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 its 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_tarval *tv   = new_tarval_from_long(nr, mode);
 115                                 c = new_r_Const(current_ir_graph, tv);
 116                         }
 117
 118                         set_irn_n(succ, pos, c);
 119                         DBG_OPT_CONFIRM_C(irn, c);
 120                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 121
 122                         env->num_consts += 1;
 123                 }
 124         }
 125 }  /* handle_case */
 126
 127 /**
 128  * Handle a mode_b input of Cond nodes.
 129  *
 130  * @param block     the block which is entered by the branch
 131  * @param selector  the mode_b node expressing the branch condition
 132  * @param pnc       the true/false condition branch
 133  * @param env       statistical environment
 134  */
 135 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env)
 136 {
 137         ir_node *cond, *old, *other_blk = NULL, *con = NULL;
 138         ir_node *c_b = NULL, *c_o = NULL;
 139         const ir_edge_t *edge, *next;
 140
 141         for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
 142                 ir_node *user     = get_edge_src_irn(edge);
 143                 int     pos       = get_edge_src_pos(edge);
 144                 ir_node *user_blk = get_effective_use_block(user, pos);
 145
 146                 next = get_irn_out_edge_next(selector, edge);
 147                 if (block_dominates(block, user_blk)) {
 148                         /*
 149                          * Ok, we found a usage of selector in a block
 150                          * dominated by the branch block.
 151                          * We can replace the input with true/false.
 152                          */
 153                         if (con == NULL) {
 154                                 ir_graph *irg = get_irn_irg(block);
 155                                 con = new_r_Const(irg, 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_graph *irg    = get_irn_irg(block);
 216                                         ir_node *c_true  = new_r_Const(irg, tarval_b_true);
 217                                         ir_node *c_false = new_r_Const(irg, tarval_b_false);
 218                                         env->num_consts += 2;
 219                                         if (pnc == pn_Cond_true) {
 220                                                 c_b = c_true;
 221                                                 c_o = c_false;
 222                                         } else {
 223                                                 c_b = c_false;
 224                                                 c_o = c_true;
 225                                         }
 226                                 }
 227                                 for (i = n - 1; i >= 0; --i) {
 228                                         ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 229
 230                                         if (block_dominates(block, pred_blk))
 231                                                 in[i] = c_b;
 232                                         else
 233                                                 in[i] = c_o;
 234                                 }
 235                                 phi = new_r_Phi(user_blk, n, in, mode_b);
 236                                 set_irn_n(user, pos, phi);
 237                                 env->num_eq += 1;
 238                         }
 239                 }
 240         }
 241 }
 242
 243 /**
 244  * Handle an IF-branch.
 245  *
 246  * @param block   the block which is entered by the branch
 247  * @param cmp     the Cmp node expressing the branch condition
 248  * @param rel     the Compare relation for taking this branch
 249  * @param env     statistical environment
 250  */
 251 static void handle_if(ir_node *block, ir_node *cmp, ir_relation rel, env_t *env)
 252 {
 253         ir_node *left  = get_Cmp_left(cmp);
 254         ir_node *right = get_Cmp_right(cmp);
 255         ir_node *cond_block;
 256         ir_op *op;
 257         const ir_edge_t *edge, *next;
 258
 259         /* Beware of Bads */
 260         if (is_Bad(left) || is_Bad(right))
 261                 return;
 262
 263         op = get_irn_op(left);
 264
 265         /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
 266            These are removed anyway */
 267         if (op == op_Const && is_Const(right))
 268                 return;
 269
 270         /* try to place the constant on the right side for a Confirm */
 271         if (op == op_Const || op == op_SymConst) {
 272                 ir_node *t = left;
 273
 274                 left  = right;
 275                 right = t;
 276
 277                 rel = get_inversed_relation(rel);
 278         }
 279
 280         /*
 281          * First case: both values are identical.
 282          * replace the left one by the right (potentially const) one.
 283          */
 284         if (rel == ir_relation_equal) {
 285                 cond_block = get_Block_cfgpred_block(block, 0);
 286                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 287                         ir_node *user = get_edge_src_irn(edge);
 288                         int     pos   = get_edge_src_pos(edge);
 289                         ir_node *blk  = get_effective_use_block(user, pos);
 290
 291                         next = get_irn_out_edge_next(left, edge);
 292                         if (block_dominates(block, blk)) {
 293                                 /*
 294                                  * Ok, we found a usage of left in a block
 295                                  * dominated by the branch block.
 296                                  * We can replace the input with right.
 297                                  */
 298                                 set_irn_n(user, pos, right);
 299                                 DBG_OPT_CONFIRM(left, right);
 300
 301                                 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
 302
 303                                 env->num_eq += 1;
 304                         } else if (block_dominates(blk, cond_block)
 305                                         && is_Const(right)
 306                                         && get_irn_pinned(user) == op_pin_state_floats) {
 307                                 /*
 308                                  * left == Const and we found a movable user of left in a
 309                                  * dominator of the Cond block
 310                                  */
 311                                 const ir_edge_t *user_edge;
 312                                 const ir_edge_t *user_next;
 313                                 foreach_out_edge_safe(user, user_edge, user_next) {
 314                                         ir_node *usr_of_usr = get_edge_src_irn(user_edge);
 315                                         int      npos       = get_edge_src_pos(user_edge);
 316                                         ir_node *user_blk   = get_effective_use_block(usr_of_usr, npos);
 317
 318                                         if (block_dominates(block, user_blk)) {
 319                                                 /*
 320                                                  * The user of the user is dominated by our true/false
 321                                                  * block. So, create a copy of user WITH the constant
 322                                                  * replacing its pos'th input.
 323                                                  *
 324                                                  * This is always good for unop's and might be good
 325                                                  * for binops.
 326                                                  *
 327                                                  * If user has other user in the false/true block, code
 328                                                  * placement will move it down.
 329                                                  * If there are users in cond block or upper, we create
 330                                                  * "redundant ops", because one will have a const op,
 331                                                  * the other no const ...
 332                                                  */
 333                                                 ir_node *new_op = exact_copy(user);
 334                                                 set_nodes_block(new_op, block);
 335                                                 set_irn_n(new_op, pos, right);
 336                                                 set_irn_n(usr_of_usr, npos, new_op);
 337                                                 env->num_eq += 1;
 338                                         }
 339                                 }
 340                         }
 341                 }
 342         } else { /* not ir_relation_equal cases */
 343                 ir_node *c = NULL;
 344
 345                 foreach_out_edge_safe(left, edge, next) {
 346                         ir_node *succ = get_edge_src_irn(edge);
 347                         int     pos   = get_edge_src_pos(edge);
 348                         ir_node *blk  = get_effective_use_block(succ, pos);
 349
 350                         if (block_dominates(block, blk)) {
 351                                 /*
 352                                  * Ok, we found a usage of left in a block
 353                                  * dominated by the branch block.
 354                                  * We can replace the input with a Confirm(left, pnc, right).
 355                                  */
 356                                 if (! c)
 357                                         c = new_r_Confirm(block, left, right, rel);
 358
 359                                 pos = get_edge_src_pos(edge);
 360                                 set_irn_n(succ, pos, c);
 361                                 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 362
 363                                 env->num_confirms += 1;
 364                         }
 365                 }
 366
 367                 if (! is_Const(right)) {
 368                         /* also construct inverse Confirms */
 369                         ir_node *rc = NULL;
 370
 371                         rel = get_inversed_relation(rel);
 372                         foreach_out_edge_safe(right, edge, next) {
 373                                 ir_node *succ = get_edge_src_irn(edge);
 374                                 int     pos;
 375                                 ir_node *blk;
 376
 377                                 if (succ == c)
 378                                         continue;
 379
 380                                 pos  = get_edge_src_pos(edge);
 381                                 blk  = get_effective_use_block(succ, pos);
 382
 383                                 if (block_dominates(block, blk)) {
 384                                         /*
 385                                          * Ok, we found a usage of right in a block
 386                                          * dominated by the branch block.
 387                                          * We can replace the input with a Confirm(right, rel^-1, left).
 388                                          */
 389                                         if (! rc)
 390                                                 rc = new_r_Confirm(block, right, left, rel);
 391
 392                                         pos = get_edge_src_pos(edge);
 393                                         set_irn_n(succ, pos, rc);
 394                                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, rc));
 395
 396                                         env->num_confirms += 1;
 397                                 }
 398                         }
 399                 }
 400         }
 401 }  /* handle_if */
 402
 403 /**
 404  * Pre-block-walker: Called for every block to insert Confirm nodes
 405  */
 406 static void insert_Confirm_in_block(ir_node *block, void *data)
 407 {
 408         ir_node *cond, *proj, *selector;
 409         ir_mode *mode;
 410         env_t   *env = (env_t*) data;
 411
 412         /*
 413          * we can only handle blocks with only ONE control flow
 414          * predecessor yet.
 415          */
 416         if (get_Block_n_cfgpreds(block) != 1)
 417                 return;
 418
 419         proj = get_Block_cfgpred(block, 0);
 420         if (! is_Proj(proj))
 421                 return;
 422
 423         cond = get_Proj_pred(proj);
 424         if (! is_Cond(cond))
 425                 return;
 426
 427         selector = get_Cond_selector(cond);
 428         mode = get_irn_mode(selector);
 429
 430         if (mode == mode_b) {
 431                 ir_relation rel;
 432
 433                 handle_modeb(block, selector, (pn_Cond) get_Proj_proj(proj), env);
 434
 435                 if (! is_Cmp(selector))
 436                         return;
 437
 438                 rel = get_Cmp_relation(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(selector));
 443                         rel = get_negated_relation(rel);
 444                 }
 445                 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, selector, rel));
 446
 447                 handle_if(block, selector, rel, 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_relation(ptr) == ir_relation_less_greater) {
 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                                 ir_graph *irg  = get_irn_irg(block);
 519                                 c = new_r_Const(irg, get_mode_null(mode));
 520                                 c = new_r_Confirm(block, ptr, c, ir_relation_less_greater);
 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 *data)
 536 {
 537         ir_node *ptr;
 538         env_t   *env = (env_t*) data;
 539
 540         switch (get_irn_opcode(node)) {
 541         case iro_Block:
 542                 insert_Confirm_in_block(node, env);
 543                 break;
 544         case iro_Load:
 545                 ptr = get_Load_ptr(node);
 546                 if (! is_non_null_Confirm(ptr))
 547                         insert_non_null(ptr, get_nodes_block(node), env);
 548                 break;
 549         case iro_Store:
 550                 ptr = get_Store_ptr(node);
 551                 if (! is_non_null_Confirm(ptr))
 552                         insert_non_null(ptr, get_nodes_block(node), env);
 553                 break;
 554         default:
 555                 break;
 556         }
 557 }  /* insert_Confirm */
 558
 559 /*
 560  * Construct Confirm nodes
 561  */
 562 void construct_confirms(ir_graph *irg)
 563 {
 564         env_t env;
 565         int edges_active = edges_activated(irg);
 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         DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
 596         DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
 597         DB((dbg, LEVEL_1, "# node equalities   : %u\n", env.num_eq));
 598         DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
 599
 600         /* deactivate edges if they where off */
 601         if (! edges_active)
 602                 edges_deactivate(irg);
 603 }  /* construct_confirms */
 604
 605 /* Construct a pass. */
 606 ir_graph_pass_t *construct_confirms_pass(const char *name)
 607 {
 608         return def_graph_pass(name ? name : "confirm", construct_confirms);
 609 }  /* construct_confirms_pass */
 610
 611 static void remove_confirm(ir_node *n, void *env)
 612 {
 613         ir_node *value;
 614
 615         (void) env;
 616         if (!is_Confirm(n))
 617                 return;
 618
 619         value = get_Confirm_value(n);
 620         exchange(n, value);
 621 }
 622
 623 /*
 624  * Remove all Confirm nodes from a graph.
 625  */
 626 void remove_confirms(ir_graph *irg)
 627 {
 628         irg_walk_graph(irg, NULL, remove_confirm, NULL);
 629 }  /* remove_confirms */
 630
 631 /* Construct a pass. */
 632 ir_graph_pass_t *remove_confirms_pass(const char *name)
 633 {
 634         return def_graph_pass(name ? name : "rem_confirm", remove_confirms);
 635 }  /* remove_confirms_pass */