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                                         env->num_consts += 2;
 218                                         if (pnc == pn_Cond_true) {
 219                                                 c_b = c_true;
 220                                                 c_o = c_false;
 221                                         } else {
 222                                                 c_b = c_false;
 223                                                 c_o = c_true;
 224                                         }
 225                                 }
 226                                 for (i = n - 1; i >= 0; --i) {
 227                                         ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 228
 229                                         if (block_dominates(block, pred_blk))
 230                                                 in[i] = c_b;
 231                                         else
 232                                                 in[i] = c_o;
 233                                 }
 234                                 phi = new_r_Phi(user_blk, n, in, mode_b);
 235                                 set_irn_n(user, pos, phi);
 236                                 env->num_eq += 1;
 237                         }
 238                 }
 239         }
 240 }
 241
 242 /**
 243  * Handle an IF-branch.
 244  *
 245  * @param block   the block which is entered by the branch
 246  * @param cmp     the Cmp node expressing the branch condition
 247  * @param pnc     the Compare relation for taking this branch
 248  * @param env     statistical environment
 249  */
 250 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env)
 251 {
 252         ir_node *left  = get_Cmp_left(cmp);
 253         ir_node *right = get_Cmp_right(cmp);
 254         ir_node *cond_block;
 255         ir_op *op;
 256         const ir_edge_t *edge, *next;
 257
 258         /* Beware of Bads */
 259         if (is_Bad(left) || is_Bad(right))
 260                 return;
 261
 262         op = get_irn_op(left);
 263
 264         /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
 265            These are removed anyway */
 266         if (op == op_Const && is_Const(right))
 267                 return;
 268
 269         /* try to place the constant on the right side for a Confirm */
 270         if (op == op_Const || op == op_SymConst) {
 271                 ir_node *t = left;
 272
 273                 left  = right;
 274                 right = t;
 275
 276                 pnc = get_inversed_pnc(pnc);
 277         }
 278
 279         /*
 280          * First case: both values are identical.
 281          * replace the left one by the right (potentially const) one.
 282          */
 283         if (pnc == pn_Cmp_Eq) {
 284                 cond_block = get_Block_cfgpred_block(block, 0);
 285                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 286                         ir_node *user = get_edge_src_irn(edge);
 287                         int     pos   = get_edge_src_pos(edge);
 288                         ir_node *blk  = get_effective_use_block(user, pos);
 289
 290                         next = get_irn_out_edge_next(left, edge);
 291                         if (block_dominates(block, blk)) {
 292                                 /*
 293                                  * Ok, we found a usage of left in a block
 294                                  * dominated by the branch block.
 295                                  * We can replace the input with right.
 296                                  */
 297                                 set_irn_n(user, pos, right);
 298                                 DBG_OPT_CONFIRM(left, right);
 299
 300                                 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
 301
 302                                 env->num_eq += 1;
 303                         } else if (block_dominates(blk, cond_block)
 304                                         && is_Const(right)
 305                                         && get_irn_pinned(user) == op_pin_state_floats) {
 306                                 /*
 307                                  * left == Const and we found a movable user of left in a
 308                                  * dominator of the Cond block
 309                                  */
 310                                 const ir_edge_t *edge, *next;
 311                                 for (edge = get_irn_out_edge_first(user); edge; edge = next) {
 312                                         ir_node *usr_of_usr = get_edge_src_irn(edge);
 313                                         int      npos = get_edge_src_pos(edge);
 314                                         ir_node *blk  = get_effective_use_block(usr_of_usr, npos);
 315
 316                                         next = get_irn_out_edge_next(user, edge);
 317                                         if (block_dominates(block, blk)) {
 318                                                 /*
 319                                                  * The user of the user is dominated by our true/false
 320                                                  * block. So, create a copy of user WITH the constant
 321                                                  * replacing it's pos'th input.
 322                                                  *
 323                                                  * This is always good for unop's and might be good
 324                                                  * for binops.
 325                                                  *
 326                                                  * If user has other user in the false/true block, code
 327                                                  * placement will move it down.
 328                                                  * If there are users in cond block or upper, we create
 329                                                  * "redundant ops", because one will have a const op,
 330                                                  * the other no const ...
 331                                                  */
 332                                                 ir_node *new_op = exact_copy(user);
 333                                                 set_nodes_block(new_op, block);
 334                                                 set_irn_n(new_op, pos, right);
 335                                                 set_irn_n(usr_of_usr, npos, new_op);
 336                                                 env->num_eq += 1;
 337                                         }
 338                                 }
 339                         }
 340                 }
 341         } else { /* not pn_Cmp_Eq cases */
 342                 ir_node *c = NULL;
 343
 344                 foreach_out_edge_safe(left, edge, next) {
 345                         ir_node *succ = get_edge_src_irn(edge);
 346                         int     pos   = get_edge_src_pos(edge);
 347                         ir_node *blk  = get_effective_use_block(succ, pos);
 348
 349                         if (block_dominates(block, blk)) {
 350                                 /*
 351                                  * Ok, we found a usage of left in a block
 352                                  * dominated by the branch block.
 353                                  * We can replace the input with a Confirm(left, pnc, right).
 354                                  */
 355                                 if (! c)
 356                                         c = new_r_Confirm(block, left, right, pnc);
 357
 358                                 pos = get_edge_src_pos(edge);
 359                                 set_irn_n(succ, pos, c);
 360                                 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 361
 362                                 env->num_confirms += 1;
 363                         }
 364                 }
 365
 366                 if (! is_Const(right)) {
 367                         /* also construct inverse Confirms */
 368                         ir_node *rc = NULL;
 369
 370                         pnc = get_inversed_pnc(pnc);
 371                         foreach_out_edge_safe(right, edge, next) {
 372                                 ir_node *succ = get_edge_src_irn(edge);
 373                                 int     pos;
 374                                 ir_node *blk;
 375
 376                                 if (succ == c)
 377                                         continue;
 378
 379                                 pos  = get_edge_src_pos(edge);
 380                                 blk  = get_effective_use_block(succ, pos);
 381
 382                                 if (block_dominates(block, blk)) {
 383                                         /*
 384                                          * Ok, we found a usage of right in a block
 385                                          * dominated by the branch block.
 386                                          * We can replace the input with a Confirm(right, pnc^-1, left).
 387                                          */
 388                                         if (! rc)
 389                                                 rc = new_r_Confirm(block, right, left, pnc);
 390
 391                                         pos = get_edge_src_pos(edge);
 392                                         set_irn_n(succ, pos, rc);
 393                                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
 394
 395                                         env->num_confirms += 1;
 396                                 }
 397                         }
 398                 }
 399         }
 400 }  /* handle_if */
 401
 402 /**
 403  * Pre-block-walker: Called for every block to insert Confirm nodes
 404  */
 405 static void insert_Confirm_in_block(ir_node *block, void *env)
 406 {
 407         ir_node *cond, *proj, *selector;
 408         ir_mode *mode;
 409
 410         /*
 411          * we can only handle blocks with only ONE control flow
 412          * predecessor yet.
 413          */
 414         if (get_Block_n_cfgpreds(block) != 1)
 415                 return;
 416
 417         proj = get_Block_cfgpred(block, 0);
 418         if (! is_Proj(proj))
 419                 return;
 420
 421         cond = get_Proj_pred(proj);
 422         if (! is_Cond(cond))
 423                 return;
 424
 425         selector = get_Cond_selector(cond);
 426         mode = get_irn_mode(selector);
 427
 428         if (mode == mode_b) {
 429                 ir_node *cmp;
 430                 pn_Cmp pnc;
 431
 432                 handle_modeb(block, selector, get_Proj_proj(proj), env);
 433
 434                 /* this should be an IF, check this */
 435                 if (! is_Proj(selector))
 436                         return;
 437
 438                 cmp = get_Proj_pred(selector);
 439                 if (! is_Cmp(cmp))
 440                         return;
 441
 442                 pnc = get_Proj_proj(selector);
 443
 444                 if (get_Proj_proj(proj) != pn_Cond_true) {
 445                         /* it's the false branch */
 446                         mode = get_irn_mode(get_Cmp_left(cmp));
 447                         pnc = get_negated_pnc(pnc, mode);
 448                 }
 449                 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, cmp, pnc));
 450
 451                 handle_if(block, cmp, pnc, env);
 452         } else if (mode_is_int(mode)) {
 453                 long proj_nr = get_Proj_proj(proj);
 454
 455                 /* this is a CASE, but we cannot handle the default case */
 456                 if (proj_nr == get_Cond_default_proj(cond))
 457                         return;
 458
 459                 handle_case(block, get_Cond_selector(cond), proj_nr, env);
 460         }
 461 }  /* insert_Confirm_in_block */
 462
 463 /**
 464  * Checks if a node is a non-null Confirm.
 465  */
 466 static int is_non_null_Confirm(const ir_node *ptr)
 467 {
 468         for (;;) {
 469                 if (! is_Confirm(ptr))
 470                         break;
 471                 if (get_Confirm_cmp(ptr) == pn_Cmp_Lg) {
 472                         ir_node *bound = get_Confirm_bound(ptr);
 473
 474                         if (is_Const(bound) && is_Const_null(bound))
 475                                 return 1;
 476                 }
 477                 ptr = get_Confirm_value(ptr);
 478         }
 479         /*
 480          * While a SymConst is not a Confirm, it is non-null
 481          * anyway. This helps to reduce the number of
 482          * constructed Confirms.
 483          */
 484         if (is_SymConst_addr_ent(ptr))
 485                 return 1;
 486         return 0;
 487 }  /* is_non_null_Confirm */
 488
 489 /**
 490  * The given pointer will be dereferenced, add non-null Confirms.
 491  *
 492  * @param ptr    a node representing an address
 493  * @param block  the block of the dereferencing instruction
 494  * @param env    environment
 495  */
 496 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env)
 497 {
 498         const ir_edge_t *edge, *next;
 499         ir_node         *c = NULL;
 500
 501         foreach_out_edge_safe(ptr, edge, next) {
 502                 ir_node *succ = get_edge_src_irn(edge);
 503                 int     pos;
 504                 ir_node *blk;
 505
 506
 507                 /* for now, we place a Confirm only in front of a Cmp */
 508                 if (! is_Cmp(succ))
 509                         continue;
 510
 511                 pos = get_edge_src_pos(edge);
 512                 blk = get_effective_use_block(succ, pos);
 513
 514                 if (block_dominates(block, blk)) {
 515                         /*
 516                          * Ok, we found a usage of ptr in a block
 517                          * dominated by the Load/Store block.
 518                          * We can replace the input with a Confirm(ptr, !=, NULL).
 519                          */
 520                         if (c == NULL) {
 521                                 ir_mode *mode = get_irn_mode(ptr);
 522                                 c = new_Const(get_mode_null(mode));
 523
 524                                 c = new_r_Confirm(block, ptr, c, pn_Cmp_Lg);
 525                         }
 526
 527                         set_irn_n(succ, pos, c);
 528                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 529
 530                         env->num_non_null += 1;
 531                         env->num_confirms += 1;
 532                 }
 533         }
 534 }  /* insert_non_null */
 535
 536 /**
 537  * Pre-walker: Called for every node to insert Confirm nodes
 538  */
 539 static void insert_Confirm(ir_node *node, void *env)
 540 {
 541         ir_node *ptr;
 542
 543         switch (get_irn_opcode(node)) {
 544         case iro_Block:
 545                 insert_Confirm_in_block(node, env);
 546                 break;
 547         case iro_Load:
 548                 ptr = get_Load_ptr(node);
 549                 if (! is_non_null_Confirm(ptr))
 550                         insert_non_null(ptr, get_nodes_block(node), env);
 551                 break;
 552         case iro_Store:
 553                 ptr = get_Store_ptr(node);
 554                 if (! is_non_null_Confirm(ptr))
 555                         insert_non_null(ptr, get_nodes_block(node), env);
 556                 break;
 557         default:
 558                 break;
 559         }
 560 }  /* insert_Confirm */
 561
 562 /*
 563  * Construct Confirm nodes
 564  */
 565 void construct_confirms(ir_graph *irg)
 566 {
 567         env_t env;
 568         int edges_active = edges_activated(irg);
 569
 570         FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
 571
 572         remove_critical_cf_edges(irg);
 573
 574         /* we need dominance info */
 575         assure_doms(irg);
 576
 577         assert(get_irg_pinned(irg) == op_pin_state_pinned &&
 578                "Nodes must be placed to insert Confirms");
 579
 580         if (! edges_active) {
 581                 /* We need edges */
 582                 edges_activate(irg);
 583         }
 584
 585         env.num_confirms = 0;
 586         env.num_consts   = 0;
 587         env.num_eq       = 0;
 588         env.num_non_null = 0;
 589
 590         if (get_opt_global_null_ptr_elimination()) {
 591                 /* do global NULL test elimination */
 592                 irg_walk_graph(irg, insert_Confirm, NULL, &env);
 593         } else {
 594                 /* now, visit all blocks and add Confirms where possible */
 595                 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
 596         }
 597
 598         if (env.num_confirms | env.num_consts | env.num_eq) {
 599                 /* we have add nodes or changed DF edges */
 600                 set_irg_outs_inconsistent(irg);
 601
 602                 /* the new nodes are not in the loop info */
 603                 set_irg_loopinfo_inconsistent(irg);
 604         }
 605
 606         DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
 607         DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
 608         DB((dbg, LEVEL_1, "# node equalities   : %u\n", env.num_eq));
 609         DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
 610
 611         /* deactivate edges if they where off */
 612         if (! edges_active)
 613                 edges_deactivate(irg);
 614 }  /* construct_confirms */
 615
 616 /* Construct a pass. */
 617 ir_graph_pass_t *construct_confirms_pass(const char *name)
 618 {
 619         return def_graph_pass(name ? name : "confirm", construct_confirms);
 620 }  /* construct_confirms_pass */
 621
 622 #if 0
 623 /**
 624  * Post-walker: Remove Confirm nodes
 625  */
 626 static void rem_Confirm(ir_node *n, void *env)
 627 {
 628         (void) env;
 629         if (is_Confirm(n)) {
 630                 ir_node *value = get_Confirm_value(n);
 631                 if (value != n)
 632                         exchange(n, value);
 633                 else {
 634                         /*
 635                          * Strange: a Confirm is its own bound. This can happen
 636                          * in dead blocks when Phi nodes are already removed.
 637                          */
 638                         exchange(n, new_Bad());
 639                 }
 640         }
 641 }  /* rem_Confirm */
 642 #endif
 643
 644 /*
 645  * Remove all Confirm nodes from a graph.
 646  */
 647 void remove_confirms(ir_graph *irg)
 648 {
 649         int rem = get_opt_remove_confirm();
 650
 651         set_opt_remove_confirm(1);
 652         optimize_graph_df(irg);
 653         set_opt_remove_confirm(rem);
 654 }  /* remove_confirms */
 655
 656 /* Construct a pass. */
 657 ir_graph_pass_t *remove_confirms_pass(const char *name)
 658 {
 659         return def_graph_pass(name ? name : "rem_confirm", remove_confirms);
 660 }  /* remove_confirms_pass */