED_P (curr->prev->to)
 469           && TYPECODE_UNSIGNED_P (curr->to))
 470         has_signed_unsigned = 1;
 471       if (TYPECODE_UNSIGNED_P (curr->prev->to)
 472           && TYPECODE_SIGNED_P (curr->to))
 473         has_unsigned_signed = 1;
 474     }
 475
 476   if (TYPECODE_INTEGER_P (conversion->from)
 477       && TYPECODE_INTEGER_P (conversion->to)
 478       && GET_TYPECODE_SIZE (conversion->to)
 479       > GET_TYPECODE_SIZE (conversion->from)
 480       && (has_signed_unsigned || has_unsigned_signed))
 481     return 0;
 482
 483   if (has_float_int && has_int_float || has_sign_extend && has_zero_extend)
 484     return 0;
 485
 486   /* Make sure the sequence of destination typecode sizes is
 487      strictly nondecreasing or strictly nonincreasing.  */
 488   prev_size = GET_TYPECODE_SIZE (conversion->to);
 489   for (curr = list; curr; curr = curr->prev)
 490     {
 491       curr_size = GET_TYPECODE_SIZE (curr->to);
 492       if (curr_size != prev_size)
 493         break;
 494     }
 495   if (!curr)
 496     return 1;
 497
 498   if (curr_size < prev_size)
 499     for (prev_size = curr_size; curr; curr = curr->prev)
 500       {
 501         curr_size = GET_TYPECODE_SIZE (curr->to);
 502         if (curr_size > prev_size)
 503           return 0;
 504         prev_size = curr_size;
 505       }
 506   else
 507     for (prev_size = curr_size; curr; curr = curr->prev)
 508       {
 509         curr_size = GET_TYPECODE_SIZE (curr->to);
 510         if (curr_size < prev_size)
 511           return 0;
 512         prev_size = curr_size;
 513       }
 514   return 1;
 515 }
 516
 517
 518 /* Exhaustively search all reasonable conversions to find one to
 519    convert the given types.  */
 520 static struct conversion_recipe
 521 deduce_conversion (from, to)
 522      enum typecode from, to;
 523 {
 524   struct rl
 525     {
 526       struct conversion_list *list;
 527       struct rl *next;
 528     } *prev, curr, *good, *temp;
 529   struct conversion_list *conv, *best;
 530   int i, cost, bestcost;
 531   struct conversion_recipe result;
 532   struct obstack recipe_obstack;
 533
 534
 535   obstack_init (&recipe_obstack);
 536   curr.next = (struct rl *) obstack_alloc (&recipe_obstack, sizeof (struct rl));
 537   curr.next->list =
 538     (struct conversion_list *) obstack_alloc (&recipe_obstack,
 539                                               sizeof (struct conversion_list));
 540   curr.next->list->opcode = -1;
 541   curr.next->list->to = from;
 542   curr.next->list->cost = 0;
 543   curr.next->list->prev = 0;
 544   curr.next->next = 0;
 545   good = 0;
 546
 547   while (curr.next)
 548     {
 549       /* Remove successful conversions from further consideration.  */
 550       for (prev = &curr; prev; prev = prev->next)
 551         if (prev->next && prev->next->list->to == to)
 552           {
 553             temp = prev->next->next;
 554             prev->next->next = good;
 555             good = prev->next;
 556             prev->next = temp;
 557           }
 558
 559       /* Go through each of the pending conversion chains, trying
 560          all possible candidate conversions on them.  */
 561       for (prev = curr.next, curr.next = 0; prev; prev = prev->next)
 562         for (i = 0; i < NUM_CONVERSIONS; ++i)
 563           if (conversion_info[i].from == prev->list->to
 564               && conversion_reasonable_p (&conversion_info[i], prev->list))
 565             {
 566               temp = (struct rl *) obstack_alloc (&recipe_obstack,
 567                                                   sizeof (struct rl));
 568               temp->list = (struct conversion_list *)
 569                 obstack_alloc (&recipe_obstack,
 570                                sizeof (struct conversion_list));
 571               temp->list->opcode = conversion_info[i].opcode;
 572               temp->list->to = conversion_info[i].to;
 573               temp->list->cost = conversion_info[i].cost;
 574               temp->list->prev = prev->list;
 575               temp->next = curr.next;
 576               curr.next = temp;
 577             }
 578     }
 579
 580   bestcost = BIG_ARBITRARY_NUMBER;
 581   best = 0;
 582   for (temp = good; temp; temp = temp->next)
 583     {
 584       for (conv = temp->list, cost = 0; conv; conv = conv->prev)
 585         cost += conv->cost;
 586       if (cost < bestcost)
 587         {
 588           bestcost = cost;
 589           best = temp->list;
 590         }
 591     }
 592
 593   if (!best)
 594     abort ();
 595
 596   for (i = 0, conv = best; conv; conv = conv->prev)
 597     if (conv->opcode != -1)
 598       ++i;
 599
 600   result.opcodes = (unsigned char *) xmalloc (i);
 601   result.nopcodes = i;
 602   for (conv = best; conv; conv = conv->prev)
 603     if (conv->opcode != -1)
 604       result.opcodes[--i] = conv->opcode;
 605   result.cost = bestcost;
 606   obstack_free (&recipe_obstack, 0);
 607   return result;
 608 }
 609
 610 #define DEDUCE_CONVERSION(FROM, TO)                             \
 611   (conversion_recipe[(int) FROM][(int) TO].opcodes ? 0          \
 612    : (conversion_recipe[(int) FROM][(int) TO]                   \
 613        = deduce_conversion (FROM, TO), 0))
 614
 615
 616 /* Emit a conversion between the given scalar types.  */
 617 void
 618 emit_typecode_conversion (from, to)
 619      enum typecode from, to;
 620 {
 621   int i;
 622
 623   DEDUCE_CONVERSION (from, to);
 624   for (i = 0; i < conversion_recipe[(int) from][(int) to].nopcodes; ++i)
 625     bc_emit_instruction (conversion_recipe[(int) from][(int) to].opcodes[i]);
 626 }
 627
 628
 629 /* Initialize mode_to_code_map[] */
 630 void
 631 bc_init_mode_to_code_map ()
 632 {
 633   int mode;
 634
 635   for (mode = 0; mode < MAX_MACHINE_MODE + 1; mode++)
 636     {
 637       signed_mode_to_code_map[mode] =
 638         unsigned_mode_to_code_map[mode] =
 639           LAST_AND_UNUSED_TYPECODE;
 640     }
 641
 642 #define DEF_MODEMAP(SYM, CODE, UCODE, CONST, LOAD, STORE) \
 643   { signed_mode_to_code_map[(int) SYM] = CODE; \
 644     unsigned_mode_to_code_map[(int) SYM] = UCODE; }
 645 #include "modemap.def"
 646 #undef DEF_MODEMAP
 647
 648   /* Initialize opcode maps for const, load, and store */
 649   bc_init_mode_to_opcode_maps ();
 650 }
 651
 652 /* Given a machine mode return the preferred typecode.  */
 653 enum typecode
 654 preferred_typecode (mode, unsignedp)
 655      enum machine_mode mode;
 656      int unsignedp;
 657 {
 658   enum typecode code = (unsignedp
 659                         ? unsigned_mode_to_code_map
 660                         : signed_mode_to_code_map) [MIN ((int) mode,
 661                                                          (int) MAX_MACHINE_MODE)];
 662
 663   if (code == LAST_AND_UNUSED_TYPECODE)
 664     abort ();
 665
 666   return code;
 667 }
 668
 669
 670 /* Expand a conversion between the given types.  */
 671 void
 672 bc_expand_conversion (from, to)
 673      tree from, to;
 674 {
 675   enum typecode fcode, tcode;
 676
 677   fcode = preferred_typecode (TYPE_MODE (from), TREE_UNSIGNED (from));
 678   tcode = preferred_typecode (TYPE_MODE (to), TREE_UNSIGNED (to));
 679
 680   emit_typecode_conversion (fcode, tcode);
 681 }
 682
 683 /* Expand a conversion of the given type to a truth value.  */
 684 void
 685 bc_expand_truth_conversion (from)
 686      tree from;
 687 {
 688   enum typecode fcode;
 689
 690   fcode = preferred_typecode (TYPE_MODE (from), TREE_UNSIGNED (from));
 691   emit_typecode_conversion (fcode, Tcode);
 692 }
 693
 694 /* Emit an appropriate binary operation.  */
 695 void
 696 bc_expand_binary_operation (optab, resulttype, arg0, arg1)
 697      struct binary_operator optab[];
 698      tree resulttype, arg0, arg1;
 699 {
 700   int i, besti, cost, bestcost;
 701   enum typecode resultcode, arg0code, arg1code;
 702
 703   resultcode = preferred_typecode (TYPE_MODE (resulttype), TREE_UNSIGNED (resulttype));
 704   arg0code = preferred_typecode (TYPE_MODE (TREE_TYPE (arg0)), TREE_UNSIGNED (resulttype));
 705   arg1code = preferred_typecode (TYPE_MODE (TREE_TYPE (arg1)), TREE_UNSIGNED (resulttype));
 706
 707   besti = -1;
 708   bestcost = BIG_ARBITRARY_NUMBER;
 709
 710   for (i = 0; optab[i].opcode != -1; ++i)
 711     {
 712       cost = 0;
 713       DEDUCE_CONVERSION (arg0code, optab[i].arg0);
 714       cost += conversion_recipe[(int) arg0code][(int) optab[i].arg0].cost;
 715       DEDUCE_CONVERSION (arg1code, optab[i].arg1);
 716       cost += conversion_recipe[(int) arg1code][(int) optab[i].arg1].cost;
 717       if (cost < bestcost)
 718         {
 719           besti = i;
 720           bestcost = cost;
 721         }
 722     }
 723
 724   if (besti == -1)
 725     abort ();
 726
 727   expand_expr (arg1, 0, VOIDmode, 0);
 728   emit_typecode_conversion (arg1code, optab[besti].arg1);
 729   expand_expr (arg0, 0, VOIDmode, 0);
 730   emit_typecode_conversion (arg0code, optab[besti].arg0);
 731   bc_emit_instruction (optab[besti].opcode);
 732   emit_typecode_conversion (optab[besti].result, resultcode);
 733 }
 734
 735 /* Emit an appropriate unary operation.  */
 736 void
 737 bc_expand_unary_operation (optab, resulttype, arg0)
 738      struct unary_operator optab[];
 739      tree resulttype, arg0;
 740 {
 741   int i, besti, cost, bestcost;
 742   enum typecode resultcode, arg0code;
 743
 744   resultcode = preferred_typecode (TYPE_MODE (resulttype), TREE_UNSIGNED (resulttype));
 745   arg0code = preferred_typecode (TYPE_MODE (TREE_TYPE (arg0)), TREE_UNSIGNED (TREE_TYPE (arg0)));
 746
 747   besti = -1;
 748   bestcost = BIG_ARBITRARY_NUMBER;
 749
 750   for (i = 0; optab[i].opcode != -1; ++i)
 751     {
 752       DEDUCE_CONVERSION (arg0code, optab[i].arg0);
 753       cost = conversion_recipe[(int) arg0code][(int) optab[i].arg0].cost;
 754       if (cost < bestcost)
 755         {
 756           besti = i;
 757           bestcost = cost;
 758         }
 759     }
 760
 761   if (besti == -1)
 762     abort ();
 763
 764   expand_expr (arg0, 0, VOIDmode, 0);
 765   emit_typecode_conversion (arg0code, optab[besti].arg0);
 766   bc_emit_instruction (optab[besti].opcode);
 767   emit_typecode_conversion (optab[besti].result, resultcode);
 768 }
 769
 770
 771 /* Emit an appropriate increment.  */
 772 void
 773 bc_expand_increment (optab, type)
 774      struct increment_operator optab[];
 775      tree type;
 776 {
 777   enum typecode code;
 778   int i;
 779
 780   code = preferred_typecode (TYPE_MODE (type), TREE_UNSIGNED (type));
 781   for (i = 0; (int) optab[i].opcode >= 0; ++i)
 782     if (code == optab[i].arg)
 783       {
 784         bc_emit_instruction (optab[i].opcode);
 785         return;
 786       }
 787   abort ();
 788 }