nsz Git - libfirm/blob - ir/ana/irconsconfirm.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    Construction of Confirm nodes
  23  * @author   Michael Beck
  24  * @date     6.2005
  25  * @version  $Id$
  26  */
  27 #include "config.h"
  28
  29 #include "irgraph_t.h"
  30 #include "irnode_t.h"
  31 #include "ircons_t.h"
  32 #include "irgmod.h"
  33 #include "iropt_dbg.h"
  34 #include "iredges_t.h"
  35 #include "irgwalk.h"
  36 #include "irprintf.h"
  37 #include "irgopt.h"
  38 #include "irpass.h"
  39 #include "irtools.h"
  40 #include "array_t.h"
  41 #include "debug.h"
  42 #include "irflag.h"
  43
  44 /**
  45  * Walker environment.
  46  */
  47 typedef struct _env_t {
  48         unsigned num_confirms;  /**< Number of inserted Confirm nodes. */
  49         unsigned num_consts;    /**< Number of constants placed. */
  50         unsigned num_eq;        /**< Number of equalities placed. */
  51         unsigned num_non_null;  /**< Number of non-null Confirms. */
  52 } env_t;
  53
  54 /** The debug handle. */
  55 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
  56
  57 /**
  58  * Return the effective use block of a node and it's predecessor on
  59  * position pos.
  60  *
  61  * @param node  the node
  62  * @param pos   the position of the used input
  63  *
  64  * This handles correctly Phi nodes.
  65  */
  66 static ir_node *get_effective_use_block(ir_node *node, int pos)
  67 {
  68         if (is_Phi(node)) {
  69                 /* the effective use of a Phi argument is in its predecessor block */
  70                 node = get_nodes_block(node);
  71                 return get_Block_cfgpred_block(node, pos);
  72         }
  73         return get_nodes_block(node);
  74 }
  75
  76 /**
  77  * Handle a CASE-branch.
  78  *
  79  * @param block   the block which is entered by the branch
  80  * @param irn     the node expressing the switch value
  81  * @param nr      the branch label
  82  * @param env     statistical environment
  83  *
  84  * Branch labels are a simple case. We can replace the value
  85  * by a Const with the branch label.
  86  */
  87 static void handle_case(ir_node *block, ir_node *irn, long nr, env_t *env)
  88 {
  89         const ir_edge_t *edge, *next;
  90         ir_node *c = NULL;
  91
  92         if (is_Bad(irn))
  93                 return;
  94
  95         for (edge = get_irn_out_edge_first(irn); edge; edge = next) {
  96                 ir_node *succ = get_edge_src_irn(edge);
  97                 int     pos   = get_edge_src_pos(edge);
  98                 ir_node *blk  = get_effective_use_block(succ, pos);
  99
 100                 next = get_irn_out_edge_next(irn, edge);
 101
 102                 if (block_dominates(block, blk)) {
 103                         /*
 104                          * Ok, we found a user of irn that is placed
 105                          * in a block dominated by the branch block.
 106                          * We can replace the input with the Constant
 107                          * branch label.
 108                          */
 109
 110                         if (! c) {
 111                                 ir_mode *mode = get_irn_mode(irn);
 112                                 ir_type *tp   = get_irn_type(irn);
 113                                 tarval *tv    = new_tarval_from_long(nr, mode);
 114                                 c = new_r_Const_type(current_ir_graph, tv, tp);
 115                         }
 116
 117                         set_irn_n(succ, pos, c);
 118                         DBG_OPT_CONFIRM_C(irn, c);
 119                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 120
 121                         env->num_consts += 1;
 122                 }
 123         }
 124 }  /* handle_case */
 125
 126 /**
 127  * Handle a mode_b input of Cond nodes.
 128  *
 129  * @param block     the block which is entered by the branch
 130  * @param selector  the mode_b node expressing the branch condition
 131  * @param pnc       the true/false condition branch
 132  * @param env       statistical environment
 133  */
 134 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env)
 135 {
 136         ir_node *cond, *old, *cond_block = NULL, *other_blk = NULL, *con = NULL;
 137         ir_node *c_b = NULL, *c_o = NULL;
 138         const ir_edge_t *edge, *next;
 139
 140         for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
 141                 ir_node *user     = get_edge_src_irn(edge);
 142                 int     pos       = get_edge_src_pos(edge);
 143                 ir_node *user_blk = get_effective_use_block(user, pos);
 144
 145                 next = get_irn_out_edge_next(selector, edge);
 146                 if (block_dominates(block, user_blk)) {
 147                         /*
 148                          * Ok, we found a usage of selector in a block
 149                          * dominated by the branch block.
 150                          * We can replace the input with true/false.
 151                          */
 152                         if (con == NULL) {
 153                                 con = new_Const(pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
 154                         }
 155                         old = get_irn_n(user, pos);
 156                         set_irn_n(user, pos, con);
 157                         DBG_OPT_CONFIRM_C(old, con);
 158
 159                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, con));
 160
 161                         env->num_consts += 1;
 162                 } else {
 163                         int i, n;
 164
 165                         /* get the other block */
 166                         if (other_blk == NULL) {
 167                                 /* we have already tested, that block has only ONE Cond predecessor */
 168                                 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
 169                                 cond_block = get_nodes_block(cond);
 170                                 foreach_out_edge(cond, edge) {
 171                                         ir_node *proj = get_edge_src_irn(edge);
 172                                         if (get_Proj_proj(proj) == (long)pnc)
 173                                                 continue;
 174                                         edge = get_irn_out_edge_first(proj);
 175                                         other_blk = get_edge_src_irn(edge);
 176                                         break;
 177                                 }
 178                                 assert(other_blk);
 179
 180                                 /*
 181                                  * Note the special case here: if block is a then, there might be no else
 182                                  * block. In that case the other_block is the user_blk itself and pred_block
 183                                  * is the cond_block ...
 184                                  *
 185                                  * Best would be to introduce a block here, removing this critical edge.
 186                                  * For some reasons I cannot repair dominance here, so I have to remove
 187                                  * ALL critical edges...
 188                                  * FIXME: This should not be needed if we could repair dominance ...
 189                                  */
 190                         }
 191
 192                         n = get_Block_n_cfgpreds(user_blk);
 193
 194                         /*
 195                          * We have found a user in a non-dominated block:
 196                          * check, if all its block predecessors are dominated.
 197                          * If yes, place a Phi.
 198                          */
 199                         for (i = n - 1; i >= 0; --i) {
 200                                 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 201
 202                                 if (!block_dominates(block, pred_blk) &&
 203                                     !block_dominates(other_blk, pred_blk)) {
 204                                         /* can't do anything */
 205                                         break;
 206                                 }
 207                         }
 208                         if (i < 0) {
 209                                 ir_node *phi, **in;
 210
 211                                 NEW_ARR_A(ir_node *, in, n);
 212                                 /* ok, ALL predecessors are either dominated by block OR other block */
 213                                 if (c_b == NULL) {
 214                                         ir_node *c_true  = new_Const(tarval_b_true);
 215                                         ir_node *c_false = new_Const(tarval_b_false);
 216                                         if (pnc == pn_Cond_true) {
 217                                                 c_b = c_true;
 218                                                 c_o = c_false;
 219                                         } else {
 220                                                 c_b = c_false;
 221                                                 c_o = c_true;
 222                                         }
 223                                 }
 224                                 for (i = n - 1; i >= 0; --i) {
 225                                         ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 226
 227                                         if (block_dominates(block, pred_blk))
 228                                                 in[i] = c_b;
 229                                         else
 230                                                 in[i] = c_o;
 231                                 }
 232                                 phi = new_r_Phi(user_blk, n, in, mode_b);
 233                                 set_irn_n(user, pos, phi);
 234                         }
 235                 }
 236         }
 237 }
 238
 239 /**
 240  * Handle an IF-branch.
 241  *
 242  * @param block   the block which is entered by the branch
 243  * @param cmp     the Cmp node expressing the branch condition
 244  * @param pnc     the Compare relation for taking this branch
 245  * @param env     statistical environment
 246  */
 247 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env)
 248 {
 249         ir_node *left  = get_Cmp_left(cmp);
 250         ir_node *right = get_Cmp_right(cmp);
 251         ir_node *cond_block;
 252         ir_op *op;
 253         const ir_edge_t *edge, *next;
 254
 255         /* Beware of Bads */
 256         if (is_Bad(left) || is_Bad(right))
 257                 return;
 258
 259         op = get_irn_op(left);
 260
 261         /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
 262            These are removed anyway */
 263         if (op == op_Const && is_Const(right))
 264                 return;
 265
 266         /* try to place the constant on the right side for a Confirm */
 267         if (op == op_Const || op == op_SymConst) {
 268                 ir_node *t = left;
 269
 270                 left  = right;
 271                 right = t;
 272
 273                 pnc = get_inversed_pnc(pnc);
 274         }
 275
 276         /*
 277          * First case: both values are identical.
 278          * replace the left one by the right (potentially const) one.
 279          */
 280         if (pnc == pn_Cmp_Eq) {
 281                 cond_block = get_Block_cfgpred_block(block, 0);
 282                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 283                         ir_node *user = get_edge_src_irn(edge);
 284                         int     pos   = get_edge_src_pos(edge);
 285                         ir_node *blk  = get_effective_use_block(user, pos);
 286
 287                         next = get_irn_out_edge_next(left, edge);
 288                         if (block_dominates(block, blk)) {
 289                                 /*
 290                                  * Ok, we found a usage of left in a block
 291                                  * dominated by the branch block.
 292                                  * We can replace the input with right.
 293                                  */
 294                                 set_irn_n(user, pos, right);
 295                                 DBG_OPT_CONFIRM(left, right);
 296
 297                                 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
 298
 299                                 env->num_eq += 1;
 300                         } else if (block_dominates(blk, cond_block)) {
 301                                 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
 302                                         /*
 303                                          * left == Const and we found a movable user of left in a
 304                                          * dominator of the Cond block
 305                                          */
 306                                         const ir_edge_t *edge, *next;
 307                                         for (edge = get_irn_out_edge_first(user); edge; edge = next) {
 308                                                 ir_node *usr_of_usr = get_edge_src_irn(edge);
 309                                                 int      npos = get_edge_src_pos(edge);
 310                                                 ir_node *blk  = get_effective_use_block(usr_of_usr, npos);
 311
 312                                                 next = get_irn_out_edge_next(user, edge);
 313                                                 if (block_dominates(block, blk)) {
 314                                                         /*
 315                                                          * The user of the user is dominated by our true/false
 316                                                          * block. So, create a copy of user WITH the constant
 317                                                          * replacing it's pos'th input.
 318                                                          *
 319                                                          * This is always good for unop's and might be good
 320                                                          * for binops.
 321                                                          *
 322                                                          * If user has other user in the false/true block, code
 323                                                          * placement will move it down.
 324                                                          * If there are users in cond block or upper, we create
 325                                                          * "redundant ops", because one will have a const op,
 326                                                          * the other no const ...
 327                                                          */
 328                                                         ir_node *new_op = exact_copy(user);
 329                                                         set_nodes_block(new_op, block);
 330                                                         set_irn_n(new_op, pos, right);
 331                                                         set_irn_n(usr_of_usr, npos, new_op);
 332                                                 }
 333                                         }
 334                                 }
 335                         }
 336                 }
 337         } else { /* not pn_Cmp_Eq cases */
 338                 ir_node *c = NULL;
 339
 340                 foreach_out_edge_safe(left, edge, next) {
 341                         ir_node *succ = get_edge_src_irn(edge);
 342                         int     pos   = get_edge_src_pos(edge);
 343                         ir_node *blk  = get_effective_use_block(succ, pos);
 344
 345                         if (block_dominates(block, blk)) {
 346                                 /*
 347                                  * Ok, we found a usage of left in a block
 348                                  * dominated by the branch block.
 349                                  * We can replace the input with a Confirm(left, pnc, right).
 350                                  */
 351                                 if (! c)
 352                                         c = new_r_Confirm(block, left, right, pnc);
 353
 354                                 pos = get_edge_src_pos(edge);
 355                                 set_irn_n(succ, pos, c);
 356                                 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 357
 358                                 env->num_confirms += 1;
 359                         }
 360                 }
 361
 362                 if (! is_Const(right)) {
 363                         /* also construct inverse Confirms */
 364                         ir_node *rc = NULL;
 365
 366                         pnc = get_inversed_pnc(pnc);
 367                         foreach_out_edge_safe(right, edge, next) {
 368                                 ir_node *succ = get_edge_src_irn(edge);
 369                                 int     pos;
 370                                 ir_node *blk;
 371
 372                                 if (succ == c)
 373                                         continue;
 374
 375                                 pos  = get_edge_src_pos(edge);
 376                                 blk  = get_effective_use_block(succ, pos);
 377
 378                                 if (block_dominates(block, blk)) {
 379                                         /*
 380                                          * Ok, we found a usage of right in a block
 381                                          * dominated by the branch block.
 382                                          * We can replace the input with a Confirm(right, pnc^-1, left).
 383                                          */
 384                                         if (! rc)
 385                                                 rc = new_r_Confirm(block, right, left, pnc);
 386
 387                                         pos = get_edge_src_pos(edge);
 388                                         set_irn_n(succ, pos, rc);
 389                                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
 390
 391                                         env->num_confirms += 1;
 392                                 }
 393                         }
 394                 }
 395         }
 396 }  /* handle_if */
 397
 398 /**
 399  * Pre-block-walker: Called for every block to insert Confirm nodes
 400  */
 401 static void insert_Confirm_in_block(ir_node *block, void *env)
 402 {
 403         ir_node *cond, *proj, *selector;
 404         ir_mode *mode;
 405
 406         /*
 407          * we can only handle blocks with only ONE control flow
 408          * predecessor yet.
 409          */
 410         if (get_Block_n_cfgpreds(block) != 1)
 411                 return;
 412
 413         proj = get_Block_cfgpred(block, 0);
 414         if (! is_Proj(proj))
 415                 return;
 416
 417         cond = get_Proj_pred(proj);
 418         if (! is_Cond(cond))
 419                 return;
 420
 421         selector = get_Cond_selector(cond);
 422         mode = get_irn_mode(selector);
 423
 424         if (mode == mode_b) {
 425                 ir_node *cmp;
 426                 pn_Cmp pnc;
 427
 428                 handle_modeb(block, selector, get_Proj_proj(proj), env);
 429
 430                 /* this should be an IF, check this */
 431                 if (! is_Proj(selector))
 432                         return;
 433
 434                 cmp = get_Proj_pred(selector);
 435                 if (! is_Cmp(cmp))
 436                         return;
 437
 438                 pnc = get_Proj_proj(selector);
 439
 440                 if (get_Proj_proj(proj) != pn_Cond_true) {
 441                         /* it's the false branch */
 442                         mode = get_irn_mode(get_Cmp_left(cmp));
 443                         pnc = get_negated_pnc(pnc, mode);
 444                 }
 445                 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, cmp, pnc));
 446
 447                 handle_if(block, cmp, pnc, env);
 448         } else if (mode_is_int(mode)) {
 449                 long proj_nr = get_Proj_proj(proj);
 450
 451                 /* this is a CASE, but we cannot handle the default case */
 452                 if (proj_nr == get_Cond_default_proj(cond))
 453                         return;
 454
 455                 handle_case(block, get_Cond_selector(cond), proj_nr, env);
 456         }
 457 }  /* insert_Confirm_in_block */
 458
 459 /**
 460  * Checks if a node is a non-null Confirm.
 461  */
 462 static int is_non_null_Confirm(const ir_node *ptr)
 463 {
 464         for (;;) {
 465                 if (! is_Confirm(ptr))
 466                         break;
 467                 if (get_Confirm_cmp(ptr) == pn_Cmp_Lg) {
 468                         ir_node *bound = get_Confirm_bound(ptr);
 469
 470                         if (is_Const(bound) && is_Const_null(bound))
 471                                 return 1;
 472                 }
 473                 ptr = get_Confirm_value(ptr);
 474         }
 475         /*
 476          * While a SymConst is not a Confirm, it is non-null
 477          * anyway. This helps to reduce the number of
 478          * constructed Confirms.
 479          */
 480         if (is_SymConst_addr_ent(ptr))
 481                 return 1;
 482         return 0;
 483 }  /* is_non_null_Confirm */
 484
 485 /**
 486  * The given pointer will be dereferenced, add non-null Confirms.
 487  *
 488  * @param ptr    a node representing an address
 489  * @param block  the block of the dereferencing instruction
 490  * @param env    environment
 491  */
 492 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env)
 493 {
 494         const ir_edge_t *edge, *next;
 495         ir_node         *c = NULL;
 496
 497         foreach_out_edge_safe(ptr, edge, next) {
 498                 ir_node *succ = get_edge_src_irn(edge);
 499                 int     pos;
 500                 ir_node *blk;
 501
 502
 503                 /* for now, we place a Confirm only in front of a Cmp */
 504                 if (! is_Cmp(succ))
 505                         continue;
 506
 507                 pos = get_edge_src_pos(edge);
 508                 blk = get_effective_use_block(succ, pos);
 509
 510                 if (block_dominates(block, blk)) {
 511                         /*
 512                          * Ok, we found a usage of ptr in a block
 513                          * dominated by the Load/Store block.
 514                          * We can replace the input with a Confirm(ptr, !=, NULL).
 515                          */
 516                         if (c == NULL) {
 517                                 ir_mode *mode = get_irn_mode(ptr);
 518                                 c = new_Const(get_mode_null(mode));
 519
 520                                 c = new_r_Confirm(block, ptr, c, pn_Cmp_Lg);
 521                         }
 522
 523                         set_irn_n(succ, pos, c);
 524                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 525
 526                         env->num_non_null += 1;
 527                         env->num_confirms += 1;
 528                 }
 529         }
 530 }  /* insert_non_null */
 531
 532 /**
 533  * Pre-walker: Called for every node to insert Confirm nodes
 534  */
 535 static void insert_Confirm(ir_node *node, void *env)
 536 {
 537         ir_node *ptr;
 538
 539         switch (get_irn_opcode(node)) {
 540         case iro_Block:
 541                 insert_Confirm_in_block(node, env);
 542                 break;
 543         case iro_Load:
 544                 ptr = get_Load_ptr(node);
 545                 if (! is_non_null_Confirm(ptr))
 546                         insert_non_null(ptr, get_nodes_block(node), env);
 547                 break;
 548         case iro_Store:
 549                 ptr = get_Store_ptr(node);
 550                 if (! is_non_null_Confirm(ptr))
 551                         insert_non_null(ptr, get_nodes_block(node), env);
 552                 break;
 553         default:
 554                 break;
 555         }
 556 }  /* insert_Confirm */
 557
 558 /*
 559  * Construct Confirm nodes
 560  */
 561 void construct_confirms(ir_graph *irg)
 562 {
 563         env_t env;
 564         int edges_active = edges_activated(irg);
 565
 566
 567         FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
 568
 569         remove_critical_cf_edges(irg);
 570
 571         /* we need dominance info */
 572         assure_doms(irg);
 573
 574         assert(get_irg_pinned(irg) == op_pin_state_pinned &&
 575                "Nodes must be placed to insert Confirms");
 576
 577         if (! edges_active) {
 578                 /* We need edges */
 579                 edges_activate(irg);
 580         }
 581
 582         env.num_confirms = 0;
 583         env.num_consts   = 0;
 584         env.num_eq       = 0;
 585         env.num_non_null = 0;
 586
 587         if (get_opt_global_null_ptr_elimination()) {
 588                 /* do global NULL test elimination */
 589                 irg_walk_graph(irg, insert_Confirm, NULL, &env);
 590         } else {
 591                 /* now, visit all blocks and add Confirms where possible */
 592                 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
 593         }
 594
 595         if (env.num_confirms | env.num_consts | env.num_eq) {
 596                 /* we have add nodes or changed DF edges */
 597                 set_irg_outs_inconsistent(irg);
 598
 599                 /* the new nodes are not in the loop info */
 600                 set_irg_loopinfo_inconsistent(irg);
 601         }
 602
 603         DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
 604         DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
 605         DB((dbg, LEVEL_1, "# node equalities   : %u\n", env.num_eq));
 606         DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
 607
 608         /* deactivate edges if they where off */
 609         if (! edges_active)
 610                 edges_deactivate(irg);
 611 }  /* construct_confirms */
 612
 613 /* Construct a pass. */
 614 ir_graph_pass_t *construct_confirms_pass(const char *name)
 615 {
 616         return def_graph_pass(name ? name : "confirm", construct_confirms);
 617 }  /* construct_confirms_pass */
 618
 619 #if 0
 620 /**
 621  * Post-walker: Remove Confirm nodes
 622  */
 623 static void rem_Confirm(ir_node *n, void *env)
 624 {
 625         (void) env;
 626         if (is_Confirm(n)) {
 627                 ir_node *value = get_Confirm_value(n);
 628                 if (value != n)
 629                         exchange(n, value);
 630                 else {
 631                         /*
 632                          * Strange: a Confirm is its own bound. This can happen
 633                          * in dead blocks when Phi nodes are already removed.
 634                          */
 635                         exchange(n, new_Bad());
 636                 }
 637         }
 638 }  /* rem_Confirm */
 639 #endif
 640
 641 /*
 642  * Remove all Confirm nodes from a graph.
 643  */
 644 void remove_confirms(ir_graph *irg)
 645 {
 646         int rem = get_opt_remove_confirm();
 647
 648         set_opt_remove_confirm(1);
 649         optimize_graph_df(irg);
 650         set_opt_remove_confirm(rem);
 651 }  /* remove_confirms */
 652
 653 /* Construct a pass. */
 654 ir_graph_pass_t *remove_confirms_pass(const char *name)
 655 {
 656         return def_graph_pass(name ? name : "rem_confirm", remove_confirms);
 657 }  /* remove_confirms_pass */