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