nsz Git - libfirm/blob - ir/opt/ldstopt.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   Load/Store optimizations.
  23  * @author  Michael Beck
  24  * @version $Id$
  25  */
  26 #ifdef HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <string.h>
  31
  32 #include "iroptimize.h"
  33 #include "irnode_t.h"
  34 #include "irgraph_t.h"
  35 #include "irmode_t.h"
  36 #include "iropt_t.h"
  37 #include "ircons_t.h"
  38 #include "irgmod.h"
  39 #include "irgwalk.h"
  40 #include "irvrfy.h"
  41 #include "tv_t.h"
  42 #include "dbginfo_t.h"
  43 #include "iropt_dbg.h"
  44 #include "irflag_t.h"
  45 #include "array.h"
  46 #include "irhooks.h"
  47 #include "iredges.h"
  48 #include "irtools.h"
  49 #include "opt_polymorphy.h"
  50 #include "irmemory.h"
  51 #include "xmalloc.h"
  52 #include "irphase_t.h"
  53 #include "irgopt.h"
  54 #include "debug.h"
  55
  56 /** The debug handle. */
  57 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
  58
  59 #ifdef DO_CACHEOPT
  60 #include "cacheopt/cachesim.h"
  61 #endif
  62
  63 #undef IMAX
  64 #define IMAX(a,b)       ((a) > (b) ? (a) : (b))
  65
  66 #define MAX_PROJ        IMAX(IMAX(pn_Load_max, pn_Store_max), pn_Call_max)
  67
  68 enum changes_t {
  69         DF_CHANGED = 1,       /**< data flow changed */
  70         CF_CHANGED = 2,       /**< control flow changed */
  71 };
  72
  73 /**
  74  * walker environment
  75  */
  76 typedef struct _walk_env_t {
  77         struct obstack obst;          /**< list of all stores */
  78         unsigned changes;             /**< a bitmask of graph changes */
  79 } walk_env_t;
  80
  81 /** A Load/Store info. */
  82 typedef struct _ldst_info_t {
  83         ir_node  *projs[MAX_PROJ];    /**< list of Proj's of this node */
  84         ir_node  *exc_block;          /**< the exception block if available */
  85         int      exc_idx;             /**< predecessor index in the exception block */
  86         unsigned visited;             /**< visited counter for breaking loops */
  87 } ldst_info_t;
  88
  89 /**
  90  * flags for control flow.
  91  */
  92 enum block_flags_t {
  93         BLOCK_HAS_COND = 1,      /**< Block has conditional control flow */
  94         BLOCK_HAS_EXC  = 2       /**< Block has exceptional control flow */
  95 };
  96
  97 /**
  98  * a Block info.
  99  */
 100 typedef struct _block_info_t {
 101         unsigned flags;               /**< flags for the block */
 102 } block_info_t;
 103
 104 /** the master visited flag for loop detection. */
 105 static unsigned master_visited = 0;
 106
 107 #define INC_MASTER()       ++master_visited
 108 #define MARK_NODE(info)    (info)->visited = master_visited
 109 #define NODE_VISITED(info) (info)->visited >= master_visited
 110
 111 /**
 112  * get the Load/Store info of a node
 113  */
 114 static ldst_info_t *get_ldst_info(ir_node *node, struct obstack *obst) {
 115         ldst_info_t *info = get_irn_link(node);
 116
 117         if (! info) {
 118                 info = obstack_alloc(obst, sizeof(*info));
 119                 memset(info, 0, sizeof(*info));
 120                 set_irn_link(node, info);
 121         }
 122         return info;
 123 }  /* get_ldst_info */
 124
 125 /**
 126  * get the Block info of a node
 127  */
 128 static block_info_t *get_block_info(ir_node *node, struct obstack *obst) {
 129         block_info_t *info = get_irn_link(node);
 130
 131         if (! info) {
 132                 info = obstack_alloc(obst, sizeof(*info));
 133                 memset(info, 0, sizeof(*info));
 134                 set_irn_link(node, info);
 135         }
 136         return info;
 137 }  /* get_block_info */
 138
 139 /**
 140  * update the projection info for a Load/Store
 141  */
 142 static unsigned update_projs(ldst_info_t *info, ir_node *proj)
 143 {
 144         long nr = get_Proj_proj(proj);
 145
 146         assert(0 <= nr && nr <= MAX_PROJ && "Wrong proj from LoadStore");
 147
 148         if (info->projs[nr]) {
 149                 /* there is already one, do CSE */
 150                 exchange(proj, info->projs[nr]);
 151                 return DF_CHANGED;
 152         }
 153         else {
 154                 info->projs[nr] = proj;
 155                 return 0;
 156         }
 157 }  /* update_projs */
 158
 159 /**
 160  * update the exception block info for a Load/Store node.
 161  *
 162  * @param info   the load/store info struct
 163  * @param block  the exception handler block for this load/store
 164  * @param pos    the control flow input of the block
 165  */
 166 static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
 167 {
 168         assert(info->exc_block == NULL && "more than one exception block found");
 169
 170         info->exc_block = block;
 171         info->exc_idx   = pos;
 172         return 0;
 173 }  /* update_exc */
 174
 175 /** Return the number of uses of an address node */
 176 #define get_irn_n_uses(adr)     get_irn_n_edges(adr)
 177
 178 /**
 179  * walker, collects all Load/Store/Proj nodes
 180  *
 181  * walks from Start -> End
 182  */
 183 static void collect_nodes(ir_node *node, void *env)
 184 {
 185         ir_opcode   opcode = get_irn_opcode(node);
 186         ir_node     *pred, *blk, *pred_blk;
 187         ldst_info_t *ldst_info;
 188         walk_env_t  *wenv = env;
 189
 190         if (opcode == iro_Proj) {
 191                 pred   = get_Proj_pred(node);
 192                 opcode = get_irn_opcode(pred);
 193
 194                 if (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call) {
 195                         ldst_info = get_ldst_info(pred, &wenv->obst);
 196
 197                         wenv->changes |= update_projs(ldst_info, node);
 198
 199                         /*
 200                          * Place the Proj's to the same block as the
 201                          * predecessor Load. This is always ok and prevents
 202                          * "non-SSA" form after optimizations if the Proj
 203                          * is in a wrong block.
 204                          */
 205                         blk      = get_nodes_block(node);
 206                         pred_blk = get_nodes_block(pred);
 207                         if (blk != pred_blk) {
 208                                 wenv->changes |= DF_CHANGED;
 209                                 set_nodes_block(node, pred_blk);
 210                         }
 211                 }
 212         } else if (opcode == iro_Block) {
 213                 int i;
 214
 215                 for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
 216                         ir_node      *pred_block, *proj;
 217                         block_info_t *bl_info;
 218                         int          is_exc = 0;
 219
 220                         pred = proj = get_Block_cfgpred(node, i);
 221
 222                         if (is_Proj(proj)) {
 223                                 pred   = get_Proj_pred(proj);
 224                                 is_exc = get_Proj_proj(proj) == pn_Generic_X_except;
 225                         }
 226
 227                         /* ignore Bad predecessors, they will be removed later */
 228                         if (is_Bad(pred))
 229                                 continue;
 230
 231                         pred_block = get_nodes_block(pred);
 232                         bl_info    = get_block_info(pred_block, &wenv->obst);
 233
 234                         if (is_fragile_op(pred) && is_exc)
 235                                 bl_info->flags |= BLOCK_HAS_EXC;
 236                         else if (is_irn_forking(pred))
 237                                 bl_info->flags |= BLOCK_HAS_COND;
 238
 239                         opcode = get_irn_opcode(pred);
 240                         if (is_exc && (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call)) {
 241                                 ldst_info = get_ldst_info(pred, &wenv->obst);
 242
 243                                 wenv->changes |= update_exc(ldst_info, node, i);
 244                         }
 245                 }
 246         }
 247 }  /* collect_nodes */
 248
 249 /**
 250  * Returns an entity if the address ptr points to a constant one.
 251  *
 252  * @param ptr  the address
 253  *
 254  * @return an entity or NULL
 255  */
 256 static ir_entity *find_constant_entity(ir_node *ptr)
 257 {
 258         for (;;) {
 259                 if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
 260                         ir_entity *ent = get_SymConst_entity(ptr);
 261                         if (variability_constant == get_entity_variability(ent))
 262                                 return ent;
 263                         return NULL;
 264                 } else if (is_Sel(ptr)) {
 265                         ir_entity *ent = get_Sel_entity(ptr);
 266                         ir_type   *tp  = get_entity_owner(ent);
 267
 268                         /* Do not fiddle with polymorphism. */
 269                         if (is_Class_type(get_entity_owner(ent)) &&
 270                                 ((get_entity_n_overwrites(ent)    != 0) ||
 271                                 (get_entity_n_overwrittenby(ent) != 0)   ) )
 272                                 return NULL;
 273
 274                         if (is_Array_type(tp)) {
 275                                 /* check bounds */
 276                                 int i, n;
 277
 278                                 for (i = 0, n = get_Sel_n_indexs(ptr); i < n; ++i) {
 279                                         ir_node *bound;
 280                                         tarval *tlower, *tupper;
 281                                         ir_node *index = get_Sel_index(ptr, i);
 282                                         tarval *tv     = computed_value(index);
 283
 284                                         /* check if the index is constant */
 285                                         if (tv == tarval_bad)
 286                                                 return NULL;
 287
 288                                         bound  = get_array_lower_bound(tp, i);
 289                                         tlower = computed_value(bound);
 290                                         bound  = get_array_upper_bound(tp, i);
 291                                         tupper = computed_value(bound);
 292
 293                                         if (tlower == tarval_bad || tupper == tarval_bad)
 294                                                 return NULL;
 295
 296                                         if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
 297                                                 return NULL;
 298                                         if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
 299                                                 return NULL;
 300
 301                                         /* ok, bounds check finished */
 302                                 }
 303                         }
 304
 305                         if (variability_constant == get_entity_variability(ent))
 306                                 return ent;
 307
 308                         /* try next */
 309                         ptr = get_Sel_ptr(ptr);
 310                 } else if (is_Add(ptr)) {
 311                         ir_node *l = get_Add_left(ptr);
 312                         ir_node *r = get_Add_right(ptr);
 313
 314                         if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
 315                                 ptr = l;
 316                         else if (get_irn_mode(r) == get_irn_mode(ptr) && is_Const(l))
 317                                 ptr = r;
 318                         else
 319                                 return NULL;
 320
 321                         /* for now, we support only one addition, reassoc should fold all others */
 322                         if (! is_SymConst(ptr) && !is_Sel(ptr))
 323                                 return NULL;
 324                 } else if (is_Sub(ptr)) {
 325                         ir_node *l = get_Sub_left(ptr);
 326                         ir_node *r = get_Sub_right(ptr);
 327
 328                         if (get_irn_mode(l) == get_irn_mode(ptr) &&     is_Const(r))
 329                                 ptr = l;
 330                         else
 331                                 return NULL;
 332                         /* for now, we support only one substraction, reassoc should fold all others */
 333                         if (! is_SymConst(ptr) && !is_Sel(ptr))
 334                                 return NULL;
 335                 } else
 336                         return NULL;
 337         }
 338 }  /* find_constant_entity */
 339
 340 /**
 341  * Return the Selection index of a Sel node from dimension n
 342  */
 343 static long get_Sel_array_index_long(ir_node *n, int dim) {
 344         ir_node *index = get_Sel_index(n, dim);
 345         assert(is_Const(index));
 346         return get_tarval_long(get_Const_tarval(index));
 347 }  /* get_Sel_array_index_long */
 348
 349 /**
 350  * Returns the accessed component graph path for an
 351  * node computing an address.
 352  *
 353  * @param ptr    the node computing the address
 354  * @param depth  current depth in steps upward from the root
 355  *               of the address
 356  */
 357 static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) {
 358         compound_graph_path *res = NULL;
 359         ir_entity           *root, *field, *ent;
 360         int                 path_len, pos, idx;
 361         tarval              *tv;
 362         ir_type             *tp;
 363
 364         if (is_SymConst(ptr)) {
 365                 /* a SymConst. If the depth is 0, this is an access to a global
 366                  * entity and we don't need a component path, else we know
 367                  * at least it's length.
 368                  */
 369                 assert(get_SymConst_kind(ptr) == symconst_addr_ent);
 370                 root = get_SymConst_entity(ptr);
 371                 res = (depth == 0) ? NULL : new_compound_graph_path(get_entity_type(root), depth);
 372         } else if (is_Sel(ptr)) {
 373                 /* it's a Sel, go up until we find the root */
 374                 res = rec_get_accessed_path(get_Sel_ptr(ptr), depth+1);
 375                 if (res == NULL)
 376                         return NULL;
 377
 378                 /* fill up the step in the path at the current position */
 379                 field    = get_Sel_entity(ptr);
 380                 path_len = get_compound_graph_path_length(res);
 381                 pos      = path_len - depth - 1;
 382                 set_compound_graph_path_node(res, pos, field);
 383
 384                 if (is_Array_type(get_entity_owner(field))) {
 385                         assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
 386                         set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
 387                 }
 388         } else if (is_Add(ptr)) {
 389                 ir_node *l = get_Add_left(ptr);
 390                 ir_node *r = get_Add_right(ptr);
 391                 ir_mode *mode;
 392
 393                 if (is_Const(r)) {
 394                         ptr = l;
 395                         tv  = get_Const_tarval(r);
 396                 } else {
 397                         ptr = r;
 398                         tv  = get_Const_tarval(l);
 399                 }
 400 ptr_arith:
 401                 mode = get_tarval_mode(tv);
 402
 403                 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
 404                 if (is_Sel(ptr)) {
 405                         field = get_Sel_entity(ptr);
 406                 } else {
 407                         field = get_SymConst_entity(ptr);
 408                 }
 409                 idx = 0;
 410                 for (ent = field;;) {
 411                         tp = get_entity_type(ent);
 412                         if (! is_Array_type(tp))
 413                                 break;
 414                         ent = get_array_element_entity(tp);
 415                         ++idx;
 416                 }
 417                 /* should be at least ONE array */
 418                 if (idx == 0)
 419                         return NULL;
 420
 421                 res = rec_get_accessed_path(ptr, depth + idx);
 422                 if (res == NULL)
 423                         return NULL;
 424
 425                 path_len = get_compound_graph_path_length(res);
 426                 pos      = path_len - depth - idx;
 427
 428                 for (ent = field;;) {
 429                         unsigned size;
 430                         tarval   *sz, *tv_index, *tlower, *tupper;
 431                         long     index;
 432                         ir_node  *bound;
 433
 434                         tp = get_entity_type(ent);
 435                         if (! is_Array_type(tp))
 436                                 break;
 437                         ent = get_array_element_entity(tp);
 438                         set_compound_graph_path_node(res, pos, ent);
 439
 440                         size = get_type_size_bytes(get_entity_type(ent));
 441                         sz   = new_tarval_from_long(size, mode);
 442
 443                         tv_index = tarval_div(tv, sz);
 444                         tv       = tarval_mod(tv, sz);
 445
 446                         if (tv_index == tarval_bad || tv == tarval_bad)
 447                                 return NULL;
 448
 449                         assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
 450                         bound  = get_array_lower_bound(tp, 0);
 451                         tlower = computed_value(bound);
 452                         bound  = get_array_upper_bound(tp, 0);
 453                         tupper = computed_value(bound);
 454
 455                         if (tlower == tarval_bad || tupper == tarval_bad)
 456                                 return NULL;
 457
 458                         if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
 459                                 return NULL;
 460                         if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
 461                                 return NULL;
 462
 463                         /* ok, bounds check finished */
 464                         index = get_tarval_long(tv_index);
 465                         set_compound_graph_path_array_index(res, pos, index);
 466                         ++pos;
 467                 }
 468                 if (! tarval_is_null(tv)) {
 469                         /* hmm, wrong access */
 470                         return NULL;
 471                 }
 472         } else if (is_Sub(ptr)) {
 473                 ir_node *l = get_Sub_left(ptr);
 474                 ir_node *r = get_Sub_right(ptr);
 475
 476                 ptr = l;
 477                 tv  = get_Const_tarval(r);
 478                 tv  = tarval_neg(tv);
 479                 goto ptr_arith;
 480         }
 481         return res;
 482 }  /* rec_get_accessed_path */
 483
 484 /**
 485  * Returns an access path or NULL.  The access path is only
 486  * valid, if the graph is in phase_high and _no_ address computation is used.
 487  */
 488 static compound_graph_path *get_accessed_path(ir_node *ptr) {
 489         return rec_get_accessed_path(ptr, 0);
 490 }  /* get_accessed_path */
 491
 492 typedef struct path_entry {
 493         ir_entity         *ent;
 494         struct path_entry *next;
 495         long              index;
 496 } path_entry;
 497
 498 static ir_node *rec_find_compound_ent_value(ir_node *ptr, path_entry *next) {
 499         path_entry       entry, *p;
 500         ir_entity        *ent;
 501         ir_initializer_t *initializer;
 502
 503         entry.next      = next;
 504
 505         if (is_Sel(ptr)) {
 506                 ir_entity *field;
 507                 ir_type   *tp;
 508
 509                 entry.ent = field = get_Sel_entity(ptr);
 510                 tp = get_entity_owner(field);
 511                 if (is_Array_type(tp)) {
 512                         assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
 513                         entry.index     = get_Sel_array_index_long(ptr, 0) - get_array_lower_bound_int(tp, 0);
 514                 } else {
 515                         int i, n_members = get_compound_n_members(tp);
 516                         for (i = 0; i < n_members; ++i) {
 517                                 if (get_compound_member(tp, i) == field)
 518                                         break;
 519                         }
 520                         if (i >= n_members) {
 521                                 /* not found: should NOT happen */
 522                                 return NULL;
 523                         }
 524                         entry.index = i;
 525                 }
 526                 return rec_find_compound_ent_value(get_Sel_ptr(ptr), &entry);
 527         }
 528
 529         /* found the end */
 530         assert(is_SymConst(ptr));
 531
 532         ent = get_SymConst_entity(ptr);
 533         initializer = get_entity_initializer(ent);
 534         for (p = next; p != NULL; p = p->next) {
 535                 unsigned n;
 536
 537                 if (initializer->kind != IR_INITIALIZER_COMPOUND)
 538                         return NULL;
 539
 540                 n = get_initializer_compound_n_entries(initializer);
 541                 if (p->index >= n)
 542                         return NULL;
 543                 initializer = get_initializer_compound_value(initializer, p->index);
 544         }
 545
 546         switch (initializer->kind) {
 547         case IR_INITIALIZER_CONST:
 548                 return get_initializer_const_value(initializer);
 549         case IR_INITIALIZER_TARVAL:
 550         case IR_INITIALIZER_NULL:
 551         default:
 552                 return NULL;
 553         }
 554 }
 555
 556 static ir_node *find_compound_ent_value(ir_node *ptr) {
 557         return rec_find_compound_ent_value(ptr, NULL);
 558 }
 559
 560 /* forward */
 561 static void reduce_adr_usage(ir_node *ptr);
 562
 563 /**
 564  * Update a Load that may lost it's usage.
 565  */
 566 static void handle_load_update(ir_node *load) {
 567         ldst_info_t *info = get_irn_link(load);
 568
 569         /* do NOT touch volatile loads for now */
 570         if (get_Load_volatility(load) == volatility_is_volatile)
 571                 return;
 572
 573         if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
 574                 ir_node *ptr = get_Load_ptr(load);
 575                 ir_node *mem = get_Load_mem(load);
 576
 577                 /* a Load which value is neither used nor exception checked, remove it */
 578                 exchange(info->projs[pn_Load_M], mem);
 579                 if (info->projs[pn_Load_X_regular])
 580                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 581                 kill_node(load);
 582                 reduce_adr_usage(ptr);
 583         }
 584 }  /* handle_load_update */
 585
 586 /**
 587  * A Use of an address node is vanished. Check if this was a Proj
 588  * node and update the counters.
 589  */
 590 static void reduce_adr_usage(ir_node *ptr) {
 591         if (is_Proj(ptr)) {
 592                 if (get_irn_n_edges(ptr) <= 0) {
 593                         /* this Proj is dead now */
 594                         ir_node *pred = get_Proj_pred(ptr);
 595
 596                         if (is_Load(pred)) {
 597                                 ldst_info_t *info = get_irn_link(pred);
 598                                 info->projs[get_Proj_proj(ptr)] = NULL;
 599
 600                                 /* this node lost it's result proj, handle that */
 601                                 handle_load_update(pred);
 602                         }
 603                 }
 604         }
 605 }  /* reduce_adr_usage */
 606
 607 /**
 608  * Check, if an already existing value of mode old_mode can be converted
 609  * into the needed one new_mode without loss.
 610  */
 611 static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode) {
 612         if (old_mode == new_mode)
 613                 return 1;
 614
 615         /* if both modes are two-complement ones, we can always convert the
 616            Stored value into the needed one. */
 617         if (get_mode_size_bits(old_mode) >= get_mode_size_bits(new_mode) &&
 618                   get_mode_arithmetic(old_mode) == irma_twos_complement &&
 619                   get_mode_arithmetic(new_mode) == irma_twos_complement)
 620                 return 1;
 621         return 0;
 622 }  /* can_use_stored_value */
 623
 624 /**
 625  * Check whether a Call is at least pure, ie. does only read memory.
 626  */
 627 static unsigned is_Call_pure(ir_node *call) {
 628         ir_type *call_tp = get_Call_type(call);
 629         unsigned prop = get_method_additional_properties(call_tp);
 630
 631         /* check first the call type */
 632         if ((prop & (mtp_property_const|mtp_property_pure)) == 0) {
 633                 /* try the called entity */
 634                 ir_node *ptr = get_Call_ptr(call);
 635
 636                 if (is_Global(ptr)) {
 637                         ir_entity *ent = get_Global_entity(ptr);
 638
 639                         prop = get_entity_additional_properties(ent);
 640                 }
 641         }
 642         return (prop & (mtp_property_const|mtp_property_pure)) != 0;
 643 }  /* is_Call_pure */
 644
 645 /**
 646  * Follow the memory chain as long as there are only Loads,
 647  * alias free Stores, and constant Calls and try to replace the
 648  * current Load by a previous ones.
 649  * Note that in unreachable loops it might happen that we reach
 650  * load again, as well as we can fall into a cycle.
 651  * We break such cycles using a special visited flag.
 652  *
 653  * INC_MASTER() must be called before dive into
 654  */
 655 static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
 656         unsigned res = 0;
 657         ldst_info_t *info = get_irn_link(load);
 658         ir_node *pred;
 659         ir_node *ptr       = get_Load_ptr(load);
 660         ir_node *mem       = get_Load_mem(load);
 661         ir_mode *load_mode = get_Load_mode(load);
 662
 663         for (pred = curr; load != pred; ) {
 664                 ldst_info_t *pred_info = get_irn_link(pred);
 665
 666                 /*
 667                  * BEWARE: one might think that checking the modes is useless, because
 668                  * if the pointers are identical, they refer to the same object.
 669                  * This is only true in strong typed languages, not in C were the following
 670                  * is possible a = *(ir_type1 *)p; b = *(ir_type2 *)p ...
 671                  */
 672                 if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
 673                     can_use_stored_value(get_irn_mode(get_Store_value(pred)), load_mode)) {
 674                         /*
 675                          * a Load immediately after a Store -- a read after write.
 676                          * We may remove the Load, if both Load & Store does not have an exception handler
 677                          * OR they are in the same MacroBlock. In the latter case the Load cannot
 678                          * throw an exception when the previous Store was quiet.
 679                          *
 680                          * Why we need to check for Store Exception? If the Store cannot
 681                          * be executed (ROM) the exception handler might simply jump into
 682                          * the load MacroBlock :-(
 683                          * We could make it a little bit better if we would know that the exception
 684                          * handler of the Store jumps directly to the end...
 685                          */
 686                         if ((pred_info->projs[pn_Store_X_except] == NULL && info->projs[pn_Load_X_except] == NULL) ||
 687                             get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
 688                                 ir_node *value = get_Store_value(pred);
 689
 690                                 DBG_OPT_RAW(load, value);
 691
 692                                 /* add an convert if needed */
 693                                 if (get_irn_mode(get_Store_value(pred)) != load_mode) {
 694                                         value = new_r_Conv(current_ir_graph, get_nodes_block(load), value, load_mode);
 695                                 }
 696
 697                                 if (info->projs[pn_Load_M])
 698                                         exchange(info->projs[pn_Load_M], mem);
 699
 700                                 /* no exception */
 701                                 if (info->projs[pn_Load_X_except]) {
 702                                         exchange( info->projs[pn_Load_X_except], new_Bad());
 703                                         res |= CF_CHANGED;
 704                                 }
 705                                 if (info->projs[pn_Load_X_regular]) {
 706                                         exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 707                                         res |= CF_CHANGED;
 708                                 }
 709
 710                                 if (info->projs[pn_Load_res])
 711                                         exchange(info->projs[pn_Load_res], value);
 712
 713                                 kill_node(load);
 714                                 reduce_adr_usage(ptr);
 715                                 return res | DF_CHANGED;
 716                         }
 717                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
 718                            can_use_stored_value(get_Load_mode(pred), load_mode)) {
 719                         /*
 720                          * a Load after a Load -- a read after read.
 721                          * We may remove the second Load, if it does not have an exception handler
 722                          * OR they are in the same MacroBlock. In the later case the Load cannot
 723                          * throw an exception when the previous Load was quiet.
 724                          *
 725                          * Here, there is no need to check if the previous Load has an exception
 726                          * hander because they would have exact the same exception...
 727                          */
 728                         if (info->projs[pn_Load_X_except] == NULL || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
 729                                 ir_node *value;
 730
 731                                 DBG_OPT_RAR(load, pred);
 732
 733                                 /* the result is used */
 734                                 if (info->projs[pn_Load_res]) {
 735                                         if (pred_info->projs[pn_Load_res] == NULL) {
 736                                                 /* create a new Proj again */
 737                                                 pred_info->projs[pn_Load_res] = new_r_Proj(current_ir_graph, get_nodes_block(pred), pred, get_Load_mode(pred), pn_Load_res);
 738                                         }
 739                                         value = pred_info->projs[pn_Load_res];
 740
 741                                         /* add an convert if needed */
 742                                         if (get_Load_mode(pred) != load_mode) {
 743                                                 value = new_r_Conv(current_ir_graph, get_nodes_block(load), value, load_mode);
 744                                         }
 745
 746                                         exchange(info->projs[pn_Load_res], value);
 747                                 }
 748
 749                                 if (info->projs[pn_Load_M])
 750                                         exchange(info->projs[pn_Load_M], mem);
 751
 752                                 /* no exception */
 753                                 if (info->projs[pn_Load_X_except]) {
 754                                         exchange(info->projs[pn_Load_X_except], new_Bad());
 755                                         res |= CF_CHANGED;
 756                                 }
 757                                 if (info->projs[pn_Load_X_regular]) {
 758                                         exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 759                                         res |= CF_CHANGED;
 760                                 }
 761
 762                                 kill_node(load);
 763                                 reduce_adr_usage(ptr);
 764                                 return res |= DF_CHANGED;
 765                         }
 766                 }
 767
 768                 if (is_Store(pred)) {
 769                         /* check if we can pass through this store */
 770                         ir_alias_relation rel = get_alias_relation(
 771                                 current_ir_graph,
 772                                 get_Store_ptr(pred),
 773                                 get_irn_mode(get_Store_value(pred)),
 774                                 ptr, load_mode);
 775                         /* if the might be an alias, we cannot pass this Store */
 776                         if (rel != ir_no_alias)
 777                                 break;
 778                         pred = skip_Proj(get_Store_mem(pred));
 779                 } else if (is_Load(pred)) {
 780                         pred = skip_Proj(get_Load_mem(pred));
 781                 } else if (is_Call(pred)) {
 782                         if (is_Call_pure(pred)) {
 783                                 /* The called graph is at least pure, so there are no Store's
 784                                    in it. We can handle it like a Load and skip it. */
 785                                 pred = skip_Proj(get_Call_mem(pred));
 786                         } else {
 787                                 /* there might be Store's in the graph, stop here */
 788                                 break;
 789                         }
 790                 } else {
 791                         /* follow only Load chains */
 792                         break;
 793                 }
 794
 795                 /* check for cycles */
 796                 if (NODE_VISITED(pred_info))
 797                         break;
 798                 MARK_NODE(pred_info);
 799         }
 800
 801         if (is_Sync(pred)) {
 802                 int i;
 803
 804                 /* handle all Sync predecessors */
 805                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
 806                         res |= follow_Mem_chain(load, skip_Proj(get_Sync_pred(pred, i)));
 807                         if (res)
 808                                 return res;
 809                 }
 810         }
 811
 812         return res;
 813 }  /* follow_Mem_chain */
 814
 815 /**
 816  * optimize a Load
 817  *
 818  * @param load  the Load node
 819  */
 820 static unsigned optimize_load(ir_node *load)
 821 {
 822         ldst_info_t *info = get_irn_link(load);
 823         ir_node *mem, *ptr, *new_node;
 824         ir_entity *ent;
 825         unsigned res = 0;
 826
 827         /* do NOT touch volatile loads for now */
 828         if (get_Load_volatility(load) == volatility_is_volatile)
 829                 return 0;
 830
 831         /* the address of the load to be optimized */
 832         ptr = get_Load_ptr(load);
 833
 834         /*
 835          * Check if we can remove the exception from a Load:
 836          * This can be done, if the address is from an Sel(Alloc) and
 837          * the Sel type is a subtype of the allocated type.
 838          *
 839          * This optimizes some often used OO constructs,
 840          * like x = new O; x->t;
 841          */
 842         if (info->projs[pn_Load_X_except]) {
 843                 if (is_Sel(ptr)) {
 844                         ir_node *mem = get_Sel_mem(ptr);
 845
 846                         /* FIXME: works with the current FE, but better use the base */
 847                         if (is_Alloc(skip_Proj(mem))) {
 848                                 /* ok, check the types */
 849                                 ir_entity *ent    = get_Sel_entity(ptr);
 850                                 ir_type   *s_type = get_entity_type(ent);
 851                                 ir_type   *a_type = get_Alloc_type(mem);
 852
 853                                 if (is_SubClass_of(s_type, a_type)) {
 854                                         /* ok, condition met: there can't be an exception because
 855                                         * Alloc guarantees that enough memory was allocated */
 856
 857                                         exchange(info->projs[pn_Load_X_except], new_Bad());
 858                                         info->projs[pn_Load_X_except] = NULL;
 859                                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 860                                         info->projs[pn_Load_X_regular] = NULL;
 861                                         res |= CF_CHANGED;
 862                                 }
 863                         }
 864                 } else if (is_Alloc(skip_Proj(skip_Cast(ptr)))) {
 865                                 /* simple case: a direct load after an Alloc. Firm Alloc throw
 866                                  * an exception in case of out-of-memory. So, there is no way for an
 867                                  * exception in this load.
 868                                  * This code is constructed by the "exception lowering" in the Jack compiler.
 869                                  */
 870                                 exchange(info->projs[pn_Load_X_except], new_Bad());
 871                                 info->projs[pn_Load_X_except] = NULL;
 872                                 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 873                                 info->projs[pn_Load_X_regular] = NULL;
 874                                 res |= CF_CHANGED;
 875                 }
 876         }
 877
 878         /* The mem of the Load. Must still be returned after optimization. */
 879         mem  = get_Load_mem(load);
 880
 881         if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
 882                 /* a Load which value is neither used nor exception checked, remove it */
 883                 exchange(info->projs[pn_Load_M], mem);
 884
 885                 if (info->projs[pn_Load_X_regular]) {
 886                         /* should not happen, but if it does, remove it */
 887                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 888                         res |= CF_CHANGED;
 889                 }
 890                 kill_node(load);
 891                 reduce_adr_usage(ptr);
 892                 return res | DF_CHANGED;
 893         }
 894
 895         /* Load from a constant polymorphic field, where we can resolve
 896            polymorphism. */
 897         new_node = transform_node_Load(load);
 898         if (new_node != load) {
 899                 if (info->projs[pn_Load_M]) {
 900                         exchange(info->projs[pn_Load_M], mem);
 901                         info->projs[pn_Load_M] = NULL;
 902                 }
 903                 if (info->projs[pn_Load_X_except]) {
 904                         exchange(info->projs[pn_Load_X_except], new_Bad());
 905                         info->projs[pn_Load_X_except] = NULL;
 906                         res |= CF_CHANGED;
 907                 }
 908                 if (info->projs[pn_Load_X_regular]) {
 909                         exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 910                         info->projs[pn_Load_X_regular] = NULL;
 911                         res |= CF_CHANGED;
 912                 }
 913                 if (info->projs[pn_Load_res])
 914                         exchange(info->projs[pn_Load_res], new_node);
 915
 916                 kill_node(load);
 917                 reduce_adr_usage(ptr);
 918                 return res | DF_CHANGED;
 919         }
 920
 921         /* check if we can determine the entity that will be loaded */
 922         ent = find_constant_entity(ptr);
 923         if (ent) {
 924                 if ((allocation_static == get_entity_allocation(ent)) &&
 925                         (visibility_external_allocated != get_entity_visibility(ent))) {
 926                         /* a static allocation that is not external: there should be NO exception
 927                          * when loading. */
 928
 929                         /* no exception, clear the info field as it might be checked later again */
 930                         if (info->projs[pn_Load_X_except]) {
 931                                 exchange(info->projs[pn_Load_X_except], new_Bad());
 932                                 info->projs[pn_Load_X_except] = NULL;
 933                                 res |= CF_CHANGED;
 934                         }
 935                         if (info->projs[pn_Load_X_regular]) {
 936                                 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
 937                                 info->projs[pn_Load_X_regular] = NULL;
 938                                 res |= CF_CHANGED;
 939                         }
 940
 941                         if (variability_constant == get_entity_variability(ent)) {
 942                                 if (is_atomic_entity(ent)) {
 943                                         /* Might not be atomic after
 944                                            lowering of Sels.  In this
 945                                            case we could also load, but
 946                                            it's more complicated. */
 947                                         /* more simpler case: we load the content of a constant value:
 948                                          * replace it by the constant itself
 949                                          */
 950
 951                                         /* no memory */
 952                                         if (info->projs[pn_Load_M]) {
 953                                                 exchange(info->projs[pn_Load_M], mem);
 954                                                 res |= DF_CHANGED;
 955                                         }
 956                                         /* no result :-) */
 957                                         if (info->projs[pn_Load_res]) {
 958                                                 if (is_atomic_entity(ent)) {
 959                                                         ir_node *c = copy_const_value(get_irn_dbg_info(load), get_atomic_ent_value(ent));
 960
 961                                                         DBG_OPT_RC(load, c);
 962                                                         exchange(info->projs[pn_Load_res], c);
 963                                                         res |= DF_CHANGED;
 964                                                 }
 965                                         }
 966                                         kill_node(load);
 967                                         reduce_adr_usage(ptr);
 968                                         return res;
 969                                 } else {
 970                                         ir_node *c = NULL;
 971                                         if (ent->has_initializer) {
 972                                                 /* new style initializer */
 973                                                 c = find_compound_ent_value(ptr);
 974                                         } else {
 975                                                 /* old style initializer */
 976                                                 compound_graph_path *path = get_accessed_path(ptr);
 977
 978                                                 if (path) {
 979                                                         assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
 980
 981                                                         c = get_compound_ent_value_by_path(ent, path);
 982                                                         free_compound_graph_path(path);
 983                                                 }
 984                                         }
 985                                         if (c != NULL) {
 986                                                 if (info->projs[pn_Load_M]) {
 987                                                         exchange(info->projs[pn_Load_M], mem);
 988                                                         res |= DF_CHANGED;
 989                                                 }
 990                                                 if (info->projs[pn_Load_res]) {
 991                                                         exchange(info->projs[pn_Load_res], copy_const_value(get_irn_dbg_info(load), c));
 992                                                         res |= DF_CHANGED;
 993                                                 }
 994                                                 kill_node(load);
 995                                                 reduce_adr_usage(ptr);
 996                                                 return res;
 997                                         } else {
 998                                                 /*  We can not determine a correct access path.  E.g., in jack, we load
 999                                                 a byte from an object to generate an exception.   Happens in test program
1000                                                 Reflectiontest.
1001                                                 printf(">>>>>>>>>>>>> Found access to constant entity %s in function %s\n", get_entity_name(ent),
1002                                                 get_entity_name(get_irg_entity(current_ir_graph)));
1003                                                 ir_printf("  load: %+F\n", load);
1004                                                 ir_printf("  ptr:  %+F\n", ptr);
1005                                                 */
1006                                         }
1007                                 }
1008                         }
1009                 }
1010         }
1011
1012         /* Check, if the address of this load is used more than once.
1013          * If not, this load cannot be removed in any case. */
1014         if (get_irn_n_uses(ptr) <= 1)
1015                 return res;
1016
1017         /*
1018          * follow the memory chain as long as there are only Loads
1019          * and try to replace current Load or Store by a previous one.
1020          * Note that in unreachable loops it might happen that we reach
1021          * load again, as well as we can fall into a cycle.
1022          * We break such cycles using a special visited flag.
1023          */
1024         INC_MASTER();
1025         res = follow_Mem_chain(load, skip_Proj(mem));
1026         return res;
1027 }  /* optimize_load */
1028
1029 /**
1030  * Check whether a value of mode new_mode would completely overwrite a value
1031  * of mode old_mode in memory.
1032  */
1033 static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
1034 {
1035         return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
1036 }  /* is_completely_overwritten */
1037
1038 /**
1039  * follow the memory chain as long as there are only Loads and alias free Stores.
1040  *
1041  * INC_MASTER() must be called before dive into
1042  */
1043 static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
1044         unsigned res = 0;
1045         ldst_info_t *info = get_irn_link(store);
1046         ir_node *pred;
1047         ir_node *ptr = get_Store_ptr(store);
1048         ir_node *mem = get_Store_mem(store);
1049         ir_node *value = get_Store_value(store);
1050         ir_mode *mode  = get_irn_mode(value);
1051         ir_node *block = get_nodes_block(store);
1052         ir_node *mblk  = get_Block_MacroBlock(block);
1053
1054         for (pred = curr; pred != store;) {
1055                 ldst_info_t *pred_info = get_irn_link(pred);
1056
1057                 /*
1058                  * BEWARE: one might think that checking the modes is useless, because
1059                  * if the pointers are identical, they refer to the same object.
1060                  * This is only true in strong typed languages, not is C were the following
1061                  * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
1062                  * However, if the mode that is written have a bigger  or equal size the the old
1063                  * one, the old value is completely overwritten and can be killed ...
1064                  */
1065                 if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
1066                     get_nodes_MacroBlock(pred) == mblk &&
1067                     is_completely_overwritten(get_irn_mode(get_Store_value(pred)), mode)) {
1068                         /*
1069                          * a Store after a Store in the same MacroBlock -- a write after write.
1070                          * We may remove the first Store, if it does not have an exception handler.
1071                          *
1072                          * TODO: What, if both have the same exception handler ???
1073                          */
1074                         if (get_Store_volatility(pred) != volatility_is_volatile && !pred_info->projs[pn_Store_X_except]) {
1075                                 DBG_OPT_WAW(pred, store);
1076                                 exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred));
1077                                 kill_node(pred);
1078                                 reduce_adr_usage(ptr);
1079                                 return DF_CHANGED;
1080                         }
1081                 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
1082                            value == pred_info->projs[pn_Load_res]) {
1083                         /*
1084                          * a Store of a value just loaded from the same address
1085                          * -- a write after read.
1086                          * We may remove the Store, if it does not have an exception
1087                          * handler.
1088                          */
1089                         if (! info->projs[pn_Store_X_except]) {
1090                                 DBG_OPT_WAR(store, pred);
1091                                 exchange(info->projs[pn_Store_M], mem);
1092                                 kill_node(store);
1093                                 reduce_adr_usage(ptr);
1094                                 return DF_CHANGED;
1095                         }
1096                 }
1097
1098                 if (is_Store(pred)) {
1099                         /* check if we can pass thru this store */
1100                         ir_alias_relation rel = get_alias_relation(
1101                                 current_ir_graph,
1102                                 get_Store_ptr(pred),
1103                                 get_irn_mode(get_Store_value(pred)),
1104                                 ptr, mode);
1105                         /* if the might be an alias, we cannot pass this Store */
1106                         if (rel != ir_no_alias)
1107                                 break;
1108                         pred = skip_Proj(get_Store_mem(pred));
1109                 } else if (is_Load(pred)) {
1110                         ir_alias_relation rel = get_alias_relation(
1111                                 current_ir_graph, get_Load_ptr(pred), get_Load_mode(pred),
1112                                 ptr, mode);
1113                         if (rel != ir_no_alias)
1114                                 break;
1115
1116                         pred = skip_Proj(get_Load_mem(pred));
1117                 } else {
1118                         /* follow only Load chains */
1119                         break;
1120                 }
1121
1122                 /* check for cycles */
1123                 if (NODE_VISITED(pred_info))
1124                         break;
1125                 MARK_NODE(pred_info);
1126         }
1127
1128         if (is_Sync(pred)) {
1129                 int i;
1130
1131                 /* handle all Sync predecessors */
1132                 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1133                         res |= follow_Mem_chain_for_Store(store, skip_Proj(get_Sync_pred(pred, i)));
1134                         if (res)
1135                                 break;
1136                 }
1137         }
1138         return res;
1139 }  /* follow_Mem_chain_for_Store */
1140
1141 /**
1142  * optimize a Store
1143  *
1144  * @param store  the Store node
1145  */
1146 static unsigned optimize_store(ir_node *store) {
1147         ir_node *ptr, *mem;
1148
1149         if (get_Store_volatility(store) == volatility_is_volatile)
1150                 return 0;
1151
1152         ptr = get_Store_ptr(store);
1153
1154         /* Check, if the address of this Store is used more than once.
1155          * If not, this Store cannot be removed in any case. */
1156         if (get_irn_n_uses(ptr) <= 1)
1157                 return 0;
1158
1159         mem = get_Store_mem(store);
1160
1161         /* follow the memory chain as long as there are only Loads */
1162         INC_MASTER();
1163
1164         return follow_Mem_chain_for_Store(store, skip_Proj(mem));
1165 }  /* optimize_store */
1166
1167 /**
1168  * walker, optimizes Phi after Stores to identical places:
1169  * Does the following optimization:
1170  * @verbatim
1171  *
1172  *   val1   val2   val3          val1  val2  val3
1173  *    |      |      |               \    |    /
1174  *  Store  Store  Store              \   |   /
1175  *      \    |    /                   PhiData
1176  *       \   |   /                       |
1177  *        \  |  /                      Store
1178  *          PhiM
1179  *
1180  * @endverbatim
1181  * This reduces the number of stores and allows for predicated execution.
1182  * Moves Stores back to the end of a function which may be bad.
1183  *
1184  * This is only possible if the predecessor blocks have only one successor.
1185  */
1186 static unsigned optimize_phi(ir_node *phi, walk_env_t *wenv)
1187 {
1188         int i, n;
1189         ir_node *store, *old_store, *ptr, *block, *phi_block, *phiM, *phiD, *exc, *projM;
1190         ir_mode *mode;
1191         ir_node **inM, **inD, **projMs;
1192         int *idx;
1193         dbg_info *db = NULL;
1194         ldst_info_t *info;
1195         block_info_t *bl_info;
1196         unsigned res = 0;
1197
1198         /* Must be a memory Phi */
1199         if (get_irn_mode(phi) != mode_M)
1200                 return 0;
1201
1202         n = get_Phi_n_preds(phi);
1203         if (n <= 0)
1204                 return 0;
1205
1206         /* must be only one user */
1207         projM = get_Phi_pred(phi, 0);
1208         if (get_irn_n_edges(projM) != 1)
1209                 return 0;
1210
1211         store = skip_Proj(projM);
1212         old_store = store;
1213         if (!is_Store(store))
1214                 return 0;
1215
1216         block = get_nodes_block(store);
1217
1218         /* abort on dead blocks */
1219         if (is_Block_dead(block))
1220                 return 0;
1221
1222         /* check if the block is post dominated by Phi-block
1223            and has no exception exit */
1224         bl_info = get_irn_link(block);
1225         if (bl_info->flags & BLOCK_HAS_EXC)
1226                 return 0;
1227
1228         phi_block = get_nodes_block(phi);
1229         if (! block_strictly_postdominates(phi_block, block))
1230                 return 0;
1231
1232         /* this is the address of the store */
1233         ptr  = get_Store_ptr(store);
1234         mode = get_irn_mode(get_Store_value(store));
1235         info = get_irn_link(store);
1236         exc  = info->exc_block;
1237
1238         for (i = 1; i < n; ++i) {
1239                 ir_node *pred = get_Phi_pred(phi, i);
1240
1241                 if (get_irn_n_edges(pred) != 1)
1242                         return 0;
1243
1244                 pred = skip_Proj(pred);
1245                 if (!is_Store(pred))
1246                         return 0;
1247
1248                 if (ptr != get_Store_ptr(pred) || mode != get_irn_mode(get_Store_value(pred)))
1249                         return 0;
1250
1251                 info = get_irn_link(pred);
1252
1253                 /* check, if all stores have the same exception flow */
1254                 if (exc != info->exc_block)
1255                         return 0;
1256
1257                 /* abort on dead blocks */
1258                 block = get_nodes_block(pred);
1259                 if (is_Block_dead(block))
1260                         return 0;
1261
1262                 /* check if the block is post dominated by Phi-block
1263                    and has no exception exit. Note that block must be different from
1264                    Phi-block, else we would move a Store from end End of a block to its
1265                    Start... */
1266                 bl_info = get_irn_link(block);
1267                 if (bl_info->flags & BLOCK_HAS_EXC)
1268                         return 0;
1269                 if (block == phi_block || ! block_postdominates(phi_block, block))
1270                         return 0;
1271         }
1272
1273         /*
1274          * ok, when we are here, we found all predecessors of a Phi that
1275          * are Stores to the same address and size. That means whatever
1276          * we do before we enter the block of the Phi, we do a Store.
1277          * So, we can move the Store to the current block:
1278          *
1279          *   val1    val2    val3          val1  val2  val3
1280          *    |       |       |               \    |    /
1281          * | Str | | Str | | Str |             \   |   /
1282          *      \     |     /                   PhiData
1283          *       \    |    /                       |
1284          *        \   |   /                       Str
1285          *           PhiM
1286          *
1287          * Is only allowed if the predecessor blocks have only one successor.
1288          */
1289
1290         NEW_ARR_A(ir_node *, projMs, n);
1291         NEW_ARR_A(ir_node *, inM, n);
1292         NEW_ARR_A(ir_node *, inD, n);
1293         NEW_ARR_A(int, idx, n);
1294
1295         /* Prepare: Collect all Store nodes.  We must do this
1296            first because we otherwise may loose a store when exchanging its
1297            memory Proj.
1298          */
1299         for (i = n - 1; i >= 0; --i) {
1300                 ir_node *store;
1301
1302                 projMs[i] = get_Phi_pred(phi, i);
1303                 assert(is_Proj(projMs[i]));
1304
1305                 store = get_Proj_pred(projMs[i]);
1306                 info  = get_irn_link(store);
1307
1308                 inM[i] = get_Store_mem(store);
1309                 inD[i] = get_Store_value(store);
1310                 idx[i] = info->exc_idx;
1311         }
1312         block = get_nodes_block(phi);
1313
1314         /* second step: create a new memory Phi */
1315         phiM = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inM, mode_M);
1316
1317         /* third step: create a new data Phi */
1318         phiD = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inD, mode);
1319
1320         /* rewire memory and kill the node */
1321         for (i = n - 1; i >= 0; --i) {
1322                 ir_node *proj  = projMs[i];
1323
1324                 if(is_Proj(proj)) {
1325                         ir_node *store = get_Proj_pred(proj);
1326                         exchange(proj, inM[i]);
1327                         kill_node(store);
1328                 }
1329         }
1330
1331         /* fourth step: create the Store */
1332         store = new_rd_Store(db, current_ir_graph, block, phiM, ptr, phiD);
1333 #ifdef DO_CACHEOPT
1334         co_set_irn_name(store, co_get_irn_ident(old_store));
1335 #endif
1336
1337         projM = new_rd_Proj(NULL, current_ir_graph, block, store, mode_M, pn_Store_M);
1338
1339         info = get_ldst_info(store, &wenv->obst);
1340         info->projs[pn_Store_M] = projM;
1341
1342         /* fifths step: repair exception flow */
1343         if (exc) {
1344                 ir_node *projX = new_rd_Proj(NULL, current_ir_graph, block, store, mode_X, pn_Store_X_except);
1345
1346                 info->projs[pn_Store_X_except] = projX;
1347                 info->exc_block                = exc;
1348                 info->exc_idx                  = idx[0];
1349
1350                 for (i = 0; i < n; ++i) {
1351                         set_Block_cfgpred(exc, idx[i], projX);
1352                 }
1353
1354                 if (n > 1) {
1355                         /* the exception block should be optimized as some inputs are identical now */
1356                 }
1357
1358                 res |= CF_CHANGED;
1359         }
1360
1361         /* sixth step: replace old Phi */
1362         exchange(phi, projM);
1363
1364         return res | DF_CHANGED;
1365 }  /* optimize_phi */
1366
1367 /**
1368  * walker, do the optimizations
1369  */
1370 static void do_load_store_optimize(ir_node *n, void *env) {
1371         walk_env_t *wenv = env;
1372
1373         switch (get_irn_opcode(n)) {
1374
1375         case iro_Load:
1376                 wenv->changes |= optimize_load(n);
1377                 break;
1378
1379         case iro_Store:
1380                 wenv->changes |= optimize_store(n);
1381                 break;
1382
1383         case iro_Phi:
1384                 wenv->changes |= optimize_phi(n, wenv);
1385                 break;
1386
1387         default:
1388                 ;
1389         }
1390 }  /* do_load_store_optimize */
1391
1392 /** A scc. */
1393 typedef struct scc {
1394         ir_node *head;          /**< the head of the list */
1395 } scc;
1396
1397 /** A node entry. */
1398 typedef struct node_entry {
1399         unsigned DFSnum;    /**< the DFS number of this node */
1400         unsigned low;       /**< the low number of this node */
1401         ir_node  *header;   /**< the header of this node */
1402         int      in_stack;  /**< flag, set if the node is on the stack */
1403         ir_node  *next;     /**< link to the next node the the same scc */
1404         scc      *pscc;     /**< the scc of this node */
1405         unsigned POnum;     /**< the post order number for blocks */
1406 } node_entry;
1407
1408 /** A loop entry. */
1409 typedef struct loop_env {
1410         ir_phase ph;           /**< the phase object */
1411         ir_node  **stack;      /**< the node stack */
1412         int      tos;          /**< tos index */
1413         unsigned nextDFSnum;   /**< the current DFS number */
1414         unsigned POnum;        /**< current post order number */
1415
1416         unsigned changes;      /**< a bitmask of graph changes */
1417 } loop_env;
1418
1419 /**
1420 * Gets the node_entry of a node
1421 */
1422 static node_entry *get_irn_ne(ir_node *irn, loop_env *env) {
1423         ir_phase   *ph = &env->ph;
1424         node_entry *e  = phase_get_irn_data(&env->ph, irn);
1425
1426         if (! e) {
1427                 e = phase_alloc(ph, sizeof(*e));
1428                 memset(e, 0, sizeof(*e));
1429                 phase_set_irn_data(ph, irn, e);
1430         }
1431         return e;
1432 }  /* get_irn_ne */
1433
1434 /**
1435  * Push a node onto the stack.
1436  *
1437  * @param env   the loop environment
1438  * @param n     the node to push
1439  */
1440 static void push(loop_env *env, ir_node *n) {
1441         node_entry *e;
1442
1443         if (env->tos == ARR_LEN(env->stack)) {
1444                 int nlen = ARR_LEN(env->stack) * 2;
1445                 ARR_RESIZE(ir_node *, env->stack, nlen);
1446         }
1447         env->stack[env->tos++] = n;
1448         e = get_irn_ne(n, env);
1449         e->in_stack = 1;
1450 }  /* push */
1451
1452 /**
1453  * pop a node from the stack
1454  *
1455  * @param env   the loop environment
1456  *
1457  * @return  The topmost node
1458  */
1459 static ir_node *pop(loop_env *env) {
1460         ir_node *n = env->stack[--env->tos];
1461         node_entry *e = get_irn_ne(n, env);
1462
1463         e->in_stack = 0;
1464         return n;
1465 }  /* pop */
1466
1467 /**
1468  * Check if irn is a region constant.
1469  * The block or irn must strictly dominate the header block.
1470  *
1471  * @param irn           the node to check
1472  * @param header_block  the header block of the induction variable
1473  */
1474 static int is_rc(ir_node *irn, ir_node *header_block) {
1475         ir_node *block = get_nodes_block(irn);
1476
1477         return (block != header_block) && block_dominates(block, header_block);
1478 }  /* is_rc */
1479
1480 typedef struct phi_entry phi_entry;
1481 struct phi_entry {
1482         ir_node   *phi;    /**< A phi with a region const memory. */
1483         int       pos;     /**< The position of the region const memory */
1484         ir_node   *load;   /**< the newly created load for this phi */
1485         phi_entry *next;
1486 };
1487
1488 /**
1489  * Move loops out of loops if possible.
1490  *
1491  * @param pscc   the loop described by an SCC
1492  * @param env    the loop environment
1493  */
1494 static void move_loads_out_of_loops(scc *pscc, loop_env *env) {
1495         ir_node   *phi, *load, *next, *other, *next_other;
1496         ir_entity *ent;
1497         int       j;
1498         phi_entry *phi_list = NULL;
1499
1500         /* collect all outer memories */
1501         for (phi = pscc->head; phi != NULL; phi = next) {
1502                 node_entry *ne = get_irn_ne(phi, env);
1503                 next = ne->next;
1504
1505                 /* check all memory Phi's */
1506                 if (! is_Phi(phi))
1507                         continue;
1508
1509                 assert(get_irn_mode(phi) == mode_M && "DFS geturn non-memory Phi");
1510
1511                 for (j = get_irn_arity(phi) - 1; j >= 0; --j) {
1512                         ir_node    *pred = get_irn_n(phi, j);
1513                         node_entry *pe   = get_irn_ne(pred, env);
1514
1515                         if (pe->pscc != ne->pscc) {
1516                                 /* not in the same SCC, is region const */
1517                                 phi_entry *pe = phase_alloc(&env->ph, sizeof(*pe));
1518
1519                                 pe->phi  = phi;
1520                                 pe->pos  = j;
1521                                 pe->next = phi_list;
1522                                 phi_list = pe;
1523                         }
1524                 }
1525         }
1526         /* no Phis no fun */
1527         assert(phi_list != NULL && "DFS found a loop without Phi");
1528
1529         for (load = pscc->head; load; load = next) {
1530                 ir_mode *load_mode;
1531                 node_entry *ne = get_irn_ne(load, env);
1532                 next = ne->next;
1533
1534                 if (is_Load(load)) {
1535                         ldst_info_t *info = get_irn_link(load);
1536                         ir_node     *ptr = get_Load_ptr(load);
1537
1538                         /* for now, we cannot handle Loads with exceptions */
1539                         if (info->projs[pn_Load_res] == NULL || info->projs[pn_Load_X_regular] != NULL || info->projs[pn_Load_X_except] != NULL)
1540                                 continue;
1541
1542                         /* for now, we can only handle Load(Global) */
1543                         if (! is_Global(ptr))
1544                                 continue;
1545                         ent = get_Global_entity(ptr);
1546                         load_mode = get_Load_mode(load);
1547                         for (other = pscc->head; other != NULL; other = next_other) {
1548                                 node_entry *ne = get_irn_ne(other, env);
1549                                 next_other = ne->next;
1550
1551                                 if (is_Store(other)) {
1552                                         ir_alias_relation rel = get_alias_relation(
1553                                                 current_ir_graph,
1554                                                 get_Store_ptr(other),
1555                                                 get_irn_mode(get_Store_value(other)),
1556                                                 ptr, load_mode);
1557                                         /* if the might be an alias, we cannot pass this Store */
1558                                         if (rel != ir_no_alias)
1559                                                 break;
1560                                 }
1561                                 /* only pure Calls are allowed here, so ignore them */
1562                         }
1563                         if (other == NULL) {
1564                                 ldst_info_t *ninfo;
1565                                 phi_entry   *pe;
1566                                 dbg_info    *db;
1567
1568                                 /* for now, we cannot handle more than one input */
1569                                 if (phi_list->next != NULL)
1570                                         return;
1571
1572                                 /* yep, no aliasing Store found, Load can be moved */
1573                                 DB((dbg, LEVEL_1, "  Found a Load that could be moved: %+F\n", load));
1574
1575                                 db   = get_irn_dbg_info(load);
1576                                 for (pe = phi_list; pe != NULL; pe = pe->next) {
1577                                         int     pos   = pe->pos;
1578                                         ir_node *phi  = pe->phi;
1579                                         ir_node *blk  = get_nodes_block(phi);
1580                                         ir_node *pred = get_Block_cfgpred_block(blk, pos);
1581                                         ir_node *irn, *mem;
1582
1583                                         pe->load = irn = new_rd_Load(db, current_ir_graph, pred, get_Phi_pred(phi, pos), ptr, load_mode);
1584                                         ninfo = get_ldst_info(irn, phase_obst(&env->ph));
1585
1586                                         ninfo->projs[pn_Load_M] = mem = new_r_Proj(current_ir_graph, pred, irn, mode_M, pn_Load_M);
1587                                         set_Phi_pred(phi, pos, mem);
1588
1589                                         ninfo->projs[pn_Load_res] = new_r_Proj(current_ir_graph, pred, irn, load_mode, pn_Load_res);
1590
1591                                         DB((dbg, LEVEL_1, "  Created %+F in %+F\n", irn, pred));
1592                                 }
1593
1594                                 /* now kill the old Load */
1595                                 exchange(info->projs[pn_Load_M], get_Load_mem(load));
1596                                 exchange(info->projs[pn_Load_res], ninfo->projs[pn_Load_res]);
1597
1598                                 env->changes |= DF_CHANGED;
1599                         }
1600                 }
1601         }
1602 }  /* move_loads_out_of_loops */
1603
1604 /**
1605  * Process a loop SCC.
1606  *
1607  * @param pscc  the SCC
1608  * @param env   the loop environment
1609  */
1610 static void process_loop(scc *pscc, loop_env *env) {
1611         ir_node *irn, *next, *header = NULL;
1612         node_entry *b, *h = NULL;
1613         int j, only_phi, num_outside, process = 0;
1614         ir_node *out_rc;
1615
1616         /* find the header block for this scc */
1617         for (irn = pscc->head; irn; irn = next) {
1618                 node_entry *e = get_irn_ne(irn, env);
1619                 ir_node *block = get_nodes_block(irn);
1620
1621                 next = e->next;
1622                 b = get_irn_ne(block, env);
1623
1624                 if (header) {
1625                         if (h->POnum < b->POnum) {
1626                                 header = block;
1627                                 h      = b;
1628                         }
1629                 }
1630                 else {
1631                         header = block;
1632                         h      = b;
1633                 }
1634         }
1635
1636         /* check if this scc contains only Phi, Loads or Stores nodes */
1637         only_phi    = 1;
1638         num_outside = 0;
1639         out_rc      = NULL;
1640         for (irn = pscc->head; irn; irn = next) {
1641                 node_entry *e = get_irn_ne(irn, env);
1642
1643                 next = e->next;
1644                 switch (get_irn_opcode(irn)) {
1645                 case iro_Call:
1646                         if (is_Call_pure(irn)) {
1647                                 /* pure calls can be treated like loads */
1648                                 only_phi = 0;
1649                                 break;
1650                         }
1651                         /* non-pure calls must be handle like may-alias Stores */
1652                         goto fail;
1653                 case iro_CopyB:
1654                         /* cannot handle CopyB yet */
1655                         goto fail;
1656                 case iro_Load:
1657                         process = 1;
1658                         if (get_Load_volatility(irn) == volatility_is_volatile) {
1659                                 /* cannot handle loops with volatile Loads */
1660                                 goto fail;
1661                         }
1662                         only_phi = 0;
1663                         break;
1664                 case iro_Store:
1665                         if (get_Store_volatility(irn) == volatility_is_volatile) {
1666                                 /* cannot handle loops with volatile Stores */
1667                                 goto fail;
1668                         }
1669                         only_phi = 0;
1670                         break;
1671                 default:
1672                         only_phi = 0;
1673                         break;
1674                 case iro_Phi:
1675                         for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
1676                                 ir_node *pred  = get_irn_n(irn, j);
1677                                 node_entry *pe = get_irn_ne(pred, env);
1678
1679                                 if (pe->pscc != e->pscc) {
1680                                         /* not in the same SCC, must be a region const */
1681                                         if (! is_rc(pred, header)) {
1682                                                 /* not a memory loop */
1683                                                 goto fail;
1684                                         }
1685                                         if (! out_rc) {
1686                                                 out_rc = pred;
1687                                                 ++num_outside;
1688                                         } else if (out_rc != pred) {
1689                                                 ++num_outside;
1690                                         }
1691                                 }
1692                         }
1693                         break;
1694                 }
1695         }
1696         if (! process)
1697                 goto fail;
1698
1699         /* found a memory loop */
1700         DB((dbg, LEVEL_2, "  Found a memory loop:\n  "));
1701         if (only_phi && num_outside == 1) {
1702                 /* a phi cycle with only one real predecessor can be collapsed */
1703                 DB((dbg, LEVEL_2, "  Found an USELESS Phi cycle:\n  "));
1704
1705                 for (irn = pscc->head; irn; irn = next) {
1706                         node_entry *e = get_irn_ne(irn, env);
1707                         next = e->next;
1708                         e->header = NULL;
1709                         exchange(irn, out_rc);
1710                 }
1711                 env->changes |= DF_CHANGED;
1712                 return;
1713         }
1714
1715         /* set the header for every node in this scc */
1716         for (irn = pscc->head; irn; irn = next) {
1717                 node_entry *e = get_irn_ne(irn, env);
1718                 e->header = header;
1719                 next = e->next;
1720                 DB((dbg, LEVEL_2, " %+F,", irn));
1721         }
1722         DB((dbg, LEVEL_2, "\n"));
1723
1724         move_loads_out_of_loops(pscc, env);
1725
1726 fail:
1727         ;
1728 }  /* process_loop */
1729
1730 /**
1731  * Process a SCC.
1732  *
1733  * @param pscc  the SCC
1734  * @param env   the loop environment
1735  */
1736 static void process_scc(scc *pscc, loop_env *env) {
1737         ir_node *head = pscc->head;
1738         node_entry *e = get_irn_ne(head, env);
1739
1740 #ifdef DEBUG_libfirm
1741         {
1742                 ir_node *irn, *next;
1743
1744                 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
1745                 for (irn = pscc->head; irn; irn = next) {
1746                         node_entry *e = get_irn_ne(irn, env);
1747
1748                         next = e->next;
1749
1750                         DB((dbg, LEVEL_4, " %+F,", irn));
1751                 }
1752                 DB((dbg, LEVEL_4, "\n"));
1753         }
1754 #endif
1755
1756         if (e->next != NULL) {
1757                 /* this SCC has more than one member */
1758                 process_loop(pscc, env);
1759         }
1760 }  /* process_scc */
1761
1762 /**
1763  * Do Tarjan's SCC algorithm and drive load/store optimization.
1764  *
1765  * @param irn  start at this node
1766  * @param env  the loop environment
1767  */
1768 static void dfs(ir_node *irn, loop_env *env)
1769 {
1770         int i, n;
1771         node_entry *node = get_irn_ne(irn, env);
1772
1773         mark_irn_visited(irn);
1774
1775         node->DFSnum = env->nextDFSnum++;
1776         node->low    = node->DFSnum;
1777         push(env, irn);
1778
1779         /* handle preds */
1780         if (is_Phi(irn) || is_Sync(irn)) {
1781                 n = get_irn_arity(irn);
1782                 for (i = 0; i < n; ++i) {
1783                         ir_node *pred = get_irn_n(irn, i);
1784                         node_entry *o = get_irn_ne(pred, env);
1785
1786                         if (irn_not_visited(pred)) {
1787                                 dfs(pred, env);
1788                                 node->low = MIN(node->low, o->low);
1789                         }
1790                         if (o->DFSnum < node->DFSnum && o->in_stack)
1791                                 node->low = MIN(o->DFSnum, node->low);
1792                 }
1793         } else if (is_fragile_op(irn)) {
1794                 ir_node *pred = get_fragile_op_mem(irn);
1795                 node_entry *o = get_irn_ne(pred, env);
1796
1797                 if (irn_not_visited(pred)) {
1798                         dfs(pred, env);
1799                         node->low = MIN(node->low, o->low);
1800                 }
1801                 if (o->DFSnum < node->DFSnum && o->in_stack)
1802                         node->low = MIN(o->DFSnum, node->low);
1803         } else if (is_Proj(irn)) {
1804                 ir_node *pred = get_Proj_pred(irn);
1805                 node_entry *o = get_irn_ne(pred, env);
1806
1807                 if (irn_not_visited(pred)) {
1808                         dfs(pred, env);
1809                         node->low = MIN(node->low, o->low);
1810                 }
1811                 if (o->DFSnum < node->DFSnum && o->in_stack)
1812                         node->low = MIN(o->DFSnum, node->low);
1813         }
1814         else {
1815                  /* IGNORE predecessors */
1816         }
1817
1818         if (node->low == node->DFSnum) {
1819                 scc *pscc = phase_alloc(&env->ph, sizeof(*pscc));
1820                 ir_node *x;
1821
1822                 pscc->head = NULL;
1823                 do {
1824                         node_entry *e;
1825
1826                         x = pop(env);
1827                         e = get_irn_ne(x, env);
1828                         e->pscc    = pscc;
1829                         e->next    = pscc->head;
1830                         pscc->head = x;
1831                 } while (x != irn);
1832
1833                 process_scc(pscc, env);
1834         }
1835 }  /* dfs */
1836
1837 /**
1838  * Do the DFS on the memory edges a graph.
1839  *
1840  * @param irg  the graph to process
1841  * @param env  the loop environment
1842  */
1843 static void do_dfs(ir_graph *irg, loop_env *env) {
1844         ir_graph *rem = current_ir_graph;
1845         ir_node  *endblk, *end;
1846         int      i;
1847
1848         current_ir_graph = irg;
1849         inc_irg_visited(irg);
1850
1851         /* visit all memory nodes */
1852         endblk = get_irg_end_block(irg);
1853         for (i = get_Block_n_cfgpreds(endblk) - 1; i >= 0; --i) {
1854                 ir_node *pred = get_Block_cfgpred(endblk, i);
1855
1856                 pred = skip_Proj(pred);
1857                 if (is_Return(pred))
1858                         dfs(get_Return_mem(pred), env);
1859                 else if (is_Raise(pred))
1860                         dfs(get_Raise_mem(pred), env);
1861                 else if (is_fragile_op(pred))
1862                         dfs(get_fragile_op_mem(pred), env);
1863                 else {
1864                         assert(0 && "Unknown EndBlock predecessor");
1865                 }
1866         }
1867
1868         /* visit the keep-alives */
1869         end = get_irg_end(irg);
1870         for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
1871                 ir_node *ka = get_End_keepalive(end, i);
1872
1873                 if (is_Phi(ka) && irn_not_visited(ka))
1874                         dfs(ka, env);
1875         }
1876         current_ir_graph = rem;
1877 }  /* do_dfs */
1878
1879 /**
1880  * Initialize new phase data. We do this always explicit, so return NULL here
1881  */
1882 static void *init_loop_data(ir_phase *ph, const ir_node *irn, void *data) {
1883         (void)ph;
1884         (void)irn;
1885         (void)data;
1886         return NULL;
1887 }  /* init_loop_data */
1888
1889 /**
1890  * Optimize Loads/Stores in loops.
1891  *
1892  * @param irg  the graph
1893  */
1894 static int optimize_loops(ir_graph *irg) {
1895         loop_env env;
1896
1897         env.stack         = NEW_ARR_F(ir_node *, 128);
1898         env.tos           = 0;
1899         env.nextDFSnum    = 0;
1900         env.POnum         = 0;
1901         env.changes       = 0;
1902         phase_init(&env.ph, "ldstopt", irg, PHASE_DEFAULT_GROWTH, init_loop_data, NULL);
1903
1904         /* calculate the SCC's and drive loop optimization. */
1905         do_dfs(irg, &env);
1906
1907         DEL_ARR_F(env.stack);
1908         phase_free(&env.ph);
1909
1910         return env.changes;
1911 }  /* optimize_loops */
1912
1913 /*
1914  * do the load store optimization
1915  */
1916 void optimize_load_store(ir_graph *irg) {
1917         walk_env_t env;
1918
1919         FIRM_DBG_REGISTER(dbg, "firm.opt.ldstopt");
1920
1921         assert(get_irg_phase_state(irg) != phase_building);
1922         assert(get_irg_pinned(irg) != op_pin_state_floats &&
1923                 "LoadStore optimization needs pinned graph");
1924
1925         /* we need landing pads */
1926         remove_critical_cf_edges(irg);
1927
1928         edges_assure(irg);
1929
1930         /* for Phi optimization post-dominators are needed ... */
1931         assure_postdoms(irg);
1932
1933         if (get_opt_alias_analysis()) {
1934                 assure_irg_address_taken_computed(irg);
1935                 assure_irp_globals_address_taken_computed();
1936         }
1937
1938         obstack_init(&env.obst);
1939         env.changes = 0;
1940
1941         /* init the links, then collect Loads/Stores/Proj's in lists */
1942         master_visited = 0;
1943         irg_walk_graph(irg, firm_clear_link, collect_nodes, &env);
1944
1945         /* now we have collected enough information, optimize */
1946         irg_walk_graph(irg, NULL, do_load_store_optimize, &env);
1947
1948         env.changes |= optimize_loops(irg);
1949
1950         obstack_free(&env.obst, NULL);
1951
1952         /* Handle graph state */
1953         if (env.changes) {
1954                 set_irg_outs_inconsistent(irg);
1955         }
1956
1957         if (env.changes & CF_CHANGED) {
1958                 /* is this really needed: Yes, control flow changed, block might
1959                 have Bad() predecessors. */
1960                 set_irg_doms_inconsistent(irg);
1961         }
1962 }  /* optimize_load_store */