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 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  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 "irtools.h"
  41 #include "array_t.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 } env_t;
  51
  52 /**
  53  * Return the effective use block of a node and it's predecessor on
  54  * position pos.
  55  *
  56  * @param node  the node
  57  * @param pos   the position of the used input
  58  *
  59  * This handles correctly Phi nodes.
  60  */
  61 static ir_node *get_effective_use_block(ir_node *node, int pos) {
  62         if (is_Phi(node)) {
  63                 /* the effective use of a Phi argument is in its predecessor block */
  64                 node = get_nodes_block(node);
  65                 return get_Block_cfgpred_block(node, pos);
  66         }
  67         return get_nodes_block(node);
  68 }
  69
  70 /**
  71  * Handle a CASE-branch.
  72  *
  73  * @param block   the block which is entered by the branch
  74  * @param irn     the node expressing the switch value
  75  * @param nr      the branch label
  76  * @param env     statistical environment
  77  *
  78  * Branch labels are a simple case. We can replace the value
  79  * by a Const with the branch label.
  80  */
  81 static void handle_case(ir_node *block, ir_node *irn, long nr, env_t *env) {
  82         const ir_edge_t *edge, *next;
  83         ir_node *c = NULL;
  84
  85         if (is_Bad(irn))
  86                 return;
  87
  88         for (edge = get_irn_out_edge_first(irn); edge; edge = next) {
  89                 ir_node *succ = get_edge_src_irn(edge);
  90                 int     pos   = get_edge_src_pos(edge);
  91                 ir_node *blk  = get_effective_use_block(succ, pos);
  92
  93                 next = get_irn_out_edge_next(irn, edge);
  94
  95                 if (block_dominates(block, blk)) {
  96                         /*
  97                          * Ok, we found a user of irn that is placed
  98                          * in a block dominated by the branch block.
  99                          * We can replace the input with the Constant
 100                          * branch label.
 101                          */
 102
 103                         if (! c) {
 104                                 ir_mode *mode = get_irn_mode(irn);
 105                                 ir_type *tp   = get_irn_type(irn);
 106                                 tarval *tv    = new_tarval_from_long(nr, mode);
 107                                 c = new_r_Const_type(current_ir_graph, block, mode, tv, tp);
 108                         }
 109
 110                         set_irn_n(succ, pos, c);
 111                         DBG_OPT_CONFIRM_C(irn, c);
 112 //                      ir_printf("1 Replacing input %d of node %n with %n\n", pos, succ, c);
 113
 114                         env->num_consts += 1;
 115                 }
 116         }
 117 }  /* handle_case */
 118
 119 /**
 120  * Handle a mode_b input of Cond nodes.
 121  *
 122  * @param block     the block which is entered by the branch
 123  * @param selector  the mode_b node expressing the branch condition
 124  * @param pnc       the true/false condition branch
 125  * @param env       statistical environment
 126  */
 127 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env) {
 128         ir_node *cond, *old, *cond_block = NULL, *other_blk = NULL, *con = NULL;
 129         ir_node *c_b = NULL, *c_o = NULL;
 130         const ir_edge_t *edge, *next;
 131
 132         for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
 133                 ir_node *user     = get_edge_src_irn(edge);
 134                 int     pos       = get_edge_src_pos(edge);
 135                 ir_node *user_blk = get_effective_use_block(user, pos);
 136
 137                 next = get_irn_out_edge_next(selector, edge);
 138                 if (block_dominates(block, user_blk)) {
 139                         /*
 140                          * Ok, we found a usage of selector in a block
 141                          * dominated by the branch block.
 142                          * We can replace the input with true/false.
 143                          */
 144                         if (con == NULL) {
 145                                 con = new_Const(mode_b, pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
 146                         }
 147                         old = get_irn_n(user, pos);
 148                         set_irn_n(user, pos, con);
 149                         DBG_OPT_CONFIRM_C(old, con);
 150
 151                         // ir_printf("2 Replacing input %d of node %n with %n\n", pos, user, con);
 152
 153                         env->num_consts += 1;
 154                 } else {
 155                         int i, n;
 156
 157                         /* get the other block */
 158                         if (other_blk == NULL) {
 159                                 /* we have already tested, that block has only ONE Cond predecessor */
 160                                 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
 161                                 cond_block = get_nodes_block(cond);
 162                                 foreach_out_edge(cond, edge) {
 163                                         ir_node *proj = get_edge_src_irn(edge);
 164                                         if (get_Proj_proj(proj) == (long)pnc)
 165                                                 continue;
 166                                         edge = get_irn_out_edge_first(proj);
 167                                         other_blk = get_edge_src_irn(edge);
 168                                         break;
 169                                 }
 170                                 assert(other_blk);
 171
 172                                 /*
 173                                  * Note the special case here: if block is a then, there might be no else
 174                                  * block. In that case the other_block is the user_blk itself and pred_block
 175                                  * is the cond_block ...
 176                                  *
 177                                  * Best would be to introduce a block here, removing this critical edge.
 178                                  * For some reasons I cannot repair dominance here, so I have to remove
 179                                  * ALL critical edges...
 180                                  * FIXME: This should not be needed if we could repair dominance ...
 181                                  */
 182                         }
 183
 184                         n = get_Block_n_cfgpreds(user_blk);
 185
 186                         /*
 187                          * We have found a user in a non-dominated block:
 188                          * check, if all its block predecessors are dominated.
 189                          * If yes, place a Phi.
 190                          */
 191                         for (i = n - 1; i >= 0; --i) {
 192                                 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 193
 194                                 if (!block_dominates(block, pred_blk) &&
 195                                     !block_dominates(other_blk, pred_blk)) {
 196                                         /* can't do anything */
 197                                         break;
 198                                 }
 199                         }
 200                         if (i < 0) {
 201                                 ir_node *phi, **in;
 202
 203                                 NEW_ARR_A(ir_node *, in, n);
 204                                 /* ok, ALL predecessors are either dominated by block OR other block */
 205                                 if (c_b == NULL) {
 206                                         ir_node *c_true  = new_Const(mode_b, tarval_b_true);
 207                                         ir_node *c_false = new_Const(mode_b, tarval_b_false);
 208                                         c_b = new_r_Confirm(current_ir_graph, cond_block, selector,
 209                                                 pnc == pn_Cond_true ? c_true : c_false, pn_Cmp_Eq);
 210                                         c_o = new_r_Confirm(current_ir_graph, cond_block, selector,
 211                                                 pnc == pn_Cond_false ? c_true : c_false, pn_Cmp_Eq);
 212                                 }
 213                                 for (i = n - 1; i >= 0; --i) {
 214                                         ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 215
 216                                         if (block_dominates(block, pred_blk))
 217                                                 in[i] = c_b;
 218                                         else
 219                                                 in[i] = c_o;
 220                                 }
 221                                 phi = new_r_Phi(current_ir_graph, user_blk, n, in, mode_b);
 222                                 set_irn_n(user, pos, phi);
 223                         }
 224                 }
 225         }
 226 }
 227
 228 /**
 229  * Handle an IF-branch.
 230  *
 231  * @param block   the block which is entered by the branch
 232  * @param cmp     the Cmp node expressing the branch condition
 233  * @param pnc     the Compare relation for taking this branch
 234  * @param env     statistical environment
 235  */
 236 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env) {
 237         ir_node *left  = get_Cmp_left(cmp);
 238         ir_node *right = get_Cmp_right(cmp);
 239         ir_node *cond_block;
 240         ir_op *op;
 241         const ir_edge_t *edge, *next;
 242
 243         /* Beware of Bads */
 244         if (is_Bad(left) || is_Bad(right))
 245                 return;
 246
 247         op = get_irn_op(left);
 248
 249         /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
 250            These are removed anyway */
 251         if (op == op_Const && is_Const(right))
 252                 return;
 253
 254         /* try to place the constant on the right side for a Confirm */
 255         if (op == op_Const || op == op_SymConst) {
 256                 ir_node *t = left;
 257
 258                 left  = right;
 259                 right = t;
 260
 261                 pnc = get_inversed_pnc(pnc);
 262         }
 263
 264         /*
 265          * First case: both values are identical.
 266          * replace the left one by the right (potentially const) one.
 267          */
 268         if (pnc == pn_Cmp_Eq) {
 269                 cond_block = get_Block_cfgpred_block(block, 0);
 270                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 271                         ir_node *user = get_edge_src_irn(edge);
 272                         int     pos   = get_edge_src_pos(edge);
 273                         ir_node *blk  = get_effective_use_block(user, pos);
 274
 275                         next = get_irn_out_edge_next(left, edge);
 276                         if (block_dominates(block, blk)) {
 277                                 /*
 278                                  * Ok, we found a usage of left in a block
 279                                  * dominated by the branch block.
 280                                  * We can replace the input with right.
 281                                  */
 282                                 set_irn_n(user, pos, right);
 283                                 DBG_OPT_CONFIRM(left, right);
 284
 285 //                              ir_printf("2 Replacing input %d of node %n with %n\n", pos, user, right);
 286
 287                                 env->num_eq += 1;
 288                         } else if (block_dominates(blk, cond_block)) {
 289                                 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
 290                                         /*
 291                                          * left == Const and we found a movable user of left in a
 292                                          * dominator of the Cond block
 293                                          */
 294                                         const ir_edge_t *edge, *next;
 295                                         for (edge = get_irn_out_edge_first(user); edge; edge = next) {
 296                                                 ir_node *usr_of_usr = get_edge_src_irn(edge);
 297                                                 int      npos = get_edge_src_pos(edge);
 298                                                 ir_node *blk  = get_effective_use_block(usr_of_usr, npos);
 299
 300                                                 next = get_irn_out_edge_next(user, edge);
 301                                                 if (block_dominates(block, blk)) {
 302                                                         /*
 303                                                          * The user of the user is dominated by our true/false
 304                                                          * block. So, create a copy of user WITH the constant
 305                                                          * replacing it's pos'th input.
 306                                                          *
 307                                                          * This is always good for unop's and might be good
 308                                                          * for binops.
 309                                                          *
 310                                                          * If user has other user in the false/true block, code
 311                                                          * placement will move it down.
 312                                                          * If there are users in cond block or upper, we create
 313                                                          * "redundant ops", because one will have a const op,
 314                                                          * the other no const ...
 315                                                          */
 316                                                         ir_node *new_op = exact_copy(user);
 317                                                         set_nodes_block(new_op, block);
 318                                                         set_irn_n(new_op, pos, right);
 319                                                         set_irn_n(usr_of_usr, npos, new_op);
 320                                                 }
 321                                         }
 322                                 }
 323                         }
 324                 }
 325         } else { /* not pn_Cmp_Eq cases */
 326                 ir_node *c = NULL;
 327
 328                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 329                         ir_node *succ = get_edge_src_irn(edge);
 330                         int     pos   = get_edge_src_pos(edge);
 331                         ir_node *blk  = get_effective_use_block(succ, pos);
 332
 333                         next = get_irn_out_edge_next(left, edge);
 334                         if (block_dominates(block, blk)) {
 335                                 /*
 336                                  * Ok, we found a usage of left in a block
 337                                  * dominated by the branch block.
 338                                  * We can replace the input with a Confirm(left, pnc, right).
 339                                  */
 340                                 if (! c)
 341                                         c = new_r_Confirm(current_ir_graph, block, left, right, pnc);
 342
 343                                 pos = get_edge_src_pos(edge);
 344                                 set_irn_n(succ, pos, c);
 345 //                              ir_printf("3 Replacing input %d of node %n with %n\n", pos, user, c);
 346
 347                                 env->num_confirms += 1;
 348                         }
 349                 }
 350         }
 351 }  /* handle_if */
 352
 353 /**
 354  * Pre-walker: Called for every block to insert Confirm nodes
 355  */
 356 static void insert_Confirm(ir_node *block, void *env) {
 357         ir_node *cond, *proj, *selector;
 358         ir_mode *mode;
 359
 360         /*
 361          * we can only handle blocks with only ONE control flow
 362          * predecessor yet.
 363          */
 364         if (get_Block_n_cfgpreds(block) != 1)
 365                 return;
 366
 367         proj = get_Block_cfgpred(block, 0);
 368         if (! is_Proj(proj))
 369                 return;
 370
 371         cond = get_Proj_pred(proj);
 372         if (! is_Cond(cond))
 373                 return;
 374
 375         selector = get_Cond_selector(cond);
 376         mode = get_irn_mode(selector);
 377
 378         if (mode == mode_b) {
 379                 ir_node *cmp;
 380                 pn_Cmp pnc;
 381
 382                 handle_modeb(block, selector, get_Proj_proj(proj), env);
 383
 384                 /* this should be an IF, check this */
 385                 if (! is_Proj(selector))
 386                         return;
 387
 388                 cmp = get_Proj_pred(selector);
 389                 if (! is_Cmp(cmp))
 390                         return;
 391
 392                 pnc = get_Proj_proj(selector);
 393
 394                 if (get_Proj_proj(proj) != pn_Cond_true) {
 395                         /* it's the false branch */
 396                         pnc = get_negated_pnc(pnc, mode);
 397                 }
 398 //              ir_printf("At %n using %n Confirm %=\n", block, cmp, pnc);
 399
 400                 handle_if(block, cmp, pnc, env);
 401         } else if (mode_is_int(mode)) {
 402                 long proj_nr = get_Proj_proj(proj);
 403
 404                 /* this is a CASE, but we cannot handle the default case */
 405                 if (proj_nr == get_Cond_defaultProj(cond))
 406                         return;
 407
 408                 handle_case(block, get_Cond_selector(cond), proj_nr, env);
 409         }
 410 }  /* insert_Confirm */
 411
 412 /*
 413  * Construct Confirm nodes
 414  */
 415 void construct_confirms(ir_graph *irg) {
 416         env_t env;
 417         int edges_active = edges_activated(irg);
 418
 419         remove_critical_cf_edges(irg);
 420
 421         /* we need dominance info */
 422         assure_doms(irg);
 423
 424         assert(get_irg_pinned(irg) == op_pin_state_pinned &&
 425                "Nodes must be placed to insert Confirms");
 426
 427         if (! edges_active) {
 428                 /* We need edges */
 429                 edges_activate(irg);
 430         }
 431
 432         env.num_confirms = 0;
 433         env.num_consts   = 0;
 434         env.num_eq       = 0;
 435
 436         /* now, visit all blocks and add Confirms where possible */
 437         irg_block_walk_graph(irg, insert_Confirm, NULL, &env);
 438
 439         if (env.num_confirms | env.num_consts | env.num_eq) {
 440                 /* we have add nodes or changed DF edges */
 441                 set_irg_outs_inconsistent(irg);
 442
 443                 /* the new nodes are not in the loop info */
 444                 set_irg_loopinfo_inconsistent(irg);
 445         }
 446
 447 #if 0
 448         printf("# Confirms inserted : %u\n", env.num_confirms);
 449         printf("# Const replacements: %u\n", env.num_consts);
 450         printf("# node equalities   : %u\n", env.num_eq);
 451 #endif
 452
 453         /* deactivate edges if they where off */
 454         if (! edges_active)
 455                 edges_deactivate(irg);
 456 }  /* construct_confirms */
 457
 458 #if 0
 459 /**
 460  * Post-walker: Remove Confirm nodes
 461  */
 462 static void rem_Confirm(ir_node *n, void *env) {
 463         (void) env;
 464         if (is_Confirm(n)) {
 465                 ir_node *value = get_Confirm_value(n);
 466                 if (value != n)
 467                         exchange(n, value);
 468                 else {
 469                         /*
 470                          * Strange: a Confirm is it's own bound. This can happen
 471                          * in dead blocks when Phi nodes are already removed.
 472                          */
 473                         exchange(n, new_Bad());
 474                 }
 475         }
 476 }  /* rem_Confirm */
 477 #endif
 478
 479 /*
 480  * Remove all Confirm nodes from a graph.
 481  */
 482 void remove_confirms(ir_graph *irg) {
 483         set_opt_remove_confirm(1);
 484         optimize_graph_df(irg);
 485 }  /* remove_confirms */