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