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/controlflow optimisations
  23  * @author  Matthias Braun, Christoph Mallon
  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 "ircons.h"
  33 #include "irgmod.h"
  34 #include "irgwalk.h"
  35 #include "irprintf.h"
  36 #include "irnode_t.h"
  37 #include "tv.h"
  38
  39 typedef struct cond_pair {
  40         ir_node *cmp_lo;
  41         ir_node *cmp_hi;
  42         pn_Cmp   pnc_lo;
  43         pn_Cmp   pnc_hi;
  44         ir_node *proj_lo;
  45         ir_node *proj_hi;
  46         tarval  *tv_lo;
  47         tarval  *tv_hi;
  48 } cond_pair;
  49
  50 static int find_cond_pair(ir_node *const l, ir_node *const r, cond_pair *const res)
  51 {
  52         if (is_Proj(l) && is_Proj(r)) {
  53                 ir_node *const lo = get_Proj_pred(l);
  54                 ir_node *const ro = get_Proj_pred(r);
  55
  56                 if (is_Cmp(lo) && is_Cmp(ro)) {
  57                         ir_node *const lol = get_Cmp_left(lo);
  58                         ir_node *const lor = get_Cmp_right(lo);
  59                         ir_node *const rol = get_Cmp_left(ro);
  60                         ir_node *const ror = get_Cmp_right(ro);
  61
  62                         if(is_Const(lor) && is_Const_null(lor) && is_Const(ror) && is_Const_null(ror) && get_Proj_proj(l) == pn_Cmp_Lg && get_Proj_proj(r) == pn_Cmp_Lg) {
  63                                 ir_fprintf(stderr, "found zero zero\n");
  64                         }
  65
  66                         /* TODO float */
  67                         /* The constants shall be unequal.  Local optimisations handle the
  68                          * equal case */
  69                         if (lol == rol && mode_is_int(get_irn_mode(lol)) && lor != ror && is_Const(lor) && is_Const(ror)) {
  70                                 tarval *const tv_l  = get_Const_tarval(lor);
  71                                 tarval *const tv_r  = get_Const_tarval(ror);
  72                                 pn_Cmp  const pnc_l = get_Proj_proj(l);
  73                                 pn_Cmp  const pnc_r = get_Proj_proj(r);
  74                                 pn_Cmp  const rel   = tarval_cmp(tv_l, tv_r);
  75
  76                                 assert(rel != pn_Cmp_Eq);
  77
  78                                 if (rel == pn_Cmp_Lt) {
  79                                         res->cmp_lo  = lo;
  80                                         res->cmp_hi  = ro;
  81                                         res->pnc_lo  = pnc_l;
  82                                         res->pnc_hi  = pnc_r;
  83                                         res->proj_lo = l;
  84                                         res->proj_hi = r;
  85                                         res->tv_lo   = tv_l;
  86                                         res->tv_hi   = tv_r;
  87                                 } else {
  88                                         assert(rel == pn_Cmp_Gt);
  89                                         res->cmp_lo  = ro;
  90                                         res->cmp_hi  = lo;
  91                                         res->pnc_lo  = pnc_r;
  92                                         res->pnc_hi  = pnc_l;
  93                                         res->proj_lo = r;
  94                                         res->proj_hi = l;
  95                                         res->tv_lo   = tv_r;
  96                                         res->tv_hi   = tv_l;
  97                                 }
  98                                 return 1;
  99                         }
 100                 }
 101         }
 102         return 0;
 103 }
 104
 105 static ir_node *bool_and(cond_pair* const cpair)
 106 {
 107         ir_node *const cmp_lo  = cpair->cmp_lo;
 108         ir_node *const cmp_hi  = cpair->cmp_hi;
 109         pn_Cmp   const pnc_lo  = cpair->pnc_lo;
 110         pn_Cmp   const pnc_hi  = cpair->pnc_hi;
 111         ir_node *const proj_lo = cpair->proj_lo;
 112         ir_node *const proj_hi = cpair->proj_hi;
 113         tarval  *const tv_lo   = cpair->tv_lo;
 114         tarval  *const tv_hi   = cpair->tv_hi;
 115
 116         /* Beware of NaN's, we can only check for (ordered) != here (which is Lg, not Ne) */
 117         if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 118                         (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 119                 /* x <|<=|== lo | x ==|>=|> hi -> false */
 120                 ir_node *const t = new_Const(tarval_b_false);
 121                 return t;
 122         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 123                                                  (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 124                 /* x <|<=|== lo && x <|<=|!= hi -> x <|<=|== lo */
 125                 return proj_lo;
 126         } else if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 127                                                  (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 128                 /* x >=|>|!= lo || x ==|>=|> hi -> x ==|>=|> hi */
 129                 return proj_hi;
 130         } else if (tarval_is_one(tarval_sub(tv_hi, tv_lo, NULL))) { /* lo + 1 == hi */
 131                 if (pnc_lo == pn_Cmp_Ge && pnc_hi == pn_Cmp_Lt) {
 132                         /* x >= c || x < c + 1 -> x == c */
 133                         ir_node  *const block = get_nodes_block(cmp_lo);
 134                         ir_node  *const p = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Eq);
 135                         return p;
 136                 } else if (pnc_lo == pn_Cmp_Gt) {
 137                         if (pnc_hi == pn_Cmp_Lg) {
 138                                 /* x > c || x != c + 1 -> x > c + 1 */
 139                                 ir_node  *const block = get_nodes_block(cmp_hi);
 140                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Gt);
 141                                 return p;
 142                         } else if (pnc_hi == pn_Cmp_Lt) {
 143                                 /* x > c || x < c + 1 -> false */
 144                                 ir_node *const t = new_Const(tarval_b_false);
 145                                 return t;
 146                         } else if (pnc_hi == pn_Cmp_Le) {
 147                                 /* x > c || x <= c + 1 -> x != c + 1 */
 148                                 ir_node  *const block = get_nodes_block(cmp_hi);
 149                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Eq);
 150                                 return p;
 151                         }
 152                 } else if (pnc_lo == pn_Cmp_Lg && pnc_hi == pn_Cmp_Lt) {
 153                         /* x != c || c < c + 1 -> x < c */
 154                         ir_node  *const block = get_nodes_block(cmp_lo);
 155                         ir_node  *const p     = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Lt);
 156                         return p;
 157                 }
 158         }
 159         return NULL;
 160 }
 161
 162 static ir_node *bool_or(cond_pair *const cpair)
 163 {
 164         ir_node *const cmp_lo  = cpair->cmp_lo;
 165         ir_node *const cmp_hi  = cpair->cmp_hi;
 166         pn_Cmp   const pnc_lo  = cpair->pnc_lo;
 167         pn_Cmp   const pnc_hi  = cpair->pnc_hi;
 168         ir_node *const proj_lo = cpair->proj_lo;
 169         ir_node *const proj_hi = cpair->proj_hi;
 170         tarval  *const tv_lo   = cpair->tv_lo;
 171         tarval  *const tv_hi   = cpair->tv_hi;
 172
 173         /* Beware of NaN's, we can only check for (ordered) != here (which is Lg, not Ne) */
 174         if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 175                         (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 176                 /* x >=|>|!= lo | x <|<=|!= hi -> true */
 177                 ir_node *const t = new_Const(tarval_b_true);
 178                 return t;
 179         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 180                                                  (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 181                 /* x <|<=|== lo || x <|<=|!= hi -> x <|<=|!= hi */
 182                 return proj_hi;
 183         } else if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 184                                                  (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 185                 /* x >=|>|!= lo || x ==|>=|> hi -> x >=|>|!= lo */
 186                 return proj_lo;
 187         } else if (tarval_is_one(tarval_sub(tv_hi, tv_lo, NULL))) { /* lo + 1 == hi */
 188                 if (pnc_lo == pn_Cmp_Lt && pnc_hi == pn_Cmp_Ge) {
 189                         /* x < c || x >= c + 1 -> x != c */
 190                         ir_node  *const block = get_nodes_block(cmp_lo);
 191                         ir_node  *const p = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Lg);
 192                         return p;
 193                 } else if (pnc_lo == pn_Cmp_Le) {
 194                         if (pnc_hi == pn_Cmp_Eq) {
 195                                 /* x <= c || x == c + 1 -> x <= c + 1 */
 196                                 ir_node  *const block = get_nodes_block(cmp_hi);
 197                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Le);
 198                                 return p;
 199                         } else if (pnc_hi == pn_Cmp_Ge) {
 200                                 /* x <= c || x >= c + 1 -> true */
 201                                 ir_node *const t = new_Const(tarval_b_true);
 202                                 return t;
 203                         } else if (pnc_hi == pn_Cmp_Gt) {
 204                                 /* x <= c || x > c + 1 -> x != c + 1 */
 205                                 ir_node  *const block = get_nodes_block(cmp_hi);
 206                                 ir_node  *const p = new_r_Proj(block, cmp_hi, mode_b, pn_Cmp_Lg);
 207                                 return p;
 208                         }
 209                 } else if (pnc_lo == pn_Cmp_Eq && pnc_hi == pn_Cmp_Ge) {
 210                         /* x == c || x >= c + 1 -> x >= c */
 211                         ir_node  *const block = get_nodes_block(cmp_lo);
 212                         ir_node  *const p     = new_r_Proj(block, cmp_lo, mode_b, pn_Cmp_Ge);
 213                         return p;
 214                 }
 215         }
 216         return NULL;
 217 }
 218
 219 static void bool_walk(ir_node *n, void *env)
 220 {
 221         (void)env;
 222
 223         if (get_irn_mode(n) != mode_b)
 224                 return;
 225
 226         if (is_And(n)) {
 227                 ir_node *const l = get_And_left(n);
 228                 ir_node *const r = get_And_right(n);
 229                 ir_node *      replacement;
 230                 cond_pair      cpair;
 231                 if (!find_cond_pair(l, r, &cpair))
 232                         return;
 233                 replacement = bool_and(&cpair);
 234                 if (replacement)
 235                         exchange(n, replacement);
 236         } else if (is_Or(n)) {
 237                 ir_node *const l = get_Or_left(n);
 238                 ir_node *const r = get_Or_right(n);
 239                 ir_node *      replacement;
 240                 cond_pair      cpair;
 241                 if (!find_cond_pair(l, r, &cpair))
 242                         return;
 243                 replacement = bool_or(&cpair);
 244                 if (replacement)
 245                         exchange(n, replacement);
 246         }
 247 }
 248
 249 /**
 250  * Walker, clear Block mark and Phi list
 251  */
 252 static void clear_block_infos(ir_node *node, void *env)
 253 {
 254         (void) env;
 255
 256         /* we visit blocks before any other nodes (from the block) */
 257         if (!is_Block(node))
 258                 return;
 259
 260         /* clear the PHI list */
 261         set_Block_phis(node, NULL);
 262         set_Block_mark(node, 0);
 263 }
 264
 265 /**
 266  * Walker: collect Phi nodes and update the
 267  */
 268 static void collect_phis(ir_node *node, void *env)
 269 {
 270         (void) env;
 271
 272         if (is_Phi(node)) {
 273                 ir_node *block = get_nodes_block(node);
 274                 add_Block_phi(block, node);
 275                 return;
 276         }
 277
 278         /* Ignore control flow nodes, these will be removed. */
 279         if (get_irn_pinned(node) == op_pin_state_pinned &&
 280                         !is_Block(node) && !is_cfop(node)) {
 281                 ir_node *block = get_nodes_block(node);
 282                 set_Block_mark(block, 1);
 283         }
 284 }
 285
 286 /**
 287  * If node is a Jmp in a block containing no pinned instruction
 288  * and having only one predecessor, skip the block and return its
 289  * cf predecessor, else the node itself.
 290  */
 291 static ir_node *skip_empty_block(ir_node *node)
 292 {
 293         ir_node      *block;
 294
 295         if(!is_Jmp(node))
 296                 return node;
 297
 298         block = get_nodes_block(node);
 299         if(get_Block_n_cfgpreds(block) != 1)
 300                 return node;
 301
 302         if(get_Block_mark(block))
 303                 return node;
 304
 305         return get_Block_cfgpred(block, 0);
 306 }
 307
 308 static void find_cf_and_or_walker(ir_node *block, void *env)
 309 {
 310         int i, i2;
 311         int n_cfgpreds = get_Block_n_cfgpreds(block);
 312         (void) env;
 313
 314         if(n_cfgpreds < 2)
 315                 return;
 316
 317         /* Find the following structure:
 318          *
 319          *        upper_block
 320          *         /       |
 321          *        /        |
 322          *   lower_block   |
 323          *     /  \        |
 324          *   ...   \       |
 325          *           block
 326          */
 327
 328 restart:
 329         for(i = 0; i < n_cfgpreds; ++i) {
 330                 ir_node      *lower_block;
 331                 ir_node      *lower_cf;
 332                 ir_node      *cond;
 333                 ir_node      *cond_selector;
 334                 ir_node      *lower_pred;
 335
 336                 lower_cf = get_Block_cfgpred(block, i);
 337                 lower_cf = skip_empty_block(lower_cf);
 338                 if(!is_Proj(lower_cf))
 339                         continue;
 340
 341                 cond = get_Proj_pred(lower_cf);
 342                 if(!is_Cond(cond))
 343                         continue;
 344
 345                 lower_block = get_nodes_block(cond);
 346                 if(get_Block_n_cfgpreds(lower_block) != 1)
 347                         continue;
 348
 349                 /* the block must not produce any side-effects */
 350                 if(get_Block_mark(lower_block))
 351                         continue;
 352
 353                 cond_selector = get_Cond_selector(cond);
 354                 if(get_irn_mode(cond_selector) != mode_b)
 355                         continue;
 356
 357                 lower_pred = get_Block_cfgpred_block(lower_block, 0);
 358
 359                 for(i2 = 0; i2 < n_cfgpreds; ++i2) {
 360                         ir_node   *upper_block;
 361                         ir_node   *upper_cf;
 362                         ir_node   *upper_cond;
 363                         ir_node   *upper_cond_selector;
 364                         ir_node   *replacement;
 365                         cond_pair  cpair;
 366
 367                         upper_cf    = get_Block_cfgpred(block, i2);
 368                         upper_cf    = skip_empty_block(upper_cf);
 369                         if(is_Bad(upper_cf))
 370                                 continue;
 371                         upper_block = get_nodes_block(upper_cf);
 372                         if(upper_block != lower_pred)
 373                                 continue;
 374
 375                         assert(is_Proj(upper_cf));
 376                         upper_cond = get_Proj_pred(upper_cf);
 377                         assert(is_Cond(upper_cond));
 378                         upper_cond_selector = get_Cond_selector(upper_cond);
 379                         if(get_irn_mode(upper_cond_selector) != mode_b)
 380                                 continue;
 381
 382                         /* we have found the structure */
 383                         /* TODO: check phis */
 384                         if(!find_cond_pair(cond_selector, upper_cond_selector, &cpair))
 385                                 continue;
 386
 387                         /* normalize pncs: we need the true case to jump into the
 388                          * common block (ie. conjunctive normal form) */
 389                         if(get_Proj_proj(lower_cf) == pn_Cond_false) {
 390                                 if(cpair.proj_lo == cond_selector) {
 391                                         ir_mode *mode = get_tarval_mode(cpair.tv_lo);
 392                                         cpair.pnc_lo  = get_negated_pnc(cpair.pnc_lo, mode);
 393                                         cpair.proj_lo = new_r_Proj(lower_block,
 394                                                         get_Proj_pred(cpair.proj_lo), mode_b, cpair.pnc_lo);
 395                                 } else {
 396                                         ir_mode *mode = get_tarval_mode(cpair.tv_hi);
 397                                         assert(cpair.proj_hi == cond_selector);
 398                                         cpair.pnc_hi  = get_negated_pnc(cpair.pnc_hi, mode);
 399                                         cpair.proj_hi = new_r_Proj(lower_block,
 400                                                         get_Proj_pred(cpair.proj_hi), mode_b, cpair.pnc_hi);
 401                                 }
 402                         }
 403                         if(get_Proj_proj(upper_cf) == pn_Cond_false) {
 404                                 if(cpair.proj_lo == upper_cond_selector) {
 405                                         ir_mode *mode = get_tarval_mode(cpair.tv_lo);
 406                                         cpair.pnc_lo  = get_negated_pnc(cpair.pnc_lo, mode);
 407                                         cpair.proj_lo = new_r_Proj(upper_block,
 408                                                         get_Proj_pred(cpair.proj_lo), mode_b, cpair.pnc_lo);
 409                                 } else {
 410                                         ir_mode *mode = get_tarval_mode(cpair.tv_hi);
 411                                         assert(cpair.proj_hi == upper_cond_selector);
 412                                         cpair.pnc_hi  = get_negated_pnc(cpair.pnc_hi, mode);
 413                                         cpair.proj_hi = new_r_Proj(upper_block,
 414                                                         get_Proj_pred(cpair.proj_hi), mode_b, cpair.pnc_hi);
 415                                 }
 416                         }
 417
 418                         /* can we optimize the case? */
 419                         replacement = bool_or(&cpair);
 420                         if(replacement == NULL)
 421                                 continue;
 422
 423                         /* move all nodes from lower block to upper block */
 424                         exchange(lower_block, upper_block);
 425
 426                         set_Block_cfgpred(block, i2, new_Bad());
 427
 428                         /* the optimisations expected the true case to jump */
 429                         if(get_Proj_proj(lower_cf) == pn_Cond_false) {
 430                                 ir_node *block = get_nodes_block(replacement);
 431                                 replacement    = new_rd_Not(NULL, block, replacement, mode_b);
 432                         }
 433                         set_Cond_selector(cond, replacement);
 434
 435                         ir_fprintf(stderr, "replaced (ub %+F)\n", upper_block);
 436                         goto restart;
 437                 }
 438         }
 439 }
 440
 441 void opt_bool(ir_graph *const irg)
 442 {
 443         irg_walk_graph(irg, NULL, bool_walk, NULL);
 444
 445         ir_reserve_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_PHI_LIST);
 446
 447         irg_walk_graph(irg, clear_block_infos, collect_phis, NULL);
 448
 449         irg_block_walk_graph(irg, NULL, find_cf_and_or_walker, NULL);
 450
 451         set_irg_outs_inconsistent(irg);
 452         set_irg_doms_inconsistent(irg);
 453         set_irg_extblk_inconsistent(irg);
 454         set_irg_loopinfo_inconsistent(irg);
 455
 456         ir_free_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_PHI_LIST);
 457 }