nsz Git - libfirm/blob - ir/opt/boolopt.c

   1 /*
   2  * Copyright (C) 1995-2008 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   boolean condition/control flow optimizations
  23  * @author  Matthias Braun, Christoph Mallon, Michael Beck
  24  * @version $Id: cfopt.c 22579 2008-10-07 14:54:04Z beck $
  25  */
  26 #include "config.h"
  27
  28 #include <assert.h>
  29 #include <string.h>
  30
  31 #include "adt/obst.h"
  32 #include "../adt/array_t.h"
  33 #include "iroptimize.h"
  34 #include "ircons.h"
  35 #include "irgmod.h"
  36 #include "irgwalk.h"
  37 #include "irprintf.h"
  38 #include "irnode_t.h"
  39 #include "tv.h"
  40 #include "irpass.h"
  41 #include "debug.h"
  42
  43 /** Describes a pair of relative conditions lo < hi, lo pnc_lo x, hi pnc_hi x */
  44 typedef struct cond_pair {
  45         ir_node *cmp_lo;  /**< The lo compare node. */
  46         ir_node *cmp_hi;  /**< The hi compare node. */
  47         pn_Cmp   pnc_lo;  /**< The lo relation node. */
  48         pn_Cmp   pnc_hi;  /**< The hi relation node. */
  49         ir_node *proj_lo; /**< The mode_b result proj of cmp_lo. */
  50         ir_node *proj_hi; /**< The mode_b result proj of cmp_hi. */
  51         tarval  *tv_lo;   /**< The tarval of cmp_lo node. */
  52         tarval  *tv_hi;   /**< The tarval of cmp_hi node. */
  53         ir_mode *lo_mode; /**< The mode of the cmp_lo operands. */
  54 } cond_pair;
  55
  56 /** Environment for all walker in boolopt. */
  57 typedef struct {
  58         int changed;  /**< Set if the graph was changed. */
  59 } bool_opt_env_t;
  60
  61 DEBUG_ONLY(static firm_dbg_module_t *dbg);
  62
  63 /**
  64  * Check if tho given nodes, l and r, represent two compares with
  65  * ... . If yes, return non-zero and fill the res struct.
  66  */
  67 static int find_cond_pair(ir_node *const l, ir_node *const r, cond_pair *const res)
  68 {
  69         if (is_Proj(l) && is_Proj(r)) {
  70                 ir_node *const lo = get_Proj_pred(l);
  71                 ir_node *const ro = get_Proj_pred(r);
  72
  73                 if (is_Cmp(lo) && is_Cmp(ro)) {
  74                         ir_node *const lol   = get_Cmp_left(lo);
  75                         ir_node *const lor   = get_Cmp_right(lo);
  76                         ir_node *const rol   = get_Cmp_left(ro);
  77                         ir_node *const ror   = get_Cmp_right(ro);
  78                         pn_Cmp   const pnc_l = get_Proj_proj(l);
  79                         pn_Cmp   const pnc_r = get_Proj_proj(r);
  80
  81                         if (is_Const(lor) && is_Const_null(lor) &&
  82                             is_Const(ror) && is_Const_null(ror) &&
  83                             pnc_l == pnc_r &&
  84                             (pnc_l == pn_Cmp_Lg || pnc_l == pn_Cmp_Eq)) {
  85                                 /* lo == (lol !=|== NULL) && ro == (rol !=|== NULL) */
  86                                 DB((dbg, LEVEL_1, "found <null null>\n"));
  87
  88                                 res->cmp_lo  = lo;
  89                                 res->cmp_hi  = ro;
  90                                 res->pnc_lo  = pnc_l;
  91                                 res->pnc_hi  = pnc_l;
  92                                 res->proj_lo = l;
  93                                 res->proj_hi = r;
  94                                 res->tv_lo   = get_Const_tarval(lor);
  95                                 res->tv_hi   = get_Const_tarval(ror);
  96                                 res->lo_mode = get_irn_mode(lor);
  97
  98                                 return 1;
  99                         }
 100
 101                         if (lol == rol && lor != ror && is_Const(lor) && is_Const(ror)) {
 102                                 /* lo == (x CMP c_l), ro == (x cmp c_r) */
 103                                 tarval *const tv_l  = get_Const_tarval(lor);
 104                                 tarval *const tv_r  = get_Const_tarval(ror);
 105                                 pn_Cmp  const rel   = tarval_cmp(tv_l, tv_r);
 106
 107                                 res->lo_mode = get_irn_mode(lol);
 108
 109                                 if (rel == pn_Cmp_Lt) {
 110                                         /* c_l < c_r */
 111                                         res->cmp_lo  = lo;
 112                                         res->cmp_hi  = ro;
 113                                         res->pnc_lo  = pnc_l;
 114                                         res->pnc_hi  = pnc_r;
 115                                         res->proj_lo = l;
 116                                         res->proj_hi = r;
 117                                         res->tv_lo   = tv_l;
 118                                         res->tv_hi   = tv_r;
 119                                 } else if (rel == pn_Cmp_Gt) {
 120                                         /* c_l > c_r */
 121                                         res->cmp_lo  = ro;
 122                                         res->cmp_hi  = lo;
 123                                         res->pnc_lo  = pnc_r;
 124                                         res->pnc_hi  = pnc_l;
 125                                         res->proj_lo = r;
 126                                         res->proj_hi = l;
 127                                         res->tv_lo   = tv_r;
 128                                         res->tv_hi   = tv_l;
 129                                 } else {
 130                                         /* The constants shall be unequal but comparable.
 131                                          * Local optimizations handle the equal case. */
 132                                         return 0;
 133                                 }
 134                                 return 1;
 135                         }
 136                 }
 137         }
 138         return 0;
 139 }
 140
 141 /**
 142  * Handle (lo pnc_lo x) AND (hi pnc_hi x)
 143  */
 144 static ir_node *bool_and(cond_pair* const cpair)
 145 {
 146         ir_node *const cmp_lo  = cpair->cmp_lo;
 147         ir_node *const cmp_hi  = cpair->cmp_hi;
 148         pn_Cmp         pnc_lo  = cpair->pnc_lo;
 149         pn_Cmp   const pnc_hi  = cpair->pnc_hi;
 150         ir_node *const proj_lo = cpair->proj_lo;
 151         ir_node *const proj_hi = cpair->proj_hi;
 152         tarval  *      tv_lo   = cpair->tv_lo;
 153         tarval  *      tv_hi   = cpair->tv_hi;
 154         ir_mode *      mode    = cpair->lo_mode;
 155
 156         if (pnc_lo == pn_Cmp_Eq && pnc_hi == pn_Cmp_Eq &&
 157             tarval_is_null(tv_lo) && tarval_is_null(tv_hi) &&
 158             mode == get_tarval_mode(tv_hi)) {
 159                 /* p == NULL && q == NULL ==> (p&q) == NULL) */
 160                 ir_node *block, *lol, *hil, *cmp, *c, *p;
 161
 162                 if (mode_is_reference(mode)) {
 163                         mode = find_unsigned_mode(mode);
 164                         if (! mode)
 165                                 return NULL;
 166                         tv_lo = tarval_convert_to(tv_lo, mode);
 167                         if (tv_lo == tarval_bad)
 168                                 return NULL;
 169                 }
 170                 if (mode_is_int(mode)) {
 171                         block = get_nodes_block(cmp_lo);
 172                         lol   = get_Cmp_left(cmp_lo);
 173                         lol   = new_r_Conv(block, lol, mode);
 174                         hil   = get_Cmp_left(cmp_hi);
 175                         hil   = new_r_Conv(block, hil, mode);
 176                         p     = new_r_And(block, lol, hil, mode);
 177                         c     = new_Const(tv_lo);
 178                         cmp   = new_r_Cmp(block, p, c);
 179                         p     = new_r_Proj(block, cmp, mode_b, pn_Cmp_Eq);
 180                         return p;
 181                 }
 182         }
 183
 184         /* TODO: for now reject float modes */
 185         if (! mode_is_int(mode))
 186                 return 0;
 187
 188         /* Beware of NaN's, we can only check for (ordered) != here (which is Lg, not Ne) */
 189         if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 190             (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 191                 /* x <|<=|== lo && x ==|>=|> hi ==> false */
 192                 ir_node *const t = new_Const(tarval_b_false);
 193                 return t;
 194         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 195                    (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 196                 /* x <|<=|== lo && x <|<=|!= hi ==> x <|<=|== lo */
 197                 return proj_lo;
 198         } else if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 199                    (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 200                 /* x >=|>|!= lo && x ==|>=|> hi ==> x ==|>=|> hi */
 201                 return proj_hi;
 202         } else if (tarval_is_one(tarval_sub(tv_hi, tv_lo, NULL))) { /* lo + 1 == hi */
 203                 if (pnc_lo == pn_Cmp_Ge && pnc_hi == pn_Cmp_Lt) {
 204                         /* x >= c && x < c + 1 ==> x == c */
 205                         ir_node  *const block = get_nodes_block(cmp_lo);
 206                         ir_node  *const p = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Eq);
 207                         return p;
 208                 } else if (pnc_lo == pn_Cmp_Gt) {
 209                         if (pnc_hi == pn_Cmp_Lg) {
 210                                 /* x > c && x != c + 1 ==> x > c + 1 */
 211                                 ir_node  *const block = get_nodes_block(cmp_hi);
 212                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Gt);
 213                                 return p;
 214                         } else if (pnc_hi == pn_Cmp_Lt) {
 215                                 /* x > c && x < c + 1 ==> false */
 216                                 ir_node *const t = new_Const(tarval_b_false);
 217                                 return t;
 218                         } else if (pnc_hi == pn_Cmp_Le) {
 219                                 /* x > c && x <= c + 1 ==> x != c + 1 */
 220                                 ir_node  *const block = get_nodes_block(cmp_hi);
 221                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Eq);
 222                                 return p;
 223                         }
 224                 } else if (pnc_lo == pn_Cmp_Lg && pnc_hi == pn_Cmp_Lt) {
 225                         /* x != c && c < c + 1 ==> x < c */
 226                         ir_node  *const block = get_nodes_block(cmp_lo);
 227                         ir_node  *const p     = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Lt);
 228                         return p;
 229                 }
 230         } else if ((pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Ge) &&
 231                    (pnc_hi == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le) &&
 232                    get_mode_arithmetic(mode) == irma_twos_complement) {
 233                 /* works for two-complements only */
 234                 /* x >|\= lo && x <|<= hi ==> (x - lo) <u|<=u (hi-lo) */
 235                 if (pnc_lo == pn_Cmp_Gt) {
 236                         /* must convert to >= */
 237                         ir_mode *mode = get_tarval_mode(tv_lo);
 238                         tarval *n = tarval_add(tv_lo, get_mode_one(mode));
 239                         if (n != tarval_bad && tarval_cmp(n, tv_lo) == pn_Cmp_Gt) {
 240                                 /* no overflow */
 241                                 tv_lo = n;
 242                                 pnc_lo = pn_Cmp_Ge;
 243                         }
 244                 }
 245                 if (pnc_lo == pn_Cmp_Ge) {
 246                         /* all fine */
 247                         ir_node *const block = get_nodes_block(cmp_hi);
 248                         ir_node *      x     = get_Cmp_left(cmp_hi);
 249                         ir_mode *      mode  = get_irn_mode(x);
 250                         ir_node *sub, *cmp, *c, *subc, *p;
 251
 252                         if (mode_is_signed(mode)) {
 253                                 /* convert to unsigned */
 254                                 mode = find_unsigned_mode(mode);
 255                                 if (mode == NULL)
 256                                         return NULL;
 257                                 x     = new_r_Conv(block, x, mode);
 258                                 tv_lo = tarval_convert_to(tv_lo, mode);
 259                                 tv_hi = tarval_convert_to(tv_hi, mode);
 260                                 if (tv_lo == tarval_bad || tv_hi == tarval_bad)
 261                                         return NULL;
 262                         }
 263                         c    = new_Const(tv_lo);
 264                         sub  = new_r_Sub(block, x, c, mode);
 265                         subc = new_r_Sub(block, new_Const(tv_hi), c, mode);
 266                         cmp  = new_r_Cmp(block, sub, subc);
 267                         p    = new_r_Proj(block, cmp, mode_b, pnc_hi);
 268                         return p;
 269                 }
 270         }
 271         return NULL;
 272 }
 273
 274 /**
 275  * Handle (lo pnc_lo x) OR (hi pnc_hi x)
 276  */
 277 static ir_node *bool_or(cond_pair *const cpair)
 278 {
 279         ir_node *const cmp_lo  = cpair->cmp_lo;
 280         ir_node *const cmp_hi  = cpair->cmp_hi;
 281         pn_Cmp         pnc_lo  = cpair->pnc_lo;
 282         pn_Cmp   const pnc_hi  = cpair->pnc_hi;
 283         ir_node *const proj_lo = cpair->proj_lo;
 284         ir_node *const proj_hi = cpair->proj_hi;
 285         tarval  *      tv_lo   = cpair->tv_lo;
 286         tarval  *      tv_hi   = cpair->tv_hi;
 287         ir_mode *      mode    = cpair->lo_mode;
 288
 289         if (pnc_lo == pn_Cmp_Lg && pnc_hi == pn_Cmp_Lg &&
 290                 tarval_is_null(tv_lo) && tarval_is_null(tv_hi) &&
 291                 mode == get_tarval_mode(tv_hi)) {
 292                 /* p != NULL || q != NULL ==> (p|q) != NULL) */
 293                 ir_node *block, *lol, *hil, *cmp, *c, *p;
 294
 295                 if (mode_is_reference(mode)) {
 296                         mode = find_unsigned_mode(mode);
 297                         if (! mode)
 298                                 return NULL;
 299                         tv_lo = tarval_convert_to(tv_lo, mode);
 300                         if (tv_lo == tarval_bad)
 301                                 return NULL;
 302                 }
 303                 if (mode_is_int(mode)) {
 304                         block = get_nodes_block(cmp_lo);
 305                         lol   = get_Cmp_left(cmp_lo);
 306                         lol   = new_r_Conv(block, lol, mode);
 307                         hil   = get_Cmp_left(cmp_hi);
 308                         hil   = new_r_Conv(block, hil, mode);
 309                         p     = new_r_Or(block, lol, hil, mode);
 310                         c     = new_Const(tv_lo);
 311                         cmp   = new_r_Cmp(block, p, c);
 312                         p     = new_r_Proj(block, cmp, mode_b, pn_Cmp_Lg);
 313                         return p;
 314                 }
 315         }
 316
 317         /* TODO: for now reject float modes */
 318         if (! mode_is_int(mode))
 319                 return 0;
 320
 321         /* Beware of NaN's, we can only check for (ordered) != here (which is Lg, not Ne) */
 322         if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 323             (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 324                 /* x >=|>|!= lo | x <|<=|!= hi ==> true */
 325                 ir_node *const t = new_Const(tarval_b_true);
 326                 return t;
 327         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 328                    (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 329                 /* x <|<=|== lo || x <|<=|!= hi ==> x <|<=|!= hi */
 330                 return proj_hi;
 331         } else if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 332                    (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 333                 /* x >=|>|!= lo || x ==|>=|> hi ==> x >=|>|!= lo */
 334                 return proj_lo;
 335         } else if (tarval_is_one(tarval_sub(tv_hi, tv_lo, NULL))) { /* lo + 1 == hi */
 336                 if (pnc_lo == pn_Cmp_Lt && pnc_hi == pn_Cmp_Ge) {
 337                         /* x < c || x >= c + 1 ==> x != c */
 338                         ir_node  *const block = get_nodes_block(cmp_lo);
 339                         ir_node  *const p = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Lg);
 340                         return p;
 341                 } else if (pnc_lo == pn_Cmp_Le) {
 342                         if (pnc_hi == pn_Cmp_Eq) {
 343                                 /* x <= c || x == c + 1 ==> x <= c + 1 */
 344                                 ir_node  *const block = get_nodes_block(cmp_hi);
 345                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Le);
 346                                 return p;
 347                         } else if (pnc_hi == pn_Cmp_Ge) {
 348                                 /* x <= c || x >= c + 1 ==> true */
 349                                 ir_node *const t = new_Const(tarval_b_true);
 350                                 return t;
 351                         } else if (pnc_hi == pn_Cmp_Gt) {
 352                                 /* x <= c || x > c + 1 ==> x != c + 1 */
 353                                 ir_node  *const block = get_nodes_block(cmp_hi);
 354                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Lg);
 355                                 return p;
 356                         }
 357                 } else if (pnc_lo == pn_Cmp_Eq && pnc_hi == pn_Cmp_Ge) {
 358                         /* x == c || x >= c + 1 ==> x >= c */
 359                         ir_node  *const block = get_nodes_block(cmp_lo);
 360                         ir_node  *const p     = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Ge);
 361                         return p;
 362                 }
 363         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le) &&
 364                    (pnc_hi == pn_Cmp_Gt || pnc_lo == pn_Cmp_Ge) &&
 365                    get_mode_arithmetic(mode) == irma_twos_complement) {
 366                 /* works for two-complements only */
 367                 /* x <|\= lo  || x >|>= hi ==> (x - lo) >u|>=u (hi-lo) */
 368                 if (pnc_lo == pn_Cmp_Lt) {
 369                         /* must convert to <= */
 370                         ir_mode *mode = get_tarval_mode(tv_lo);
 371                         tarval *n = tarval_sub(tv_lo, get_mode_one(mode), NULL);
 372                         if (n != tarval_bad && tarval_cmp(n, tv_lo) == pn_Cmp_Lt) {
 373                                 /* no overflow */
 374                                 tv_lo = n;
 375                                 pnc_lo = pn_Cmp_Le;
 376                         }
 377                 }
 378                 if (pnc_lo == pn_Cmp_Le) {
 379                         /* all fine */
 380                         ir_node *const block = get_nodes_block(cmp_hi);
 381                         ir_node *      x     = get_Cmp_left(cmp_hi);
 382                         ir_mode *      mode  = get_irn_mode(x);
 383                         ir_node *sub, *cmp, *c, *subc, *p;
 384
 385                         if (mode_is_signed(mode)) {
 386                                 /* convert to unsigned */
 387                                 mode = find_unsigned_mode(mode);
 388                                 if (mode == NULL)
 389                                         return NULL;
 390                                 x     = new_r_Conv(block, x, mode);
 391                                 tv_lo = tarval_convert_to(tv_lo, mode);
 392                                 tv_hi = tarval_convert_to(tv_hi, mode);
 393                                 if (tv_lo == tarval_bad || tv_hi == tarval_bad)
 394                                         return NULL;
 395                         }
 396                         c    = new_Const(tv_lo);
 397                         sub  = new_r_Sub(block, x, c, mode);
 398                         subc = new_r_Sub(block, new_Const(tv_hi), c, mode);
 399                         cmp  = new_r_Cmp(block, sub, subc);
 400                         p    = new_r_Proj(block, cmp, mode_b, pnc_hi);
 401                         return p;
 402                 }
 403         }
 404         return NULL;
 405 }
 406
 407 /**
 408  * Walker, tries to optimize Andb and Orb nodes.
 409  */
 410 static void bool_walk(ir_node *n, void *ctx)
 411 {
 412         bool_opt_env_t *env = ctx;
 413
 414         if (get_irn_mode(n) != mode_b)
 415                 return;
 416
 417         if (is_And(n)) {
 418                 ir_node *const l = get_And_left(n);
 419                 ir_node *const r = get_And_right(n);
 420                 ir_node *      replacement;
 421                 cond_pair      cpair;
 422                 if (!find_cond_pair(l, r, &cpair))
 423                         return;
 424                 replacement = bool_and(&cpair);
 425                 if (replacement) {
 426                         exchange(n, replacement);
 427                         env->changed = 1;
 428                 }
 429         } else if (is_Or(n)) {
 430                 ir_node *const l = get_Or_left(n);
 431                 ir_node *const r = get_Or_right(n);
 432                 ir_node *      replacement;
 433                 cond_pair      cpair;
 434                 if (!find_cond_pair(l, r, &cpair))
 435                         return;
 436                 replacement = bool_or(&cpair);
 437                 if (replacement) {
 438                         exchange(n, replacement);
 439                         env->changed = 1;
 440                 }
 441         }
 442 }
 443
 444 /**
 445  * Walker, clear Block marker and Phi lists.
 446  */
 447 static void clear_block_infos(ir_node *node, void *env)
 448 {
 449         (void) env;
 450
 451         /* we visit blocks before any other nodes (from the block) */
 452         if (!is_Block(node))
 453                 return;
 454
 455         /* clear the PHI list */
 456         set_Block_phis(node, NULL);
 457         set_Block_mark(node, 0);
 458 }
 459
 460 /**
 461  * Walker: collect Phi nodes and mark
 462  */
 463 static void collect_phis(ir_node *node, void *env)
 464 {
 465         (void) env;
 466
 467         if (is_Phi(node)) {
 468                 ir_node *block = get_nodes_block(node);
 469                 add_Block_phi(block, node);
 470                 return;
 471         }
 472
 473         /* Ignore control flow nodes, these will be removed. */
 474         if (get_irn_pinned(node) == op_pin_state_pinned &&
 475                         !is_Block(node) && !is_cfop(node)) {
 476                                 /* found a pinned non-cf node, mark its block */
 477                 ir_node *block = get_nodes_block(node);
 478                 set_Block_mark(block, 1);
 479         }
 480 }
 481
 482 /**
 483  * If node is a Jmp in a block containing no pinned instruction
 484  * and having only one predecessor, skip the block and return its
 485  * cf predecessor, else the node itself.
 486  */
 487 static ir_node *skip_empty_blocks(ir_node *node)
 488 {
 489         while (is_Jmp(node)) {
 490                 ir_node *block = get_nodes_block(node);
 491
 492                 if (get_Block_n_cfgpreds(block) != 1)
 493                         break;
 494
 495                 if (get_Block_mark(block))
 496                         break;
 497
 498                 node = get_Block_cfgpred(block, 0);
 499         }
 500         return node;
 501 }
 502
 503 /**
 504  * Check if two block inputs can be fused.
 505  * This can be done, if block contains no Phi node that depends on
 506  * different inputs idx_i and idx_j.
 507  */
 508 static int can_fuse_block_inputs(const ir_node *block, int idx_i, int idx_j) {
 509         const ir_node *phi;
 510
 511         for (phi = get_Block_phis(block); phi != NULL; phi = get_Phi_next(phi)) {
 512                 if (get_Phi_pred(phi, idx_i) != get_Phi_pred(phi, idx_j))
 513                         return 0;
 514         }
 515         return 1;
 516 }
 517
 518 /**
 519  * Remove block input with given index.
 520  */
 521 static void remove_block_input(ir_node *block, int idx)
 522 {
 523         int i, j, n = get_Block_n_cfgpreds(block) - 1;
 524         ir_node *phi, **ins;
 525
 526         NEW_ARR_A(ir_node *, ins, n);
 527
 528         if (n == 1) {
 529                 /* all Phis will be deleted */
 530                 ir_node *next_phi;
 531
 532                 for (phi = get_Block_phis(block); phi != NULL; phi = next_phi) {
 533                         next_phi = get_Phi_next(phi);
 534                         exchange(phi, get_Phi_pred(phi, idx ^ 1));
 535                 }
 536                 set_Block_phis(block, NULL);
 537         } else {
 538                 for (phi = get_Block_phis(block); phi != NULL; phi = get_Phi_next(phi)) {
 539                         for (i = j = 0; i <= n; ++i) {
 540                                 if (i != idx)
 541                                         ins[j++] = get_Phi_pred(phi, i);
 542                         }
 543                         set_irn_in(phi, n, ins);
 544                 }
 545         }
 546         for (i = j = 0; i <= n; ++i) {
 547                 if (i != idx)
 548                         ins[j++] = get_Block_cfgpred(block, i);
 549         }
 550         set_irn_in(block, n, ins);
 551 }
 552
 553 /**
 554  * Under the preposition that we have a chain of blocks from
 555  * from_block to to_block, collapse them all into to_block.
 556  */
 557 static void move_nodes_to_block(ir_node *jmp, ir_node *to_block) {
 558         ir_node *new_jmp = NULL;
 559         ir_node *block, *next_block;
 560
 561         for (block = get_nodes_block(jmp); block != to_block; block = next_block) {
 562                 new_jmp = get_Block_cfgpred(block, 0);
 563                 next_block = get_nodes_block(new_jmp);
 564                 exchange(block, to_block);
 565         }
 566         if (new_jmp)
 567                 exchange(jmp, new_jmp);
 568 }
 569
 570 /**
 571  * Block walker:
 572  *
 573  * if we can find the following structure,
 574  *
 575  *        upper_block
 576  *         /       |
 577  *        /        |
 578  *   lower_block   |
 579  *     /  \        |
 580  *   ... low_idx up_idx
 581  *          \      |
 582  *            block
 583  *
 584  * try to convert it into a (x pnc_lo c_lo) || (x pnc_hi c_hi)
 585  * and optimize.
 586  */
 587 static void find_cf_and_or_walker(ir_node *block, void *ctx)
 588 {
 589         int low_idx, up_idx;
 590         int n_cfgpreds = get_Block_n_cfgpreds(block);
 591         bool_opt_env_t *env = ctx;
 592
 593 restart:
 594         if (n_cfgpreds < 2)
 595                 return;
 596
 597         for (low_idx = 0; low_idx < n_cfgpreds; ++low_idx) {
 598                 ir_node      *lower_block;
 599                 ir_node      *lower_cf;
 600                 ir_node      *cond;
 601                 ir_node      *cond_selector;
 602                 ir_node      *lower_pred;
 603
 604                 lower_cf = get_Block_cfgpred(block, low_idx);
 605                 lower_cf = skip_empty_blocks(lower_cf);
 606                 if (!is_Proj(lower_cf))
 607                         continue;
 608
 609                 cond = get_Proj_pred(lower_cf);
 610                 if (!is_Cond(cond))
 611                         continue;
 612
 613                 lower_block = get_nodes_block(cond);
 614                 if (get_Block_n_cfgpreds(lower_block) != 1)
 615                         continue;
 616
 617                 /* the block must not produce any side-effects */
 618                 if (get_Block_mark(lower_block))
 619                         continue;
 620
 621                 cond_selector = get_Cond_selector(cond);
 622                 if (get_irn_mode(cond_selector) != mode_b)
 623                         continue;
 624
 625                 lower_pred = get_Block_cfgpred_block(lower_block, 0);
 626
 627                 for (up_idx = 0; up_idx < n_cfgpreds; ++up_idx) {
 628                         ir_node   *upper_block;
 629                         ir_node   *upper_cf;
 630                         ir_node   *upper_cond;
 631                         ir_node   *upper_cond_selector;
 632                         ir_node   *replacement;
 633                         cond_pair  cpair;
 634
 635                         upper_cf    = get_Block_cfgpred(block, up_idx);
 636                         upper_cf    = skip_empty_blocks(upper_cf);
 637                         if (is_Bad(upper_cf))
 638                                 continue;
 639                         upper_block = get_nodes_block(upper_cf);
 640                         if (upper_block != lower_pred)
 641                                 continue;
 642
 643                         assert(is_Proj(upper_cf));
 644                         upper_cond = get_Proj_pred(upper_cf);
 645                         assert(is_Cond(upper_cond));
 646                         upper_cond_selector = get_Cond_selector(upper_cond);
 647                         if (get_irn_mode(upper_cond_selector) != mode_b)
 648                                 continue;
 649
 650                         /* we have found the structure */
 651                         /* check Phis: There must be NO Phi in block that
 652                            depends on the existence of low block */
 653                         if (!can_fuse_block_inputs(block, low_idx, up_idx))
 654                                 continue;
 655
 656                         /* all fine, try it */
 657                         if (!find_cond_pair(cond_selector, upper_cond_selector, &cpair))
 658                                 continue;
 659
 660                         /* normalize pncs: we need the true case to jump into the
 661                          * common block (ie. conjunctive normal form) */
 662                         if (get_Proj_proj(lower_cf) == pn_Cond_false) {
 663                                 if (cpair.proj_lo == cond_selector) {
 664                                         ir_mode *mode = get_tarval_mode(cpair.tv_lo);
 665                                         cpair.pnc_lo  = get_negated_pnc(cpair.pnc_lo, mode);
 666                                         cpair.proj_lo = new_r_Proj(lower_block,
 667                                                         get_Proj_pred(cpair.proj_lo), mode_b, cpair.pnc_lo);
 668                                 } else {
 669                                         ir_mode *mode = get_tarval_mode(cpair.tv_hi);
 670                                         assert(cpair.proj_hi == cond_selector);
 671                                         cpair.pnc_hi  = get_negated_pnc(cpair.pnc_hi, mode);
 672                                         cpair.proj_hi = new_r_Proj(lower_block,
 673                                                         get_Proj_pred(cpair.proj_hi), mode_b, cpair.pnc_hi);
 674                                 }
 675                         }
 676                         if (get_Proj_proj(upper_cf) == pn_Cond_false) {
 677                                 if (cpair.proj_lo == upper_cond_selector) {
 678                                         ir_mode *mode = get_tarval_mode(cpair.tv_lo);
 679                                         cpair.pnc_lo  = get_negated_pnc(cpair.pnc_lo, mode);
 680                                         cpair.proj_lo = new_r_Proj(upper_block,
 681                                                         get_Proj_pred(cpair.proj_lo), mode_b, cpair.pnc_lo);
 682                                 } else {
 683                                         ir_mode *mode = get_tarval_mode(cpair.tv_hi);
 684                                         assert(cpair.proj_hi == upper_cond_selector);
 685                                         cpair.pnc_hi  = get_negated_pnc(cpair.pnc_hi, mode);
 686                                         cpair.proj_hi = new_r_Proj(upper_block,
 687                                                         get_Proj_pred(cpair.proj_hi), mode_b, cpair.pnc_hi);
 688                                 }
 689                         }
 690
 691                         /* can we optimize the case? */
 692                         replacement = bool_or(&cpair);
 693                         if (replacement == NULL)
 694                                 continue;
 695
 696                         env->changed = 1;
 697
 698                         /* move all expressions on the path to lower/upper block */
 699                         move_nodes_to_block(get_Block_cfgpred(block, up_idx), upper_block);
 700                         move_nodes_to_block(get_Block_cfgpred(block, low_idx), lower_block);
 701
 702                         /* move all nodes from lower block to upper block */
 703                         exchange(lower_block, upper_block);
 704
 705                         remove_block_input(block, up_idx);
 706                         --n_cfgpreds;
 707
 708                         /* the optimizations expected the true case to jump */
 709                         if (get_Proj_proj(lower_cf) == pn_Cond_false) {
 710                                 ir_node *block = get_nodes_block(replacement);
 711                                 replacement    = new_rd_Not(NULL, block, replacement, mode_b);
 712                         }
 713                         set_Cond_selector(cond, replacement);
 714
 715                         DB((dbg, LEVEL_1, "%+F: replaced (ub %+F)\n", current_ir_graph, upper_block));
 716                         goto restart;
 717                 }
 718         }
 719 }
 720
 721 void opt_bool(ir_graph *const irg)
 722 {
 723         bool_opt_env_t env;
 724
 725         /* register a debug mask */
 726         FIRM_DBG_REGISTER(dbg, "firm.opt.bool");
 727
 728         /* works better with one return block only */
 729         normalize_one_return(irg);
 730
 731         env.changed = 0;
 732
 733         /* optimize simple Andb and Orb cases */
 734         irg_walk_graph(irg, NULL, bool_walk, &env);
 735
 736         ir_reserve_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_PHI_LIST);
 737
 738         /* now more complicated cases: find control flow And/Or and optimize. */
 739         irg_walk_graph(irg, clear_block_infos, collect_phis, NULL);
 740         irg_block_walk_graph(irg, NULL, find_cf_and_or_walker, &env);
 741
 742         if (env.changed) {
 743                 set_irg_outs_inconsistent(irg);
 744                 set_irg_doms_inconsistent(irg);
 745                 set_irg_extblk_inconsistent(irg);
 746                 set_irg_loopinfo_inconsistent(irg);
 747         }
 748
 749         ir_free_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_PHI_LIST);
 750 }
 751
 752 /* Creates an ir_graph pass for opt_bool. */
 753 ir_graph_pass_t *opt_bool_pass(const char *name)
 754 {
 755         return def_graph_pass(name ? name : "opt_bool", opt_bool);
 756 }  /* opt_bool_pass */