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 "irtools.h"
  40
  41 /**
  42  * Walker environment.
  43  */
  44 typedef struct _env_t {
  45   unsigned num_confirms;  /**< number of inserted Confirm nodes */
  46   unsigned num_consts;    /**< number of constants placed */
  47   unsigned num_eq;        /**< number of equalities placed */
  48 } env_t;
  49
  50 /**
  51  * Return the effective use block of a node and it's predecessor on
  52  * position pos.
  53  *
  54  * @param node  the node
  55  * @param pos   the position of the used input
  56  *
  57  * This handles correctly Phi nodes.
  58  */
  59 static ir_node *get_effective_use_block(ir_node *node, int pos) {
  60         if (is_Phi(node)) {
  61                 /* the effective use of a Phi is in its predecessor block */
  62                 node = get_irn_n(node, pos);
  63         }
  64         return get_nodes_block(node);
  65 }
  66
  67 /**
  68  * Handle a CASE-branch.
  69  *
  70  * @param block   the block which is entered by the branch
  71  * @param irn     the node expressing the switch value
  72  * @param nr      the branch label
  73  * @param env     statistical environment
  74  *
  75  * Branch labels are a simple case. We can replace the value
  76  * by a Const with the branch label.
  77  */
  78 static void handle_case(ir_node *block, ir_node *irn, long nr, env_t *env) {
  79         const ir_edge_t *edge, *next;
  80         ir_node *c = NULL;
  81
  82         if (is_Bad(irn))
  83                 return;
  84
  85         for (edge = get_irn_out_edge_first(irn); edge; edge = next) {
  86                 ir_node *succ = get_edge_src_irn(edge);
  87                 int     pos   = get_edge_src_pos(edge);
  88                 ir_node *blk  = get_effective_use_block(succ, pos);
  89
  90                 next = get_irn_out_edge_next(irn, edge);
  91
  92                 if (block_dominates(block, blk)) {
  93                         /*
  94                          * Ok, we found a user of irn that is placed
  95                          * in a block dominated by the branch block.
  96                          * We can replace the input with the Constant
  97                          * branch label.
  98                          */
  99
 100                         if (! c) {
 101                                 ir_mode *mode = get_irn_mode(irn);
 102                                 ir_type *tp   = get_irn_type(irn);
 103                                 tarval *tv    = new_tarval_from_long(nr, mode);
 104                                 c = new_r_Const_type(current_ir_graph, block, mode, tv, tp);
 105                         }
 106
 107                         set_irn_n(succ, pos, c);
 108                         DBG_OPT_CONFIRM_C(irn, c);
 109 //                      ir_printf("1 Replacing input %d of node %n with %n\n", pos, succ, c);
 110
 111                         env->num_consts += 1;
 112                 }
 113         }
 114 }  /* handle_case */
 115
 116 /**
 117  * Handle a mode_b input of Cond nodes.
 118  *
 119  * @param block     the block which is entered by the branch
 120  * @param selector  the mode_b node expressing the branch condition
 121  * @param pnc       the true/false condition branch
 122  * @param env       statistical environment
 123  */
 124 static void handle_modeb(ir_node *block, ir_node *selector, pn_Cond pnc, env_t *env) {
 125         ir_node *cond, *old, *cond_block, *other_blk = NULL, *con = NULL;
 126         ir_node *c_b = NULL, *c_o = NULL;
 127         const ir_edge_t *edge, *next;
 128
 129         for (edge = get_irn_out_edge_first(selector); edge; edge = next) {
 130                 ir_node *user     = get_edge_src_irn(edge);
 131                 int     pos       = get_edge_src_pos(edge);
 132                 ir_node *user_blk = get_effective_use_block(user, pos);
 133
 134                 next = get_irn_out_edge_next(selector, edge);
 135                 if (block_dominates(block, user_blk)) {
 136                         /*
 137                          * Ok, we found a usage of selector in a block
 138                          * dominated by the branch block.
 139                          * We can replace the input with true/false.
 140                          */
 141                         if (con == NULL) {
 142                                 con = new_Const(mode_b, pnc == pn_Cond_true ? tarval_b_true : tarval_b_false);
 143                         }
 144                         old = get_irn_n(user, pos);
 145                         set_irn_n(user, pos, con);
 146                         DBG_OPT_CONFIRM_C(old, con);
 147
 148                         // ir_printf("2 Replacing input %d of node %n with %n\n", pos, user, con);
 149
 150                         env->num_consts += 1;
 151                 } else {
 152                         int i, n;
 153
 154                         /* get the other block */
 155                         if (other_blk == NULL) {
 156                                 /* we have already tested, that block has only ONE Cond predecessor */
 157                                 cond = get_Proj_pred(get_Block_cfgpred(block, 0));
 158                                 cond_block = get_nodes_block(cond);
 159                                 foreach_out_edge(cond, edge) {
 160                                         ir_node *proj = get_edge_src_irn(edge);
 161                                         if (get_Proj_proj(proj) == pnc)
 162                                                 continue;
 163                                         edge = get_irn_out_edge_first(proj);
 164                                         other_blk = get_edge_src_irn(edge);
 165                                         break;
 166                                 }
 167                                 assert(other_blk);
 168                         }
 169
 170                         n = get_Block_n_cfgpreds(user_blk);
 171
 172                         /*
 173                          * We have found a user in a non-dominated block:
 174                          * check, if all its block predecessors are dominated.
 175                          * If yes, place a Phi.
 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                         for (i = n - 1; i >= 0; --i) {
 182                                 ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 183
 184                                 if (cond_block != pred_blk &&
 185                                         !block_dominates(block, pred_blk) &&
 186                                         !block_dominates(other_blk, pred_blk)) {
 187                                         /* can't do anything */
 188                                         break;
 189                                 }
 190                         }
 191                         if (i < 0) {
 192                                 ir_node *phi, **in;
 193
 194                                 NEW_ARR_A(ir_node *, in, n);
 195                                 /* ok, ALL predecessors are either dominated by block OR other block */
 196                                 if (c_b == NULL) {
 197                                         ir_node *c_true  = new_Const(mode_b, tarval_b_true);
 198                                         ir_node *c_false = new_Const(mode_b, tarval_b_false);
 199                                         c_b = new_r_Confirm(current_ir_graph, cond_block, selector,
 200                                                 pnc == pn_Cond_true ? c_true : c_false, pn_Cmp_Eq);
 201                                         c_o = new_r_Confirm(current_ir_graph, cond_block, selector,
 202                                                 pnc == pn_Cond_false ? c_true : c_false, pn_Cmp_Eq);
 203                                 }
 204                                 for (i = n - 1; i >= 0; --i) {
 205                                         ir_node *pred_blk = get_Block_cfgpred_block(user_blk, i);
 206
 207                                         if (block_dominates(block, pred_blk))
 208                                                 in[i] = c_b;
 209                                         else
 210                                                 in[i] = c_o;
 211                                 }
 212                                 phi = new_r_Phi(current_ir_graph, user_blk, n, in, mode_b);
 213                                 set_irn_n(user, pos, phi);
 214                         }
 215                 }
 216         }
 217 }
 218
 219 /**
 220  * Handle an IF-branch.
 221  *
 222  * @param block   the block which is entered by the branch
 223  * @param cmp     the Cmp node expressing the branch condition
 224  * @param pnc     the Compare relation for taking this branch
 225  * @param env     statistical environment
 226  */
 227 static void handle_if(ir_node *block, ir_node *cmp, pn_Cmp pnc, env_t *env) {
 228         ir_node *left  = get_Cmp_left(cmp);
 229         ir_node *right = get_Cmp_right(cmp);
 230         ir_node *cond_block;
 231         ir_op *op;
 232         const ir_edge_t *edge, *next;
 233
 234         /* Beware of Bads */
 235         if (is_Bad(left) || is_Bad(right))
 236                 return;
 237
 238         op = get_irn_op(left);
 239
 240         /* Do not create Confirm nodes for Cmp(Const, Const) constructs.
 241            These are removed anyway */
 242         if (op == op_Const && is_Const(right))
 243                 return;
 244
 245         /* try to place the constant on the right side for a Confirm */
 246         if (op == op_Const || op == op_SymConst) {
 247                 ir_node *t = left;
 248
 249                 left  = right;
 250                 right = t;
 251
 252                 pnc = get_inversed_pnc(pnc);
 253         }
 254
 255         /*
 256          * First case: both values are identical.
 257          * replace the left one by the right (potentially const) one.
 258          */
 259         if (pnc == pn_Cmp_Eq) {
 260                 cond_block = get_Block_cfgpred_block(block, 0);
 261                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 262                         ir_node *user = get_edge_src_irn(edge);
 263                         int     pos   = get_edge_src_pos(edge);
 264                         ir_node *blk  = get_effective_use_block(user, pos);
 265
 266                         next = get_irn_out_edge_next(left, edge);
 267                         if (block_dominates(block, blk)) {
 268                                 /*
 269                                  * Ok, we found a usage of left in a block
 270                                  * dominated by the branch block.
 271                                  * We can replace the input with right.
 272                                  */
 273                                 set_irn_n(user, pos, right);
 274                                 DBG_OPT_CONFIRM(left, right);
 275
 276 //                              ir_printf("2 Replacing input %d of node %n with %n\n", pos, user, right);
 277
 278                                 env->num_eq += 1;
 279                         } else if (block_dominates(blk, cond_block)) {
 280                                 if (is_Const(right) && get_irn_pinned(user) == op_pin_state_floats) {
 281                                         /*
 282                                          * left == Const and we found a movable user of left in a
 283                                          * dominator of the Cond block
 284                                          */
 285                                         const ir_edge_t *edge, *next;
 286                                         for (edge = get_irn_out_edge_first(user); edge; edge = next) {
 287                                                 ir_node *usr_of_usr = get_edge_src_irn(edge);
 288                                                 int      npos = get_edge_src_pos(edge);
 289                                                 ir_node *blk  = get_effective_use_block(usr_of_usr, npos);
 290
 291                                                 next = get_irn_out_edge_next(user, edge);
 292                                                 if (block_dominates(block, blk)) {
 293                                                         /*
 294                                                          * The user of the user is dominated by our true/false
 295                                                          * block. So, create a copy of user WITH the constant
 296                                                          * replacing it's pos'th input.
 297                                                          *
 298                                                          * This is always good for unop's and might be good
 299                                                          * for binops.
 300                                                          *
 301                                                          * If user has other user in the false/true block, code
 302                                                          * placement will move it down.
 303                                                          * If there are users in cond block or upper, we create
 304                                                          * "redundant ops", because one will have a const op,
 305                                                          * the other no const ...
 306                                                          */
 307                                                         ir_node *new_op = exact_copy(user);
 308                                                         set_nodes_block(new_op, block);
 309                                                         set_irn_n(new_op, pos, right);
 310                                                         set_irn_n(usr_of_usr, npos, new_op);
 311                                                 }
 312                                         }
 313                                 }
 314                         }
 315                 }
 316         } else { /* not pn_Cmp_Eq cases */
 317                 ir_node *c = NULL;
 318
 319                 for (edge = get_irn_out_edge_first(left); edge; edge = next) {
 320                         ir_node *succ = get_edge_src_irn(edge);
 321                         int     pos   = get_edge_src_pos(edge);
 322                         ir_node *blk  = get_effective_use_block(succ, pos);
 323
 324                         next = get_irn_out_edge_next(left, edge);
 325                         if (block_dominates(block, blk)) {
 326                                 /*
 327                                  * Ok, we found a usage of left in a block
 328                                  * dominated by the branch block.
 329                                  * We can replace the input with a Confirm(left, pnc, right).
 330                                  */
 331                                 if (! c)
 332                                         c = new_r_Confirm(current_ir_graph, block, left, right, pnc);
 333
 334                                 pos = get_edge_src_pos(edge);
 335                                 set_irn_n(succ, pos, c);
 336 //                              ir_printf("3 Replacing input %d of node %n with %n\n", pos, user, c);
 337
 338                                 env->num_confirms += 1;
 339                         }
 340                 }
 341         }
 342 }  /* handle_if */
 343
 344 /**
 345  * Pre-walker: Called for every block to insert Confirm nodes
 346  */
 347 static void insert_Confirm(ir_node *block, void *env) {
 348         ir_node *cond, *proj, *selector;
 349         ir_mode *mode;
 350
 351         /*
 352          * we can only handle blocks with only ONE control flow
 353          * predecessor yet.
 354          */
 355         if (get_Block_n_cfgpreds(block) != 1)
 356                 return;
 357
 358         proj = get_Block_cfgpred(block, 0);
 359         if (! is_Proj(proj))
 360                 return;
 361
 362         cond = get_Proj_pred(proj);
 363         if (! is_Cond(cond))
 364                 return;
 365
 366         selector = get_Cond_selector(cond);
 367         mode = get_irn_mode(selector);
 368
 369         if (mode == mode_b) {
 370                 ir_node *cmp;
 371                 pn_Cmp pnc;
 372
 373                 handle_modeb(block, selector, get_Proj_proj(proj), env);
 374
 375                 /* this should be an IF, check this */
 376                 if (get_irn_op(selector) != op_Proj)
 377                         return;
 378
 379                 cmp = get_Proj_pred(selector);
 380                 if (get_irn_op(cmp) != op_Cmp)
 381                         return;
 382
 383                 pnc = get_Proj_proj(selector);
 384
 385                 if (get_Proj_proj(proj) != pn_Cond_true) {
 386                         /* it's the false branch */
 387                         pnc = get_negated_pnc(pnc, mode);
 388                 }
 389 //              ir_printf("At %n using %n Confirm %=\n", block, cmp, pnc);
 390
 391                 handle_if(block, cmp, pnc, env);
 392         } else if (mode_is_int(mode)) {
 393                 long proj_nr = get_Proj_proj(proj);
 394
 395                 /* this is a CASE, but we cannot handle the default case */
 396                 if (proj_nr == get_Cond_defaultProj(cond))
 397                         return;
 398
 399                 handle_case(block, get_Cond_selector(cond), proj_nr, env);
 400         }
 401 }  /* insert_Confirm */
 402
 403 /*
 404  * Construct Confirm nodes
 405  */
 406 void construct_confirms(ir_graph *irg) {
 407         env_t env;
 408         int edges_active = edges_activated(irg);
 409
 410         /* we need dominance info */
 411         assure_doms(irg);
 412
 413         assert(get_irg_pinned(irg) == op_pin_state_pinned &&
 414                "Nodes must be placed to insert Confirms");
 415
 416         if (! edges_active) {
 417                 /* We need edges */
 418                 edges_activate(irg);
 419         }
 420
 421         env.num_confirms = 0;
 422         env.num_consts   = 0;
 423         env.num_eq       = 0;
 424
 425         /* now, visit all blocks and add Confirms where possible */
 426         irg_block_walk_graph(irg, insert_Confirm, NULL, &env);
 427
 428         if (env.num_confirms | env.num_consts | env.num_eq) {
 429                 /* we have add nodes or changed DF edges */
 430                 set_irg_outs_inconsistent(irg);
 431
 432                 /* the new nodes are not in the loop info */
 433                 set_irg_loopinfo_inconsistent(irg);
 434         }
 435
 436 #if 0
 437         printf("# Confirms inserted : %u\n", env.num_confirms);
 438         printf("# Const replacements: %u\n", env.num_consts);
 439         printf("# node equalities   : %u\n", env.num_eq);
 440 #endif
 441
 442         /* deactivate edges if they where off */
 443         if (! edges_active)
 444                 edges_deactivate(irg);
 445 }  /* construct_confirms */
 446
 447 /**
 448  * Post-walker: Remove Confirm nodes
 449  */
 450 static void rem_Confirm(ir_node *n, void *env) {
 451         (void) env;
 452         if (get_irn_op(n) == op_Confirm) {
 453                 ir_node *value = get_Confirm_value(n);
 454                 if (value != n)
 455                         exchange(n, value);
 456                 else {
 457                         /*
 458                          * Strange: a Confirm is it's own bound. This can happen
 459                          * in dead blocks when Phi nodes are already removed.
 460                          */
 461                         exchange(n, new_Bad());
 462                 }
 463         }
 464 }  /* rem_Confirm */
 465
 466 /*
 467  * Remove all Confirm nodes from a graph.
 468  */
 469 void remove_confirms(ir_graph *irg) {
 470         set_opt_remove_confirm(1);
 471         optimize_graph_df(irg);
 472 }  /* remove_confirms */