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 #include "config.h"
  27
  28 #include "adt/pdeq.h"
  29 #include "adt/obst.h"
  30 #include "adt/xmalloc.h"
  31 #include "debug.h"
  32 #include "ircons.h"
  33 #include "irdom.h"
  34 #include "iredges.h"
  35 #include "irgmod.h"
  36 #include "irgraph.h"
  37 #include "irgwalk.h"
  38 #include "irnode.h"
  39 #include "iroptimize.h"
  40 #include "irtools.h"
  41 #include "tv.h"
  42 #include "irpass.h"
  43 #include "irmemory.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         ir_tarval* z; // safe zeroes, 0 = bit is zero,       1 = bit maybe is 1
 127         ir_tarval* o; // safe ones,   0 = bit maybe is zero, 1 = bit is 1
 128 } bitinfo;
 129
 130 typedef struct environment_t {
 131         unsigned modified:1;     /**< Set, if the graph was modified. */
 132 } environment_t;
 133
 134 static inline bitinfo* get_bitinfo(ir_node const* const irn)
 135 {
 136         return (bitinfo*)get_irn_link(irn);
 137 }
 138
 139 static int set_bitinfo(ir_node* const irn, ir_tarval* const z, ir_tarval* const o)
 140 {
 141         bitinfo* b = get_bitinfo(irn);
 142         if (b == NULL) {
 143                 b = OALLOCZ(&obst, bitinfo);
 144                 set_irn_link(irn, b);
 145         } else if (z == b->z && o == b->o) {
 146                 return 0;
 147         }
 148         b->z = z;
 149         b->o = o;
 150         DB((dbg, LEVEL_3, "%+F: 0:%T 1:%T\n", irn, z, o));
 151         return 1;
 152 }
 153
 154 static int mode_is_intb(ir_mode const* const m)
 155 {
 156         return mode_is_int(m) || m == mode_b;
 157 }
 158
 159 static int transfer(ir_node* const irn)
 160 {
 161         ir_mode* const m = get_irn_mode(irn);
 162         ir_tarval*     z;
 163         ir_tarval*     o;
 164
 165         if (m == mode_X) {
 166                 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
 167                 switch (get_irn_opcode(irn)) {
 168                         case iro_Proj: {
 169                                 ir_node* const pred = get_Proj_pred(irn);
 170                                 if (is_Start(pred)) {
 171                                         z = get_tarval_b_true();
 172                                         o = get_tarval_b_false();
 173                                 } else if (is_Cond(pred)) {
 174                                         ir_node*   const selector = get_Cond_selector(pred);
 175                                         bitinfo*   const b        = get_bitinfo(selector);
 176                                         ir_tarval* const bz       = b->z;
 177                                         ir_tarval* const bo       = b->o;
 178                                         if (get_irn_mode(selector) == mode_b) {
 179                                                 if (bz == bo) {
 180                                                         if ((bz == get_tarval_b_true()) == get_Proj_proj(irn)) {
 181                                                                 z = o = get_tarval_b_true();
 182                                                         } else {
 183                                                                 z = o = get_tarval_b_false();
 184                                                         }
 185                                                 } else {
 186                                                         goto result_unknown_X;
 187                                                 }
 188                                         } else {
 189                                                 long const val = get_Proj_proj(irn);
 190                                                 if (val != get_Cond_default_proj(pred)) {
 191                                                         ir_tarval* const tv = new_tarval_from_long(val, get_irn_mode(selector));
 192                                                         if (!tarval_is_null(tarval_andnot(tv, bz)) ||
 193                                                                         !tarval_is_null(tarval_andnot(bo, tv))) {
 194                                                                 // At least one bit differs.
 195                                                                 z = o = get_tarval_b_false();
 196 #if 0 // TODO must handle default Proj
 197                                                         } else if (bz == bo && bz == tv) {
 198                                                                 z = o = get_tarval_b_true();
 199 #endif
 200                                                         } else {
 201                                                                 goto result_unknown_X;
 202                                                         }
 203                                                 } else {
 204                                                         goto cannot_analyse_X;
 205                                                 }
 206                                         }
 207                                 } else {
 208                                         goto cannot_analyse_X;
 209                                 }
 210                                 break;
 211                         }
 212
 213                         case iro_Jmp: {
 214                                 bitinfo* const b = get_bitinfo(get_nodes_block(irn));
 215                                 z = b->z;
 216                                 o = b->o;
 217                                 break;
 218                         }
 219
 220                         default:
 221 cannot_analyse_X:
 222                                 DB((dbg, LEVEL_4, "cannot analyse %+F\n", irn));
 223 result_unknown_X:
 224                                 z = get_tarval_b_true();
 225                                 o = get_tarval_b_false();
 226                                 break;
 227                 }
 228         } else if (is_Block(irn)) {
 229                 int       reachable = 0;
 230                 int const arity     = get_Block_n_cfgpreds(irn);
 231                 int       i;
 232
 233                 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
 234                 for (i = 0; i != arity; ++i) {
 235                         bitinfo* const b = get_bitinfo(get_Block_cfgpred(irn, i));
 236                         if (b != NULL && b->z == get_tarval_b_true()) {
 237                                 reachable = 1;
 238                                 break;
 239                         }
 240                 }
 241
 242                 o = get_tarval_b_false();
 243                 z = reachable || irn == get_irg_start_block(get_irn_irg(irn)) ? get_tarval_b_true() : o;
 244         } else if (mode_is_intb(m)) {
 245                 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
 246                 switch (get_irn_opcode(irn)) {
 247                         case iro_Const: {
 248                                 z = o = get_Const_tarval(irn);
 249                                 break;
 250                         }
 251
 252                         case iro_Shl: {
 253                                 bitinfo*   const l  = get_bitinfo(get_Shl_left(irn));
 254                                 bitinfo*   const r  = get_bitinfo(get_Shl_right(irn));
 255                                 ir_tarval* const rz = r->z;
 256                                 if (rz == r->o) {
 257                                         z = tarval_shl(l->z, rz);
 258                                         o = tarval_shl(l->o, rz);
 259                                 } else {
 260                                         goto cannot_analyse;
 261                                 }
 262                                 break;
 263                         }
 264
 265                         case iro_Shr: {
 266                                 bitinfo*   const l  = get_bitinfo(get_Shr_left(irn));
 267                                 bitinfo*   const r  = get_bitinfo(get_Shr_right(irn));
 268                                 ir_tarval* const rz = r->z;
 269                                 if (rz == r->o) {
 270                                         z = tarval_shr(l->z, rz);
 271                                         o = tarval_shr(l->o, rz);
 272                                 } else {
 273                                         goto cannot_analyse;
 274                                 }
 275                                 break;
 276                         }
 277
 278                         case iro_Shrs: {
 279                                 bitinfo*   const l  = get_bitinfo(get_Shrs_left(irn));
 280                                 bitinfo*   const r  = get_bitinfo(get_Shrs_right(irn));
 281                                 ir_tarval* const rz = r->z;
 282                                 if (rz == r->o) {
 283                                         z = tarval_shrs(l->z, rz);
 284                                         o = tarval_shrs(l->o, rz);
 285                                 } else {
 286                                         goto cannot_analyse;
 287                                 }
 288                                 break;
 289                         }
 290
 291                         case iro_Rotl: {
 292                                 bitinfo*   const l  = get_bitinfo(get_Rotl_left(irn));
 293                                 bitinfo*   const r  = get_bitinfo(get_Rotl_right(irn));
 294                                 ir_tarval* const rz = r->z;
 295                                 if (rz == r->o) {
 296                                         z = tarval_rotl(l->z, rz);
 297                                         o = tarval_rotl(l->o, rz);
 298                                 } else {
 299                                         goto cannot_analyse;
 300                                 }
 301                                 break;
 302                         }
 303
 304                         case iro_Add: {
 305                                 bitinfo*   const l  = get_bitinfo(get_Add_left(irn));
 306                                 bitinfo*   const r  = get_bitinfo(get_Add_right(irn));
 307                                 ir_tarval* const lz = l->z;
 308                                 ir_tarval* const lo = l->o;
 309                                 ir_tarval* const rz = r->z;
 310                                 ir_tarval* const ro = r->o;
 311                                 if (lz == lo && rz == ro) {
 312                                         z = o = tarval_add(lz, rz);
 313                                 } else {
 314                                         // TODO improve: can only do lower disjoint bits
 315                                         /* Determine where any of the operands has zero bits, i.e. where no
 316                                          * carry out is generated if there is not carry in */
 317                                         ir_tarval* const no_c_in_no_c_out = tarval_and(lz, rz);
 318                                         /* Generate a mask of the lower consecutive zeroes: x | -x.  In this
 319                                          * range the addition is disjoint and therefore Add behaves like Or.
 320                                          */
 321                                         ir_tarval* const low_zero_mask = tarval_or(no_c_in_no_c_out, tarval_neg(no_c_in_no_c_out));
 322                                         ir_tarval* const low_one_mask  = tarval_not(low_zero_mask);
 323                                         z = tarval_or( tarval_or(lz, rz), low_zero_mask);
 324                                         o = tarval_and(tarval_or(lo, ro), low_one_mask);
 325                                 }
 326                                 break;
 327                         }
 328
 329                         case iro_Sub: {
 330                                 bitinfo* const l = get_bitinfo(get_Sub_left(irn));
 331                                 bitinfo* const r = get_bitinfo(get_Sub_right(irn));
 332                                 if (l != NULL && r != NULL) { // Sub might subtract pointers.
 333                                         ir_tarval* const lz = l->z;
 334                                         ir_tarval* const lo = l->o;
 335                                         ir_tarval* const rz = r->z;
 336                                         ir_tarval* const ro = r->o;
 337                                         if (lz == lo && rz == ro) {
 338                                                 z = o = tarval_sub(lz, rz, NULL);
 339                                         } else if (tarval_is_null(tarval_andnot(rz, lo))) {
 340                                                 /* Every possible one of the subtrahend is backed by a safe one of the
 341                                                  * minuend, i.e. there are no borrows. */
 342                                                 // TODO extend no-borrow like carry for Add above
 343                                                 z = tarval_andnot(lz, ro);
 344                                                 o = tarval_andnot(lo, rz);
 345                                         } else {
 346                                                 goto cannot_analyse;
 347                                         }
 348                                 } else {
 349                                         goto cannot_analyse;
 350                                 }
 351                                 break;
 352                         }
 353
 354                         case iro_Mul: {
 355                                 bitinfo*   const l  = get_bitinfo(get_Mul_left(irn));
 356                                 bitinfo*   const r  = get_bitinfo(get_Mul_right(irn));
 357                                 ir_tarval* const lz = l->z;
 358                                 ir_tarval* const lo = l->o;
 359                                 ir_tarval* const rz = r->z;
 360                                 ir_tarval* const ro = r->o;
 361                                 if (lz == lo && rz == ro) {
 362                                         z = o = tarval_mul(lz, rz);
 363                                 } else {
 364                                         // TODO improve
 365                                         // Determine safe lower zeroes: x | -x.
 366                                         ir_tarval* const lzn = tarval_or(lz, tarval_neg(lz));
 367                                         ir_tarval* const rzn = tarval_or(rz, tarval_neg(rz));
 368                                         // Concatenate safe lower zeroes.
 369                                         if (tarval_cmp(lzn, rzn) == ir_relation_less) {
 370                                                 z = tarval_mul(tarval_eor(lzn, tarval_shl(lzn, get_tarval_one(m))), rzn);
 371                                         } else {
 372                                                 z = tarval_mul(tarval_eor(rzn, tarval_shl(rzn, get_tarval_one(m))), lzn);
 373                                         }
 374                                         o = get_tarval_null(m);
 375                                 }
 376                                 break;
 377                         }
 378
 379                         case iro_Minus: {
 380                                 bitinfo* const b = get_bitinfo(get_Minus_op(irn));
 381                                 if (b->z == b->o) {
 382                                         z = o = tarval_neg(b->z);
 383                                 } else {
 384                                         goto cannot_analyse;
 385                                 }
 386                                 break;
 387                         }
 388
 389                         case iro_And: {
 390                                 bitinfo* const l = get_bitinfo(get_And_left(irn));
 391                                 bitinfo* const r = get_bitinfo(get_And_right(irn));
 392                                 z = tarval_and(l->z, r->z);
 393                                 o = tarval_and(l->o, r->o);
 394                                 break;
 395                         }
 396
 397                         case iro_Or: {
 398                                 bitinfo* const l = get_bitinfo(get_Or_left(irn));
 399                                 bitinfo* const r = get_bitinfo(get_Or_right(irn));
 400                                 z = tarval_or(l->z, r->z);
 401                                 o = tarval_or(l->o, r->o);
 402                                 break;
 403                         }
 404
 405                         case iro_Eor: {
 406                                 bitinfo*   const l  = get_bitinfo(get_Eor_left(irn));
 407                                 bitinfo*   const r  = get_bitinfo(get_Eor_right(irn));
 408                                 ir_tarval* const lz = l->z;
 409                                 ir_tarval* const lo = l->o;
 410                                 ir_tarval* const rz = r->z;
 411                                 ir_tarval* const ro = r->o;
 412                                 z = tarval_or(tarval_andnot(lz, ro), tarval_andnot(rz, lo));
 413                                 o = tarval_or(tarval_andnot(ro, lz), tarval_andnot(lo, rz));
 414                                 break;
 415                         }
 416
 417                         case iro_Not: {
 418                                 bitinfo* const b = get_bitinfo(get_Not_op(irn));
 419                                 z = tarval_not(b->o);
 420                                 o = tarval_not(b->z);
 421                                 break;
 422                         }
 423
 424                         case iro_Conv: {
 425                                 bitinfo* const b = get_bitinfo(get_Conv_op(irn));
 426                                 if (b == NULL) // Happens when converting from float values.
 427                                         goto result_unknown;
 428                                 z = tarval_convert_to(b->z, m);
 429                                 o = tarval_convert_to(b->o, m);
 430                                 break;
 431                         }
 432
 433                         case iro_Mux: {
 434                                 bitinfo* const f = get_bitinfo(get_Mux_false(irn));
 435                                 bitinfo* const t = get_bitinfo(get_Mux_true(irn));
 436                                 bitinfo* const c = get_bitinfo(get_Mux_sel(irn));
 437                                 if (c->o == get_tarval_b_true()) {
 438                                         z = t->z;
 439                                         o = t->o;
 440                                 } else if (c->z == get_tarval_b_false()) {
 441                                         z = f->z;
 442                                         o = f->o;
 443                                 } else {
 444                                         z = tarval_or( f->z, t->z);
 445                                         o = tarval_and(f->o, t->o);
 446                                 }
 447                                 break;
 448                         }
 449
 450                         case iro_Phi: {
 451                                 ir_node* const block = get_nodes_block(irn);
 452                                 int      const arity = get_Phi_n_preds(irn);
 453                                 int            i;
 454
 455                                 z = get_tarval_null(m);
 456                                 o = get_tarval_all_one(m);
 457                                 for (i = 0; i != arity; ++i) {
 458                                         bitinfo* const b_cfg = get_bitinfo(get_Block_cfgpred(block, i));
 459                                         if (b_cfg != NULL && b_cfg->z != get_tarval_b_false()) {
 460                                                 bitinfo* const b = get_bitinfo(get_Phi_pred(irn, i));
 461                                                 z = tarval_or( z, b->z);
 462                                                 o = tarval_and(o, b->o);
 463                                         }
 464                                 }
 465                                 break;
 466                         }
 467
 468                         case iro_Cmp: {
 469                                 bitinfo* const l = get_bitinfo(get_Cmp_left(irn));
 470                                 bitinfo* const r = get_bitinfo(get_Cmp_right(irn));
 471                                 if (l == NULL || r == NULL) {
 472                                         goto result_unknown; // Cmp compares something we cannot evaluate.
 473                                 } else {
 474                                         ir_tarval*  const lz       = l->z;
 475                                         ir_tarval*  const lo       = l->o;
 476                                         ir_tarval*  const rz       = r->z;
 477                                         ir_tarval*  const ro       = r->o;
 478                                         ir_relation const relation = get_Cmp_relation(irn);
 479                                         switch (relation) {
 480                                                 case ir_relation_less_greater:
 481                                                         if (!tarval_is_null(tarval_andnot(ro, lz)) ||
 482                                                                         !tarval_is_null(tarval_andnot(lo, rz))) {
 483                                                                 // At least one bit differs.
 484                                                                 z = o = get_tarval_b_true();
 485                                                         } else if (lz == lo && rz == ro && lz == rz) {
 486                                                                 z = o = get_tarval_b_false();
 487                                                         } else {
 488                                                                 goto result_unknown;
 489                                                         }
 490                                                         break;
 491
 492                                                 case ir_relation_equal:
 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                                                 case ir_relation_less_equal:
 505                                                 case ir_relation_less:
 506                                                         /* TODO handle negative values */
 507                                                         if (tarval_is_negative(lz) || tarval_is_negative(lo) ||
 508                                                                         tarval_is_negative(rz) || tarval_is_negative(ro))
 509                                                                 goto result_unknown;
 510
 511                                                         if (tarval_cmp(lz, ro) & relation) {
 512                                                                 /* Left upper bound is smaller(/equal) than right lower bound. */
 513                                                                 z = o = get_tarval_b_true();
 514                                                         } else if (!(tarval_cmp(lo, rz) & relation)) {
 515                                                                 /* Left lower bound is not smaller(/equal) than right upper bound. */
 516                                                                 z = o = get_tarval_b_false();
 517                                                         } else {
 518                                                                 goto result_unknown;
 519                                                         }
 520                                                         break;
 521
 522                                                 case ir_relation_greater_equal:
 523                                                 case ir_relation_greater:
 524                                                         /* TODO handle negative values */
 525                                                         if (tarval_is_negative(lz) || tarval_is_negative(lo) ||
 526                                                                         tarval_is_negative(rz) || tarval_is_negative(ro))
 527                                                                 goto result_unknown;
 528
 529                                                         if (!(tarval_cmp(lz, ro) & relation)) {
 530                                                                 /* Left upper bound is not greater(/equal) than right lower bound. */
 531                                                                 z = o = get_tarval_b_false();
 532                                                         } else if (tarval_cmp(lo, rz) & relation) {
 533                                                                 /* Left lower bound is greater(/equal) than right upper bound. */
 534                                                                 z = o = get_tarval_b_true();
 535                                                         } else {
 536                                                                 goto result_unknown;
 537                                                         }
 538                                                         break;
 539
 540                                                 default:
 541                                                         goto cannot_analyse;
 542                                         }
 543                                 }
 544                                 break;
 545                         }
 546
 547                         default: {
 548 cannot_analyse:
 549                                 DB((dbg, LEVEL_4, "cannot analyse %+F\n", irn));
 550 result_unknown:
 551                                 z = get_tarval_all_one(m);
 552                                 o = get_tarval_null(m);
 553                                 break;
 554                         }
 555                 }
 556         } else {
 557                 return 0;
 558         }
 559
 560         return set_bitinfo(irn, z, o);
 561 }
 562
 563 static void first_round(ir_node* const irn, void* const env)
 564 {
 565         pdeq* const q = (pdeq*)env;
 566
 567         transfer(irn);
 568         if (is_Phi(irn) || is_Block(irn)) {
 569                 /* Only Phis (and their users) need another round, if we did not have
 570                  * information about all their inputs in the first round, i.e. in loops. */
 571                 /* TODO inserts all Phis, should only insert Phis, which did no have all
 572                  * predecessors available */
 573                 pdeq_putr(q, irn);
 574         }
 575 }
 576
 577 static void apply_result(ir_node* const irn, void* ctx)
 578 {
 579         environment_t* env = (environment_t*)ctx;
 580         bitinfo* const b   = get_bitinfo(irn);
 581         ir_tarval*     z;
 582         ir_tarval*     o;
 583
 584         if (!b) return;
 585         if (is_Const(irn)) return; // It cannot get any better than a Const.
 586
 587         z = b->z;
 588         o = b->o;
 589         // Only display information if we could find out anything about the value.
 590         DEBUG_ONLY(if (!tarval_is_all_one(z) || !tarval_is_null(o)))
 591                 DB((dbg, LEVEL_2, "%+F: 0:%T 1:%T%s\n", irn, z, o, z == o ? " --- constant" : ""));
 592
 593         // Replace node with constant value by Const.
 594         if (z == o) {
 595                 ir_mode* const m = get_irn_mode(irn);
 596                 ir_node*       n;
 597                 if (mode_is_intb(m)) {
 598                         ir_graph *irg = get_irn_irg(irn);
 599                         n = new_r_Const(irg, z);
 600                 } else if (m == mode_X) {
 601                         ir_node*  const block = get_nodes_block(irn);
 602                         ir_graph* const irg   = get_Block_irg(block);
 603                         if (z == get_tarval_b_true()) {
 604                                 // Might produce an endless loop, so keep the block.
 605                                 add_End_keepalive(get_irg_end(irg), block);
 606                                 n = new_r_Jmp(block);
 607                         } else {
 608                                 n = new_r_Bad(irg);
 609                                 /* Transferring analysis information to the bad node makes it a
 610                                  * candidate for replacement. */
 611                                 goto exchange_only;
 612                         }
 613                 } else {
 614                         return;
 615                 }
 616                 set_irn_link(n, b);
 617 exchange_only:
 618                 exchange(irn, n);
 619                 env->modified = 1;
 620         }
 621
 622         switch (get_irn_opcode(irn)) {
 623                 case iro_And: {
 624                         ir_node*       const l  = get_And_left(irn);
 625                         ir_node*       const r  = get_And_right(irn);
 626                         bitinfo const* const bl = get_bitinfo(l);
 627                         bitinfo const* const br = get_bitinfo(r);
 628                         if (bl->z == bl->o) {
 629                                 if (tarval_is_null(tarval_andnot(br->z, bl->z))) {
 630                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 631                                         exchange(irn, r);
 632                                         env->modified = 1;
 633                                 }
 634                         } else if (br->z == br->o) {
 635                                 if (tarval_is_null(tarval_andnot(bl->z, br->z))) {
 636                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 637                                         exchange(irn, l);
 638                                         env->modified = 1;
 639                                 }
 640                         }
 641                         break;
 642                 }
 643
 644                 case iro_Or: {
 645                         ir_node*       const l  = get_Or_left(irn);
 646                         ir_node*       const r  = get_Or_right(irn);
 647                         bitinfo const* const bl = get_bitinfo(l);
 648                         bitinfo const* const br = get_bitinfo(r);
 649                         if (bl->z == bl->o) {
 650                                 if (tarval_is_null(tarval_andnot(bl->o, br->o))) {
 651                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 652                                         exchange(irn, r);
 653                                         env->modified = 1;
 654                                 }
 655                         } else if (br->z == br->o) {
 656                                 if (tarval_is_null(tarval_andnot(br->o, bl->o))) {
 657                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 658                                         exchange(irn, l);
 659                                         env->modified = 1;
 660                                 }
 661                         }
 662                         break;
 663                 }
 664         }
 665 }
 666
 667 static void queue_users(pdeq* const q, ir_node* const n)
 668 {
 669         if (get_irn_mode(n) == mode_X) {
 670                 /* When the state of a control flow node changes, not only queue its
 671                  * successor blocks, but also the Phis in these blocks, because the Phis
 672                  * must reconsider this input path. */
 673                 ir_edge_t const* e;
 674                 foreach_out_edge(n, e) {
 675                         ir_node*  const  src = get_edge_src_irn(e);
 676                         pdeq_putr(q, src);
 677                         /* should always be a block */
 678                         if (is_Block(src)) {
 679                                 ir_node *phi;
 680                                 for (phi = get_Block_phis(src); phi; phi = get_Phi_next(phi))
 681                                         pdeq_putr(q, phi);
 682                         }
 683                 }
 684         } else {
 685                 ir_edge_t const* e;
 686                 foreach_out_edge(n, e) {
 687                         ir_node* const src = get_edge_src_irn(e);
 688                         if (get_irn_mode(src) == mode_T) {
 689                                 queue_users(q, src);
 690                         } else {
 691                                 pdeq_putr(q, src);
 692                         }
 693                 }
 694         }
 695 }
 696
 697 static void clear_links(ir_node *irn, void *env)
 698 {
 699         (void) env;
 700         set_irn_link(irn, NULL);
 701         if (is_Block(irn))
 702                 set_Block_phis(irn, NULL);
 703 }
 704
 705 static void build_phi_lists(ir_node *irn, void *env)
 706 {
 707         (void) env;
 708         if (is_Phi(irn))
 709                 add_Block_phi(get_nodes_block(irn), irn);
 710 }
 711
 712 void fixpoint_vrp(ir_graph* const irg)
 713 {
 714         environment_t env;
 715
 716         FIRM_DBG_REGISTER(dbg, "firm.opt.fp-vrp");
 717         DB((dbg, LEVEL_1, "===> Performing constant propagation on %+F\n", irg));
 718
 719         obstack_init(&obst);
 720
 721         /* HACK: to avoid finding dead code */
 722         edges_deactivate(irg);
 723         edges_activate(irg);
 724
 725         edges_assure(irg);
 726         assure_doms(irg);
 727
 728         ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK | IR_RESOURCE_PHI_LIST);
 729
 730         {
 731                 pdeq* const q = new_pdeq();
 732
 733                 /* We need this extra step because the dom tree does not contain unreachable
 734                    blocks in Firm. Moreover build phi list. */
 735                 irg_walk_graph(irg, clear_links, build_phi_lists, NULL);
 736
 737                 /* TODO Improve iteration order. Best is reverse postorder in data flow
 738                  * direction and respecting loop nesting for fastest convergence. */
 739                 irg_walk_blkwise_dom_top_down(irg, firm_clear_link, first_round, q);
 740
 741                 while (!pdeq_empty(q)) {
 742                         ir_node* const n = (ir_node*)pdeq_getl(q);
 743                         if (transfer(n))
 744                                 queue_users(q, n);
 745                 }
 746
 747                 del_pdeq(q);
 748         }
 749
 750         DB((dbg, LEVEL_2, "---> Applying analysis results\n"));
 751         env.modified = 0;
 752         irg_walk_graph(irg, NULL, apply_result, &env);
 753
 754         if (env.modified) {
 755                 /* control flow might changed */
 756                 set_irg_outs_inconsistent(irg);
 757                 set_irg_extblk_inconsistent(irg);
 758                 set_irg_doms_inconsistent(irg);
 759                 set_irg_loopinfo_inconsistent(irg);
 760                 set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
 761         }
 762
 763         ir_free_resources(irg, IR_RESOURCE_IRN_LINK | IR_RESOURCE_PHI_LIST);
 764
 765         obstack_free(&obst, NULL);
 766 }
 767
 768 ir_graph_pass_t *fixpoint_vrp_irg_pass(const char *name)
 769 {
 770         return def_graph_pass(name ? name : "fixpoint_vrp", fixpoint_vrp);
 771 }