nsz Git - libfirm/blob - ir/opt/fp-vrp.c

   1 /*
   2  * Copyright (C) 1995-2010 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   6  * This file may be distributed and/or modified under the terms of the
   7  * GNU General Public License version 2 as published by the Free Software
   8  * Foundation and appearing in the file LICENSE.GPL included in the
   9  * packaging of this file.
  10  *
  11  * Licensees holding valid libFirm Professional Edition licenses may use
  12  * this file in accordance with the libFirm Commercial License.
  13  * Agreement provided with the Software.
  14  *
  15  * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
  16  * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief   Data-flow driven minimal fixpoint value range propagation
  23  * @author  Christoph Mallon
  24  * @version $Id$
  25  */
  26
  27 #include "config.h"
  28
  29 #include "adt/pdeq.h"
  30 #include "adt/obst.h"
  31 #include "adt/xmalloc.h"
  32 #include "debug.h"
  33 #include "ircons.h"
  34 #include "irdom.h"
  35 #include "iredges.h"
  36 #include "irgmod.h"
  37 #include "irgraph.h"
  38 #include "irgwalk.h"
  39 #include "irnode.h"
  40 #include "iroptimize.h"
  41 #include "irtools.h"
  42 #include "tv.h"
  43 #include "irpass.h"
  44
  45 /* TODO:
  46  * - Implement cleared/set bit calculation for Add, Sub, Minus, Mul, Div, Mod, Shl, Shr, Shrs, Rotl
  47  * - Implement min/max calculation for And, Eor, Or, Not, Conv, Shl, Shr, Shrs, Rotl, Mux
  48  * - Implement min/max calculation for Add, Sub, Minus, Mul, Div, Mod, Conv, Shl, Shr, Shrs, Rotl, Mux
  49  */
  50
  51 /* Tables of the cleared/set bit lattice
  52  *
  53  * Encoding of the lattice
  54  * zo
  55  * 00 0 zero
  56  * 01 - impossible state, is zero /and/ one
  57  * 10 T top, may be either zero or one
  58  * 11 1 one
  59  *
  60  * S = Sum
  61  * c = Carry
  62  * D = Difference
  63  * b = Borrow
  64  *
  65  * Not
  66  * A ~
  67  * 0 1
  68  * 1 0
  69  * T T
  70  *
  71  * Half adder, half subtractor, and, xor, or, Mux
  72  * AB  Sc  Db  &  ^  |  M
  73  * 00  00  00  0  0  0  0
  74  * 01  10  11  0  1  1  T
  75  * 0T  T0  TT  0  T  T  T
  76  * 10  10  10  0  1  1  T
  77  * 11  01  00  1  0  1  1
  78  * 1T  TT  T0  T  T  1  T
  79  * T0  T0  T0  0  T  T  T
  80  * T1  TT  TT  T  T  1  T
  81  * TT  TT  TT  T  T  T  T
  82  *
  83  * Full adder, full subtractor
  84  * ABc-1  Sc  Db
  85  * 000    00  00
  86  * 001    10  11
  87  * 00T    T0  TT
  88  * 010    10  11
  89  * 011    01  01
  90  * 01T    TT  T1
  91  * 0T0    T0  TT
  92  * 0T1    TT  T1
  93  * 0TT    TT  TT
  94  * 100    10  10
  95  * 101    01  00
  96  * 10T    TT  T0
  97  * 110    01  00
  98  * 111    11  11
  99  * 11T    T1  TT
 100  * 1T0    TT  T0
 101  * 1T1    T1  TT
 102  * 1TT    TT  TT
 103  * T00    T0  T0
 104  * T01    TT  TT
 105  * T0T    TT  TT
 106  * T10    TT  TT
 107  * T11    T1  T1
 108  * T1T    TT  TT
 109  * TT0    TT  TT
 110  * TT1    TT  TT
 111  * TTT    TT  TT
 112  *
 113  *
 114  * Assume: Xmin <= Xmax and no overflow
 115  * A + B = (Amin + Bmin, Amax + Bmax)
 116  *    -A = (-Amax, -Amin)
 117  * A - B = A + -B = (Amin (-B)min, Amax + (-B)max) = (Amin - Bmax, Amax - Bmin)
 118  */
 119
 120 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
 121
 122 static struct obstack obst;
 123
 124 typedef struct bitinfo
 125 {
 126         tarval* z; // safe zeroes, 0 = bit is zero,       1 = bit maybe is 1
 127         tarval* o; // safe ones,   0 = bit maybe is zero, 1 = bit is 1
 128 } bitinfo;
 129
 130 static inline bitinfo* get_bitinfo(ir_node const* const irn)
 131 {
 132         return get_irn_link(irn);
 133 }
 134
 135 static int set_bitinfo(ir_node* const irn, tarval* const z, tarval* const o)
 136 {
 137         bitinfo* b = get_bitinfo(irn);
 138         if (b == NULL) {
 139                 b = OALLOCZ(&obst, bitinfo);
 140                 set_irn_link(irn, b);
 141         } else if (z == b->z && o == b->o) {
 142                 return 0;
 143         }
 144         b->z = z;
 145         b->o = o;
 146         DB((dbg, LEVEL_3, "%+F: 0:%T 1:%T\n", irn, z, o));
 147         return 1;
 148 }
 149
 150 static int mode_is_intb(ir_mode const* const m)
 151 {
 152         return mode_is_int(m) || m == mode_b;
 153 }
 154
 155 static int transfer(ir_node* const irn)
 156 {
 157         ir_mode* const m = get_irn_mode(irn);
 158         tarval*        z;
 159         tarval*        o;
 160
 161         if (m == mode_X) {
 162                 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
 163                 switch (get_irn_opcode(irn)) {
 164                         case iro_Proj: {
 165                                 ir_node* const pred = get_Proj_pred(irn);
 166                                 if (is_Start(pred)) {
 167                                         z = get_tarval_b_true();
 168                                         o = get_tarval_b_false();
 169                                 } else if (is_Cond(pred)) {
 170                                         ir_node* const selector = get_Cond_selector(pred);
 171                                         bitinfo* const b        = get_bitinfo(selector);
 172                                         tarval*  const bz       = b->z;
 173                                         tarval*  const bo       = b->o;
 174                                         if (get_irn_mode(selector) == mode_b) {
 175                                                 if (bz == bo) {
 176                                                         if ((bz == get_tarval_b_true()) == get_Proj_proj(irn)) {
 177                                                                 z = o = get_tarval_b_true();
 178                                                         } else {
 179                                                                 z = o = get_tarval_b_false();
 180                                                         }
 181                                                 } else {
 182                                                         goto result_unknown_X;
 183                                                 }
 184                                         } else {
 185                                                 long const val = get_Proj_proj(irn);
 186                                                 if (val != get_Cond_default_proj(pred)) {
 187                                                         tarval* const tv = new_tarval_from_long(val, get_irn_mode(selector));
 188                                                         if (!tarval_is_null(tarval_andnot(tv, bz)) ||
 189                                                                         !tarval_is_null(tarval_andnot(bo, tv))) {
 190                                                                 // At least one bit differs.
 191                                                                 z = o = get_tarval_b_false();
 192 #if 0 // TODO must handle default Proj
 193                                                         } else if (bz == bo && bz == tv) {
 194                                                                 z = o = get_tarval_b_true();
 195 #endif
 196                                                         } else {
 197                                                                 goto result_unknown_X;
 198                                                         }
 199                                                 } else {
 200                                                         goto cannot_analyse_X;
 201                                                 }
 202                                         }
 203                                 } else {
 204                                         goto cannot_analyse_X;
 205                                 }
 206                                 break;
 207                         }
 208
 209                         case iro_Jmp: {
 210                                 bitinfo* const b = get_bitinfo(get_nodes_block(irn));
 211                                 z = b->z;
 212                                 o = b->o;
 213                                 break;
 214                         }
 215
 216                         default:
 217 cannot_analyse_X:
 218                                 DB((dbg, LEVEL_4, "cannot analyse %+F\n", irn));
 219 result_unknown_X:
 220                                 z = get_tarval_b_true();
 221                                 o = get_tarval_b_false();
 222                                 break;
 223                 }
 224         } else if (is_Block(irn)) {
 225                 int       reachable = 0;
 226                 int const arity     = get_Block_n_cfgpreds(irn);
 227                 int       i;
 228
 229                 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
 230                 for (i = 0; i != arity; ++i) {
 231                         bitinfo* const b = get_bitinfo(get_Block_cfgpred(irn, i));
 232                         if (b != NULL && b->z == get_tarval_b_true()) {
 233                                 reachable = 1;
 234                                 break;
 235                         }
 236                 }
 237
 238                 o = get_tarval_b_false();
 239                 z = reachable || irn == get_irg_start_block(get_irn_irg(irn)) ? get_tarval_b_true() : o;
 240         } else if (mode_is_intb(m)) {
 241                 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
 242                 switch (get_irn_opcode(irn)) {
 243                         case iro_Const: {
 244                                 z = o = get_Const_tarval(irn);
 245                                 break;
 246                         }
 247
 248                         case iro_Shl: {
 249                                 bitinfo* const l  = get_bitinfo(get_Shl_left(irn));
 250                                 bitinfo* const r  = get_bitinfo(get_Shl_right(irn));
 251                                 tarval*  const rz = r->z;
 252                                 if (rz == r->o) {
 253                                         z = tarval_shl(l->z, rz);
 254                                         o = tarval_shl(l->o, rz);
 255                                 } else {
 256                                         goto cannot_analyse;
 257                                 }
 258                                 break;
 259                         }
 260
 261                         case iro_Shr: {
 262                                 bitinfo* const l  = get_bitinfo(get_Shr_left(irn));
 263                                 bitinfo* const r  = get_bitinfo(get_Shr_right(irn));
 264                                 tarval*  const rz = r->z;
 265                                 if (rz == r->o) {
 266                                         z = tarval_shr(l->z, rz);
 267                                         o = tarval_shr(l->o, rz);
 268                                 } else {
 269                                         goto cannot_analyse;
 270                                 }
 271                                 break;
 272                         }
 273
 274                         case iro_Shrs: {
 275                                 bitinfo* const l  = get_bitinfo(get_Shrs_left(irn));
 276                                 bitinfo* const r  = get_bitinfo(get_Shrs_right(irn));
 277                                 tarval*  const rz = r->z;
 278                                 if (rz == r->o) {
 279                                         z = tarval_shrs(l->z, rz);
 280                                         o = tarval_shrs(l->o, rz);
 281                                 } else {
 282                                         goto cannot_analyse;
 283                                 }
 284                                 break;
 285                         }
 286
 287                         case iro_Rotl: {
 288                                 bitinfo* const l  = get_bitinfo(get_Rotl_left(irn));
 289                                 bitinfo* const r  = get_bitinfo(get_Rotl_right(irn));
 290                                 tarval*  const rz = r->z;
 291                                 if (rz == r->o) {
 292                                         z = tarval_rotl(l->z, rz);
 293                                         o = tarval_rotl(l->o, rz);
 294                                 } else {
 295                                         goto cannot_analyse;
 296                                 }
 297                                 break;
 298                         }
 299
 300                         case iro_Add: {
 301                                 bitinfo* const l  = get_bitinfo(get_Add_left(irn));
 302                                 bitinfo* const r  = get_bitinfo(get_Add_right(irn));
 303                                 tarval*  const lz = l->z;
 304                                 tarval*  const lo = l->o;
 305                                 tarval*  const rz = r->z;
 306                                 tarval*  const ro = r->o;
 307                                 if (lz == lo && rz == ro) {
 308                                         z = o = tarval_add(lz, rz);
 309                                 } else {
 310                                         // TODO improve: can only do lower disjoint bits
 311                                         /* Determine where any of the operands has zero bits, i.e. where no
 312                                          * carry out is generated if there is not carry in */
 313                                         tarval* const no_c_in_no_c_out = tarval_and(lz, rz);
 314                                         /* Generate a mask of the lower consecutive zeroes: x | -x.  In this
 315                                          * range the addition is disjoint and therefore Add behaves like Or.
 316                                          */
 317                                         tarval* const low_zero_mask = tarval_or(no_c_in_no_c_out, tarval_neg(no_c_in_no_c_out));
 318                                         tarval* const low_one_mask  = tarval_not(low_zero_mask);
 319                                         z = tarval_or( tarval_or(lz, rz), low_zero_mask);
 320                                         o = tarval_and(tarval_or(lo, ro), low_one_mask);
 321                                 }
 322                                 break;
 323                         }
 324
 325                         case iro_Sub: {
 326                                 bitinfo* const l = get_bitinfo(get_Sub_left(irn));
 327                                 bitinfo* const r = get_bitinfo(get_Sub_right(irn));
 328                                 if (l != NULL && r != NULL) { // Sub might subtract pointers.
 329                                         tarval* const lz = l->z;
 330                                         tarval* const lo = l->o;
 331                                         tarval* const rz = r->z;
 332                                         tarval* const ro = r->o;
 333                                         if (lz == lo && rz == ro) {
 334                                                 z = o = tarval_sub(lz, rz, NULL);
 335                                         } else if (tarval_is_null(tarval_andnot(rz, lo))) {
 336                                                 /* Every possible one of the subtrahend is backed by a safe one of the
 337                                                  * minuend, i.e. there are no borrows. */
 338                                                 // TODO extend no-borrow like carry for Add above
 339                                                 z = tarval_andnot(lz, ro);
 340                                                 o = tarval_andnot(lo, rz);
 341                                         } else {
 342                                                 goto cannot_analyse;
 343                                         }
 344                                 } else {
 345                                         goto cannot_analyse;
 346                                 }
 347                                 break;
 348                         }
 349
 350                         case iro_Mul: {
 351                                 bitinfo* const l  = get_bitinfo(get_Mul_left(irn));
 352                                 bitinfo* const r  = get_bitinfo(get_Mul_right(irn));
 353                                 tarval*  const lz = l->z;
 354                                 tarval*  const lo = l->o;
 355                                 tarval*  const rz = r->z;
 356                                 tarval*  const ro = r->o;
 357                                 if (lz == lo && rz == ro) {
 358                                         z = o = tarval_mul(lz, rz);
 359                                 } else {
 360                                         // TODO improve
 361                                         // Determine safe lower zeroes: x | -x.
 362                                         tarval* const lzn = tarval_or(lz, tarval_neg(lz));
 363                                         tarval* const rzn = tarval_or(rz, tarval_neg(rz));
 364                                         // Concatenate safe lower zeroes.
 365                                         if (tarval_cmp(lzn, rzn) == pn_Cmp_Lt) {
 366                                                 z = tarval_mul(tarval_eor(lzn, tarval_shl(lzn, get_tarval_one(m))), rzn);
 367                                         } else {
 368                                                 z = tarval_mul(tarval_eor(rzn, tarval_shl(rzn, get_tarval_one(m))), lzn);
 369                                         }
 370                                         o = get_tarval_null(m);
 371                                 }
 372                                 break;
 373                         }
 374
 375                         case iro_Minus: {
 376                                 bitinfo* const b = get_bitinfo(get_Minus_op(irn));
 377                                 if (b->z == b->o) {
 378                                         z = o = tarval_neg(b->z);
 379                                 } else {
 380                                         goto cannot_analyse;
 381                                 }
 382                                 break;
 383                         }
 384
 385                         case iro_And: {
 386                                 bitinfo* const l = get_bitinfo(get_And_left(irn));
 387                                 bitinfo* const r = get_bitinfo(get_And_right(irn));
 388                                 z = tarval_and(l->z, r->z);
 389                                 o = tarval_and(l->o, r->o);
 390                                 break;
 391                         }
 392
 393                         case iro_Or: {
 394                                 bitinfo* const l = get_bitinfo(get_Or_left(irn));
 395                                 bitinfo* const r = get_bitinfo(get_Or_right(irn));
 396                                 z = tarval_or(l->z, r->z);
 397                                 o = tarval_or(l->o, r->o);
 398                                 break;
 399                         }
 400
 401                         case iro_Eor: {
 402                                 bitinfo* const l  = get_bitinfo(get_Eor_left(irn));
 403                                 bitinfo* const r  = get_bitinfo(get_Eor_right(irn));
 404                                 tarval*  const lz = l->z;
 405                                 tarval*  const lo = l->o;
 406                                 tarval*  const rz = r->z;
 407                                 tarval*  const ro = r->o;
 408                                 z = tarval_or(tarval_andnot(lz, ro), tarval_andnot(rz, lo));
 409                                 o = tarval_or(tarval_andnot(ro, lz), tarval_andnot(lo, rz));
 410                                 break;
 411                         }
 412
 413                         case iro_Not: {
 414                                 bitinfo* const b = get_bitinfo(get_Not_op(irn));
 415                                 z = tarval_not(b->o);
 416                                 o = tarval_not(b->z);
 417                                 break;
 418                         }
 419
 420                         case iro_Conv: {
 421                                 bitinfo* const b = get_bitinfo(get_Conv_op(irn));
 422                                 if (b == NULL) // Happens when converting from float values.
 423                                         goto result_unknown;
 424                                 z = tarval_convert_to(b->z, m);
 425                                 o = tarval_convert_to(b->o, m);
 426                                 break;
 427                         }
 428
 429                         case iro_Mux: {
 430                                 bitinfo* const f = get_bitinfo(get_Mux_false(irn));
 431                                 bitinfo* const t = get_bitinfo(get_Mux_true(irn));
 432                                 bitinfo* const c = get_bitinfo(get_Mux_sel(irn));
 433                                 if (c->o == get_tarval_b_true()) {
 434                                         z = t->z;
 435                                         o = t->o;
 436                                 } else if (c->z == get_tarval_b_false()) {
 437                                         z = f->z;
 438                                         o = f->o;
 439                                 } else {
 440                                         z = tarval_or( f->z, t->z);
 441                                         o = tarval_and(f->o, t->o);
 442                                 }
 443                         }
 444
 445                         case iro_Phi: {
 446                                 ir_node* const block = get_nodes_block(irn);
 447                                 int      const arity = get_Phi_n_preds(irn);
 448                                 int            i;
 449
 450                                 z = get_tarval_null(m);
 451                                 o = get_tarval_all_one(m);
 452                                 for (i = 0; i != arity; ++i) {
 453                                         bitinfo* const b_cfg = get_bitinfo(get_Block_cfgpred(block, i));
 454                                         if (b_cfg != NULL && b_cfg->z != get_tarval_b_false()) {
 455                                                 bitinfo* const b = get_bitinfo(get_Phi_pred(irn, i));
 456                                                 z = tarval_or( z, b->z);
 457                                                 o = tarval_and(o, b->o);
 458                                         }
 459                                 }
 460                                 break;
 461                         }
 462
 463                         case iro_Proj: {
 464                                 ir_node* const pred = get_Proj_pred(irn);
 465                                 if (is_Cmp(pred)) { // TODO generalize
 466                                         bitinfo* const l = get_bitinfo(get_Cmp_left(pred));
 467                                         bitinfo* const r = get_bitinfo(get_Cmp_right(pred));
 468                                         if (l == NULL || r == NULL)
 469                                                 goto result_unknown; // Cmp compares something we cannot evaluate.
 470                                         switch (get_Proj_proj(irn)) {
 471                                                 case pn_Cmp_Lg: {
 472                                                         tarval* const lz = l->z;
 473                                                         tarval* const lo = l->o;
 474                                                         tarval* const rz = r->z;
 475                                                         tarval* const ro = r->o;
 476                                                         if (!tarval_is_null(tarval_andnot(ro, lz)) ||
 477                                                                         !tarval_is_null(tarval_andnot(lo, rz))) {
 478                                                                 // At least one bit differs.
 479                                                                 z = o = get_tarval_b_true();
 480                                                         } else if (lz == lo && rz == ro && lz == rz) {
 481                                                                 z = o = get_tarval_b_false();
 482                                                         } else {
 483                                                                 goto result_unknown;
 484                                                         }
 485                                                         break;
 486                                                 }
 487
 488                                                 case pn_Cmp_Eq: {
 489                                                         tarval* const lz = l->z;
 490                                                         tarval* const lo = l->o;
 491                                                         tarval* const rz = r->z;
 492                                                         tarval* const ro = r->o;
 493                                                         if (!tarval_is_null(tarval_andnot(ro, lz)) ||
 494                                                                         !tarval_is_null(tarval_andnot(lo, rz))) {
 495                                                                 // At least one bit differs.
 496                                                                 z = o = get_tarval_b_false();
 497                                                         } else if (lz == lo && rz == ro && lz == rz) {
 498                                                                 z = o = get_tarval_b_true();
 499                                                         } else {
 500                                                                 goto result_unknown;
 501                                                         }
 502                                                         break;
 503                                                 }
 504
 505                                                 default:
 506                                                         goto cannot_analyse;
 507                                         }
 508                                 } else {
 509                                         goto cannot_analyse;
 510                                 }
 511                                 break;
 512                         }
 513
 514                         default: {
 515 cannot_analyse:
 516                                 DB((dbg, LEVEL_4, "cannot analyse %+F\n", irn));
 517 result_unknown:
 518                                 z = get_tarval_all_one(m);
 519                                 o = get_tarval_null(m);
 520                                 break;
 521                         }
 522                 }
 523         } else {
 524                 return 0;
 525         }
 526
 527         return set_bitinfo(irn, z, o);
 528 }
 529
 530 static void first_round(ir_node* const irn, void* const env)
 531 {
 532         pdeq* const q = env;
 533
 534         transfer(irn);
 535         if (is_Phi(irn) || is_Block(irn)) {
 536                 /* Only Phis (and their users) need another round, if we did not have
 537                  * information about all their inputs in the first round, i.e. in loops. */
 538                 /* TODO inserts all Phis, should only insert Phis, which did no have all
 539                  * predecessors available */
 540                 pdeq_putr(q, irn);
 541         }
 542 }
 543
 544 static void apply_result(ir_node* const irn, void* const env)
 545 {
 546         bitinfo* const b = get_bitinfo(irn);
 547         tarval*        z;
 548         tarval*        o;
 549         (void)env;
 550
 551         if (!b) return;
 552         if (is_Const(irn)) return; // It cannot get any better than a Const.
 553
 554         z = b->z;
 555         o = b->o;
 556         // Only display information if we could find out anything about the value.
 557         DEBUG_ONLY(if (!tarval_is_all_one(z) || !tarval_is_null(o)))
 558                 DB((dbg, LEVEL_2, "%+F: 0:%T 1:%T%s\n", irn, z, o, z == o ? " --- constant" : ""));
 559
 560         // Replace node with constant value by Const.
 561         if (z == o) {
 562                 ir_mode* const m = get_irn_mode(irn);
 563                 ir_node*       n;
 564                 if (mode_is_intb(m)) {
 565                         n = new_Const(z);
 566                 } else if (m == mode_X) {
 567                         ir_node*  const block = get_nodes_block(irn);
 568                         ir_graph* const irg   = get_Block_irg(block);
 569                         if (z == get_tarval_b_true()) {
 570                                 // Might produce an endless loop, so keep the block.
 571                                 add_End_keepalive(get_irg_end(irg), block);
 572                                 n = new_r_Jmp(block);
 573                         } else {
 574                                 n = new_r_Bad(irg);
 575                                 /* Transferring analysis information to the bad node makes it a
 576                                  * candidate for replacement. */
 577                                 goto exchange_only;
 578                         }
 579                 } else {
 580                         return;
 581                 }
 582                 set_irn_link(n, b);
 583 exchange_only:
 584                 exchange(irn, n);
 585         }
 586
 587         switch (get_irn_opcode(irn)) {
 588                 case iro_And: {
 589                         ir_node*       const l  = get_And_left(irn);
 590                         ir_node*       const r  = get_And_right(irn);
 591                         bitinfo const* const bl = get_bitinfo(l);
 592                         bitinfo const* const br = get_bitinfo(r);
 593                         if (bl->z == bl->o) {
 594                                 if (tarval_is_null(tarval_andnot(br->z, bl->z))) {
 595                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 596                                         exchange(irn, r);
 597                                 }
 598                         } else if (br->z == br->o) {
 599                                 if (tarval_is_null(tarval_andnot(bl->z, br->z))) {
 600                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 601                                         exchange(irn, l);
 602                                 }
 603                         }
 604                         break;
 605                 }
 606
 607                 case iro_Or: {
 608                         ir_node*       const l  = get_Or_left(irn);
 609                         ir_node*       const r  = get_Or_right(irn);
 610                         bitinfo const* const bl = get_bitinfo(l);
 611                         bitinfo const* const br = get_bitinfo(r);
 612                         if (bl->z == bl->o) {
 613                                 if (tarval_is_null(tarval_andnot(bl->o, br->o))) {
 614                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 615                                         exchange(irn, r);
 616                                 }
 617                         } else if (br->z == br->o) {
 618                                 if (tarval_is_null(tarval_andnot(br->o, bl->o))) {
 619                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 620                                         exchange(irn, l);
 621                                 }
 622                         }
 623                         break;
 624                 }
 625         }
 626 }
 627
 628 static void queue_users(pdeq* const q, ir_node* const n)
 629 {
 630         if (get_irn_mode(n) == mode_X) {
 631                 /* When the state of a control flow node changes, not only queue its
 632                  * successor blocks, but also the Phis in these blocks, because the Phis
 633                  * must reconsider this input path. */
 634                 ir_edge_t const* e;
 635                 foreach_out_edge(n, e) {
 636                         ir_node*  const  src = get_edge_src_irn(e);
 637                         ir_edge_t const* src_e;
 638                         pdeq_putr(q, src);
 639                         foreach_out_edge(src, src_e) {
 640                                 ir_node* const src_src = get_edge_src_irn(src_e);
 641                                 if (is_Phi(src_src))
 642                                         pdeq_putr(q, src_src);
 643                         }
 644                 }
 645         } else {
 646                 ir_edge_t const* e;
 647                 foreach_out_edge(n, e) {
 648                         ir_node* const src = get_edge_src_irn(e);
 649                         if (get_irn_mode(src) == mode_T) {
 650                                 queue_users(q, src);
 651                         } else {
 652                                 pdeq_putr(q, src);
 653                         }
 654                 }
 655         }
 656 }
 657
 658 void fixpoint_vrp(ir_graph* const irg)
 659 {
 660         FIRM_DBG_REGISTER(dbg, "firm.opt.fp-vrp");
 661         DB((dbg, LEVEL_1, "===> Performing constant propagation on %+F\n", irg));
 662
 663         obstack_init(&obst);
 664
 665         edges_assure(irg);
 666         assure_doms(irg);
 667
 668         { pdeq* const q = new_pdeq();
 669
 670                 /* TODO Improve iteration order. Best is reverse postorder in data flow
 671                  * direction and respecting loop nesting for fastest convergence. */
 672                 irg_walk_blkwise_dom_top_down(irg, firm_clear_link, first_round, q);
 673
 674                 while (!pdeq_empty(q)) {
 675                         ir_node* const n = pdeq_getl(q);
 676                         if (transfer(n))
 677                                 queue_users(q, n);
 678                 }
 679
 680                 del_pdeq(q);
 681         }
 682
 683         DB((dbg, LEVEL_2, "---> Applying analysis results\n"));
 684         irg_walk_graph(irg, NULL, apply_result, NULL);
 685
 686         obstack_free(&obst, NULL);
 687 }
 688
 689 ir_graph_pass_t *fixpoint_vrp_irg_pass(const char *name)
 690 {
 691         return def_graph_pass(name ? name : "fixpoint_vrp", fixpoint_vrp);
 692 }