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
  42 /**
  43  * Walker environment.
  44  */
  45 typedef struct _env_t {
  46         unsigned num_confirms;  /**< number of inserted Confirm nodes */
  47         unsigned num_consts;    /**< number of constants placed */
  48         unsigned num_eq;        /**< number of equalities placed */
  49 } env_t;
  50
  51 /**
  52  * Return the effective use block of a node and it's predecessor on
  53  * position pos.
  54  *
  55  * @param node  the node
  56  * @param pos   the position of the used input
  57  *
  58  * This handles correctly Phi nodes.
  59  */
  60 static ir_node *get_effective_use_block(ir_node *node, int pos) {
  61         if (is_Phi(node)) {
  62                 /* the effective use of a Phi argument is in its predecessor block */
  63                 node = get_nodes_block(node);
  64                 return get_Block_cfgpred_block(node, pos);
  65         }
  66         return get_nodes_block(node);
  67 }
  68
  69 /**
  70  * Handle a CASE-branch.
  71  *
  72  * @param block   the block which is entered by the branch
  73  * @param irn     the node expressing the switch value
  74  * @param nr      the branch label
  75  * @param env     statistical environment
  76  *
  77  * Branch labels are a simple case. We can replace the value
  78  * by a Const with the branch label.
  79  */
  80 static void handle_case(ir_node *block, ir_node *irn, long nr, env_t *env) {
  81         const ir_edge_t *edge, *next;
  82         ir_node *c = NULL;
  83
  84         if (is_Bad(irn))
  85                 return;
  86
  87         for (edge = get_irn_out_edge_first(irn); edge; edge = next) {
  88                 ir_node *succ = get_edge_src_irn(edge);
  89                 int     pos   = get_edge_src_pos(edge);
  90                 ir_node *blk  = get_effective_use_block(succ, pos);
  91
  92                 next = get_irn_out_edge_next(irn, edge);
  93
  94                 if (block_dominates(block, blk)) {
  95                         /*
  96                          * Ok, we found a user of irn that is placed
  97                          * in a block dominated by the branch block.
  98                          * We can replace the input with the Constant
  99                          * branch label.
 100                          */
 101
 102                         if (! c) {
 103                                 ir_mode *mode = get_irn_mode(irn);
 104                                 ir_type *tp   = get_irn_type(irn);
 105                                 tarval *tv    = new_tarval_from_long(nr, mode);
 106                                 c = new_r_Const_type(current_ir_graph, block, mode, tv, tp);
 107                         }
 108
 109                         set_irn_n(succ, pos, c);
 110                         DBG_OPT_CONFIRM_C(irn, c);
 111 //                      ir_printf("1 Replacing input %d of node %n with %n\n", pos, succ, c);
 112
 113                         env->num_consts += 1;
 114                 }
 115         }
 116 }  /* handle_case */
 117
 118 /**
 119  * Handle a mode_b input of Cond nodes.
 120  *
 121  * @param block     the block which is entered by the branch
 122  * @param selector  the mode_b node expressing the branch condition
 123  * @param pnc       the true/false condition branch
 124  * @param env       statistical environment
 125  */
 126 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env) {
 127         ir_node *cond, *old, *cond_block, *other_blk = NULL, *con = NULL;
 128         ir_node *c_b = NULL, *c_o = NULL;
 129         const ir_edge_t *edge, *next;
 130
 131         for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
 132                 ir_node *user     = get_edge_src_irn(edge);
 133                 int     pos       = get_edge_src_pos(edge);
 134                 ir_node *user_blk = get_effective_use_block(user, pos);
 135
 136                 next = get_irn_out_edge_next(selector, edge);
 137                 if (block_dominates(block, user_blk)) {
 138                         /*
 139                          * Ok, we found a usage of selector in a block
 140                          * dominated by the branch block.
 141                          * We can replace the input with true/false.
 142                          */
 143                         if (con == NULL) {
 144                                 con = new_Const(mode_b, pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
 145                         }
 146                         old = get_irn_n(user, pos);
 147                         set_irn_n(user, pos, con);
 148                         DBG_OPT_CONFIRM_C(old, con);
 149
 150                         // ir_printf("2 Replacing input %d of node %n with %n\n", pos, user, con);
 151
 152                         env->num_consts += 1;
 153                 } else {
 154                         int i, n;
 155
 156                         /* get the other block */
 157                         if (other_blk == NULL) {
 158                                 /* we have already tested, that block has only ONE Cond predecessor */
 159                                 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
 160                                 cond_block = get_nodes_block(cond);
 161                                 foreach_out_edge(cond, edge) {
 162                                         ir_node *proj = get_edge_src_irn(edge);
 163                                         if (get_Proj_proj(proj) == (long)pnc)
 164                                                 continue;
 165                                         edge = get_irn_out_edge_first(proj);
 166                                         other_blk = get_edge_src_irn(edge);
 167                                         break;
 168                                 }
 169                                 assert(other_blk);
 170
 171                                 /*
 172                                  * Note the special case here: if block is a then, there might be no else
 173                                  * block. In that case the other_block is the user_blk itself and pred_block
 174                                  * is the cond_block ...
 175                                  *
 176                                  * Best would be to introduce a block here, removing this critical edge.
 177                                  * For some reasons I cannot repair dominance here, so I have to remove
 178                                  * ALL critical edges...
 179                                  * FIXME: This should not be needed if we could repair dominance ...
 180                                  */
 181                         }
 182
 183                         n = get_Block_n_cfgpreds(user_blk);
 184
 185                         /*
 186                          * We have found a user in a non-dominated block:
 187                          * check, if all its block predecessors are dominated.
 188                          * If yes, place a Phi.
 189                          */
 190                         for (i = n - 1; i >= 0; --i) {
 191                                 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 192
 193                                 if (!block_dominates(block, pred_blk) &&
 194                                     !block_dominates(other_blk, pred_blk)) {
 195                                         /* can't do anything */
 196                                         break;
 197                                 }
 198                         }
 199                         if (i < 0) {
 200                                 ir_node *phi, **in;
 201
 202                                 NEW_ARR_A(ir_node *, in, n);
 203                                 /* ok, ALL predecessors are either dominated by block OR other block */
 204                                 if (c_b == NULL) {
 205                                         ir_node *c_true  = new_Const(mode_b, tarval_b_true);
 206                                         ir_node *c_false = new_Const(mode_b, tarval_b_false);
 207                                         c_b = new_r_Confirm(current_ir_graph, cond_block, selector,
 208                                                 pnc == pn_Cond_true ? c_true : c_false, pn_Cmp_Eq);
 209                                         c_o = new_r_Confirm(current_ir_graph, cond_block, selector,
 210                                                 pnc == pn_Cond_false ? c_true : c_false, pn_Cmp_Eq);
 211                                 }
 212                                 for (i = n - 1; i >= 0; --i) {
 213                                         ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 214
 215                                         if (block_dominates(block, pred_blk))
 216                                                 in[i] = c_b;
 217                                         else
 218                                                 in[i] = c_o;
 219                                 }
 220                                 phi = new_r_Phi(current_ir_graph, user_blk, n, in, mode_b);
 221                                 set_irn_n(user, pos, phi);
 222                         }
 223                 }
 224         }
 225 }
 226
 227 /**
 228  * Handle an IF-branch.
 229  *
 230  * @param block   the block which is entered by the branch
 231  * @param cmp     the Cmp node expressing the branch condition
 232  * @param pnc     the Compare relation for taking this branch
 233  * @param env     statistical environment
 234  */
 235 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env) {
 236         ir_node *left  = get_Cmp_left(cmp);
 237         ir_node *right = get_Cmp_right(cmp);
 238         ir_node *cond_block;
 239         ir_op *op;
 240         const ir_edge_t *edge, *next;
 241
 242         /* Beware of Bads */
 243         if (is_Bad(left) || is_Bad(right))
 244                 return;
 245
 246         op = get_irn_op(left);
 247
 248         /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
 249            These are removed anyway */
 250         if (op == op_Const && is_Const(right))
 251                 return;
 252
 253         /* try to place the constant on the right side for a Confirm */
 254         if (op == op_Const || op == op_SymConst) {
 255                 ir_node *t = left;
 256
 257                 left  = right;
 258                 right = t;
 259
 260                 pnc = get_inversed_pnc(pnc);
 261         }
 262
 263         /*
 264          * First case: both values are identical.
 265          * replace the left one by the right (potentially const) one.
 266          */
 267         if (pnc == pn_Cmp_Eq) {
 268                 cond_block = get_Block_cfgpred_block(block, 0);
 269                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 270                         ir_node *user = get_edge_src_irn(edge);
 271                         int     pos   = get_edge_src_pos(edge);
 272                         ir_node *blk  = get_effective_use_block(user, pos);
 273
 274                         next = get_irn_out_edge_next(left, edge);
 275                         if (block_dominates(block, blk)) {
 276                                 /*
 277                                  * Ok, we found a usage of left in a block
 278                                  * dominated by the branch block.
 279                                  * We can replace the input with right.
 280                                  */
 281                                 set_irn_n(user, pos, right);
 282                                 DBG_OPT_CONFIRM(left, right);
 283
 284 //                              ir_printf("2 Replacing input %d of node %n with %n\n", pos, user, right);
 285
 286                                 env->num_eq += 1;
 287                         } else if (block_dominates(blk, cond_block)) {
 288                                 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
 289                                         /*
 290                                          * left == Const and we found a movable user of left in a
 291                                          * dominator of the Cond block
 292                                          */
 293                                         const ir_edge_t *edge, *next;
 294                                         for (edge = get_irn_out_edge_first(user); edge; edge = next) {
 295                                                 ir_node *usr_of_usr = get_edge_src_irn(edge);
 296                                                 int      npos = get_edge_src_pos(edge);
 297                                                 ir_node *blk  = get_effective_use_block(usr_of_usr, npos);
 298
 299                                                 next = get_irn_out_edge_next(user, edge);
 300                                                 if (block_dominates(block, blk)) {
 301                                                         /*
 302                                                          * The user of the user is dominated by our true/false
 303                                                          * block. So, create a copy of user WITH the constant
 304                                                          * replacing it's pos'th input.
 305                                                          *
 306                                                          * This is always good for unop's and might be good
 307                                                          * for binops.
 308                                                          *
 309                                                          * If user has other user in the false/true block, code
 310                                                          * placement will move it down.
 311                                                          * If there are users in cond block or upper, we create
 312                                                          * "redundant ops", because one will have a const op,
 313                                                          * the other no const ...
 314                                                          */
 315                                                         ir_node *new_op = exact_copy(user);
 316                                                         set_nodes_block(new_op, block);
 317                                                         set_irn_n(new_op, pos, right);
 318                                                         set_irn_n(usr_of_usr, npos, new_op);
 319                                                 }
 320                                         }
 321                                 }
 322                         }
 323                 }
 324         } else { /* not pn_Cmp_Eq cases */
 325                 ir_node *c = NULL;
 326
 327                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 328                         ir_node *succ = get_edge_src_irn(edge);
 329                         int     pos   = get_edge_src_pos(edge);
 330                         ir_node *blk  = get_effective_use_block(succ, pos);
 331
 332                         next = get_irn_out_edge_next(left, edge);
 333                         if (block_dominates(block, blk)) {
 334                                 /*
 335                                  * Ok, we found a usage of left in a block
 336                                  * dominated by the branch block.
 337                                  * We can replace the input with a Confirm(left, pnc, right).
 338                                  */
 339                                 if (! c)
 340                                         c = new_r_Confirm(current_ir_graph, block, left, right, pnc);
 341
 342                                 pos = get_edge_src_pos(edge);
 343                                 set_irn_n(succ, pos, c);
 344 //                              ir_printf("3 Replacing input %d of node %n with %n\n", pos, user, c);
 345
 346                                 env->num_confirms += 1;
 347                         }
 348                 }
 349         }
 350 }  /* handle_if */
 351
 352 /**
 353  * Pre-walker: Called for every block to insert Confirm nodes
 354  */
 355 static void insert_Confirm(ir_node *block, void *env) {
 356         ir_node *cond, *proj, *selector;
 357         ir_mode *mode;
 358
 359         /*
 360          * we can only handle blocks with only ONE control flow
 361          * predecessor yet.
 362          */
 363         if (get_Block_n_cfgpreds(block) != 1)
 364                 return;
 365
 366         proj = get_Block_cfgpred(block, 0);
 367         if (! is_Proj(proj))
 368                 return;
 369
 370         cond = get_Proj_pred(proj);
 371         if (! is_Cond(cond))
 372                 return;
 373
 374         selector = get_Cond_selector(cond);
 375         mode = get_irn_mode(selector);
 376
 377         if (mode == mode_b) {
 378                 ir_node *cmp;
 379                 pn_Cmp pnc;
 380
 381                 handle_modeb(block, selector, get_Proj_proj(proj), env);
 382
 383                 /* this should be an IF, check this */
 384                 if (! is_Proj(selector))
 385                         return;
 386
 387                 cmp = get_Proj_pred(selector);
 388                 if (! is_Cmp(cmp))
 389                         return;
 390
 391                 pnc = get_Proj_proj(selector);
 392
 393                 if (get_Proj_proj(proj) != pn_Cond_true) {
 394                         /* it's the false branch */
 395                         pnc = get_negated_pnc(pnc, mode);
 396                 }
 397 //              ir_printf("At %n using %n Confirm %=\n", block, cmp, pnc);
 398
 399                 handle_if(block, cmp, pnc, env);
 400         } else if (mode_is_int(mode)) {
 401                 long proj_nr = get_Proj_proj(proj);
 402
 403                 /* this is a CASE, but we cannot handle the default case */
 404                 if (proj_nr == get_Cond_defaultProj(cond))
 405                         return;
 406
 407                 handle_case(block, get_Cond_selector(cond), proj_nr, env);
 408         }
 409 }  /* insert_Confirm */
 410
 411 /*
 412  * Construct Confirm nodes
 413  */
 414 void construct_confirms(ir_graph *irg) {
 415         env_t env;
 416         int edges_active = edges_activated(irg);
 417
 418         remove_critical_cf_edges(irg);
 419
 420         /* we need dominance info */
 421         assure_doms(irg);
 422
 423         assert(get_irg_pinned(irg) == op_pin_state_pinned &&
 424                "Nodes must be placed to insert Confirms");
 425
 426         if (! edges_active) {
 427                 /* We need edges */
 428                 edges_activate(irg);
 429         }
 430
 431         env.num_confirms = 0;
 432         env.num_consts   = 0;
 433         env.num_eq       = 0;
 434
 435         /* now, visit all blocks and add Confirms where possible */
 436         irg_block_walk_graph(irg, insert_Confirm, NULL, &env);
 437
 438         if (env.num_confirms | env.num_consts | env.num_eq) {
 439                 /* we have add nodes or changed DF edges */
 440                 set_irg_outs_inconsistent(irg);
 441
 442                 /* the new nodes are not in the loop info */
 443                 set_irg_loopinfo_inconsistent(irg);
 444         }
 445
 446 #if 0
 447         printf("# Confirms inserted : %u\n", env.num_confirms);
 448         printf("# Const replacements: %u\n", env.num_consts);
 449         printf("# node equalities   : %u\n", env.num_eq);
 450 #endif
 451
 452         /* deactivate edges if they where off */
 453         if (! edges_active)
 454                 edges_deactivate(irg);
 455 }  /* construct_confirms */
 456
 457 #if 0
 458 /**
 459  * Post-walker: Remove Confirm nodes
 460  */
 461 static void rem_Confirm(ir_node *n, void *env) {
 462         (void) env;
 463         if (is_Confirm(n)) {
 464                 ir_node *value = get_Confirm_value(n);
 465                 if (value != n)
 466                         exchange(n, value);
 467                 else {
 468                         /*
 469                          * Strange: a Confirm is it's own bound. This can happen
 470                          * in dead blocks when Phi nodes are already removed.
 471                          */
 472                         exchange(n, new_Bad());
 473                 }
 474         }
 475 }  /* rem_Confirm */
 476 #endif
 477
 478 /*
 479  * Remove all Confirm nodes from a graph.
 480  */
 481 void remove_confirms(ir_graph *irg) {
 482         set_opt_remove_confirm(1);
 483         optimize_graph_df(irg);
 484 }  /* remove_confirms */