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 (mode_is_reference(mode) && 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                 mode = find_unsigned_mode(mode);
 163                 if (! mode)
 164                         return NULL;
 165                 tv_lo = tarval_convert_to(tv_lo, mode);
 166                 if (tv_lo == tarval_bad)
 167                         return NULL;
 168                 block = get_nodes_block(cmp_lo);
 169                 lol   = get_Cmp_left(cmp_lo);
 170                 lol   = new_r_Conv(block, lol, mode);
 171                 hil   = get_Cmp_left(cmp_hi);
 172                 hil   = new_r_Conv(block, hil, mode);
 173                 p     = new_r_And(block, lol, hil, mode);
 174                 c     = new_Const(tv_lo);
 175                 cmp   = new_r_Cmp(block, p, c);
 176                 p     = new_r_Proj(block, cmp, mode_b, pn_Cmp_Eq);
 177                 return p;
 178         }
 179
 180         /* TODO: for now reject float modes */
 181         if (! mode_is_int(mode))
 182                 return 0;
 183
 184         /* Beware of NaN's, we can only check for (ordered) != here (which is Lg, not Ne) */
 185         if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 186             (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 187                 /* x <|<=|== lo && x ==|>=|> hi ==> false */
 188                 ir_node *const t = new_Const(tarval_b_false);
 189                 return t;
 190         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 191                    (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 192                 /* x <|<=|== lo && x <|<=|!= hi ==> x <|<=|== lo */
 193                 return proj_lo;
 194         } else if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 195                    (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 196                 /* x >=|>|!= lo && x ==|>=|> hi ==> x ==|>=|> hi */
 197                 return proj_hi;
 198         } else if (tarval_is_one(tarval_sub(tv_hi, tv_lo, NULL))) { /* lo + 1 == hi */
 199                 if (pnc_lo == pn_Cmp_Ge && pnc_hi == pn_Cmp_Lt) {
 200                         /* x >= c && x < c + 1 ==> x == c */
 201                         ir_node  *const block = get_nodes_block(cmp_lo);
 202                         ir_node  *const p = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Eq);
 203                         return p;
 204                 } else if (pnc_lo == pn_Cmp_Gt) {
 205                         if (pnc_hi == pn_Cmp_Lg) {
 206                                 /* x > c && x != c + 1 ==> x > c + 1 */
 207                                 ir_node  *const block = get_nodes_block(cmp_hi);
 208                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Gt);
 209                                 return p;
 210                         } else if (pnc_hi == pn_Cmp_Lt) {
 211                                 /* x > c && x < c + 1 ==> false */
 212                                 ir_node *const t = new_Const(tarval_b_false);
 213                                 return t;
 214                         } else if (pnc_hi == pn_Cmp_Le) {
 215                                 /* x > c && x <= c + 1 ==> x != c + 1 */
 216                                 ir_node  *const block = get_nodes_block(cmp_hi);
 217                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Eq);
 218                                 return p;
 219                         }
 220                 } else if (pnc_lo == pn_Cmp_Lg && pnc_hi == pn_Cmp_Lt) {
 221                         /* x != c && c < c + 1 ==> x < c */
 222                         ir_node  *const block = get_nodes_block(cmp_lo);
 223                         ir_node  *const p     = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Lt);
 224                         return p;
 225                 }
 226         } else if ((pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Ge) &&
 227                    (pnc_hi == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le) &&
 228                    get_mode_arithmetic(mode) == irma_twos_complement) {
 229                 /* works for two-complements only */
 230                 /* x >|\= lo && x <|<= hi ==> (x - lo) <u|<=u (hi-lo) */
 231                 if (pnc_lo == pn_Cmp_Gt) {
 232                         /* must convert to >= */
 233                         ir_mode *mode = get_tarval_mode(tv_lo);
 234                         tarval *n = tarval_add(tv_lo, get_mode_one(mode));
 235                         if (n != tarval_bad && tarval_cmp(n, tv_lo) == pn_Cmp_Gt) {
 236                                 /* no overflow */
 237                                 tv_lo = n;
 238                                 pnc_lo = pn_Cmp_Ge;
 239                         }
 240                 }
 241                 if (pnc_lo == pn_Cmp_Ge) {
 242                         /* all fine */
 243                         ir_node *const block = get_nodes_block(cmp_hi);
 244                         ir_node *      x     = get_Cmp_left(cmp_hi);
 245                         ir_mode *      mode  = get_irn_mode(x);
 246                         ir_node *sub, *cmp, *c, *subc, *p;
 247
 248                         if (mode_is_signed(mode)) {
 249                                 /* convert to unsigned */
 250                                 mode = find_unsigned_mode(mode);
 251                                 if (mode == NULL)
 252                                         return NULL;
 253                                 x     = new_r_Conv(block, x, mode);
 254                                 tv_lo = tarval_convert_to(tv_lo, mode);
 255                                 tv_hi = tarval_convert_to(tv_hi, mode);
 256                                 if (tv_lo == tarval_bad || tv_hi == tarval_bad)
 257                                         return NULL;
 258                         }
 259                         c    = new_Const(tv_lo);
 260                         sub  = new_r_Sub(block, x, c, mode);
 261                         subc = new_r_Sub(block, new_Const(tv_hi), c, mode);
 262                         cmp  = new_r_Cmp(block, sub, subc);
 263                         p    = new_r_Proj(block, cmp, mode_b, pnc_hi);
 264                         return p;
 265                 }
 266         }
 267         return NULL;
 268 }
 269
 270 /**
 271  * Handle (lo pnc_lo x) OR (hi pnc_hi x)
 272  */
 273 static ir_node *bool_or(cond_pair *const cpair)
 274 {
 275         ir_node *const cmp_lo  = cpair->cmp_lo;
 276         ir_node *const cmp_hi  = cpair->cmp_hi;
 277         pn_Cmp         pnc_lo  = cpair->pnc_lo;
 278         pn_Cmp   const pnc_hi  = cpair->pnc_hi;
 279         ir_node *const proj_lo = cpair->proj_lo;
 280         ir_node *const proj_hi = cpair->proj_hi;
 281         tarval  *      tv_lo   = cpair->tv_lo;
 282         tarval  *      tv_hi   = cpair->tv_hi;
 283         ir_mode *      mode    = cpair->lo_mode;
 284
 285         if (mode_is_reference(mode) && pnc_lo == pn_Cmp_Lg && pnc_hi == pn_Cmp_Lg &&
 286                 tarval_is_null(tv_lo) && tarval_is_null(tv_hi) &&
 287                 mode == get_tarval_mode(tv_hi)) {
 288                 /* p != NULL || q != NULL ==> (p|q) != NULL) */
 289                 ir_node *block, *lol, *hil, *cmp, *c, *p;
 290
 291                 mode = find_unsigned_mode(mode);
 292                 if (! mode)
 293                         return NULL;
 294                 tv_lo = tarval_convert_to(tv_lo, mode);
 295                 if (tv_lo == tarval_bad)
 296                         return NULL;
 297                 block = get_nodes_block(cmp_lo);
 298                 lol   = get_Cmp_left(cmp_lo);
 299                 lol   = new_r_Conv(block, lol, mode);
 300                 hil   = get_Cmp_left(cmp_hi);
 301                 hil   = new_r_Conv(block, hil, mode);
 302                 p     = new_r_Or(block, lol, hil, mode);
 303                 c     = new_Const(tv_lo);
 304                 cmp   = new_r_Cmp(block, p, c);
 305                 p     = new_r_Proj(block, cmp, mode_b, pn_Cmp_Lg);
 306                 return p;
 307         }
 308
 309         /* TODO: for now reject float modes */
 310         if (! mode_is_int(mode))
 311                 return 0;
 312
 313         /* Beware of NaN's, we can only check for (ordered) != here (which is Lg, not Ne) */
 314         if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 315             (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 316                 /* x >=|>|!= lo | x <|<=|!= hi ==> true */
 317                 ir_node *const t = new_Const(tarval_b_true);
 318                 return t;
 319         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 320                    (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 321                 /* x <|<=|== lo || x <|<=|!= hi ==> x <|<=|!= hi */
 322                 return proj_hi;
 323         } else if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 324                    (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 325                 /* x >=|>|!= lo || x ==|>=|> hi ==> x >=|>|!= lo */
 326                 return proj_lo;
 327         } else if (tarval_is_one(tarval_sub(tv_hi, tv_lo, NULL))) { /* lo + 1 == hi */
 328                 if (pnc_lo == pn_Cmp_Lt && pnc_hi == pn_Cmp_Ge) {
 329                         /* x < c || x >= c + 1 ==> x != c */
 330                         ir_node  *const block = get_nodes_block(cmp_lo);
 331                         ir_node  *const p = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Lg);
 332                         return p;
 333                 } else if (pnc_lo == pn_Cmp_Le) {
 334                         if (pnc_hi == pn_Cmp_Eq) {
 335                                 /* x <= c || x == c + 1 ==> x <= c + 1 */
 336                                 ir_node  *const block = get_nodes_block(cmp_hi);
 337                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Le);
 338                                 return p;
 339                         } else if (pnc_hi == pn_Cmp_Ge) {
 340                                 /* x <= c || x >= c + 1 ==> true */
 341                                 ir_node *const t = new_Const(tarval_b_true);
 342                                 return t;
 343                         } else if (pnc_hi == pn_Cmp_Gt) {
 344                                 /* x <= c || x > c + 1 ==> x != c + 1 */
 345                                 ir_node  *const block = get_nodes_block(cmp_hi);
 346                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Lg);
 347                                 return p;
 348                         }
 349                 } else if (pnc_lo == pn_Cmp_Eq && pnc_hi == pn_Cmp_Ge) {
 350                         /* x == c || x >= c + 1 ==> x >= c */
 351                         ir_node  *const block = get_nodes_block(cmp_lo);
 352                         ir_node  *const p     = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Ge);
 353                         return p;
 354                 }
 355         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le) &&
 356                    (pnc_hi == pn_Cmp_Gt || pnc_lo == pn_Cmp_Ge) &&
 357                    get_mode_arithmetic(mode) == irma_twos_complement) {
 358                 /* works for two-complements only */
 359                 /* x <|\= lo  || x >|>= hi ==> (x - lo) >u|>=u (hi-lo) */
 360                 if (pnc_lo == pn_Cmp_Lt) {
 361                         /* must convert to <= */
 362                         ir_mode *mode = get_tarval_mode(tv_lo);
 363                         tarval *n = tarval_sub(tv_lo, get_mode_one(mode), NULL);
 364                         if (n != tarval_bad && tarval_cmp(n, tv_lo) == pn_Cmp_Lt) {
 365                                 /* no overflow */
 366                                 tv_lo = n;
 367                                 pnc_lo = pn_Cmp_Le;
 368                         }
 369                 }
 370                 if (pnc_lo == pn_Cmp_Le) {
 371                         /* all fine */
 372                         ir_node *const block = get_nodes_block(cmp_hi);
 373                         ir_node *      x     = get_Cmp_left(cmp_hi);
 374                         ir_mode *      mode  = get_irn_mode(x);
 375                         ir_node *sub, *cmp, *c, *subc, *p;
 376
 377                         if (mode_is_signed(mode)) {
 378                                 /* convert to unsigned */
 379                                 mode = find_unsigned_mode(mode);
 380                                 if (mode == NULL)
 381                                         return NULL;
 382                                 x     = new_r_Conv(block, x, mode);
 383                                 tv_lo = tarval_convert_to(tv_lo, mode);
 384                                 tv_hi = tarval_convert_to(tv_hi, mode);
 385                                 if (tv_lo == tarval_bad || tv_hi == tarval_bad)
 386                                         return NULL;
 387                         }
 388                         c    = new_Const(tv_lo);
 389                         sub  = new_r_Sub(block, x, c, mode);
 390                         subc = new_r_Sub(block, new_Const(tv_hi), c, mode);
 391                         cmp  = new_r_Cmp(block, sub, subc);
 392                         p    = new_r_Proj(block, cmp, mode_b, pnc_hi);
 393                         return p;
 394                 }
 395         }
 396         return NULL;
 397 }
 398
 399 /**
 400  * Walker, tries to optimize Andb and Orb nodes.
 401  */
 402 static void bool_walk(ir_node *n, void *ctx)
 403 {
 404         bool_opt_env_t *env = ctx;
 405
 406         if (get_irn_mode(n) != mode_b)
 407                 return;
 408
 409         if (is_And(n)) {
 410                 ir_node *const l = get_And_left(n);
 411                 ir_node *const r = get_And_right(n);
 412                 ir_node *      replacement;
 413                 cond_pair      cpair;
 414                 if (!find_cond_pair(l, r, &cpair))
 415                         return;
 416                 replacement = bool_and(&cpair);
 417                 if (replacement) {
 418                         exchange(n, replacement);
 419                         env->changed = 1;
 420                 }
 421         } else if (is_Or(n)) {
 422                 ir_node *const l = get_Or_left(n);
 423                 ir_node *const r = get_Or_right(n);
 424                 ir_node *      replacement;
 425                 cond_pair      cpair;
 426                 if (!find_cond_pair(l, r, &cpair))
 427                         return;
 428                 replacement = bool_or(&cpair);
 429                 if (replacement) {
 430                         exchange(n, replacement);
 431                         env->changed = 1;
 432                 }
 433         }
 434 }
 435
 436 /**
 437  * Walker, clear Block marker and Phi lists.
 438  */
 439 static void clear_block_infos(ir_node *node, void *env)
 440 {
 441         (void) env;
 442
 443         /* we visit blocks before any other nodes (from the block) */
 444         if (!is_Block(node))
 445                 return;
 446
 447         /* clear the PHI list */
 448         set_Block_phis(node, NULL);
 449         set_Block_mark(node, 0);
 450 }
 451
 452 /**
 453  * Walker: collect Phi nodes and mark
 454  */
 455 static void collect_phis(ir_node *node, void *env)
 456 {
 457         (void) env;
 458
 459         if (is_Phi(node)) {
 460                 ir_node *block = get_nodes_block(node);
 461                 add_Block_phi(block, node);
 462                 return;
 463         }
 464
 465         /* Ignore control flow nodes, these will be removed. */
 466         if (get_irn_pinned(node) == op_pin_state_pinned &&
 467                         !is_Block(node) && !is_cfop(node)) {
 468                                 /* found a pinned non-cf node, mark its block */
 469                 ir_node *block = get_nodes_block(node);
 470                 set_Block_mark(block, 1);
 471         }
 472 }
 473
 474 /**
 475  * If node is a Jmp in a block containing no pinned instruction
 476  * and having only one predecessor, skip the block and return its
 477  * cf predecessor, else the node itself.
 478  */
 479 static ir_node *skip_empty_blocks(ir_node *node)
 480 {
 481         while (is_Jmp(node)) {
 482                 ir_node *block = get_nodes_block(node);
 483
 484                 if (get_Block_n_cfgpreds(block) != 1)
 485                         break;
 486
 487                 if (get_Block_mark(block))
 488                         break;
 489
 490                 node = get_Block_cfgpred(block, 0);
 491         }
 492         return node;
 493 }
 494
 495 /**
 496  * Check if two block inputs can be fused.
 497  * This can be done, if block contains no Phi node that depends on
 498  * different inputs idx_i and idx_j.
 499  */
 500 static int can_fuse_block_inputs(const ir_node *block, int idx_i, int idx_j) {
 501         const ir_node *phi;
 502
 503         for (phi = get_Block_phis(block); phi != NULL; phi = get_Phi_next(phi)) {
 504                 if (get_Phi_pred(phi, idx_i) != get_Phi_pred(phi, idx_j))
 505                         return 0;
 506         }
 507         return 1;
 508 }
 509
 510 /**
 511  * Remove block input with given index.
 512  */
 513 static void remove_block_input(ir_node *block, int idx)
 514 {
 515         int i, j, n = get_Block_n_cfgpreds(block) - 1;
 516         ir_node *phi, **ins;
 517
 518         NEW_ARR_A(ir_node *, ins, n);
 519
 520         if (n == 1) {
 521                 /* all Phis will be deleted */
 522                 ir_node *next_phi;
 523
 524                 for (phi = get_Block_phis(block); phi != NULL; phi = next_phi) {
 525                         next_phi = get_Phi_next(phi);
 526                         exchange(phi, get_Phi_pred(phi, idx ^ 1));
 527                 }
 528                 set_Block_phis(block, NULL);
 529         } else {
 530                 for (phi = get_Block_phis(block); phi != NULL; phi = get_Phi_next(phi)) {
 531                         for (i = j = 0; i <= n; ++i) {
 532                                 if (i != idx)
 533                                         ins[j++] = get_Phi_pred(phi, i);
 534                         }
 535                         set_irn_in(phi, n, ins);
 536                 }
 537         }
 538         for (i = j = 0; i <= n; ++i) {
 539                 if (i != idx)
 540                         ins[j++] = get_Block_cfgpred(block, i);
 541         }
 542         set_irn_in(block, n, ins);
 543 }
 544
 545 /**
 546  * Under the preposition that we have a chain of blocks from
 547  * from_block to to_block, collapse them all into to_block.
 548  */
 549 static void move_nodes_to_block(ir_node *jmp, ir_node *to_block) {
 550         ir_node *new_jmp = NULL;
 551         ir_node *block, *next_block;
 552
 553         for (block = get_nodes_block(jmp); block != to_block; block = next_block) {
 554                 new_jmp = get_Block_cfgpred(block, 0);
 555                 next_block = get_nodes_block(new_jmp);
 556                 exchange(block, to_block);
 557         }
 558         if (new_jmp)
 559                 exchange(jmp, new_jmp);
 560 }
 561
 562 /**
 563  * Block walker:
 564  *
 565  * if we can find the following structure,
 566  *
 567  *        upper_block
 568  *         /       |
 569  *        /        |
 570  *   lower_block   |
 571  *     /  \        |
 572  *   ... low_idx up_idx
 573  *          \      |
 574  *            block
 575  *
 576  * try to convert it into a (x pnc_lo c_lo) || (x pnc_hi c_hi)
 577  * and optimize.
 578  */
 579 static void find_cf_and_or_walker(ir_node *block, void *ctx)
 580 {
 581         int low_idx, up_idx;
 582         int n_cfgpreds = get_Block_n_cfgpreds(block);
 583         bool_opt_env_t *env = ctx;
 584
 585 restart:
 586         if (n_cfgpreds < 2)
 587                 return;
 588
 589         for (low_idx = 0; low_idx < n_cfgpreds; ++low_idx) {
 590                 ir_node      *lower_block;
 591                 ir_node      *lower_cf;
 592                 ir_node      *cond;
 593                 ir_node      *cond_selector;
 594                 ir_node      *lower_pred;
 595
 596                 lower_cf = get_Block_cfgpred(block, low_idx);
 597                 lower_cf = skip_empty_blocks(lower_cf);
 598                 if (!is_Proj(lower_cf))
 599                         continue;
 600
 601                 cond = get_Proj_pred(lower_cf);
 602                 if (!is_Cond(cond))
 603                         continue;
 604
 605                 lower_block = get_nodes_block(cond);
 606                 if (get_Block_n_cfgpreds(lower_block) != 1)
 607                         continue;
 608
 609                 /* the block must not produce any side-effects */
 610                 if (get_Block_mark(lower_block))
 611                         continue;
 612
 613                 cond_selector = get_Cond_selector(cond);
 614                 if (get_irn_mode(cond_selector) != mode_b)
 615                         continue;
 616
 617                 lower_pred = get_Block_cfgpred_block(lower_block, 0);
 618
 619                 for (up_idx = 0; up_idx < n_cfgpreds; ++up_idx) {
 620                         ir_node   *upper_block;
 621                         ir_node   *upper_cf;
 622                         ir_node   *upper_cond;
 623                         ir_node   *upper_cond_selector;
 624                         ir_node   *replacement;
 625                         cond_pair  cpair;
 626
 627                         upper_cf    = get_Block_cfgpred(block, up_idx);
 628                         upper_cf    = skip_empty_blocks(upper_cf);
 629                         if (is_Bad(upper_cf))
 630                                 continue;
 631                         upper_block = get_nodes_block(upper_cf);
 632                         if (upper_block != lower_pred)
 633                                 continue;
 634
 635                         assert(is_Proj(upper_cf));
 636                         upper_cond = get_Proj_pred(upper_cf);
 637                         assert(is_Cond(upper_cond));
 638                         upper_cond_selector = get_Cond_selector(upper_cond);
 639                         if (get_irn_mode(upper_cond_selector) != mode_b)
 640                                 continue;
 641
 642                         /* we have found the structure */
 643                         /* check Phis: There must be NO Phi in block that
 644                            depends on the existence of low block */
 645                         if (!can_fuse_block_inputs(block, low_idx, up_idx))
 646                                 continue;
 647
 648                         /* all fine, try it */
 649                         if (!find_cond_pair(cond_selector, upper_cond_selector, &cpair))
 650                                 continue;
 651
 652                         /* normalize pncs: we need the true case to jump into the
 653                          * common block (ie. conjunctive normal form) */
 654                         if (get_Proj_proj(lower_cf) == pn_Cond_false) {
 655                                 if (cpair.proj_lo == cond_selector) {
 656                                         ir_mode *mode = get_tarval_mode(cpair.tv_lo);
 657                                         cpair.pnc_lo  = get_negated_pnc(cpair.pnc_lo, mode);
 658                                         cpair.proj_lo = new_r_Proj(lower_block,
 659                                                         get_Proj_pred(cpair.proj_lo), mode_b, cpair.pnc_lo);
 660                                 } else {
 661                                         ir_mode *mode = get_tarval_mode(cpair.tv_hi);
 662                                         assert(cpair.proj_hi == cond_selector);
 663                                         cpair.pnc_hi  = get_negated_pnc(cpair.pnc_hi, mode);
 664                                         cpair.proj_hi = new_r_Proj(lower_block,
 665                                                         get_Proj_pred(cpair.proj_hi), mode_b, cpair.pnc_hi);
 666                                 }
 667                         }
 668                         if (get_Proj_proj(upper_cf) == pn_Cond_false) {
 669                                 if (cpair.proj_lo == upper_cond_selector) {
 670                                         ir_mode *mode = get_tarval_mode(cpair.tv_lo);
 671                                         cpair.pnc_lo  = get_negated_pnc(cpair.pnc_lo, mode);
 672                                         cpair.proj_lo = new_r_Proj(upper_block,
 673                                                         get_Proj_pred(cpair.proj_lo), mode_b, cpair.pnc_lo);
 674                                 } else {
 675                                         ir_mode *mode = get_tarval_mode(cpair.tv_hi);
 676                                         assert(cpair.proj_hi == upper_cond_selector);
 677                                         cpair.pnc_hi  = get_negated_pnc(cpair.pnc_hi, mode);
 678                                         cpair.proj_hi = new_r_Proj(upper_block,
 679                                                         get_Proj_pred(cpair.proj_hi), mode_b, cpair.pnc_hi);
 680                                 }
 681                         }
 682
 683                         /* can we optimize the case? */
 684                         replacement = bool_or(&cpair);
 685                         if (replacement == NULL)
 686                                 continue;
 687
 688                         env->changed = 1;
 689
 690                         /* move all expressions on the path to lower/upper block */
 691                         move_nodes_to_block(get_Block_cfgpred(block, up_idx), upper_block);
 692                         move_nodes_to_block(get_Block_cfgpred(block, low_idx), lower_block);
 693
 694                         /* move all nodes from lower block to upper block */
 695                         exchange(lower_block, upper_block);
 696
 697                         remove_block_input(block, up_idx);
 698                         --n_cfgpreds;
 699
 700                         /* the optimizations expected the true case to jump */
 701                         if (get_Proj_proj(lower_cf) == pn_Cond_false) {
 702                                 ir_node *block = get_nodes_block(replacement);
 703                                 replacement    = new_rd_Not(NULL, block, replacement, mode_b);
 704                         }
 705                         set_Cond_selector(cond, replacement);
 706
 707                         DB((dbg, LEVEL_1, "%+F: replaced (ub %+F)\n", current_ir_graph, upper_block));
 708                         goto restart;
 709                 }
 710         }
 711 }
 712
 713 void opt_bool(ir_graph *const irg)
 714 {
 715         bool_opt_env_t env;
 716
 717         /* register a debug mask */
 718         FIRM_DBG_REGISTER(dbg, "firm.opt.bool");
 719
 720         /* works better with one return block only */
 721         normalize_one_return(irg);
 722
 723         env.changed = 0;
 724
 725         /* optimize simple Andb and Orb cases */
 726         irg_walk_graph(irg, NULL, bool_walk, &env);
 727
 728         ir_reserve_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_PHI_LIST);
 729
 730         /* now more complicated cases: find control flow And/Or and optimize. */
 731         irg_walk_graph(irg, clear_block_infos, collect_phis, NULL);
 732         irg_block_walk_graph(irg, NULL, find_cf_and_or_walker, &env);
 733
 734         if (env.changed) {
 735                 set_irg_outs_inconsistent(irg);
 736                 set_irg_doms_inconsistent(irg);
 737                 set_irg_extblk_inconsistent(irg);
 738                 set_irg_loopinfo_inconsistent(irg);
 739         }
 740
 741         ir_free_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_PHI_LIST);
 742 }
 743
 744 /* Creates an ir_graph pass for opt_bool. */
 745 ir_graph_pass_t *opt_bool_pass(const char *name)
 746 {
 747         return def_graph_pass(name ? name : "opt_bool", opt_bool);
 748 }  /* opt_bool_pass */