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, mode, 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(mode_b, 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(mode_b, tarval_b_true);
 211                                         ir_node *c_false = new_Const(mode_b, tarval_b_false);
 212                                         c_b = new_r_Confirm(current_ir_graph, cond_block, selector,
 213                                                 pnc == pn_Cond_true ? c_true : c_false, pn_Cmp_Eq);
 214                                         c_o = new_r_Confirm(current_ir_graph, cond_block, selector,
 215                                                 pnc == pn_Cond_false ? c_true : c_false, pn_Cmp_Eq);
 216                                 }
 217                                 for (i = n - 1; i >= 0; --i) {
 218                                         ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 219
 220                                         if (block_dominates(block, pred_blk))
 221                                                 in[i] = c_b;
 222                                         else
 223                                                 in[i] = c_o;
 224                                 }
 225                                 phi = new_r_Phi(current_ir_graph, user_blk, n, in, mode_b);
 226                                 set_irn_n(user, pos, phi);
 227                         }
 228                 }
 229         }
 230 }
 231
 232 /**
 233  * Handle an IF-branch.
 234  *
 235  * @param block   the block which is entered by the branch
 236  * @param cmp     the Cmp node expressing the branch condition
 237  * @param pnc     the Compare relation for taking this branch
 238  * @param env     statistical environment
 239  */
 240 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env) {
 241         ir_node *left  = get_Cmp_left(cmp);
 242         ir_node *right = get_Cmp_right(cmp);
 243         ir_node *cond_block;
 244         ir_op *op;
 245         const ir_edge_t *edge, *next;
 246
 247         /* Beware of Bads */
 248         if (is_Bad(left) || is_Bad(right))
 249                 return;
 250
 251         op = get_irn_op(left);
 252
 253         /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
 254            These are removed anyway */
 255         if (op == op_Const && is_Const(right))
 256                 return;
 257
 258         /* try to place the constant on the right side for a Confirm */
 259         if (op == op_Const || op == op_SymConst) {
 260                 ir_node *t = left;
 261
 262                 left  = right;
 263                 right = t;
 264
 265                 pnc = get_inversed_pnc(pnc);
 266         }
 267
 268         /*
 269          * First case: both values are identical.
 270          * replace the left one by the right (potentially const) one.
 271          */
 272         if (pnc == pn_Cmp_Eq) {
 273                 cond_block = get_Block_cfgpred_block(block, 0);
 274                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 275                         ir_node *user = get_edge_src_irn(edge);
 276                         int     pos   = get_edge_src_pos(edge);
 277                         ir_node *blk  = get_effective_use_block(user, pos);
 278
 279                         next = get_irn_out_edge_next(left, edge);
 280                         if (block_dominates(block, blk)) {
 281                                 /*
 282                                  * Ok, we found a usage of left in a block
 283                                  * dominated by the branch block.
 284                                  * We can replace the input with right.
 285                                  */
 286                                 set_irn_n(user, pos, right);
 287                                 DBG_OPT_CONFIRM(left, right);
 288
 289                                 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, user, right));
 290
 291                                 env->num_eq += 1;
 292                         } else if (block_dominates(blk, cond_block)) {
 293                                 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
 294                                         /*
 295                                          * left == Const and we found a movable user of left in a
 296                                          * dominator of the Cond block
 297                                          */
 298                                         const ir_edge_t *edge, *next;
 299                                         for (edge = get_irn_out_edge_first(user); edge; edge = next) {
 300                                                 ir_node *usr_of_usr = get_edge_src_irn(edge);
 301                                                 int      npos = get_edge_src_pos(edge);
 302                                                 ir_node *blk  = get_effective_use_block(usr_of_usr, npos);
 303
 304                                                 next = get_irn_out_edge_next(user, edge);
 305                                                 if (block_dominates(block, blk)) {
 306                                                         /*
 307                                                          * The user of the user is dominated by our true/false
 308                                                          * block. So, create a copy of user WITH the constant
 309                                                          * replacing it's pos'th input.
 310                                                          *
 311                                                          * This is always good for unop's and might be good
 312                                                          * for binops.
 313                                                          *
 314                                                          * If user has other user in the false/true block, code
 315                                                          * placement will move it down.
 316                                                          * If there are users in cond block or upper, we create
 317                                                          * "redundant ops", because one will have a const op,
 318                                                          * the other no const ...
 319                                                          */
 320                                                         ir_node *new_op = exact_copy(user);
 321                                                         set_nodes_block(new_op, block);
 322                                                         set_irn_n(new_op, pos, right);
 323                                                         set_irn_n(usr_of_usr, npos, new_op);
 324                                                 }
 325                                         }
 326                                 }
 327                         }
 328                 }
 329         } else { /* not pn_Cmp_Eq cases */
 330                 ir_node *c = NULL;
 331
 332                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 333                         ir_node *succ = get_edge_src_irn(edge);
 334                         int     pos   = get_edge_src_pos(edge);
 335                         ir_node *blk  = get_effective_use_block(succ, pos);
 336
 337                         next = get_irn_out_edge_next(left, edge);
 338                         if (block_dominates(block, blk)) {
 339                                 /*
 340                                  * Ok, we found a usage of left in a block
 341                                  * dominated by the branch block.
 342                                  * We can replace the input with a Confirm(left, pnc, right).
 343                                  */
 344                                 if (! c)
 345                                         c = new_r_Confirm(current_ir_graph, block, left, right, pnc);
 346
 347                                 pos = get_edge_src_pos(edge);
 348                                 set_irn_n(succ, pos, c);
 349                                 DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 350
 351                                 env->num_confirms += 1;
 352                         }
 353                 }
 354
 355                 if (! is_Const(right)) {
 356                         /* also construct inverse Confirms */
 357                         c   = NULL;
 358                         pnc = get_inversed_pnc(pnc);
 359                         for (edge = get_irn_out_edge_first(right); edge; edge = next) {
 360                                 ir_node *succ = get_edge_src_irn(edge);
 361                                 int     pos   = get_edge_src_pos(edge);
 362                                 ir_node *blk  = get_effective_use_block(succ, pos);
 363
 364                                 next = get_irn_out_edge_next(left, edge);
 365                                 if (block_dominates(block, blk)) {
 366                                         /*
 367                                          * Ok, we found a usage of right in a block
 368                                          * dominated by the branch block.
 369                                          * We can replace the input with a Confirm(right, pnc^-1, left).
 370                                          */
 371                                         if (! c)
 372                                                 c = new_r_Confirm(current_ir_graph, block, right, left, pnc);
 373
 374                                         pos = get_edge_src_pos(edge);
 375                                         set_irn_n(succ, pos, c);
 376                                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 377
 378                                         env->num_confirms += 1;
 379                                 }
 380                         }
 381                 }
 382         }
 383 }  /* handle_if */
 384
 385 /**
 386  * Pre-block-walker: Called for every block to insert Confirm nodes
 387  */
 388 static void insert_Confirm_in_block(ir_node *block, void *env) {
 389         ir_node *cond, *proj, *selector;
 390         ir_mode *mode;
 391
 392         /*
 393          * we can only handle blocks with only ONE control flow
 394          * predecessor yet.
 395          */
 396         if (get_Block_n_cfgpreds(block) != 1)
 397                 return;
 398
 399         proj = get_Block_cfgpred(block, 0);
 400         if (! is_Proj(proj))
 401                 return;
 402
 403         cond = get_Proj_pred(proj);
 404         if (! is_Cond(cond))
 405                 return;
 406
 407         selector = get_Cond_selector(cond);
 408         mode = get_irn_mode(selector);
 409
 410         if (mode == mode_b) {
 411                 ir_node *cmp;
 412                 pn_Cmp pnc;
 413
 414                 handle_modeb(block, selector, get_Proj_proj(proj), env);
 415
 416                 /* this should be an IF, check this */
 417                 if (! is_Proj(selector))
 418                         return;
 419
 420                 cmp = get_Proj_pred(selector);
 421                 if (! is_Cmp(cmp))
 422                         return;
 423
 424                 pnc = get_Proj_proj(selector);
 425
 426                 if (get_Proj_proj(proj) != pn_Cond_true) {
 427                         /* it's the false branch */
 428                         mode = get_irn_mode(get_Cmp_left(cmp));
 429                         pnc = get_negated_pnc(pnc, mode);
 430                 }
 431                 DB((dbg, LEVEL_2, "At %+F using %+F Confirm %=\n", block, cmp, pnc));
 432
 433                 handle_if(block, cmp, pnc, env);
 434         } else if (mode_is_int(mode)) {
 435                 long proj_nr = get_Proj_proj(proj);
 436
 437                 /* this is a CASE, but we cannot handle the default case */
 438                 if (proj_nr == get_Cond_defaultProj(cond))
 439                         return;
 440
 441                 handle_case(block, get_Cond_selector(cond), proj_nr, env);
 442         }
 443 }  /* insert_Confirm_in_block */
 444
 445 /**
 446  * Checks if a node is a non-null Confirm.
 447  */
 448 static int is_non_null_Confirm(const ir_node *ptr) {
 449         for (;;) {
 450                 if (! is_Confirm(ptr))
 451                         break;
 452                 if (get_Confirm_cmp(ptr) == pn_Cmp_Lg) {
 453                         ir_node *bound = get_Confirm_bound(ptr);
 454
 455                         if (is_Const(bound) && is_Const_null(bound))
 456                                 return 1;
 457                 }
 458                 ptr = get_Confirm_value(ptr);
 459         }
 460         /*
 461          * While a SymConst is not a Confirm, it is non-null
 462          * anyway. This helps to reduce the number of
 463          * constructed Confirms.
 464          */
 465         if (is_SymConst_addr_ent(ptr))
 466                 return 1;
 467         return 0;
 468 }  /* is_non_null_Confirm */
 469
 470 /**
 471  * The given pointer will be dereferenced, add non-null Confirms.
 472  *
 473  * @param ptr    a node representing an address
 474  * @param block  the block of the dereferencing instruction
 475  * @param env    environment
 476  */
 477 static void insert_non_null(ir_node *ptr, ir_node *block, env_t *env) {
 478         const ir_edge_t *edge, *next;
 479         ir_node         *c = NULL;
 480
 481         foreach_out_edge_safe(ptr, edge, next) {
 482                 ir_node *succ = get_edge_src_irn(edge);
 483                 int     pos;
 484                 ir_node *blk;
 485
 486
 487                 /* for now, we place a Confirm only in front of a Cmp */
 488                 if (! is_Cmp(succ))
 489                         continue;
 490
 491                 pos = get_edge_src_pos(edge);
 492                 blk = get_effective_use_block(succ, pos);
 493
 494                 if (block_dominates(block, blk)) {
 495                         /*
 496                          * Ok, we found a usage of ptr in a block
 497                          * dominated by the Load/Store block.
 498                          * We can replace the input with a Confirm(ptr, !=, NULL).
 499                          */
 500                         if (c == NULL) {
 501                                 ir_mode *mode = get_irn_mode(ptr);
 502                                 c = new_Const(mode, get_mode_null(mode));
 503
 504                                 c = new_r_Confirm(current_ir_graph, block, ptr, c, pn_Cmp_Lg);
 505                         }
 506
 507                         set_irn_n(succ, pos, c);
 508                         DB((dbg, LEVEL_2, "Replacing input %d of node %+F with %+F\n", pos, succ, c));
 509
 510                         env->num_non_null += 1;
 511                         env->num_confirms += 1;
 512                 }
 513         }
 514 }  /* insert_non_null */
 515
 516 /**
 517  * Pre-walker: Called for every node to insert Confirm nodes
 518  */
 519 static void insert_Confirm(ir_node *node, void *env) {
 520         ir_node *ptr;
 521
 522         switch (get_irn_opcode(node)) {
 523         case iro_Block:
 524                 insert_Confirm_in_block(node, env);
 525                 break;
 526         case iro_Load:
 527                 ptr = get_Load_ptr(node);
 528                 if (! is_non_null_Confirm(ptr))
 529                         insert_non_null(ptr, get_nodes_block(node), env);
 530                 break;
 531         case iro_Store:
 532                 ptr = get_Store_ptr(node);
 533                 if (! is_non_null_Confirm(ptr))
 534                         insert_non_null(ptr, get_nodes_block(node), env);
 535                 break;
 536         default:
 537                 break;
 538         }
 539 }  /* insert_Confirm */
 540
 541 /*
 542  * Construct Confirm nodes
 543  */
 544 void construct_confirms(ir_graph *irg) {
 545         env_t env;
 546         int edges_active = edges_activated(irg);
 547
 548
 549         FIRM_DBG_REGISTER(dbg, "firm.ana.confirm");
 550
 551         remove_critical_cf_edges(irg);
 552
 553         /* we need dominance info */
 554         assure_doms(irg);
 555
 556         assert(get_irg_pinned(irg) == op_pin_state_pinned &&
 557                "Nodes must be placed to insert Confirms");
 558
 559         if (! edges_active) {
 560                 /* We need edges */
 561                 edges_activate(irg);
 562         }
 563
 564         env.num_confirms = 0;
 565         env.num_consts   = 0;
 566         env.num_eq       = 0;
 567         env.num_non_null = 0;
 568
 569         if (get_opt_global_null_ptr_elimination()) {
 570                 /* do global NULL test elimination */
 571                 irg_walk_graph(irg, insert_Confirm, NULL, &env);
 572         } else {
 573                 /* now, visit all blocks and add Confirms where possible */
 574                 irg_block_walk_graph(irg, insert_Confirm_in_block, NULL, &env);
 575         }
 576
 577         if (env.num_confirms | env.num_consts | env.num_eq) {
 578                 /* we have add nodes or changed DF edges */
 579                 set_irg_outs_inconsistent(irg);
 580
 581                 /* the new nodes are not in the loop info */
 582                 set_irg_loopinfo_inconsistent(irg);
 583         }
 584
 585         DB((dbg, LEVEL_1, "# Confirms inserted : %u\n", env.num_confirms));
 586         DB((dbg, LEVEL_1, "# Const replacements: %u\n", env.num_consts));
 587         DB((dbg, LEVEL_1, "# node equalities   : %u\n", env.num_eq));
 588         DB((dbg, LEVEL_1, "# non-null Confirms : %u\n", env.num_non_null));
 589
 590         /* deactivate edges if they where off */
 591         if (! edges_active)
 592                 edges_deactivate(irg);
 593 }  /* construct_confirms */
 594
 595 #if 0
 596 /**
 597  * Post-walker: Remove Confirm nodes
 598  */
 599 static void rem_Confirm(ir_node *n, void *env) {
 600         (void) env;
 601         if (is_Confirm(n)) {
 602                 ir_node *value = get_Confirm_value(n);
 603                 if (value != n)
 604                         exchange(n, value);
 605                 else {
 606                         /*
 607                          * Strange: a Confirm is its own bound. This can happen
 608                          * in dead blocks when Phi nodes are already removed.
 609                          */
 610                         exchange(n, new_Bad());
 611                 }
 612         }
 613 }  /* rem_Confirm */
 614 #endif
 615
 616 /*
 617  * Remove all Confirm nodes from a graph.
 618  */
 619 void remove_confirms(ir_graph *irg) {
 620         int rem = get_opt_remove_confirm();
 621
 622         set_opt_remove_confirm(1);
 623         optimize_graph_df(irg);
 624         set_opt_remove_confirm(rem);
 625 }  /* remove_confirms */