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