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 <assert.h>
  29 #include <stdbool.h>
  30
  31 #include "adt/pdeq.h"
  32 #include "adt/obst.h"
  33 #include "adt/xmalloc.h"
  34 #include "debug.h"
  35 #include "ircons.h"
  36 #include "irdom.h"
  37 #include "iredges.h"
  38 #include "irgmod.h"
  39 #include "irgraph_t.h"
  40 #include "irgwalk.h"
  41 #include "irnode_t.h"
  42 #include "iroptimize.h"
  43 #include "irtools.h"
  44 #include "tv.h"
  45 #include "irpass.h"
  46 #include "irmemory.h"
  47 #include "opt_manage.h"
  48
  49 /* TODO:
  50  * - Implement cleared/set bit calculation for Add, Sub, Minus, Mul, Div, Mod, Shl, Shr, Shrs, Rotl
  51  * - Implement min/max calculation for And, Eor, Or, Not, Conv, Shl, Shr, Shrs, Rotl, Mux
  52  * - Implement min/max calculation for Add, Sub, Minus, Mul, Div, Mod, Conv, Shl, Shr, Shrs, Rotl, Mux
  53  */
  54
  55 /* Tables of the cleared/set bit lattice
  56  *
  57  * Encoding of the lattice
  58  * zo
  59  * 00 0 zero
  60  * 01 - impossible state, is zero /and/ one
  61  * 10 T top, may be either zero or one
  62  * 11 1 one
  63  *
  64  * S = Sum
  65  * c = Carry
  66  * D = Difference
  67  * b = Borrow
  68  *
  69  * Not
  70  * A ~
  71  * 0 1
  72  * 1 0
  73  * T T
  74  *
  75  * Half adder, half subtractor, and, xor, or, Mux
  76  * AB  Sc  Db  &  ^  |  M
  77  * 00  00  00  0  0  0  0
  78  * 01  10  11  0  1  1  T
  79  * 0T  T0  TT  0  T  T  T
  80  * 10  10  10  0  1  1  T
  81  * 11  01  00  1  0  1  1
  82  * 1T  TT  T0  T  T  1  T
  83  * T0  T0  T0  0  T  T  T
  84  * T1  TT  TT  T  T  1  T
  85  * TT  TT  TT  T  T  T  T
  86  *
  87  * Full adder, full subtractor
  88  * ABc-1  Sc  Db
  89  * 000    00  00
  90  * 001    10  11
  91  * 00T    T0  TT
  92  * 010    10  11
  93  * 011    01  01
  94  * 01T    TT  T1
  95  * 0T0    T0  TT
  96  * 0T1    TT  T1
  97  * 0TT    TT  TT
  98  * 100    10  10
  99  * 101    01  00
 100  * 10T    TT  T0
 101  * 110    01  00
 102  * 111    11  11
 103  * 11T    T1  TT
 104  * 1T0    TT  T0
 105  * 1T1    T1  TT
 106  * 1TT    TT  TT
 107  * T00    T0  T0
 108  * T01    TT  TT
 109  * T0T    TT  TT
 110  * T10    TT  TT
 111  * T11    T1  T1
 112  * T1T    TT  TT
 113  * TT0    TT  TT
 114  * TT1    TT  TT
 115  * TTT    TT  TT
 116  *
 117  *
 118  * Assume: Xmin <= Xmax and no overflow
 119  * A + B = (Amin + Bmin, Amax + Bmax)
 120  *    -A = (-Amax, -Amin)
 121  * A - B = A + -B = (Amin (-B)min, Amax + (-B)max) = (Amin - Bmax, Amax - Bmin)
 122  */
 123
 124 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
 125
 126 static struct obstack obst;
 127
 128 typedef struct bitinfo
 129 {
 130         ir_tarval* z; // safe zeroes, 0 = bit is zero,       1 = bit maybe is 1
 131         ir_tarval* o; // safe ones,   0 = bit maybe is zero, 1 = bit is 1
 132 } bitinfo;
 133
 134 typedef struct environment_t {
 135         unsigned modified:1;     /**< Set, if the graph was modified. */
 136 } environment_t;
 137
 138 static bool is_undefined(bitinfo const* const b)
 139 {
 140         return tarval_is_null(b->z) && tarval_is_all_one(b->o);
 141 }
 142
 143 static inline bitinfo* get_bitinfo(ir_node const* const irn)
 144 {
 145         return (bitinfo*)get_irn_link(irn);
 146 }
 147
 148 static int set_bitinfo(ir_node* const irn, ir_tarval* const z, ir_tarval* const o)
 149 {
 150         bitinfo* b = get_bitinfo(irn);
 151         if (b == NULL) {
 152                 b = OALLOCZ(&obst, bitinfo);
 153                 set_irn_link(irn, b);
 154         } else if (z == b->z && o == b->o) {
 155                 return 0;
 156         } else {
 157                 /* Assert monotonicity. */
 158                 assert(tarval_is_null(tarval_andnot(b->z, z)));
 159                 assert(tarval_is_null(tarval_andnot(o, b->o)));
 160         }
 161         b->z = z;
 162         b->o = o;
 163         DB((dbg, LEVEL_3, "%+F: 0:%T 1:%T\n", irn, z, o));
 164         return 1;
 165 }
 166
 167 static int mode_is_intb(ir_mode const* const m)
 168 {
 169         return mode_is_int(m) || m == mode_b;
 170 }
 171
 172 static int transfer(ir_node* const irn)
 173 {
 174         ir_tarval* const f = get_tarval_b_false();
 175         ir_tarval* const t = get_tarval_b_true();
 176         ir_mode*   const m = get_irn_mode(irn);
 177         ir_tarval*       z;
 178         ir_tarval*       o;
 179
 180         if (is_Bad(irn)) return 0;
 181
 182         if (m == mode_X) {
 183                 bitinfo* const b = get_bitinfo(get_nodes_block(irn));
 184
 185                 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
 186
 187                 /* Unreachble blocks might have no bitinfo. */
 188                 if (b == NULL || b->z == f) {
 189 unreachable_X:
 190                         z = f;
 191                         o = t;
 192                 } else switch (get_irn_opcode(irn)) {
 193                         case iro_Proj: {
 194                                 ir_node* const pred = get_Proj_pred(irn);
 195                                 if (is_Start(pred)) {
 196                                         goto result_unknown_X;
 197                                 } else if (is_Cond(pred)) {
 198                                         ir_node*   const selector = get_Cond_selector(pred);
 199                                         bitinfo*   const b        = get_bitinfo(selector);
 200                                         if (is_undefined(b)) {
 201                                                 goto unreachable_X;
 202                                         } else if (get_irn_mode(selector) == mode_b) {
 203                                                 if (b->z == b->o) {
 204                                                         if ((b->z == t) == get_Proj_proj(irn)) {
 205                                                                 z = o = t;
 206                                                         } else {
 207                                                                 z = o = f;
 208                                                         }
 209                                                 } else {
 210                                                         goto result_unknown_X;
 211                                                 }
 212                                         } else {
 213                                                 long const val = get_Proj_proj(irn);
 214                                                 if (val != get_Cond_default_proj(pred)) {
 215                                                         ir_tarval* const tv = new_tarval_from_long(val, get_irn_mode(selector));
 216                                                         if (!tarval_is_null(tarval_andnot(tv, b->z)) ||
 217                                                                         !tarval_is_null(tarval_andnot(b->o, tv))) {
 218                                                                 // At least one bit differs.
 219                                                                 z = o = f;
 220 #if 0 // TODO must handle default Proj
 221                                                         } else if (b->z == b->o && b->z == tv) {
 222                                                                 z = o = t;
 223 #endif
 224                                                         } else {
 225                                                                 goto result_unknown_X;
 226                                                         }
 227                                                 } else {
 228                                                         goto cannot_analyse_X;
 229                                                 }
 230                                         }
 231                                 } else {
 232                                         goto cannot_analyse_X;
 233                                 }
 234                                 break;
 235                         }
 236
 237                         case iro_Jmp:
 238                                 goto result_unknown_X;
 239
 240                         default:
 241 cannot_analyse_X:
 242                                 DB((dbg, LEVEL_4, "cannot analyse %+F\n", irn));
 243 result_unknown_X:
 244                                 z = t;
 245                                 o = f;
 246                                 break;
 247                 }
 248         } else if (is_Block(irn)) {
 249                 int       reachable = 0;
 250                 int const arity     = get_Block_n_cfgpreds(irn);
 251                 int       i;
 252
 253                 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
 254                 for (i = 0; i != arity; ++i) {
 255                         bitinfo* const b = get_bitinfo(get_Block_cfgpred(irn, i));
 256                         if (b != NULL && b->z == t) {
 257                                 reachable = 1;
 258                                 break;
 259                         }
 260                 }
 261
 262                 if (!reachable) {
 263                         ir_graph *const irg = get_Block_irg(irn);
 264                         reachable =
 265                                 irn == get_irg_start_block(irg) ||
 266                                 irn == get_irg_end_block(irg);
 267                 }
 268
 269                 if (reachable) {
 270                         z = t;
 271                         o = f;
 272                 } else {
 273                         z = f;
 274                         o = t;
 275                 }
 276         } else if (mode_is_intb(m)) {
 277                 bitinfo* const b = get_bitinfo(get_nodes_block(irn));
 278
 279                 DB((dbg, LEVEL_3, "transfer %+F\n", irn));
 280
 281                 if (b == NULL || b->z == f) {
 282 undefined:
 283                         z = get_tarval_null(m);
 284                         o = get_tarval_all_one(m);
 285                 } else if (is_Phi(irn)) {
 286                         ir_node* const block = get_nodes_block(irn);
 287                         int      const arity = get_Phi_n_preds(irn);
 288                         int            i;
 289
 290                         z = get_tarval_null(m);
 291                         o = get_tarval_all_one(m);
 292                         for (i = 0; i != arity; ++i) {
 293                                 bitinfo* const b_cfg = get_bitinfo(get_Block_cfgpred(block, i));
 294                                 if (b_cfg != NULL && b_cfg->z != f) {
 295                                         bitinfo* const b = get_bitinfo(get_Phi_pred(irn, i));
 296                                         /* Only use input if it's not undefined. */
 297                                         if (!is_undefined(b)) {
 298                                                 z = tarval_or( z, b->z);
 299                                                 o = tarval_and(o, b->o);
 300                                         }
 301                                 }
 302                         }
 303                 } else {
 304                         int const arity = get_irn_arity(irn);
 305                         int       i;
 306
 307                         /* Undefined if any input is undefined. */
 308                         for (i = 0; i != arity; ++i) {
 309                                 ir_node* const pred   = get_irn_n(irn, i);
 310                                 bitinfo* const pred_b = get_bitinfo(pred);
 311                                 if (pred_b != NULL && is_undefined(pred_b))
 312                                         goto undefined;
 313                         }
 314
 315                         switch (get_irn_opcode(irn)) {
 316                                 case iro_Const: {
 317                                         z = o = get_Const_tarval(irn);
 318                                         break;
 319                                 }
 320
 321                                 case iro_Confirm: {
 322                                         ir_node* const v = get_Confirm_value(irn);
 323                                         bitinfo* const b = get_bitinfo(v);
 324                                         /* TODO Use bound and relation. */
 325                                         z = b->z;
 326                                         o = b->o;
 327                                         if ((get_Confirm_relation(irn) & ~ir_relation_unordered) == ir_relation_equal) {
 328                                                 bitinfo* const bound_b = get_bitinfo(get_Confirm_bound(irn));
 329                                                 z = tarval_and(z, bound_b->z);
 330                                                 o = tarval_or( o, bound_b->o);
 331                                         }
 332                                         break;
 333                                 }
 334
 335                                 case iro_Shl: {
 336                                         bitinfo*   const l  = get_bitinfo(get_Shl_left(irn));
 337                                         bitinfo*   const r  = get_bitinfo(get_Shl_right(irn));
 338                                         ir_tarval* const rz = r->z;
 339                                         if (rz == r->o) {
 340                                                 z = tarval_shl(l->z, rz);
 341                                                 o = tarval_shl(l->o, rz);
 342                                         } else {
 343                                                 goto cannot_analyse;
 344                                         }
 345                                         break;
 346                                 }
 347
 348                                 case iro_Shr: {
 349                                         bitinfo*   const l  = get_bitinfo(get_Shr_left(irn));
 350                                         bitinfo*   const r  = get_bitinfo(get_Shr_right(irn));
 351                                         ir_tarval* const rz = r->z;
 352                                         if (rz == r->o) {
 353                                                 z = tarval_shr(l->z, rz);
 354                                                 o = tarval_shr(l->o, rz);
 355                                         } else {
 356                                                 goto cannot_analyse;
 357                                         }
 358                                         break;
 359                                 }
 360
 361                                 case iro_Shrs: {
 362                                         bitinfo*   const l  = get_bitinfo(get_Shrs_left(irn));
 363                                         bitinfo*   const r  = get_bitinfo(get_Shrs_right(irn));
 364                                         ir_tarval* const rz = r->z;
 365                                         if (rz == r->o) {
 366                                                 z = tarval_shrs(l->z, rz);
 367                                                 o = tarval_shrs(l->o, rz);
 368                                         } else {
 369                                                 goto cannot_analyse;
 370                                         }
 371                                         break;
 372                                 }
 373
 374                                 case iro_Rotl: {
 375                                         bitinfo*   const l  = get_bitinfo(get_Rotl_left(irn));
 376                                         bitinfo*   const r  = get_bitinfo(get_Rotl_right(irn));
 377                                         ir_tarval* const rz = r->z;
 378                                         if (rz == r->o) {
 379                                                 z = tarval_rotl(l->z, rz);
 380                                                 o = tarval_rotl(l->o, rz);
 381                                         } else {
 382                                                 goto cannot_analyse;
 383                                         }
 384                                         break;
 385                                 }
 386
 387                                 case iro_Add: {
 388                                         bitinfo*   const l  = get_bitinfo(get_Add_left(irn));
 389                                         bitinfo*   const r  = get_bitinfo(get_Add_right(irn));
 390                                         ir_tarval* const lz = l->z;
 391                                         ir_tarval* const lo = l->o;
 392                                         ir_tarval* const rz = r->z;
 393                                         ir_tarval* const ro = r->o;
 394                                         if (lz == lo && rz == ro) {
 395                                                 z = o = tarval_add(lz, rz);
 396                                         } else {
 397                                                 // TODO improve: can only do lower disjoint bits
 398                                                 /* Determine where any of the operands has zero bits, i.e. where no
 399                                                  * carry out is generated if there is not carry in */
 400                                                 ir_tarval* const no_c_in_no_c_out = tarval_and(lz, rz);
 401                                                 /* Generate a mask of the lower consecutive zeroes: x | -x.  In this
 402                                                  * range the addition is disjoint and therefore Add behaves like Or.
 403                                                  */
 404                                                 ir_tarval* const low_zero_mask = tarval_or(no_c_in_no_c_out, tarval_neg(no_c_in_no_c_out));
 405                                                 ir_tarval* const low_one_mask  = tarval_not(low_zero_mask);
 406                                                 z = tarval_or( tarval_or(lz, rz), low_zero_mask);
 407                                                 o = tarval_and(tarval_or(lo, ro), low_one_mask);
 408                                         }
 409                                         break;
 410                                 }
 411
 412                                 case iro_Sub: {
 413                                         bitinfo* const l = get_bitinfo(get_Sub_left(irn));
 414                                         bitinfo* const r = get_bitinfo(get_Sub_right(irn));
 415                                         if (l != NULL && r != NULL) { // Sub might subtract pointers.
 416                                                 ir_tarval* const lz = l->z;
 417                                                 ir_tarval* const lo = l->o;
 418                                                 ir_tarval* const rz = r->z;
 419                                                 ir_tarval* const ro = r->o;
 420                                                 if (lz == lo && rz == ro) {
 421                                                         z = o = tarval_sub(lz, rz, NULL);
 422                                                 } else if (tarval_is_null(tarval_andnot(rz, lo))) {
 423                                                         /* Every possible one of the subtrahend is backed by a safe one of the
 424                                                          * minuend, i.e. there are no borrows. */
 425                                                         // TODO extend no-borrow like carry for Add above
 426                                                         z = tarval_andnot(lz, ro);
 427                                                         o = tarval_andnot(lo, rz);
 428                                                 } else {
 429                                                         goto cannot_analyse;
 430                                                 }
 431                                         } else {
 432                                                 goto cannot_analyse;
 433                                         }
 434                                         break;
 435                                 }
 436
 437                                 case iro_Mul: {
 438                                         bitinfo*   const l  = get_bitinfo(get_Mul_left(irn));
 439                                         bitinfo*   const r  = get_bitinfo(get_Mul_right(irn));
 440                                         ir_tarval* const lz = l->z;
 441                                         ir_tarval* const lo = l->o;
 442                                         ir_tarval* const rz = r->z;
 443                                         ir_tarval* const ro = r->o;
 444                                         if (lz == lo && rz == ro) {
 445                                                 z = o = tarval_mul(lz, rz);
 446                                         } else {
 447                                                 // TODO improve
 448                                                 // Determine safe lower zeroes: x | -x.
 449                                                 ir_tarval* const lzn = tarval_or(lz, tarval_neg(lz));
 450                                                 ir_tarval* const rzn = tarval_or(rz, tarval_neg(rz));
 451                                                 // Concatenate safe lower zeroes.
 452                                                 if (tarval_cmp(lzn, rzn) == ir_relation_less) {
 453                                                         z = tarval_mul(tarval_eor(lzn, tarval_shl(lzn, get_tarval_one(m))), rzn);
 454                                                 } else {
 455                                                         z = tarval_mul(tarval_eor(rzn, tarval_shl(rzn, get_tarval_one(m))), lzn);
 456                                                 }
 457                                                 o = get_tarval_null(m);
 458                                         }
 459                                         break;
 460                                 }
 461
 462                                 case iro_Minus: {
 463                                         bitinfo* const b = get_bitinfo(get_Minus_op(irn));
 464                                         if (b->z == b->o) {
 465                                                 z = o = tarval_neg(b->z);
 466                                         } else {
 467                                                 goto cannot_analyse;
 468                                         }
 469                                         break;
 470                                 }
 471
 472                                 case iro_And: {
 473                                         bitinfo* const l = get_bitinfo(get_And_left(irn));
 474                                         bitinfo* const r = get_bitinfo(get_And_right(irn));
 475                                         z = tarval_and(l->z, r->z);
 476                                         o = tarval_and(l->o, r->o);
 477                                         break;
 478                                 }
 479
 480                                 case iro_Or: {
 481                                         bitinfo* const l = get_bitinfo(get_Or_left(irn));
 482                                         bitinfo* const r = get_bitinfo(get_Or_right(irn));
 483                                         z = tarval_or(l->z, r->z);
 484                                         o = tarval_or(l->o, r->o);
 485                                         break;
 486                                 }
 487
 488                                 case iro_Eor: {
 489                                         bitinfo*   const l  = get_bitinfo(get_Eor_left(irn));
 490                                         bitinfo*   const r  = get_bitinfo(get_Eor_right(irn));
 491                                         ir_tarval* const lz = l->z;
 492                                         ir_tarval* const lo = l->o;
 493                                         ir_tarval* const rz = r->z;
 494                                         ir_tarval* const ro = r->o;
 495                                         z = tarval_or(tarval_andnot(lz, ro), tarval_andnot(rz, lo));
 496                                         o = tarval_or(tarval_andnot(ro, lz), tarval_andnot(lo, rz));
 497                                         break;
 498                                 }
 499
 500                                 case iro_Not: {
 501                                         bitinfo* const b = get_bitinfo(get_Not_op(irn));
 502                                         z = tarval_not(b->o);
 503                                         o = tarval_not(b->z);
 504                                         break;
 505                                 }
 506
 507                                 case iro_Conv: {
 508                                         bitinfo* const b = get_bitinfo(get_Conv_op(irn));
 509                                         if (b == NULL) // Happens when converting from float values.
 510                                                 goto result_unknown;
 511                                         z = tarval_convert_to(b->z, m);
 512                                         o = tarval_convert_to(b->o, m);
 513                                         break;
 514                                 }
 515
 516                                 case iro_Mux: {
 517                                         bitinfo* const bf = get_bitinfo(get_Mux_false(irn));
 518                                         bitinfo* const bt = get_bitinfo(get_Mux_true(irn));
 519                                         bitinfo* const c  = get_bitinfo(get_Mux_sel(irn));
 520                                         if (c->o == t) {
 521                                                 z = bt->z;
 522                                                 o = bt->o;
 523                                         } else if (c->z == f) {
 524                                                 z = bf->z;
 525                                                 o = bf->o;
 526                                         } else {
 527                                                 z = tarval_or( bf->z, bt->z);
 528                                                 o = tarval_and(bf->o, bt->o);
 529                                         }
 530                                         break;
 531                                 }
 532
 533                                 case iro_Cmp: {
 534                                         bitinfo* const l = get_bitinfo(get_Cmp_left(irn));
 535                                         bitinfo* const r = get_bitinfo(get_Cmp_right(irn));
 536                                         if (l == NULL || r == NULL) {
 537                                                 goto result_unknown; // Cmp compares something we cannot evaluate.
 538                                         } else {
 539                                                 ir_tarval*  const lz       = l->z;
 540                                                 ir_tarval*  const lo       = l->o;
 541                                                 ir_tarval*  const rz       = r->z;
 542                                                 ir_tarval*  const ro       = r->o;
 543                                                 ir_relation const relation = get_Cmp_relation(irn);
 544                                                 switch (relation) {
 545                                                         case ir_relation_less_greater:
 546                                                                 if (!tarval_is_null(tarval_andnot(ro, lz)) ||
 547                                                                                 !tarval_is_null(tarval_andnot(lo, rz))) {
 548                                                                         // At least one bit differs.
 549                                                                         z = o = t;
 550                                                                 } else if (lz == lo && rz == ro && lz == rz) {
 551                                                                         z = o = f;
 552                                                                 } else {
 553                                                                         goto result_unknown;
 554                                                                 }
 555                                                                 break;
 556
 557                                                         case ir_relation_equal:
 558                                                                 if (!tarval_is_null(tarval_andnot(ro, lz)) ||
 559                                                                                 !tarval_is_null(tarval_andnot(lo, rz))) {
 560                                                                         // At least one bit differs.
 561                                                                         z = o = f;
 562                                                                 } else if (lz == lo && rz == ro && lz == rz) {
 563                                                                         z = o = t;
 564                                                                 } else {
 565                                                                         goto result_unknown;
 566                                                                 }
 567                                                                 break;
 568
 569                                                         case ir_relation_less_equal:
 570                                                         case ir_relation_less:
 571                                                                 /* TODO handle negative values */
 572                                                                 if (tarval_is_negative(lz) || tarval_is_negative(lo) ||
 573                                                                                 tarval_is_negative(rz) || tarval_is_negative(ro))
 574                                                                         goto result_unknown;
 575
 576                                                                 if (tarval_cmp(lz, ro) & relation) {
 577                                                                         /* Left upper bound is smaller(/equal) than right lower bound. */
 578                                                                         z = o = t;
 579                                                                 } else if (!(tarval_cmp(lo, rz) & relation)) {
 580                                                                         /* Left lower bound is not smaller(/equal) than right upper bound. */
 581                                                                         z = o = f;
 582                                                                 } else {
 583                                                                         goto result_unknown;
 584                                                                 }
 585                                                                 break;
 586
 587                                                         case ir_relation_greater_equal:
 588                                                         case ir_relation_greater:
 589                                                                 /* TODO handle negative values */
 590                                                                 if (tarval_is_negative(lz) || tarval_is_negative(lo) ||
 591                                                                                 tarval_is_negative(rz) || tarval_is_negative(ro))
 592                                                                         goto result_unknown;
 593
 594                                                                 if (!(tarval_cmp(lz, ro) & relation)) {
 595                                                                         /* Left upper bound is not greater(/equal) than right lower bound. */
 596                                                                         z = o = f;
 597                                                                 } else if (tarval_cmp(lo, rz) & relation) {
 598                                                                         /* Left lower bound is greater(/equal) than right upper bound. */
 599                                                                         z = o = t;
 600                                                                 } else {
 601                                                                         goto result_unknown;
 602                                                                 }
 603                                                                 break;
 604
 605                                                         default:
 606                                                                 goto cannot_analyse;
 607                                                 }
 608                                         }
 609                                         break;
 610                                 }
 611
 612                                 default: {
 613 cannot_analyse:
 614                                         DB((dbg, LEVEL_4, "cannot analyse %+F\n", irn));
 615 result_unknown:
 616                                         z = get_tarval_all_one(m);
 617                                         o = get_tarval_null(m);
 618                                         break;
 619                                 }
 620                         }
 621                 }
 622         } else {
 623                 return 0;
 624         }
 625
 626         return set_bitinfo(irn, z, o);
 627 }
 628
 629 static void first_round(ir_node* const irn, void* const env)
 630 {
 631         pdeq* const q = (pdeq*)env;
 632
 633         transfer(irn);
 634         if (is_Phi(irn) || is_Block(irn)) {
 635                 /* Only Phis (and their users) need another round, if we did not have
 636                  * information about all their inputs in the first round, i.e. in loops. */
 637                 /* TODO inserts all Phis, should only insert Phis, which did no have all
 638                  * predecessors available */
 639                 pdeq_putr(q, irn);
 640         }
 641 }
 642
 643 static ir_node *make_bad_block(ir_graph *irg)
 644 {
 645         ir_node *bad = new_r_Bad(irg, mode_BB);
 646         bitinfo *bb  = get_bitinfo(bad);
 647         if (bb == NULL) {
 648                 ir_tarval* const f = get_tarval_b_false();
 649                 ir_tarval* const t = get_tarval_b_true();
 650                 set_bitinfo(bad, f, t); /* Undefined. */
 651         }
 652         return bad;
 653 }
 654
 655 static void apply_result(ir_node* const irn, void* ctx)
 656 {
 657         environment_t* env = (environment_t*)ctx;
 658         ir_node*       block;
 659         bitinfo*       block_b;
 660         bitinfo*       b;
 661         ir_tarval*     z;
 662         ir_tarval*     o;
 663
 664         if (is_Block(irn)) {
 665                 block_b = get_bitinfo(irn);
 666                 /* Trivially unreachable blocks have no info. */
 667                 if (block_b == NULL || block_b->z == get_tarval_b_false()) {
 668                         ir_node  *bad = make_bad_block(get_irn_irg(irn));
 669                         exchange(irn, bad);
 670                         env->modified = 1;
 671                 }
 672                 return;
 673         }
 674
 675         block   = get_nodes_block(irn);
 676         block_b = get_bitinfo(block);
 677         /* Trivially unreachable blocks have no info. */
 678         if (block_b == NULL || block_b->z == get_tarval_b_false()) {
 679                 /* Unreachable blocks might be replaced before the nodes in them. */
 680                 ir_mode  *mode = get_irn_mode(irn);
 681                 ir_graph *irg  = get_irn_irg(irn);
 682                 ir_node  *bad  = new_r_Bad(irg, mode);
 683                 exchange(irn, bad);
 684                 env->modified = 1;
 685                 return;
 686         }
 687
 688         b = get_bitinfo(irn);
 689         if (!b) return;
 690         if (is_Const(irn)) return; // It cannot get any better than a Const.
 691
 692         z = b->z;
 693         o = b->o;
 694         // Only display information if we could find out anything about the value.
 695         DEBUG_ONLY(if (!tarval_is_all_one(z) || !tarval_is_null(o)))
 696                 DB((dbg, LEVEL_2, "%+F: 0:%T 1:%T%s\n", irn, z, o, z == o ? " --- constant" : ""));
 697
 698         // Replace node with constant value by Const.
 699         if (z == o) {
 700                 ir_mode* const m = get_irn_mode(irn);
 701                 ir_node*       n;
 702                 if (mode_is_intb(m)) {
 703                         ir_graph *irg = get_irn_irg(irn);
 704                         n = new_r_Const(irg, z);
 705                 } else if (m == mode_X) {
 706                         ir_graph* const irg = get_Block_irg(block);
 707                         if (z == get_tarval_b_true()) {
 708                                 // Might produce an endless loop, so keep the block.
 709                                 add_End_keepalive(get_irg_end(irg), block);
 710                                 n = new_r_Jmp(block);
 711                         } else {
 712                                 n = new_r_Bad(irg, mode_X);
 713                                 /* Transferring analysis information to the bad node makes it a
 714                                  * candidate for replacement. */
 715                                 goto exchange_only;
 716                         }
 717                 } else {
 718                         return;
 719                 }
 720                 set_irn_link(n, b);
 721 exchange_only:
 722                 exchange(irn, n);
 723                 env->modified = 1;
 724         }
 725
 726         switch (get_irn_opcode(irn)) {
 727                 case iro_And: {
 728                         ir_node*       const l  = get_And_left(irn);
 729                         ir_node*       const r  = get_And_right(irn);
 730                         bitinfo const* const bl = get_bitinfo(l);
 731                         bitinfo const* const br = get_bitinfo(r);
 732                         if (bl->z == bl->o) {
 733                                 if (tarval_is_null(tarval_andnot(br->z, bl->z))) {
 734                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 735                                         exchange(irn, r);
 736                                         env->modified = 1;
 737                                 }
 738                         } else if (br->z == br->o) {
 739                                 if (tarval_is_null(tarval_andnot(bl->z, br->z))) {
 740                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 741                                         exchange(irn, l);
 742                                         env->modified = 1;
 743                                 }
 744                         }
 745                         break;
 746                 }
 747
 748                 case iro_Or: {
 749                         ir_node*       const l  = get_Or_left(irn);
 750                         ir_node*       const r  = get_Or_right(irn);
 751                         bitinfo const* const bl = get_bitinfo(l);
 752                         bitinfo const* const br = get_bitinfo(r);
 753                         if (bl->z == bl->o) {
 754                                 if (tarval_is_null(tarval_andnot(bl->o, br->o))) {
 755                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 756                                         exchange(irn, r);
 757                                         env->modified = 1;
 758                                 }
 759                         } else if (br->z == br->o) {
 760                                 if (tarval_is_null(tarval_andnot(br->o, bl->o))) {
 761                                         DB((dbg, LEVEL_2, "%+F(%+F, %+F) is superfluous\n", irn, l, r));
 762                                         exchange(irn, l);
 763                                         env->modified = 1;
 764                                 }
 765                         }
 766                         break;
 767                 }
 768         }
 769 }
 770
 771 static void queue_users(pdeq* const q, ir_node* const n)
 772 {
 773         if (get_irn_mode(n) == mode_X) {
 774                 /* When the state of a control flow node changes, not only queue its
 775                  * successor blocks, but also the Phis in these blocks, because the Phis
 776                  * must reconsider this input path. */
 777                 ir_edge_t const* e;
 778                 foreach_out_edge(n, e) {
 779                         ir_node*  const  src = get_edge_src_irn(e);
 780                         pdeq_putr(q, src);
 781                         /* should always be a block */
 782                         if (is_Block(src)) {
 783                                 ir_node *phi;
 784                                 for (phi = get_Block_phis(src); phi; phi = get_Phi_next(phi))
 785                                         pdeq_putr(q, phi);
 786                         }
 787                 }
 788         } else {
 789                 ir_edge_t const* e;
 790                 foreach_out_edge(n, e) {
 791                         ir_node* const src = get_edge_src_irn(e);
 792                         if (get_irn_mode(src) == mode_T) {
 793                                 queue_users(q, src);
 794                         } else {
 795                                 pdeq_putr(q, src);
 796                         }
 797                 }
 798         }
 799 }
 800
 801 static void clear_links(ir_node *irn, void *env)
 802 {
 803         (void) env;
 804         set_irn_link(irn, NULL);
 805         if (is_Block(irn))
 806                 set_Block_phis(irn, NULL);
 807 }
 808
 809 static void build_phi_lists(ir_node *irn, void *env)
 810 {
 811         (void) env;
 812         if (is_Phi(irn))
 813                 add_Block_phi(get_nodes_block(irn), irn);
 814 }
 815
 816 static ir_graph_state_t do_fixpoint_vrp(ir_graph* const irg)
 817 {
 818         environment_t env;
 819         ir_graph_state_t res = 0;
 820
 821         FIRM_DBG_REGISTER(dbg, "firm.opt.fp-vrp");
 822         DB((dbg, LEVEL_1, "===> Performing constant propagation on %+F\n", irg));
 823
 824         obstack_init(&obst);
 825
 826         ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK | IR_RESOURCE_PHI_LIST);
 827
 828         {
 829                 pdeq* const q = new_pdeq();
 830
 831                 /* We need this extra step because the dom tree does not contain
 832                  * unreachable blocks in Firm. Moreover build phi list. */
 833                 irg_walk_anchors(irg, clear_links, build_phi_lists, NULL);
 834
 835                 {
 836                         ir_tarval* const f = get_tarval_b_false();
 837                         ir_tarval* const t = get_tarval_b_true();
 838                         set_bitinfo(get_irg_end_block(irg), t, f); /* Reachable. */
 839                 }
 840
 841                 /* TODO Improve iteration order. Best is reverse postorder in data flow
 842                  * direction and respecting loop nesting for fastest convergence. */
 843                 irg_walk_blkwise_dom_top_down(irg, NULL, first_round, q);
 844
 845                 while (!pdeq_empty(q)) {
 846                         ir_node* const n = (ir_node*)pdeq_getl(q);
 847                         if (transfer(n))
 848                                 queue_users(q, n);
 849                 }
 850
 851                 del_pdeq(q);
 852         }
 853
 854         DB((dbg, LEVEL_2, "---> Applying analysis results\n"));
 855         env.modified = 0;
 856         irg_walk_graph(irg, NULL, apply_result, &env);
 857
 858         if (! env.modified) {
 859                 res |= IR_GRAPH_STATE_CONSISTENT_DOMINANCE | IR_GRAPH_STATE_CONSISTENT_ENTITY_USAGE;
 860         }
 861
 862         ir_free_resources(irg, IR_RESOURCE_IRN_LINK | IR_RESOURCE_PHI_LIST);
 863
 864         obstack_free(&obst, NULL);
 865
 866         return res;
 867 }
 868
 869 optdesc_t opt_fpvrp = {
 870         "fp-vrp",
 871         IR_GRAPH_STATE_NO_BAD_BLOCKS | IR_GRAPH_STATE_NO_UNREACHABLE_CODE | IR_GRAPH_STATE_CONSISTENT_DOMINANCE | IR_GRAPH_STATE_CONSISTENT_OUT_EDGES,
 872         do_fixpoint_vrp,
 873 };
 874
 875 void fixpoint_vrp(ir_graph* const irg)
 876 {
 877         perform_irg_optimization(irg, &opt_fpvrp);
 878 }
 879
 880 ir_graph_pass_t *fixpoint_vrp_irg_pass(const char *name)
 881 {
 882         return def_graph_pass(name ? name : "fixpoint_vrp", fixpoint_vrp);
 883 }