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 #ifdef HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <assert.h>
  31 #include <string.h>
  32
  33 #include "adt/obst.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
  41 typedef struct cond_pair {
  42         ir_node *cmp_lo;
  43         ir_node *cmp_hi;
  44         pn_Cmp   pnc_lo;
  45         pn_Cmp   pnc_hi;
  46         ir_node *proj_lo;
  47         ir_node *proj_hi;
  48         tarval  *tv_lo;
  49         tarval  *tv_hi;
  50 } cond_pair;
  51
  52 static int find_cond_pair(ir_node *const l, ir_node *const r, cond_pair *const res)
  53 {
  54         if (is_Proj(l) && is_Proj(r)) {
  55                 ir_node *const lo = get_Proj_pred(l);
  56                 ir_node *const ro = get_Proj_pred(r);
  57
  58                 if (is_Cmp(lo) && is_Cmp(ro)) {
  59                         ir_node *const lol = get_Cmp_left(lo);
  60                         ir_node *const lor = get_Cmp_right(lo);
  61                         ir_node *const rol = get_Cmp_left(ro);
  62                         ir_node *const ror = get_Cmp_right(ro);
  63
  64                         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) {
  65                                 ir_fprintf(stderr, "found zero zero\n");
  66                         }
  67
  68                         /* TODO float */
  69                         /* The constants shall be unequal.  Local optimisations handle the
  70                          * equal case */
  71                         if (lol == rol && mode_is_int(get_irn_mode(lol)) && lor != ror && is_Const(lor) && is_Const(ror)) {
  72                                 tarval *const tv_l  = get_Const_tarval(lor);
  73                                 tarval *const tv_r  = get_Const_tarval(ror);
  74                                 pn_Cmp  const pnc_l = get_Proj_proj(l);
  75                                 pn_Cmp  const pnc_r = get_Proj_proj(r);
  76                                 pn_Cmp  const rel   = tarval_cmp(tv_l, tv_r);
  77
  78                                 assert(rel != pn_Cmp_Eq);
  79
  80                                 if (rel == pn_Cmp_Lt) {
  81                                         res->cmp_lo  = lo;
  82                                         res->cmp_hi  = ro;
  83                                         res->pnc_lo  = pnc_l;
  84                                         res->pnc_hi  = pnc_r;
  85                                         res->proj_lo = l;
  86                                         res->proj_hi = r;
  87                                         res->tv_lo   = tv_l;
  88                                         res->tv_hi   = tv_r;
  89                                 } else {
  90                                         assert(rel == pn_Cmp_Gt);
  91                                         res->cmp_lo  = ro;
  92                                         res->cmp_hi  = lo;
  93                                         res->pnc_lo  = pnc_r;
  94                                         res->pnc_hi  = pnc_l;
  95                                         res->proj_lo = r;
  96                                         res->proj_hi = l;
  97                                         res->tv_lo   = tv_r;
  98                                         res->tv_hi   = tv_l;
  99                                 }
 100                                 return 1;
 101                         }
 102                 }
 103         }
 104         return 0;
 105 }
 106
 107 static ir_node *bool_and(cond_pair* const cpair)
 108 {
 109         ir_node *const cmp_lo  = cpair->cmp_lo;
 110         ir_node *const cmp_hi  = cpair->cmp_hi;
 111         pn_Cmp   const pnc_lo  = cpair->pnc_lo;
 112         pn_Cmp   const pnc_hi  = cpair->pnc_hi;
 113         ir_node *const proj_lo = cpair->proj_lo;
 114         ir_node *const proj_hi = cpair->proj_hi;
 115         tarval  *const tv_lo   = cpair->tv_lo;
 116         tarval  *const tv_hi   = cpair->tv_hi;
 117
 118         /* Beware of NaN's, we can only check for (ordered) != here (which is Lg, not Ne) */
 119         if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 120                         (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 121                 /* x <|<=|== lo | x ==|>=|> hi -> false */
 122                 ir_node *const t = new_Const(mode_b, tarval_b_false);
 123                 return t;
 124         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 125                                                  (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 126                 /* x <|<=|== lo && x <|<=|!= hi -> x <|<=|== lo */
 127                 return proj_lo;
 128         } else if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 129                                                  (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 130                 /* x >=|>|!= lo || x ==|>=|> hi -> x ==|>=|> hi */
 131                 return proj_hi;
 132         } else if (tarval_is_one(tarval_sub(tv_hi, tv_lo, NULL))) { /* lo + 1 == hi */
 133                 if (pnc_lo == pn_Cmp_Ge && pnc_hi == pn_Cmp_Lt) {
 134                         /* x >= c || x < c + 1 -> x == c */
 135                         ir_graph *const irg   = current_ir_graph;
 136                         ir_node  *const block = get_nodes_block(cmp_lo);
 137                         ir_node  *const p = new_r_Proj(irg, block, cmp_lo, mode_b, pn_Cmp_Eq);
 138                         return p;
 139                 } else if (pnc_lo == pn_Cmp_Gt) {
 140                         if (pnc_hi == pn_Cmp_Lg) {
 141                                 /* x > c || x != c + 1 -> x > c + 1 */
 142                                 ir_graph *const irg   = current_ir_graph;
 143                                 ir_node  *const block = get_nodes_block(cmp_hi);
 144                                 ir_node  *const p = new_r_Proj(irg, block, cmp_hi, mode_b, pn_Cmp_Gt);
 145                                 return p;
 146                         } else if (pnc_hi == pn_Cmp_Lt) {
 147                                 /* x > c || x < c + 1 -> false */
 148                                 ir_node *const t = new_Const(mode_b, tarval_b_false);
 149                                 return t;
 150                         } else if (pnc_hi == pn_Cmp_Le) {
 151                                 /* x > c || x <= c + 1 -> x != c + 1 */
 152                                 ir_graph *const irg   = current_ir_graph;
 153                                 ir_node  *const block = get_nodes_block(cmp_hi);
 154                                 ir_node  *const p = new_r_Proj(irg, block, cmp_hi, mode_b, pn_Cmp_Eq);
 155                                 return p;
 156                         }
 157                 } else if (pnc_lo == pn_Cmp_Lg && pnc_hi == pn_Cmp_Lt) {
 158                         /* x != c || c < c + 1 -> x < c */
 159                         ir_graph *const irg   = current_ir_graph;
 160                         ir_node  *const block = get_nodes_block(cmp_lo);
 161                         ir_node  *const p     = new_r_Proj(irg, block, cmp_lo, mode_b, pn_Cmp_Lt);
 162                         return p;
 163                 }
 164         }
 165         return NULL;
 166 }
 167
 168 static ir_node *bool_or(cond_pair *const cpair)
 169 {
 170         ir_node *const cmp_lo  = cpair->cmp_lo;
 171         ir_node *const cmp_hi  = cpair->cmp_hi;
 172         pn_Cmp   const pnc_lo  = cpair->pnc_lo;
 173         pn_Cmp   const pnc_hi  = cpair->pnc_hi;
 174         ir_node *const proj_lo = cpair->proj_lo;
 175         ir_node *const proj_hi = cpair->proj_hi;
 176         tarval  *const tv_lo   = cpair->tv_lo;
 177         tarval  *const tv_hi   = cpair->tv_hi;
 178
 179         /* Beware of NaN's, we can only check for (ordered) != here (which is Lg, not Ne) */
 180         if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 181                         (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 182                 /* x >=|>|!= lo | x <|<=|!= hi -> true */
 183                 ir_node *const t = new_Const(mode_b, tarval_b_true);
 184                 return t;
 185         } else if ((pnc_lo == pn_Cmp_Lt || pnc_lo == pn_Cmp_Le || pnc_lo == pn_Cmp_Eq) &&
 186                                                  (pnc_hi == pn_Cmp_Lt || pnc_hi == pn_Cmp_Le || pnc_hi == pn_Cmp_Lg)) {
 187                 /* x <|<=|== lo || x <|<=|!= hi -> x <|<=|!= hi */
 188                 return proj_hi;
 189         } else if ((pnc_lo == pn_Cmp_Ge || pnc_lo == pn_Cmp_Gt || pnc_lo == pn_Cmp_Lg) &&
 190                                                  (pnc_hi == pn_Cmp_Eq || pnc_hi == pn_Cmp_Ge || pnc_hi == pn_Cmp_Gt)) {
 191                 /* x >=|>|!= lo || x ==|>=|> hi -> x >=|>|!= lo */
 192                 return proj_lo;
 193         } else if (tarval_is_one(tarval_sub(tv_hi, tv_lo, NULL))) { /* lo + 1 == hi */
 194                 if (pnc_lo == pn_Cmp_Lt && pnc_hi == pn_Cmp_Ge) {
 195                         /* x < c || x >= c + 1 -> x != c */
 196                         ir_graph *const irg   = current_ir_graph;
 197                         ir_node  *const block = get_nodes_block(cmp_lo);
 198                         ir_node  *const p = new_r_Proj(irg, block, cmp_lo, mode_b, pn_Cmp_Lg);
 199                         return p;
 200                 } else if (pnc_lo == pn_Cmp_Le) {
 201                         if (pnc_hi == pn_Cmp_Eq) {
 202                                 /* x <= c || x == c + 1 -> x <= c + 1 */
 203                                 ir_graph *const irg   = current_ir_graph;
 204                                 ir_node  *const block = get_nodes_block(cmp_hi);
 205                                 ir_node  *const p = new_r_Proj(irg, block, cmp_hi, mode_b, pn_Cmp_Le);
 206                                 return p;
 207                         } else if (pnc_hi == pn_Cmp_Ge) {
 208                                 /* x <= c || x >= c + 1 -> true */
 209                                 ir_node *const t = new_Const(mode_b, tarval_b_true);
 210                                 return t;
 211                         } else if (pnc_hi == pn_Cmp_Gt) {
 212                                 /* x <= c || x > c + 1 -> x != c + 1 */
 213                                 ir_graph *const irg   = current_ir_graph;
 214                                 ir_node  *const block = get_nodes_block(cmp_hi);
 215                                 ir_node  *const p = new_r_Proj(irg, block, cmp_hi, mode_b, pn_Cmp_Lg);
 216                                 return p;
 217                         }
 218                 } else if (pnc_lo == pn_Cmp_Eq && pnc_hi == pn_Cmp_Ge) {
 219                         /* x == c || x >= c + 1 -> x >= c */
 220                         ir_graph *const irg   = current_ir_graph;
 221                         ir_node  *const block = get_nodes_block(cmp_lo);
 222                         ir_node  *const p     = new_r_Proj(irg, block, cmp_lo, mode_b, pn_Cmp_Ge);
 223                         return p;
 224                 }
 225         }
 226         return NULL;
 227 }
 228
 229 static void bool_walk(ir_node *n, void *env)
 230 {
 231         (void)env;
 232
 233         if (get_irn_mode(n) != mode_b)
 234                 return;
 235
 236         if (is_And(n)) {
 237                 ir_node *const l = get_And_left(n);
 238                 ir_node *const r = get_And_right(n);
 239                 ir_node *      replacement;
 240                 cond_pair      cpair;
 241                 if (!find_cond_pair(l, r, &cpair))
 242                         return;
 243                 replacement = bool_and(&cpair);
 244                 if (replacement)
 245                         exchange(n, replacement);
 246         } else if (is_Or(n)) {
 247                 ir_node *const l = get_Or_left(n);
 248                 ir_node *const r = get_Or_right(n);
 249                 ir_node *      replacement;
 250                 cond_pair      cpair;
 251                 if (!find_cond_pair(l, r, &cpair))
 252                         return;
 253                 replacement = bool_or(&cpair);
 254                 if (replacement)
 255                         exchange(n, replacement);
 256         }
 257 }
 258
 259 /**
 260  * Walker, clear Block mark and Phi list
 261  */
 262 static void clear_block_infos(ir_node *node, void *env)
 263 {
 264         (void) env;
 265
 266         /* we visit blocks before any other nodes (from the block) */
 267         if (!is_Block(node))
 268                 return;
 269
 270         /* clear the PHI list */
 271         set_Block_phis(node, NULL);
 272         set_Block_mark(node, 0);
 273 }
 274
 275 /**
 276  * Walker: collect Phi nodes and update the
 277  */
 278 static void collect_phis(ir_node *node, void *env)
 279 {
 280         (void) env;
 281
 282         if (is_Phi(node)) {
 283                 ir_node *block = get_nodes_block(node);
 284                 add_Block_phi(block, node);
 285                 return;
 286         }
 287
 288         /* Ignore control flow nodes, these will be removed. */
 289         if (get_irn_pinned(node) == op_pin_state_pinned &&
 290                         !is_Block(node) && !is_cfop(node)) {
 291                 ir_node *block = get_nodes_block(node);
 292                 set_Block_mark(block, 1);
 293         }
 294 }
 295
 296 /**
 297  * If node is a Jmp in a block containing no pinned instruction
 298  * and having only one predecessor, skip the block and return its
 299  * cf predecessor, else the node itself.
 300  */
 301 static ir_node *skip_empty_block(ir_node *node)
 302 {
 303         ir_node      *block;
 304
 305         if(!is_Jmp(node))
 306                 return node;
 307
 308         block = get_nodes_block(node);
 309         if(get_Block_n_cfgpreds(block) != 1)
 310                 return node;
 311
 312         if(get_Block_mark(block))
 313                 return node;
 314
 315         return get_Block_cfgpred(block, 0);
 316 }
 317
 318 static void find_cf_and_or_walker(ir_node *block, void *env)
 319 {
 320         int i, i2;
 321         int n_cfgpreds = get_Block_n_cfgpreds(block);
 322         (void) env;
 323
 324         if(n_cfgpreds < 2)
 325                 return;
 326
 327         /* Find the following structure:
 328          *
 329          *        upper_block
 330          *         /       |
 331          *        /        |
 332          *   lower_block   |
 333          *     /  \        |
 334          *   ...   \       |
 335          *           block
 336          */
 337
 338 restart:
 339         for(i = 0; i < n_cfgpreds; ++i) {
 340                 ir_node      *lower_block;
 341                 ir_node      *lower_cf;
 342                 ir_node      *cond;
 343                 ir_node      *cond_selector;
 344                 ir_node      *lower_pred;
 345
 346                 lower_cf = get_Block_cfgpred(block, i);
 347                 lower_cf = skip_empty_block(lower_cf);
 348                 if(!is_Proj(lower_cf))
 349                         continue;
 350
 351                 cond = get_Proj_pred(lower_cf);
 352                 if(!is_Cond(cond))
 353                         continue;
 354
 355                 lower_block = get_nodes_block(cond);
 356                 if(get_Block_n_cfgpreds(lower_block) != 1)
 357                         continue;
 358
 359                 /* the block must not produce any side-effects */
 360                 if(get_Block_mark(lower_block))
 361                         continue;
 362
 363                 cond_selector = get_Cond_selector(cond);
 364                 if(get_irn_mode(cond_selector) != mode_b)
 365                         continue;
 366
 367                 lower_pred = get_Block_cfgpred_block(lower_block, 0);
 368
 369                 for(i2 = 0; i2 < n_cfgpreds; ++i2) {
 370                         ir_node   *upper_block;
 371                         ir_node   *upper_cf;
 372                         ir_node   *upper_cond;
 373                         ir_node   *upper_cond_selector;
 374                         ir_node   *replacement;
 375                         ir_graph  *irg;
 376                         cond_pair  cpair;
 377
 378                         upper_cf    = get_Block_cfgpred(block, i2);
 379                         upper_cf    = skip_empty_block(upper_cf);
 380                         if(is_Bad(upper_cf))
 381                                 continue;
 382                         upper_block = get_nodes_block(upper_cf);
 383                         if(upper_block != lower_pred)
 384                                 continue;
 385
 386                         assert(is_Proj(upper_cf));
 387                         upper_cond = get_Proj_pred(upper_cf);
 388                         assert(is_Cond(upper_cond));
 389                         upper_cond_selector = get_Cond_selector(upper_cond);
 390                         if(get_irn_mode(upper_cond_selector) != mode_b)
 391                                 continue;
 392
 393                         /* we have found the structure */
 394                         /* TODO: check phis */
 395                         if(!find_cond_pair(cond_selector, upper_cond_selector, &cpair))
 396                                 continue;
 397
 398                         /* normalize pncs: we need the true case to jump into the
 399                          * common block (ie. conjunctive normal form) */
 400                         irg = current_ir_graph;
 401                         if(get_Proj_proj(lower_cf) == pn_Cond_false) {
 402                                 if(cpair.proj_lo == cond_selector) {
 403                                         ir_mode *mode = get_tarval_mode(cpair.tv_lo);
 404                                         cpair.pnc_lo  = get_negated_pnc(cpair.pnc_lo, mode);
 405                                         cpair.proj_lo = new_r_Proj(irg, lower_block,
 406                                                         get_Proj_pred(cpair.proj_lo), mode_b, cpair.pnc_lo);
 407                                 } else {
 408                                         ir_mode *mode = get_tarval_mode(cpair.tv_hi);
 409                                         assert(cpair.proj_hi == cond_selector);
 410                                         cpair.pnc_hi  = get_negated_pnc(cpair.pnc_hi, mode);
 411                                         cpair.proj_hi = new_r_Proj(irg, lower_block,
 412                                                         get_Proj_pred(cpair.proj_hi), mode_b, cpair.pnc_hi);
 413                                 }
 414                         }
 415                         if(get_Proj_proj(upper_cf) == pn_Cond_false) {
 416                                 if(cpair.proj_lo == upper_cond_selector) {
 417                                         ir_mode *mode = get_tarval_mode(cpair.tv_lo);
 418                                         cpair.pnc_lo  = get_negated_pnc(cpair.pnc_lo, mode);
 419                                         cpair.proj_lo = new_r_Proj(irg, upper_block,
 420                                                         get_Proj_pred(cpair.proj_lo), mode_b, cpair.pnc_lo);
 421                                 } else {
 422                                         ir_mode *mode = get_tarval_mode(cpair.tv_hi);
 423                                         assert(cpair.proj_hi == upper_cond_selector);
 424                                         cpair.pnc_hi  = get_negated_pnc(cpair.pnc_hi, mode);
 425                                         cpair.proj_hi = new_r_Proj(irg, upper_block,
 426                                                         get_Proj_pred(cpair.proj_hi), mode_b, cpair.pnc_hi);
 427                                 }
 428                         }
 429
 430                         /* can we optimize the case? */
 431                         replacement = bool_or(&cpair);
 432                         if(replacement == NULL)
 433                                 continue;
 434
 435                         /* move all nodes from lower block to upper block */
 436                         exchange(lower_block, upper_block);
 437
 438                         set_Block_cfgpred(block, i2, new_Bad());
 439
 440                         /* the optimisations expected the true case to jump */
 441                         if(get_Proj_proj(lower_cf) == pn_Cond_false) {
 442                                 ir_node *block = get_nodes_block(replacement);
 443                                 replacement    = new_rd_Not(NULL, current_ir_graph, block,
 444                                                             replacement, mode_b);
 445                         }
 446                         set_Cond_selector(cond, replacement);
 447
 448                         ir_fprintf(stderr, "replaced (ub %+F)\n", upper_block);
 449                         goto restart;
 450                 }
 451         }
 452 }
 453
 454 void opt_bool(ir_graph *const irg)
 455 {
 456         irg_walk_graph(irg, NULL, bool_walk, NULL);
 457
 458         ir_reserve_resources(irg, IR_RESOURCE_BLOCK_MARK);
 459
 460         irg_walk_graph(irg, clear_block_infos, collect_phis, NULL);
 461
 462         irg_block_walk_graph(irg, NULL, find_cf_and_or_walker, NULL);
 463
 464         set_irg_outs_inconsistent(irg);
 465         set_irg_doms_inconsistent(irg);
 466         set_irg_extblk_inconsistent(irg);
 467         set_irg_loopinfo_inconsistent(irg);
 468
 469         ir_free_resources(irg, IR_RESOURCE_BLOCK_MARK);
 470 }